kc3-lang/gnulib/doc/posix-functions/realloc.texi

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• Hash : 3498a703
  Author :
  Date : 2024-07-31T17:10:56
  

  errno: make EEXIST != ENOTEMPTY on AIX
  
  Also, improve errno tests.
  * m4/calloc.m4 (gl_FUNC_CALLOC_GNU):
  * m4/malloc.m4 (gl_FUNC_MALLOC_GNU):
  * m4/realloc.m4 (gl_FUNC_REALLOC_GNU):
  * m4/scandir.m4 (gl_FUNC_SCANDIR):
  Define _LINUX_SOURCE_COMPAT, as this can sometimes help on AIX.
  * m4/errno_h.m4 (gl_HEADER_ERRNO_H):
  Define _LINUX_SOURCE_COMPAT, to make EEXIST != ENOTEMPTY.
  * m4/strerror_r.m4 (gl_FUNC_STRERROR_R):
  Define _LINUX_SOURCE_COMPAT, in case someone else does.
  * modules/errno-tests (Depends-on): Add assert-h, c99.
  * tests/test-errno.c (e1, ..., e131): Remove, replacing with ...
  (CHECK_POSIX_ERRNOS, POSITIVE_INTEGER_CONSTANT_EXPRESSION)
  (INDEXED_BY_ERRNO, ERRNO_COUNT): These new macros.
  Check that all errno values are positive integer constant expressions.
  Check that they are all distinct, except perhaps for
  EWOULDBLOCK == EAGAIN and ENOTSUP == EOPNOTSUPP.
  Also check ESOCKTNOSUPPORT, added in POSIX.1-2024.
  Also, check that errno values are distinct except when POSIX says
  they needn’t be distinct, since POSIX.1-2024 gives license to
  GNU/Linux’s non-distinct values.
  

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• doc/posix-functions/realloc.texi

• @node realloc
  @subsection @code{realloc}
  @findex realloc
  
  POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/realloc.html}
  
  Gnulib module: realloc-posix
  
  Portability problems fixed by Gnulib:
  @itemize
  @item
  Upon failure, the function does not set @code{errno} to @code{ENOMEM} on
  some platforms:
  mingw, MSVC 14.
  
  @item
  On some platforms, @code{realloc (p, n)} can succeed even if @code{n}
  exceeds @code{PTRDIFF_MAX}.  Although this behavior is arguably
  allowed by POSIX it can lead to behavior not defined by POSIX later,
  so @code{realloc-posix} does not allow going over the limit.
  @end itemize
  
  Without the @samp{realloc-gnu} module described below, it is not portable
  to call @code{realloc} with a size of 0.  With a
  NULL pointer argument, this is the same ambiguity as @code{malloc (0)}
  on whether a unique zero-size object is created.  With a non-NULL
  pointer argument @code{p}, C17 says that it is implementation-defined
  whether @code{realloc (p, 0)} frees @code{p}.
  Behavior varies on whether @code{realloc (p, 0)} always frees @code{p}
  and successfully returns a null pointer, or always
  fails and leaves @code{p} valid, or usually succeeds and returns a
  unique zero-size object; a program not suspecting these variations in
  semantics will leak memory (either the still-valid @code{p}, or the
  non-NULL return value).
  
  Extension: Gnulib provides a module @samp{realloc-gnu} that substitutes a
  @code{realloc} implementation that behaves more like the glibc implementation.
  It fixes these portability problems:
  
  @itemize
  @item
  @code{realloc (NULL, 0)} returns @code{NULL} on success on some platforms:
  AIX 7.3.
  
  @item
  On some platforms, @code{realloc (p, 0)} with non-null @code{p}
  might not free @code{p}, or might clobber @code{errno},
  or might not return @code{NULL}.
  @end itemize
  

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