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* manual/search.texi: Document MTASC-safety properties.

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Alexandre Oliva 2014-01-31 23:47:28 -02:00
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@ -1,3 +1,7 @@
2014-01-31 Alexandre Oliva <aoliva@redhat.com>
* manual/search.texi: Document MTASC-safety properties.
2014-01-31 Alexandre Oliva <aoliva@redhat.com>
* manual/resource.texi: Document MTASC-safety properties.

72
manual/search.texi
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@ -72,6 +72,7 @@ two functions can be found in @file{search.h}.
@comment search.h
@comment SVID
@deftypefun {void *} lfind (const void *@var{key}, const void *@var{base}, size_t *@var{nmemb}, size_t @var{size}, comparison_fn_t @var{compar})
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{lfind} function searches in the array with @code{*@var{nmemb}}
elements of @var{size} bytes pointed to by @var{base} for an element
which matches the one pointed to by @var{key}. The function pointed to
@ -90,6 +91,21 @@ searching.
@comment search.h
@comment SVID
@deftypefun {void *} lsearch (const void *@var{key}, void *@var{base}, size_t *@var{nmemb}, size_t @var{size}, comparison_fn_t @var{compar})
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
@c A signal handler that interrupted an insertion and performed an
@c insertion itself would leave the array in a corrupt state (e.g. one
@c new element initialized twice, with parts of both initializations
@c prevailing, and another uninitialized element), but this is just a
@c special case of races on user-controlled objects, that have to be
@c avoided by users.
@c In case of cancellation, we know the array won't be left in a corrupt
@c state; the new element is initialized before the element count is
@c incremented, and the compiler can't reorder these operations because
@c it can't know that they don't alias. So, we'll either cancel after
@c the increment and the initialization are both complete, or the
@c increment won't have taken place, and so how far the initialization
@c got doesn't matter.
The @code{lsearch} function is similar to the @code{lfind} function. It
searches the given array for an element and returns it if found. The
difference is that if no matching element is found the @code{lsearch}
@ -113,6 +129,7 @@ the header file @file{stdlib.h}.
@comment stdlib.h
@comment ISO
@deftypefun {void *} bsearch (const void *@var{key}, const void *@var{array}, size_t @var{count}, size_t @var{size}, comparison_fn_t @var{compare})
@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
The @code{bsearch} function searches the sorted array @var{array} for an object
that is equivalent to @var{key}. The array contains @var{count} elements,
each of which is of size @var{size} bytes.
@ -146,6 +163,7 @@ To sort an array using an arbitrary comparison function, use the
@comment stdlib.h
@comment ISO
@deftypefun void qsort (void *@var{array}, size_t @var{count}, size_t @var{size}, comparison_fn_t @var{compare})
@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{}}}
The @var{qsort} function sorts the array @var{array}. The array contains
@var{count} elements, each of which is of size @var{size}.
@ -256,6 +274,9 @@ The following functions are declared in the header file @file{search.h}.
@comment search.h
@comment SVID
@deftypefun int hcreate (size_t @var{nel})
@safety{@prelim{}@mtunsafe{@mtasurace{:hsearch}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c hcreate @mtasurace:hsearch @ascuheap @acucorrupt @acsmem
@c hcreate_r dup @mtsrace:htab @ascuheap @acucorrupt @acsmem
The @code{hcreate} function creates a hashing table which can contain at
least @var{nel} elements. There is no possibility to grow this table so
it is necessary to choose the value for @var{nel} wisely. The method
@ -285,6 +306,9 @@ table in use or the program runs out of memory.
@comment search.h
@comment SVID
@deftypefun void hdestroy (void)
@safety{@prelim{}@mtunsafe{@mtasurace{:hsearch}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c hdestroy @mtasurace:hsearch @ascuheap @acucorrupt @acsmem
@c hdestroy_r dup @mtsrace:htab @ascuheap @acucorrupt @acsmem
The @code{hdestroy} function can be used to free all the resources
allocated in a previous call of @code{hcreate}. After a call to this
function it is again possible to call @code{hcreate} and allocate a new
@ -328,6 +352,9 @@ this element might stay undefined since it is not used.
@comment search.h
@comment SVID
@deftypefun {ENTRY *} hsearch (ENTRY @var{item}, ACTION @var{action})
@safety{@prelim{}@mtunsafe{@mtasurace{:hsearch}}@asunsafe{}@acunsafe{@acucorrupt{/action==ENTER}}}
@c hsearch @mtasurace:hsearch @acucorrupt/action==ENTER
@c hsearch_r dup @mtsrace:htab @acucorrupt/action==ENTER
To search in a hashing table created using @code{hcreate} the
@code{hsearch} function must be used. This function can perform simple
search for an element (if @var{action} has the @code{FIND}) or it can
@ -358,6 +385,24 @@ members should be changed directly.
@comment search.h
@comment GNU
@deftypefun int hcreate_r (size_t @var{nel}, struct hsearch_data *@var{htab})
@safety{@prelim{}@mtsafe{@mtsrace{:htab}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c Unlike the lsearch array, the htab is (at least in part) opaque, so
@c let's make it absolutely clear that ensuring exclusive access is a
@c caller responsibility.
@c Cancellation is unlikely to leave the htab in a corrupt state: the
@c last field to be initialized is the one that tells whether the entire
@c data structure was initialized, and there's a function call (calloc)
@c in between that will often ensure all other fields are written before
@c the table. However, should this call be inlined (say with LTO), this
@c assumption may not hold. The calloc call doesn't cross our library
@c interface barrier, so let's consider this could happen and mark this
@c with @acucorrupt. It's no safety loss, since we already have
@c @ascuheap anyway...
@c hcreate_r @mtsrace:htab @ascuheap @acucorrupt @acsmem
@c isprime ok
@c calloc dup @ascuheap @acsmem
The @code{hcreate_r} function initializes the object pointed to by
@var{htab} to contain a hashing table with at least @var{nel} elements.
So this function is equivalent to the @code{hcreate} function except
@ -376,6 +421,16 @@ programs ran out of memory.
@comment search.h
@comment GNU
@deftypefun void hdestroy_r (struct hsearch_data *@var{htab})
@safety{@prelim{}@mtsafe{@mtsrace{:htab}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c The table is released while the table pointer still points to it.
@c Async cancellation is thus unsafe, but it already was because we call
@c free(). Using the table in a handler while it's being released would
@c also be dangerous, but calling free() already makes it unsafe, and
@c the requirement on the caller to ensure exclusive access already
@c guarantees this doesn't happen, so we don't get @asucorrupt.
@c hdestroy_r @mtsrace:htab @ascuheap @acucorrupt @acsmem
@c free dup @ascuheap @acsmem
The @code{hdestroy_r} function frees all resources allocated by the
@code{hcreate_r} function for this very same object @var{htab}. As for
@code{hdestroy} it is the programs responsibility to free the strings
@ -385,6 +440,13 @@ for the elements of the table.
@comment search.h
@comment GNU
@deftypefun int hsearch_r (ENTRY @var{item}, ACTION @var{action}, ENTRY **@var{retval}, struct hsearch_data *@var{htab})
@safety{@prelim{}@mtsafe{@mtsrace{:htab}}@assafe{}@acunsafe{@acucorrupt{/action==ENTER}}}
@c Callers have to ensure mutual exclusion; insertion, if cancelled,
@c leaves the table in a corrupt state.
@c hsearch_r @mtsrace:htab @acucorrupt/action==ENTER
@c strlen dup ok
@c strcmp dup ok
The @code{hsearch_r} function is equivalent to @code{hsearch}. The
meaning of the first two arguments is identical. But instead of
operating on a single global hashing table the function works on the
@ -436,6 +498,12 @@ in the header file @file{search.h}.
@comment search.h
@comment SVID
@deftypefun {void *} tsearch (const void *@var{key}, void **@var{rootp}, comparison_fn_t @var{compar})
@safety{@prelim{}@mtsafe{@mtsrace{:rootp}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
@c The tree is not modified in a thread-safe manner, and rotations may
@c leave the tree in an inconsistent state that could be observed in an
@c asynchronous signal handler (except for the caller-synchronization
@c requirement) or after asynchronous cancellation of the thread
@c performing the rotation or the insertion.
The @code{tsearch} function searches in the tree pointed to by
@code{*@var{rootp}} for an element matching @var{key}. The function
pointed to by @var{compar} is used to determine whether two elements
@ -465,6 +533,7 @@ of space @code{NULL} is returned.
@comment search.h
@comment SVID
@deftypefun {void *} tfind (const void *@var{key}, void *const *@var{rootp}, comparison_fn_t @var{compar})
@safety{@prelim{}@mtsafe{@mtsrace{:rootp}}@assafe{}@acsafe{}}
The @code{tfind} function is similar to the @code{tsearch} function. It
locates an element matching the one pointed to by @var{key} and returns
a pointer to this element. But if no matching element is available no
@ -479,6 +548,7 @@ elements.
@comment search.h
@comment SVID
@deftypefun {void *} tdelete (const void *@var{key}, void **@var{rootp}, comparison_fn_t @var{compar})
@safety{@prelim{}@mtsafe{@mtsrace{:rootp}}@asunsafe{@ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
To remove a specific element matching @var{key} from the tree
@code{tdelete} can be used. It locates the matching element using the
same method as @code{tfind}. The corresponding element is then removed
@ -492,6 +562,7 @@ is deleted @code{tdelete} returns some unspecified value not equal to
@comment search.h
@comment GNU
@deftypefun void tdestroy (void *@var{vroot}, __free_fn_t @var{freefct})
@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}}
If the complete search tree has to be removed one can use
@code{tdestroy}. It frees all resources allocated by the @code{tsearch}
function to generate the tree pointed to by @var{vroot}.
@ -546,6 +617,7 @@ The current node is a leaf.
@comment search.h
@comment SVID
@deftypefun void twalk (const void *@var{root}, __action_fn_t @var{action})
@safety{@prelim{}@mtsafe{@mtsrace{:root}}@assafe{}@acsafe{}}
For each node in the tree with a node pointed to by @var{root}, the
@code{twalk} function calls the function provided by the parameter
@var{action}. For leaf nodes the function is called exactly once with