RE: alloca function use discouraged

[Conrad T. Pino]

Hi Derek,

> From: Derek Robert Price [mailto:derek@ximbiot.com]
> 
> It does look like the GNULIB alloca_.h is trying to use the MSC
> version of _alloca, however:
> 
> #  ifdef _MSC_VER
> #   include <malloc.h>
> #   define alloca _alloca
> #  endif
> 
> This should mean that the alloca.c module is not required to be
> compile on Windows, so I don't know why you had to add it to get
> fnmatch to compile, if you want to look into this and fix it.  Perhaps
> HAVE_ALLOCA_H needs be defined in windows-NT/config.h.in?

I was using "grep" to locate "alloca" references and spotted that too.

I'll look into (1) if "_MSC_VER" is defined and (2) if so which module
missed the boat.

> Derek

Conrad

grep -dno "[^a-zA-Z0-9_]+alloca[^a-zA-Z0-9_]" *.h *.c

lib\alloca_.h  26      /* alloca(N) returns a pointer (void* or char*) to N 
bytes of memory
lib\alloca_.h  28         Use of alloca should be avoided:
lib\alloca_.h  39      #   define alloca __builtin_alloca
lib\alloca_.h  44      #   define alloca _alloca
lib\alloca_.h  47      #    include <alloca.h>
lib\alloca_.h  54      extern "C" void *alloca (unsigned int);
lib\alloca_.h  56      extern void *alloca ();
lib\alloca_.h  60      extern char *alloca ();

lib\alloca.c  1       /* alloca.c -- allocate automatically reclaimed memory
lib\alloca.c  4          This implementation of the PWB library alloca function,
lib\alloca.c  15         track of all alloca-allocated blocks, and reclaim any
lib\alloca.c  20         As a special case, alloca(0) reclaims storage without
lib\alloca.c  21         allocating any.  It is a good idea to use alloca(0) in
lib\alloca.c  45      /* If someone has defined alloca as a macro,
lib\alloca.c  46         there must be some other way alloca is supposed to 
work.  */
lib\alloca.c  120     /* An "alloca header" is used to:
lib\alloca.c  121        (a) chain together all alloca'ed blocks;
lib\alloca.c  141     static header *last_alloca_header = NULL; /* -> last 
alloca header.  */
lib\alloca.c  145        the procedure that called alloca.  Originally, this 
space
lib\alloca.c  161       /* Reclaim garbage, defined as all alloca'd storage that
lib\alloca.c  412        for alloca.  */
lib\alloca.c  488     # endif /* no alloca */

lib\fnmatch.c  28      # define alloca __builtin_alloca
lib\fnmatch.c  32      #  include <alloca.h>
lib\fnmatch.c  38      char *alloca ();
lib\fnmatch.c  363      wpattern = (wchar_t *) alloca (totsize * sizeof 
(wchar_t));

lib\fnmatch_loop.c  1063            newp = (struct patternlist *) alloca 
(newpsize);                  \

lib\getdate.c  79         We don't want to mess with all the portability 
hassles of alloca.
lib\getdate.c  80         In particular, most (all?) versions of bison will use 
alloca in
lib\getdate.c  84         parser.  I played with adding "#define alloca 
dont_use_alloca", to
lib\getdate.c  85         give an error if the parser generator uses alloca 
(and thus detect

lib\regex.c  256     /* Should we use malloc or alloca?  If REGEX_MALLOC is not 
defined, we
lib\regex.c  257        use `alloca' instead of `malloc'.  This is because 
using malloc in
lib\regex.c  262        Because we sometimes use alloca, some routines have to 
be macros,
lib\regex.c  263        not functions -- `alloca'-allocated space disappears at 
the end of the
lib\regex.c  274     /* Emacs already defines alloca, sometimes.  */
lib\regex.c  277     /* Make alloca work the best possible way.  */
lib\regex.c  279     #    define alloca __builtin_alloca
lib\regex.c  282     #     include <alloca.h>
lib\regex.c  286     #  endif /* not alloca */
lib\regex.c  292       (destination = (char *) alloca (nsize),                  
        \
lib\regex.c  295     /* No need to do anything to free, after alloca.  */
lib\regex.c  1377    /* Avoiding alloca during matching, to placate r_alloc.  */
lib\regex.c  1380       searching and matching functions should not call 
alloca.  On some
lib\regex.c  1381       systems, alloca is implemented in terms of malloc, and 
if we're
lib\regex.c  1399    /* When using GNU C, we are not REALLY using the C alloca, 
no matter
lib\regex.c  4184         isn't necessary unless we're trying to avoid calling 
alloca in
lib\regex.c  5219          alloca (0);
lib\regex.c  5417      alloca (0);
lib\regex.c  5476      alloca (0);
lib\regex.c  5534    /* This is a separate function so that we can force an 
alloca cleanup

lib\vasnprintf.c  29      # include <alloca.h>
lib\vasnprintf.c  151           buf = (CHAR_T *) alloca (buf_neededlength * 
sizeof (CHAR_T));

vms\config.h  151     /* Define to force lib/regex.c to use malloc instead of 
alloca.  */

vms\ndir.c  43      /* The following was snarfed from lib-src/alloca.c in GNU 
Emacs,
vms\ndir.c  55         malloc.  The Emacs executable needs alloca to call 
xmalloc, because
vms\ndir.c  57         hand, the utilities in lib-src need alloca to call 
malloc; some of