mgetgroups realloc issues

[Pádraig Brady]

Hi,


In regard to the realloc() introduced to mgetgroups.c,
I'm not exactly sure but I think the diff below is required
to handle realloc(,0) on glibc.
I.E. I think a double free would have been done and an error
reported if max_n_groups == 0 (which I presume is possible)?

diff --git a/gl/lib/mgetgroups.c b/gl/lib/mgetgroups.c
index 736dd87..d841044 100644
--- a/gl/lib/mgetgroups.c
+++ b/gl/lib/mgetgroups.c
@@ -91,7 +91,8 @@ mgetgroups (char const *username, gid_t gid, GETGROUPS_T 
**groups)
          if (ng < 0 && last_n_groups == max_n_groups)
            max_n_groups *= 2;

-         if ((h = realloc_groupbuf (g, max_n_groups)) == NULL)
+         h = realloc_groupbuf (g, max_n_groups);
+         if (max_n_groups && h == NULL)
            {
              int saved_errno = errno;
              free (g);




Also I think this may be necessary to ensure that we're
using the glibc flavour of realloc() ?

diff --git a/gl/modules/mgetgroups b/gl/modules/mgetgroups
index 8bce53a..53c8a8d 100644
--- a/gl/modules/mgetgroups
+++ b/gl/modules/mgetgroups
@@ -9,6 +9,7 @@ m4/mgetgroups.m4
 Depends-on:
 getugroups
 xalloc
+realloc

 configure.ac:
 gl_MGETGROUPS



cheers,
Pádraig.

For my own reference here is some info on the realloc(,0) issue:
http://bytes.com/groups/c/586145-realloc-zero-bytes