Re: glibc sysdeps/posix/tempname.c artificially limited to TMP_MAX

[Paul Eggert]

> From: Ulrich Drepper <address@hidden>
> Date: 26 Nov 2001 17:19:10 -0800
> 
> This is the fault of the broken systems you are trying to support.
> The correct way to handle this is to fix these systems.

True in theory, but in practice it will take many years to fix old
systems like HP-UX or Solaris (or to retire them :-), and in the
meantime if it is easy to support them then GNU applications should do so.


> You cannot simply define a maximum values and be done.  If this
> value is not at least as big as TMP_MAX you'll have to use TMP_MAX.

OK, here's a revised patch that always uses a number that is at least
as big as TMP_MAX.  Please feel free to substitute some other
reasonable number for 62**6 in the definition of ATTEMPTS_MIN, if you
think 62**6 is too large.


2001-11-27  Paul Eggert  <address@hidden>

        * sysdeps/posix/tempname.c (__gen_tempname): Try at least
        ATTEMPTS_MIN or TMP_MAX times, whichever is greater.

--- sysdeps/posix/tempname.c    2001/07/06 11:56:01     1.35
+++ sysdeps/posix/tempname.c    2001/11/27 02:20:50     1.35.0.3
@@ -231,10 +231,22 @@ __gen_tempname (char *tmpl, int kind)
   char *XXXXXX;
   static uint64_t value;
   uint64_t random_time_bits;
-  int count, fd = -1;
+  unsigned int count;
+  int fd = -1;
   int save_errno = errno;
   struct_stat64 st;
 
+  /* A lower bound on the number of temporary files to attempt to
+     generate.  The maximum total number of temporary file names that
+     can exist for a given template is 62**6.  Since unsigned int is
+     at least 32 bits wide, ATTEMPTS_MIN is always at least 965660736
+     even if some multiplications overflow; this is good enough.  */
+  unsigned int attempts_min = (unsigned int) 62 * 62 * 62 * 62 * 62 * 62;
+
+  /* The number of times to attempt to generate a temporary file.  To
+     conform to POSIX, this must be no smaller than TMP_MAX.  */
+  unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
+
   len = strlen (tmpl);
   if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
     {
@@ -261,7 +273,7 @@ __gen_tempname (char *tmpl, int kind)
 #endif
   value += random_time_bits ^ __getpid ();
 
-  for (count = 0; count < TMP_MAX; value += 7777, ++count)
+  for (count = 0; count < attempts; value += 7777, ++count)
     {
       uint64_t v = value;