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(Currency Symbol): Add INT_ constants and CODESET:
This commit is contained in:
Ulrich Drepper
parent
8a2f1f5b5f
commit
b642f10105
@ -2058,11 +2058,17 @@ one by one.
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@subsection Parsing of Integers
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@pindex stdlib.h
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These functions are declared in @file{stdlib.h}.
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@pindex wchar.h
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The @samp{str} functions are declared in @file{stdlib.h} and those
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beginning with @samp{wcs} are declared in @file{wchar.h}. One might
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wonder about the use of @code{restrict} in the prototypes of the
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functions in this section. It is seemingly useless but the @w{ISO C}
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standard uses it (for the functions defined there) so we have to do it
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as well.
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@comment stdlib.h
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@comment ISO
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@deftypefun {long int} strtol (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {long int} strtol (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtol} (``string-to-long'') function converts the initial
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part of @var{string} to a signed integer, which is returned as a value
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of type @code{long int}.
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@ -2123,9 +2129,18 @@ case there was overflow.
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There is an example at the end of this section.
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@end deftypefun
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@comment wchar.h
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@comment ISO
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@deftypefun {long int} wcstol (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstol} function is equivalent in nearly all aspect to the
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@code{strtol} function but it handles wide character string.
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The @code{wcstol} function was introduced in @w{Amendment 1} of @w{ISO C90}.
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@end deftypefun
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@comment stdlib.h
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@comment ISO
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@deftypefun {unsigned long int} strtoul (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {unsigned long int} strtoul (const char *retrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtoul} (``string-to-unsigned-long'') function is like
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@code{strtol} except it converts to an @code{unsigned long int} value.
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The syntax is the same as described above for @code{strtol}. The value
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@ -2141,9 +2156,18 @@ and an input more negative than @code{LONG_MIN} returns
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range, or @code{ERANGE} on overflow.
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@end deftypefun
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@comment wchar.h
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@comment ISO
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@deftypefun {unsigned long int} wcstoul (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoul} function is equivalent in nearly all aspect to the
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@code{strtoul} function but it handles wide character string.
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The @code{wcstoul} function was introduced in @w{Amendment 1} of @w{ISO C90}.
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@end deftypefun
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@comment stdlib.h
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@comment ISO
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@deftypefun {long long int} strtoll (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {long long int} strtoll (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtoll} function is like @code{strtol} except that it returns
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a @code{long long int} value, and accepts numbers with a correspondingly
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larger range.
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@ -2157,30 +2181,66 @@ appropriate for the sign of the value. It also sets @code{errno} to
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The @code{strtoll} function was introduced in @w{ISO C99}.
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@end deftypefun
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@comment wchar.h
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@comment ISO
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@deftypefun {long long int} wcstoll (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoll} function is equivalent in nearly all aspect to the
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@code{strtoll} function but it handles wide character string.
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The @code{wcstoll} function was introduced in @w{Amendment 1} of @w{ISO C90}.
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@end deftypefun
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@comment stdlib.h
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@comment BSD
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@deftypefun {long long int} strtoq (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {long long int} strtoq (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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@code{strtoq} (``string-to-quad-word'') is the BSD name for @code{strtoll}.
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@end deftypefun
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@comment wchar.h
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@comment GNU
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@deftypefun {long long int} wcstoq (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoq} function is equivalent in nearly all aspect to the
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@code{strtoq} function but it handles wide character string.
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The @code{wcstoq} function is a GNU extension.
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@end deftypefun
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@comment stdlib.h
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@comment ISO
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@deftypefun {unsigned long long int} strtoull (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {unsigned long long int} strtoull (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtoull} function is related to @code{strtoll} the same way
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@code{strtoul} is related to @code{strtol}.
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The @code{strtoull} function was introduced in @w{ISO C99}.
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@end deftypefun
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@comment wchar.h
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@comment ISO
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@deftypefun {unsigned long long int} wcstoull (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoull} function is equivalent in nearly all aspect to the
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@code{strtoull} function but it handles wide character string.
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The @code{wcstoull} function was introduced in @w{Amendment 1} of @w{ISO C90}.
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@end deftypefun
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@comment stdlib.h
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@comment BSD
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@deftypefun {unsigned long long int} strtouq (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@deftypefun {unsigned long long int} strtouq (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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@code{strtouq} is the BSD name for @code{strtoull}.
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@end deftypefun
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@comment wchar.h
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@comment GNU
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@deftypefun {unsigned long long int} wcstouq (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstouq} function is equivalent in nearly all aspect to the
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@code{strtouq} function but it handles wide character string.
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The @code{wcstoq} function is a GNU extension.
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@end deftypefun
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@comment inttypes.h
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@comment ???
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@deftypefun {long long int} strtoimax (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@comment ISO
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@deftypefun intmax_t strtoimax (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtoimax} function is like @code{strtol} except that it returns
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a @code{intmax_t} value, and accepts numbers of a corresponding range.
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@ -2190,21 +2250,36 @@ representable because of overflow, @code{strtoimax} returns either
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appropriate for the sign of the value. It also sets @code{errno} to
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@code{ERANGE} to indicate there was overflow.
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The symbols for @code{strtoimax} are declared in @file{inttypes.h}.
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See @ref{Integers} for a description of the @code{intmax_t} type. The
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@code{strtoimax} function was introduced in @w{ISO C99}.
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@end deftypefun
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See @ref{Integers} for a description of the @code{intmax_t} type.
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@comment wchar.h
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@comment ISO
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@deftypefun intmax_t wcstoimax (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoimax} function is equivalent in nearly all aspect to the
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@code{strtoimax} function but it handles wide character string.
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The @code{wcstoimax} function was introduced in @w{ISO C99}.
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@end deftypefun
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@comment inttypes.h
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@comment ???
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@deftypefun uintmax_t strtoumax (const char *@var{string}, char **@var{tailptr}, int @var{base})
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@comment ISO
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@deftypefun uintmax_t strtoumax (const char *restrict @var{string}, char **restrict @var{tailptr}, int @var{base})
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The @code{strtoumax} function is related to @code{strtoimax}
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the same way that @code{strtoul} is related to @code{strtol}.
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The symbols for @code{strtoimax} are declared in @file{inttypes.h}.
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See @ref{Integers} for a description of the @code{intmax_t} type. The
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@code{strtoumax} function was introduced in @w{ISO C99}.
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@end deftypefun
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See @ref{Integers} for a description of the @code{intmax_t} type.
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@comment wchar.h
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@comment ISO
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@deftypefun uintmax_t wcstoumax (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr}, int @var{base})
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The @code{wcstoumax} function is equivalent in nearly all aspect to the
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@code{strtoumax} function but it handles wide character string.
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The @code{wcstoumax} function was introduced in @w{ISO C99}.
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@end deftypefun
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@comment stdlib.h
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@ -2234,25 +2309,12 @@ The @code{atoll} function was introduced in @w{ISO C99}. It too is
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obsolete (despite having just been added); use @code{strtoll} instead.
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@end deftypefun
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@c !!! please fact check this paragraph -zw
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@findex strtol_l
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@findex strtoul_l
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@findex strtoll_l
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@findex strtoull_l
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@cindex parsing numbers and locales
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@cindex locales, parsing numbers and
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Some locales specify a printed syntax for numbers other than the one
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that these functions understand. If you need to read numbers formatted
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in some other locale, you can use the @code{strtoX_l} functions. Each
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of the @code{strtoX} functions has a counterpart with @samp{_l} added to
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its name. The @samp{_l} counterparts take an additional argument: a
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pointer to an @code{locale_t} structure, which describes how the numbers
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to be read are formatted. @xref{Locales}.
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@strong{Portability Note:} These functions are all GNU extensions. You
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can also use @code{scanf} or its relatives, which have the @samp{'} flag
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for parsing numeric input according to the current locale
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(@pxref{Numeric Input Conversions}). This feature is standard.
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All the functions mentioned in this section so far do not handle
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alternative representations of characters as described in the locale
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data. Some locales specify thousands separator and the way they have to
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be used which can help to make large numbers more readable. To read
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such numbers one has to use the @code{scanf} functions with the @samp{'}
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flag.
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Here is a function which parses a string as a sequence of integers and
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returns the sum of them:
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@ -2294,11 +2356,16 @@ sum_ints_from_string (char *string)
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@subsection Parsing of Floats
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@pindex stdlib.h
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These functions are declared in @file{stdlib.h}.
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The @samp{str} functions are declared in @file{stdlib.h} and those
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beginning with @samp{wcs} are declared in @file{wchar.h}. One might
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wonder about the use of @code{restrict} in the prototypes of the
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functions in this section. It is seemingly useless but the @w{ISO C}
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standard uses it (for the functions defined there) so we have to do it
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as well.
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@comment stdlib.h
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@comment ISO
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@deftypefun double strtod (const char *@var{string}, char **@var{tailptr})
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@deftypefun double strtod (const char *restrict @var{string}, char **restrict @var{tailptr})
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The @code{strtod} (``string-to-double'') function converts the initial
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part of @var{string} to a floating-point number, which is returned as a
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value of type @code{double}.
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@ -2394,6 +2461,24 @@ double} is a separate type).
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These functions have been GNU extensions and are new to @w{ISO C99}.
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@end deftypefun
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@comment wchar.h
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@comment ISO
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@deftypefun double wcstod (const wchar_t *restrict @var{string}, wchar_t **restrict @var{tailptr})
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@comment stdlib.h
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@comment ISO
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@deftypefunx float wcstof (const wchar_t *@var{string}, wchar_t **@var{tailptr})
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@comment stdlib.h
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@comment ISO
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@deftypefunx {long double} wcstold (const wchar_t *@var{string}, wchar_t **@var{tailptr})
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The @code{wcstod}, @code{wcstof}, and @code{wcstol} functions are
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equivalent in nearly all aspect to the @code{strtod}, @code{strtof}, and
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@code{strtold} functions but it handles wide character string.
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The @code{wcstod} function was introduced in @w{Amendment 1} of @w{ISO
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C90}. The @code{wcstof} and @code{wcstold} functions were introduced in
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@w{ISO C99}.
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@end deftypefun
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@comment stdlib.h
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@comment ISO
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@deftypefun double atof (const char *@var{string})
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@ -316,7 +316,7 @@ Here are the symbolic constants for use as the @var{parameter} argument
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to @code{sysconf}. The values are all integer constants (more
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specifically, enumeration type values).
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@table @code
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@vtable @code
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@comment unistd.h
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@comment POSIX.1
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@item _SC_ARG_MAX
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@ -752,8 +752,7 @@ support.
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@comment GNU
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@item _SC_PAGESIZE
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Inquire about the virtual memory page size of the machine.
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@code{getpagesize} returns the same value.
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@c @xref{XXX getpagesize}. !!! ???
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@code{getpagesize} returns the same value (@pxref{Query Memory Parameters}).
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@comment unistd.h
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@comment GNU
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@ -796,6 +795,21 @@ Inquire about the parameter corresponding to @code{_XOPEN_XCU_VERSION}.
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@item _SC_XOPEN_UNIX
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Inquire about the parameter corresponding to @code{_XOPEN_UNIX}.
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@comment unistd.h
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@comment X/Open
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@item _SC_XOPEN_REALTIME
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Inquire about the parameter corresponding to @code{_XOPEN_REALTIME}.
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@comment unistd.h
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@comment X/Open
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@item _SC_XOPEN_REALTIME_THREADS
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Inquire about the parameter corresponding to @code{_XOPEN_REALTIME_THREADS}.
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@comment unistd.h
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@comment X/Open
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@item _SC_XOPEN_LEGACY
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Inquire about the parameter corresponding to @code{_XOPEN_LEGACY}.
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@comment unistd.h
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@comment X/Open
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@item _SC_XOPEN_CRYPT
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@ -960,7 +974,7 @@ Inquire about the parameter corresponding to @code{NL_SETMAX}.
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@comment X/Open
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@item _SC_NL_TEXTMAX
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Inquire about the parameter corresponding to @code{NL_TEXTMAX}.
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@end table
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@end vtable
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@node Examples of Sysconf
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@subsection Examples of @code{sysconf}
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@ -1290,6 +1304,33 @@ bytes in a file name. The value of this constant is @code{256}.
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The most restrictive limit permitted by POSIX for the maximum number of
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bytes that can be written atomically to a pipe. The value of this
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constant is @code{512}.
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@comment limits.h
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@comment POSIX.1
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@item SYMLINK_MAX
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Maximum number of bytes in a symbolic link.
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@comment limits.h
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@comment POSIX.1
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@item POSIX_REC_INCR_XFER_SIZE
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Recommended increment for file transfer sizes between the
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@code{POSIX_REC_MIN_XFER_SIZE} and @code{POSIX_REC_MAX_XFER_SIZE}
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values.
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@comment limits.h
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@comment POSIX.1
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@item POSIX_REC_MAX_XFER_SIZE
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Maximum recommended file transfer size.
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@comment limits.h
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@comment POSIX.1
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@item POSIX_REC_MIN_XFER_SIZE
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Minimum recommended file transfer size.
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@comment limits.h
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@comment POSIX.1
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@item POSIX_REC_XFER_ALIGN
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Recommended file transfer buffer alignment.
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@end table
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@node Pathconf
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@ -1417,6 +1458,31 @@ Inquire about the value of @code{_POSIX_PRIO_IO}.
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@comment POSIX.1g
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@item _PC_SOCK_MAXBUF
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Inquire about the value of @code{_POSIX_PIPE_BUF}.
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@comment unistd.h
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@comment LFS
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@item _PC_FILESIZEBITS
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Inquire about the availability of large files on the filesystem.
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@comment unistd.h
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@comment POSIX.1
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@item _PC_REC_INCR_XFER_SIZE
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Inquire about the value of @code{POSIX_REC_INCR_XFER_SIZE}.
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@comment unistd.h
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@comment POSIX.1
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@item _PC_REC_MAX_XFER_SIZE
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Inquire about the value of @code{POSIX_REC_MAX_XFER_SIZE}.
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@comment unistd.h
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@comment POSIX.1
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@item _PC_REC_MIN_XFER_SIZE
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Inquire about the value of @code{POSIX_REC_MIN_XFER_SIZE}.
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@comment unistd.h
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@comment POSIX.1
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@item _PC_REC_XFER_ALIGN
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Inquire about the value of @code{POSIX_REC_XFER_ALIGN}.
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@end table
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@node Utility Limits
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@ -23,19 +23,13 @@ through a @dfn{one-way function}, a function which makes it difficult to
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work out what its input was by looking at its output, before storing in
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the file.
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The GNU C library already provides a one-way function based on MD5. The
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@code{crypt} add-on provides additional compatibility with the standard
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UNIX one-way function based on the Data Encryption Standard.
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The GNU C library already provides a one-way function based on MD5 and
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for compatibility with Unix systems the standard one-way function based
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on the Data Encryption Standard.
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It also provides support for Secure RPC, and some library functions that
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can be used to perform normal DES encryption.
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The add-on is not included in the main distribution of the GNU C library
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because some governments, most notably those of France, Russia,
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and the US, have very restrictive rules governing the distribution and
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use of encryption software. The first section below tries to describe some
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of those rules.
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@menu
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* Legal Problems:: This software can get you locked up, or worse.
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* getpass:: Prompting the user for a password.
|
||||
@ -53,8 +47,8 @@ may help you when you try to find out what the laws of your country are.
|
||||
|
||||
Some countries require that you have a licence to use, posess, or import
|
||||
cryptography. These countries are believed to include Byelorussia,
|
||||
Burma, France, India, Indonesia, Israel, Kazakhstan, Pakistan, Russia,
|
||||
and Saudi Arabia.
|
||||
Burma, India, Indonesia, Israel, Kazakhstan, Pakistan, Russia, and Saudi
|
||||
Arabia.
|
||||
|
||||
Some countries restrict the transmission of encrypted messages by radio;
|
||||
some telecommunications carriers restrict the transmission of encrypted
|
||||
@ -94,7 +88,7 @@ in a convenient way.
|
||||
|
||||
@comment unistd.h
|
||||
@comment BSD
|
||||
@deftypefun {char *} getpass (const char * @var{prompt})
|
||||
@deftypefun {char *} getpass (const char *@var{prompt})
|
||||
|
||||
@code{getpass} outputs @var{prompt}, then reads a string in from the
|
||||
terminal without echoing it. It tries to connect to the real terminal,
|
||||
@ -129,7 +123,7 @@ The substitute takes the same parameters as @code{getline}
|
||||
|
||||
@comment crypt.h
|
||||
@comment BSD, SVID
|
||||
@deftypefun {char *} crypt (const char * @var{key}, const char * @var{salt})
|
||||
@deftypefun {char *} crypt (const char *@var{key}, const char *@var{salt})
|
||||
|
||||
The @code{crypt} function takes a password, @var{key}, as a string, and
|
||||
a @var{salt} character array which is described below, and returns a
|
||||
@ -193,7 +187,7 @@ for a password and prints ``Access granted.'' if the user types
|
||||
|
||||
@comment crypt.h
|
||||
@comment GNU
|
||||
@deftypefun {char *} crypt_r (const char * @var{key}, const char * @var{salt}, {struct crypt_data *} @var{data})
|
||||
@deftypefun {char *} crypt_r (const char *@var{key}, const char *@var{salt}, {struct crypt_data *} @var{data})
|
||||
|
||||
The @code{crypt_r} function does the same thing as @code{crypt}, but
|
||||
takes an extra parameter which includes space for its result (among
|
||||
@ -238,7 +232,7 @@ specifies the unused bits.
|
||||
|
||||
@comment crypt.h
|
||||
@comment BSD, SVID
|
||||
@deftypefun void setkey (const char * @var{key})
|
||||
@deftypefun void setkey (const char *@var{key})
|
||||
|
||||
The @code{setkey} function sets an internal data structure to be an
|
||||
expanded form of @var{key}. @var{key} is specified as an array of 64
|
||||
@ -249,7 +243,7 @@ parity.
|
||||
|
||||
@comment crypt.h
|
||||
@comment BSD, SVID
|
||||
@deftypefun void encrypt (char * @var{block}, int @var{edflag})
|
||||
@deftypefun void encrypt (char *@var{block}, int @var{edflag})
|
||||
|
||||
The @code{encrypt} function encrypts @var{block} if
|
||||
@var{edflag} is 0, otherwise it decrypts @var{block}, using a key
|
||||
@ -262,10 +256,10 @@ stored in a @code{char}, but there are no parity bits in @var{block}.
|
||||
|
||||
@comment crypt.h
|
||||
@comment GNU
|
||||
@deftypefun void setkey_r (const char * @var{key}, {struct crypt_data *} @var{data})
|
||||
@deftypefun void setkey_r (const char *@var{key}, {struct crypt_data *} @var{data})
|
||||
@comment crypt.h
|
||||
@comment GNU
|
||||
@deftypefunx void encrypt_r (char * @var{block}, int @var{edflag}, {struct crypt_data *} @var{data})
|
||||
@deftypefunx void encrypt_r (char *@var{block}, int @var{edflag}, {struct crypt_data *} @var{data})
|
||||
|
||||
These are reentrant versions of @code{setkey} and @code{encrypt}. The
|
||||
only difference is the extra parameter, which stores the expanded
|
||||
@ -284,7 +278,7 @@ recommended instead.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@deftypefun int ecb_crypt (char * @var{key}, char * @var{blocks}, unsigned @var{len}, unsigned @var{mode})
|
||||
@deftypefun int ecb_crypt (char *@var{key}, char *@var{blocks}, unsigned @var{len}, unsigned @var{mode})
|
||||
|
||||
The function @code{ecb_crypt} encrypts or decrypts one or more blocks
|
||||
using DES. Each block is encrypted independently.
|
||||
@ -303,25 +297,22 @@ The result of the encryption replaces the input in @var{blocks}.
|
||||
|
||||
The @var{mode} parameter is the bitwise OR of two of the following:
|
||||
|
||||
@table @code
|
||||
@vtable @code
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DES_ENCRYPT
|
||||
@findex DES_ENCRYPT
|
||||
This constant, used in the @var{mode} parameter, specifies that
|
||||
@var{blocks} is to be encrypted.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DES_DECRYPT
|
||||
@findex DES_DECRYPT
|
||||
This constant, used in the @var{mode} parameter, specifies that
|
||||
@var{blocks} is to be decrypted.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DES_HW
|
||||
@findex DES_HW
|
||||
This constant, used in the @var{mode} parameter, asks to use a hardware
|
||||
device. If no hardware device is available, encryption happens anyway,
|
||||
but in software.
|
||||
@ -329,30 +320,26 @@ but in software.
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DES_SW
|
||||
@findex DES_SW
|
||||
This constant, used in the @var{mode} parameter, specifies that no
|
||||
hardware device is to be used.
|
||||
@end table
|
||||
@end vtable
|
||||
|
||||
The result of the function will be one of these values:
|
||||
|
||||
@table @code
|
||||
@vtable @code
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DESERR_NONE
|
||||
@findex DESERR_NONE
|
||||
The encryption succeeded.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DESERR_NOHWDEVICE
|
||||
@findex DESERR_NOHWDEVICE
|
||||
The encryption succeeded, but there was no hardware device available.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DESERR_HWERROR
|
||||
@findex DESERR_HWERROR
|
||||
The encryption failed because of a hardware problem. In the GNU
|
||||
library, this error code is also returned if the @code{crypt} add-on was
|
||||
not used to build the library.
|
||||
@ -360,10 +347,9 @@ not used to build the library.
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@item DESERR_BADPARAM
|
||||
@findex DESERR_BADPARAM
|
||||
The encryption failed because of a bad parameter, for instance @var{len}
|
||||
is not a multiple of 8 or @var{len} is larger than @code{DES_MAXDATA}.
|
||||
@end table
|
||||
@end vtable
|
||||
@end deftypefun
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@ -375,7 +361,7 @@ This macro returns 1 if @var{err} is a `success' result code from
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@deftypefun int cbc_crypt (char * @var{key}, char * @var{blocks}, unsigned @var{len}, unsigned @var{mode}, char * @var{ivec})
|
||||
@deftypefun int cbc_crypt (char *@var{key}, char *@var{blocks}, unsigned @var{len}, unsigned @var{mode}, char *@var{ivec})
|
||||
|
||||
The function @code{cbc_crypt} encrypts or decrypts one or more blocks
|
||||
using DES in Cipher Block Chaining mode.
|
||||
@ -401,7 +387,7 @@ Otherwise, all the parameters are similar to those for @code{ecb_crypt}.
|
||||
|
||||
@comment rpc/des_crypt.h
|
||||
@comment SUNRPC
|
||||
@deftypefun void des_setparity (char * @var{key})
|
||||
@deftypefun void des_setparity (char *@var{key})
|
||||
|
||||
The function @code{des_setparity} changes the 64-bit @var{key}, stored
|
||||
packed in 8-bit bytes, to have odd parity by altering the low bits of
|
||||
|
||||
@ -1119,21 +1119,26 @@ of the file that a program actually accesses are loaded. Accesses to
|
||||
not-yet-loaded parts of the mmapped region are handled in the same way as
|
||||
swapped out pages.
|
||||
|
||||
Since mmapped pages can be stored back to their file when physical memory
|
||||
is low, it is possible to mmap files orders of magnitude larger than both
|
||||
the physical memory @emph{and} swap space. The only limit is address
|
||||
space. The theoretical limit is 4GB on a 32-bit machine - however, the
|
||||
actual limit will be smaller since some areas will be reserved for other
|
||||
purposes.
|
||||
Since mmapped pages can be stored back to their file when physical
|
||||
memory is low, it is possible to mmap files orders of magnitude larger
|
||||
than both the physical memory @emph{and} swap space. The only limit is
|
||||
address space. The theoretical limit is 4GB on a 32-bit machine -
|
||||
however, the actual limit will be smaller since some areas will be
|
||||
reserved for other purposes. If the LFS interface is used the file size
|
||||
on 32-bit systems is not limited to 2GB (offsets are signed which
|
||||
reduces the addressable area of 4GB by half); the full 64-bit are
|
||||
available.
|
||||
|
||||
Memory mapping only works on entire pages of memory. Thus, addresses
|
||||
for mapping must be page-aligned, and length values will be rounded up.
|
||||
To determine the size of a page the machine uses one should use
|
||||
|
||||
@vindex _SC_PAGESIZE
|
||||
@smallexample
|
||||
size_t page_size = (size_t) sysconf (_SC_PAGESIZE);
|
||||
@end smallexample
|
||||
|
||||
@noindent
|
||||
These functions are declared in @file{sys/mman.h}.
|
||||
|
||||
@deftypefun {void *} mmap (void *@var{address}, size_t @var{length},int @var{protect}, int @var{flags}, int @var{filedes}, off_t @var{offset})
|
||||
@ -1252,6 +1257,20 @@ The file is on a filesystem that doesn't support mapping.
|
||||
|
||||
@end deftypefun
|
||||
|
||||
@deftypefun {void *} mmap64 (void *@var{address}, size_t @var{length},int @var{protect}, int @var{flags}, int @var{filedes}, off64_t @var{offset})
|
||||
The @code{mmap64} function is equivalent to the @code{mmap} function but
|
||||
the @var{offset} parameter is of type @code{off64_t}. On 32-bit systems
|
||||
this allows the file associated with the @var{filedes} descriptor to be
|
||||
larger than 2GB. @var{filedes} must be a descriptor returned from a
|
||||
call to @code{open64} or @code{fopen64} and @code{freopen64} where the
|
||||
descriptor is retrieved with @code{fileno}.
|
||||
|
||||
When the sources are translated with @code{_FILE_OFFSET_BITS == 64} this
|
||||
function is actually available under the name @code{mmap}. I.e., the
|
||||
new, extended API using 64 bit file sizes and offsets transparently
|
||||
replaces the old API.
|
||||
@end deftypefun
|
||||
|
||||
@deftypefun int munmap (void *@var{addr}, size_t @var{length})
|
||||
|
||||
@code{munmap} removes any memory maps from (@var{addr}) to (@var{addr} +
|
||||
|
||||
@ -225,6 +225,7 @@ The function @code{setlocale} sets the current locale for category
|
||||
@var{category} to @var{locale}. A list of all the locales the system
|
||||
provides can be created by running
|
||||
|
||||
@pindex locale
|
||||
@smallexample
|
||||
locale -a
|
||||
@end smallexample
|
||||
@ -676,11 +677,16 @@ A second advantage is that in addition to the numeric and monetary
|
||||
formatting information, information from the
|
||||
@code{LC_TIME} and @code{LC_MESSAGES} categories is available.
|
||||
|
||||
@pindex langinfo.h
|
||||
The type @code{nl_type} is defined in @file{nl_types.h}. The argument
|
||||
@var{item} is a numeric value defined in the header @file{langinfo.h}.
|
||||
The X/Open standard defines the following values:
|
||||
|
||||
@vtable @code
|
||||
@item CODESET
|
||||
@code{nl_langinfo} returns a string with the name of the coded character
|
||||
set used in the selected locale.
|
||||
|
||||
@item ABDAY_1
|
||||
@itemx ABDAY_2
|
||||
@itemx ABDAY_3
|
||||
@ -832,6 +838,26 @@ The same as the value returned by @code{localeconv} in the
|
||||
@item N_SIGN_POSN
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{n_sign_posn} element of the @code{struct lconv}.
|
||||
|
||||
@item INT_P_CS_PRECEDES
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_p_cs_precedes} element of the @code{struct lconv}.
|
||||
@item INT_P_SEP_BY_SPACE
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_p_sep_by_space} element of the @code{struct lconv}.
|
||||
@item INT_N_CS_PRECEDES
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_n_cs_precedes} element of the @code{struct lconv}.
|
||||
@item INT_N_SEP_BY_SPACE
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_n_sep_by_space} element of the @code{struct lconv}.
|
||||
@item INT_P_SIGN_POSN
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_p_sign_posn} element of the @code{struct lconv}.
|
||||
@item INT_N_SIGN_POSN
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@code{int_n_sign_posn} element of the @code{struct lconv}.
|
||||
|
||||
@item DECIMAL_POINT
|
||||
@itemx RADIXCHAR
|
||||
The same as the value returned by @code{localeconv} in the
|
||||
@ -862,9 +888,15 @@ to a yes/no question.
|
||||
Using this value is deprecated since it is a very special case of
|
||||
message translation, and is better handled by the message
|
||||
translation functions (@pxref{Message Translation}).
|
||||
|
||||
The use of this symbol is deprecated. Instead message translation
|
||||
should be used.
|
||||
@item NOSTR
|
||||
The return value is a locale-specific translation of the negative response
|
||||
to a yes/no question. What is said for @code{YESSTR} is also true here.
|
||||
|
||||
The use of this symbol is deprecated. Instead message translation
|
||||
should be used.
|
||||
@end vtable
|
||||
|
||||
The file @file{langinfo.h} defines a lot more symbols but none of them
|
||||
|
||||
@ -663,7 +663,9 @@ valloc (size_t size)
|
||||
return memalign (getpagesize (), size);
|
||||
@}
|
||||
@end smallexample
|
||||
@c !!! xref getpagesize
|
||||
|
||||
@ref{Query Memory Parameters} for more information about the memory
|
||||
subsystem.
|
||||
@end deftypefun
|
||||
|
||||
@node Malloc Tunable Parameters
|
||||
|
||||
@ -364,7 +364,7 @@ Sun's NSS modules are usable as modules which get indirectly loaded
|
||||
only.
|
||||
|
||||
The NSS modules in the GNU C Library are prepared to be used as normal
|
||||
libraries themselves. This is @emph{not} true at the moment, though.
|
||||
libraries themselves. This is @emph{not} true at the moment, though.
|
||||
However, the organization of the name space in the modules does not make it
|
||||
impossible like it is for Solaris. Now you can see why the modules are
|
||||
still libraries.@footnote{There is a second explanation: we were too
|
||||
@ -404,11 +404,7 @@ change of the return value and the omission of the @var{result}
|
||||
parameter. While the user-level function returns a pointer to the
|
||||
result the reentrant function return an @code{enum nss_status} value:
|
||||
|
||||
@vindex NSS_STATUS_TRYAGAIN
|
||||
@vindex NSS_STATUS_UNAVAIL
|
||||
@vindex NSS_STATUS_NOTFOUND
|
||||
@vindex NSS_STATUS_SUCCESS
|
||||
@ftable @code
|
||||
@vtable @code
|
||||
@item NSS_STATUS_TRYAGAIN
|
||||
numeric value @code{-2}
|
||||
|
||||
@ -420,7 +416,7 @@ numeric value @code{0}
|
||||
|
||||
@item NSS_STATUS_SUCCESS
|
||||
numeric value @code{1}
|
||||
@end ftable
|
||||
@end vtable
|
||||
|
||||
@noindent
|
||||
Now you see where the action items of the @file{/etc/nsswitch.conf} file
|
||||
|
||||
@ -9,6 +9,8 @@ limits on future usage.
|
||||
* Resource Usage:: Measuring various resources used.
|
||||
* Limits on Resources:: Specifying limits on resource usage.
|
||||
* Priority:: Reading or setting process run priority.
|
||||
* Memory Resources:: Querying memory available resources.
|
||||
* Processor Resources:: Learn about the processors available.
|
||||
@end menu
|
||||
|
||||
|
||||
@ -431,8 +433,9 @@ above do. The functions above are better choices.
|
||||
|
||||
@code{ulimit} and the command symbols are declared in @file{ulimit.h}.
|
||||
@pindex ulimit.h
|
||||
@comment ulimit.h
|
||||
|
||||
@comment ulimit.h
|
||||
@comment BSD
|
||||
@deftypefun int ulimit (int @var{cmd}, ...)
|
||||
|
||||
@code{ulimit} gets the current limit or sets the current and maximum
|
||||
@ -475,10 +478,10 @@ A process tried to increase a maximum limit, but is not superuser.
|
||||
@end deftypefun
|
||||
|
||||
@code{vlimit} and its resource symbols are declared in @file{sys/vlimit.h}.
|
||||
@comment sys/vlimit.h
|
||||
@pindex sys/vlimit.h
|
||||
@comment BSD
|
||||
|
||||
@comment sys/vlimit.h
|
||||
@comment BSD
|
||||
@deftypefun int vlimit (int @var{resource}, int @var{limit})
|
||||
|
||||
@code{vlimit} sets the current limit for a resource for a process.
|
||||
@ -666,7 +669,7 @@ most important feature of the absolute priority: its absoluteness.
|
||||
|
||||
@node Realtime Scheduling
|
||||
@subsection Realtime Scheduling
|
||||
@comment realtime scheduling
|
||||
@cindex realtime scheduling
|
||||
|
||||
Whenever two processes with the same absolute priority are ready to run,
|
||||
the kernel has a decision to make, because only one can run at a time.
|
||||
@ -1122,19 +1125,17 @@ runs from @code{-20} to @code{20}. A lower nice value corresponds to
|
||||
higher priority for the process. These constants describe the range of
|
||||
priority values:
|
||||
|
||||
@table @code
|
||||
@vtable @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MIN
|
||||
@vindex PRIO_MIN
|
||||
The lowest valid nice value.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MAX
|
||||
@vindex PRIO_MAX
|
||||
The highest valid nice value.
|
||||
@end table
|
||||
@end vtable
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD,POSIX
|
||||
@ -1198,34 +1199,30 @@ The arguments @var{class} and @var{id} together specify a set of
|
||||
processes in which you are interested. These are the possible values of
|
||||
@var{class}:
|
||||
|
||||
@table @code
|
||||
@vtable @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PROCESS
|
||||
@vindex PRIO_PROCESS
|
||||
One particular process. The argument @var{id} is a process ID (pid).
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PGRP
|
||||
@vindex PRIO_PGRP
|
||||
All the processes in a particular process group. The argument @var{id} is
|
||||
a process group ID (pgid).
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_USER
|
||||
@vindex PRIO_USER
|
||||
All the processes owned by a particular user (i.e. whose real uid
|
||||
indicates the user). The argument @var{id} is a user ID (uid).
|
||||
@end table
|
||||
@end vtable
|
||||
|
||||
If the argument @var{id} is 0, it stands for the calling process, its
|
||||
process group, or its owner (real uid), according to @var{class}.
|
||||
|
||||
@c ??? I don't know where we should say this comes from.
|
||||
@comment Unix
|
||||
@comment dunno.h
|
||||
@comment unistd.h
|
||||
@comment BSD
|
||||
@deftypefun int nice (int @var{increment})
|
||||
Increment the nice value of the calling process by @var{increment}.
|
||||
The return value is the same as for @code{setpriority}.
|
||||
@ -1241,3 +1238,166 @@ nice (int increment)
|
||||
@}
|
||||
@end smallexample
|
||||
@end deftypefun
|
||||
|
||||
@node Memory Resources
|
||||
@section Querying memory available resources
|
||||
|
||||
The amount of memory available in the system and the way it is organized
|
||||
determines oftentimes the way programs can and have to work. For
|
||||
functions like @code{mman} it is necessary to know about the size of
|
||||
individual memory pages and knowing how much memory is available enables
|
||||
a program to select appropriate sizes for, say, caches. Before we get
|
||||
into these details a few words about memory subsystems in traditional
|
||||
Unix systems.
|
||||
|
||||
@menu
|
||||
* Memory Subsystem:: Overview about traditional Unix memory handling.
|
||||
* Query Memory Parameters:: How to get information about the memory
|
||||
subsystem?
|
||||
@end menu
|
||||
|
||||
@node Memory Subsystem
|
||||
@subsection Overview about traditional Unix memory handling
|
||||
|
||||
@cindex address space
|
||||
@cindex physical memory
|
||||
@cindex physical address
|
||||
Unix systems normally provide processes virtual address spaces. This
|
||||
means that the addresses of the memory regions do not have to correspond
|
||||
directly to the addresses of the actual physical memory which stores the
|
||||
data. An extra level of indirection is introduced which translates
|
||||
virtual addresses into physical addresses. This is normally done by the
|
||||
hardware of the processor.
|
||||
|
||||
@cindex shared memory
|
||||
Using a virtual address space has several advantage. The most important
|
||||
is process isolation. The different processes running on the system
|
||||
cannot interfere directly with each other. No process can write into
|
||||
the address space of another process (except when shared memory is used
|
||||
but then it is wanted and controlled).
|
||||
|
||||
Another advantage of virtual memory is that the address space the
|
||||
processes see can actually be larger than the physical memory available.
|
||||
The physical memory can be extended by storage on an external media
|
||||
where the content of currently unused memory regions is stored. The
|
||||
address translation can then intercept accesses to these memory regions
|
||||
and make memory content available again by loading the data back into
|
||||
memory. This concept makes it necessary that programs which have to use
|
||||
lots of memory know the difference between available virtual address
|
||||
space and available physical memory. If the working set of virtual
|
||||
memory of all the processes is larger than the available physical memory
|
||||
the system will slow down dramatically due to constant swapping of
|
||||
memory content from the memory to the storage media and back. This is
|
||||
called ``thrashing''.
|
||||
@cindex thrashing
|
||||
|
||||
@cindex memory page
|
||||
@cindex page, memory
|
||||
A final aspect of virtual memory which is important and follows from
|
||||
what is said in the last paragraph is the granularity of the virtual
|
||||
address space handling. When we said that the virtual address handling
|
||||
stores memory content externally it cannot do this on a byte-by-byte
|
||||
basis. The administrative overhead does not allow this (leaving alone
|
||||
the processor hardware). Instead several thousand bytes are handled
|
||||
together and form a @dfn{page}. The size of each page is always a power
|
||||
of two byte. The smallest page size in use today is 4096, with 8192,
|
||||
16384, and 65536 being other popular sizes.
|
||||
|
||||
@node Query Memory Parameters
|
||||
@subsection How to get information about the memory subsystem?
|
||||
|
||||
The page size of the virtual memory the process sees is essential to
|
||||
know in several situations. Some programming interface (e.g.,
|
||||
@code{mmap}, @pxref{Memory-mapped I/O}) require the user to provide
|
||||
information adjusted to the page size. In the case of @code{mmap} is it
|
||||
necessary to provide a length argument which is a multiple of the page
|
||||
size. Another place where the knowledge about the page size is useful
|
||||
is in memory allocation. If one allocates pieces of memory in larger
|
||||
chunks which are then subdivided by the application code it is useful to
|
||||
adjust the size of the larger blocks to the page size. If the total
|
||||
memory requirement for the block is close (but not larger) to a multiple
|
||||
of the page size the kernel's memory handling can work more effectively
|
||||
since it only has to allocate memory pages which are fully used. (To do
|
||||
this optimization it is necessary to know a bit about the memory
|
||||
allocator which will require a bit of memory itself for each block and
|
||||
this overhead must not push the total size over the page size multiple.
|
||||
|
||||
The page size traditionally was a compile time constant. But recent
|
||||
development of processors changed this. Processors now support
|
||||
different page sizes and they can possibly even vary among different
|
||||
processes on the same system. Therefore the system should be queried at
|
||||
runtime about the current page size and no assumptions (except about it
|
||||
being a power of two) should be made.
|
||||
|
||||
@vindex _SC_PAGESIZE
|
||||
The correct interface to query about the page size is @code{sysconf}
|
||||
(@pxref{Sysconf Definition}) with the parameter @code{_SC_PAGESIZE}.
|
||||
There is a much older interface available, too.
|
||||
|
||||
@comment unistd.h
|
||||
@comment BSD
|
||||
@deftypefun int getpagesize (void)
|
||||
The @code{getpagesize} function returns the page size of the process.
|
||||
This value is fixed for the runtime of the process but can vary in
|
||||
different runs of the application.
|
||||
|
||||
The function is declared in @file{unistd.h}.
|
||||
@end deftypefun
|
||||
|
||||
Widely available on @w{System V} derived systems is a method to get
|
||||
information about the physical memory the system has. The call
|
||||
|
||||
@vindex _SC_PHYS_PAGES
|
||||
@cindex sysconf
|
||||
@smallexample
|
||||
sysconf (_SC_PHYS_PAGES)
|
||||
@end smallexample
|
||||
|
||||
@noindent returns the total number of page of physical the system has.
|
||||
This does not mean all this memory is available. This information can
|
||||
be found using
|
||||
|
||||
@vindex _SC_AVPHYS_PAGES
|
||||
@cindex sysconf
|
||||
@smallexample
|
||||
sysconf (_SC_AVPHYS_PAGES)
|
||||
@end smallexample
|
||||
|
||||
These two values help to optimize applications. The value returned for
|
||||
@code{_SC_AVPHYS_PAGES} is the amount of memory the application can use
|
||||
without hindering any other process (given that no other process
|
||||
increases its memory usage). The value returned for
|
||||
@code{_SC_PHYS_PAGES} is more or less a hard limit for the working set.
|
||||
If all applications together constantly use more than that amount of
|
||||
memory the system is in trouble.
|
||||
|
||||
@node Processor Resources
|
||||
@section Learn about the processors available
|
||||
|
||||
The use of threads or processes with shared memory allows an application
|
||||
to take advantage of all the processing power a system can provide. If
|
||||
the task can be parallelized the optimal way to write an application is
|
||||
to have at any time as many processes running as there are processors.
|
||||
To determine the number of processors available to the system one can
|
||||
run
|
||||
|
||||
@vindex _SC_NPROCESSORS_CONF
|
||||
@cindex sysconf
|
||||
@smallexample
|
||||
sysconf (_SC_NPROCESSORS_CONF)
|
||||
@end smallexample
|
||||
|
||||
@noindent
|
||||
which returns the number of processors the operating system configured.
|
||||
But it might be possible for the operating system to disable individual
|
||||
processors and so the call
|
||||
|
||||
@vindex _SC_NPROCESSORS_ONLN
|
||||
@cindex sysconf
|
||||
@smallexample
|
||||
sysconf (_SC_NPROCESSORS_ONLN)
|
||||
@end smallexample
|
||||
|
||||
@noindent
|
||||
returns the number of processors which are currently inline (i.e.,
|
||||
available).
|
||||
|
||||
@ -169,7 +169,7 @@ timeval_subtract (result, x, y)
|
||||
@}
|
||||
@end smallexample
|
||||
|
||||
Common functions that use @code{struct timeval} are @code{gettimeofday}
|
||||
Common functions that use @code{struct timeval} are @code{gettimeofday}
|
||||
and @code{settimeofday}.
|
||||
|
||||
|
||||
@ -2341,9 +2341,8 @@ The return value and error conditions are the same as for @code{setitimer}.
|
||||
|
||||
@comment sys/time.h
|
||||
@comment BSD
|
||||
@table @code
|
||||
@vtable @code
|
||||
@item ITIMER_REAL
|
||||
@findex ITIMER_REAL
|
||||
This constant can be used as the @var{which} argument to the
|
||||
@code{setitimer} and @code{getitimer} functions to specify the real-time
|
||||
timer.
|
||||
@ -2351,7 +2350,6 @@ timer.
|
||||
@comment sys/time.h
|
||||
@comment BSD
|
||||
@item ITIMER_VIRTUAL
|
||||
@findex ITIMER_VIRTUAL
|
||||
This constant can be used as the @var{which} argument to the
|
||||
@code{setitimer} and @code{getitimer} functions to specify the virtual
|
||||
timer.
|
||||
@ -2359,11 +2357,10 @@ timer.
|
||||
@comment sys/time.h
|
||||
@comment BSD
|
||||
@item ITIMER_PROF
|
||||
@findex ITIMER_PROF
|
||||
This constant can be used as the @var{which} argument to the
|
||||
@code{setitimer} and @code{getitimer} functions to specify the profiling
|
||||
timer.
|
||||
@end table
|
||||
@end vtable
|
||||
|
||||
@comment unistd.h
|
||||
@comment POSIX.1
|
||||
@ -2484,7 +2481,7 @@ The function returns as *@code{remaining} the elapsed time left in the
|
||||
interval for which you requested to sleep. If the interval completed
|
||||
without getting interrupted by a signal, this is zero.
|
||||
|
||||
@code{struct timespec} is described in @xref{Elapsed Time}.
|
||||
@code{struct timespec} is described in @xref{Elapsed Time}.
|
||||
|
||||
If the function returns because the interval is over the return value is
|
||||
zero. If the function returns @math{-1} the global variable @var{errno}
|
||||
@ -2513,5 +2510,3 @@ be protected using cancellation handlers.
|
||||
|
||||
The @code{nanosleep} function is declared in @file{time.h}.
|
||||
@end deftypefun
|
||||
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user