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manual: document posix_openpt (bug 17010)
State that getpt is similar to posix_openpt. Use posix_openpt instead of getpt in example. Signed-off-by: Gavin Smith <gavinsmith0123@gmail.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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@ -1947,6 +1947,33 @@ This subsection describes functions for allocating a pseudo-terminal,
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and for making this pseudo-terminal available for actual use. These
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functions are declared in the header file @file{stdlib.h}.
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@deftypefun int posix_openpt (int @var{flags})
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@standards{POSIX.1, stdlib.h}
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
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@code{posix_openpt} returns a new file descriptor for the next
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available master pseudo-terminal. In the case of an error, it returns
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a value of @math{-1} instead, and sets @code{errno} to indicate
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the error. @xref{Opening and Closing Files} for possible values
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of @code{errno}.
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@var{flags} is a bit mask created from a bitwise OR of zero or more
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of the following flags:
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@table @code
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@item O_RDWR
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Open the device for both reading and writing. It is usual to specify
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this flag.
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@item O_NOCTTY
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Do not make the device the controlling terminal for the process.
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@end table
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These flags are defined in @file{fcntl.h}. @xref{Access Modes}.
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For this function to be available, @code{_XOPEN_SOURCE} must be defined
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to a value greater than @samp{600}. @xref{Feature Test Macros}.
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@end deftypefun
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@deftypefun int getpt (void)
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@standards{GNU, stdlib.h}
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
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@ -1957,6 +1984,10 @@ functions are declared in the header file @file{stdlib.h}.
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@c a devfs, and returns the fd; static variables devpts_mounted and
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@c have_no_dev_ptmx are safely initialized so as to avoid repeated
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@c tests.
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@code{getpt} is similar to @code{posix_openpt}. This function is a
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GNU extension and should not be used in portable programs.
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The @code{getpt} function returns a new file descriptor for the next
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available master pseudo-terminal. The normal return value from
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@code{getpt} is a non-negative integer file descriptor. In the case of
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@ -1967,8 +1998,6 @@ an error, a value of @math{-1} is returned instead. The following
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@item ENOENT
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There are no free master pseudo-terminals available.
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@end table
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This function is a GNU extension.
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@end deftypefun
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@deftypefun int grantpt (int @var{filedes})
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@ -2118,6 +2147,7 @@ This function is a GNU extension.
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@end deftypefun
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Typical usage of these functions is illustrated by the following example:
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@smallexample
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int
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open_pty_pair (int *amaster, int *aslave)
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@ -2125,7 +2155,7 @@ open_pty_pair (int *amaster, int *aslave)
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int master, slave;
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char *name;
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master = getpt ();
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master = posix_openpt (O_RDWR | O_NOCTTY);
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if (master < 0)
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return 0;
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