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

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• Hash : 444f6d99
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  Date : 2011-03-24T13:38:09
  

  realloc: document portability problem
  
  * doc/posix-functions/realloc.texi (realloc): Mention pitfalls of
  passing 0 size to realloc.
  
  Signed-off-by: Eric Blake <eblake@redhat.com>
  

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• doc/posix-functions/realloc.texi

• @node realloc
  @section @code{realloc}
  @findex realloc
  
  POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/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.
  @end itemize
  
  Portability problems not fixed by Gnulib:
  @itemize
  @item
  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, C99 requires that if @code{realloc (p, 0)} returns
  @code{NULL} then @code{p} is still valid.  Among implementations that
  obey C99, behavior varies on whether @code{realloc (p, 0)} always
  fails and leaves @code{p} valid, or usually succeeds and returns a
  unique zero-size object; either way, a program not suspecting these
  semantics will leak memory (either the still-valid @code{p}, or the
  non-NULL return value).  Meanwhile, several implementations violate
  C99, by always calling @code{free (p)} but returning NULL:
  glibc, Cygwin
  @end itemize
  
  Extension: Gnulib provides a module @samp{realloc-gnu} that substitutes a
  @code{realloc} implementation that behaves more like the glibc implementation.
  

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