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[PATCH] group-member: omit unnecessary dependencies
From: |
Paul Eggert |
Subject: |
[PATCH] group-member: omit unnecessary dependencies |
Date: |
Fri, 12 Oct 2012 13:13:02 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121009 Thunderbird/16.0 |
group-member: omit unnecessary dependencies
This is for Emacs, which has its own allocator and where we
don't want to use xalloc.
* lib/group-member.c: Include xalloc-oversized.h, not xalloc.h,
since we no longer use xmalloc. Do not include stdbool.h, since
the changes below happen to remove the only use of bool.
(GROUPBUF_SIZE): New constant.
(struct group_info): Remove n_groups member. Add groupbuf member.
This lets us get the groups without using malloc, usually.
(free_group_info, get_group_info): Adjust to this.
(get_group_info): Return the number of groups found, or -1 on error.
Use plain malloc not xmalloc, and treat its failure as if there
are no groups, as the user already loses in case of error.
(group_member): Simplify, based on changes to get_group_info.
* modules/group-member (Depends-on): Remove dependencies on
xalloc and stdbool. Add dependency on xalloc-oversized.
diff --git a/lib/group-member.c b/lib/group-member.c
index 3d79b3c..5fcc7e0 100644
--- a/lib/group-member.c
+++ b/lib/group-member.c
@@ -21,52 +21,49 @@
/* Specification. */
#include <unistd.h>
-#include <stdbool.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
-#include "xalloc.h"
+#include "xalloc-oversized.h"
+
+/* Most processes have no more than this many groups, and for these
+ processes we can avoid using malloc. */
+enum { GROUPBUF_SIZE = 100 };
struct group_info
{
- int n_groups;
gid_t *group;
+ gid_t groupbuf[GROUPBUF_SIZE];
};
static void
free_group_info (struct group_info const *g)
{
- free (g->group);
+ if (g->group != g->groupbuf)
+ free (g->group);
}
-static bool
+static int
get_group_info (struct group_info *gi)
{
- int n_groups;
- int n_group_slots = getgroups (0, NULL);
- gid_t *group;
-
- if (n_group_slots < 0)
- return false;
+ int n_groups = getgroups (GROUPBUF_SIZE, gi->groupbuf);
+ gi->group = gi->groupbuf;
- /* Avoid xnmalloc, as it goes awry when SIZE_MAX < n_group_slots. */
- if (xalloc_oversized (n_group_slots, sizeof *group))
- xalloc_die ();
- group = xmalloc (n_group_slots * sizeof *group);
- n_groups = getgroups (n_group_slots, group);
-
- /* In case of error, the user loses. */
if (n_groups < 0)
{
- free (group);
- return false;
+ int n_group_slots = getgroups (0, NULL);
+ if (0 <= n_group_slots
+ && ! xalloc_oversized (n_group_slots, sizeof *gi->group))
+ {
+ gi->group = malloc (n_group_slots * sizeof *gi->group);
+ if (gi->group)
+ n_groups = getgroups (n_group_slots, gi->group);
+ }
}
- gi->n_groups = n_groups;
- gi->group = group;
-
- return true;
+ /* In case of error, the user loses. */
+ return n_groups;
}
/* Return non-zero if GID is one that we have in our groups list.
@@ -80,13 +77,11 @@ group_member (gid_t gid)
int i;
int found;
struct group_info gi;
-
- if (! get_group_info (&gi))
- return 0;
+ int n_groups = get_group_info (&gi);
/* Search through the list looking for GID. */
found = 0;
- for (i = 0; i < gi.n_groups; i++)
+ for (i = 0; i < n_groups; i++)
{
if (gid == gi.group[i])
{
diff --git a/modules/group-member b/modules/group-member
index 6c5051d..9baf8e9 100644
--- a/modules/group-member
+++ b/modules/group-member
@@ -8,9 +8,8 @@ m4/group-member.m4
Depends-on:
unistd
extensions
-getgroups [test $HAVE_GROUP_MEMBER = 0]
-xalloc [test $HAVE_GROUP_MEMBER = 0]
-stdbool [test $HAVE_GROUP_MEMBER = 0]
+getgroups [test $HAVE_GROUP_MEMBER = 0]
+xalloc-oversized [test $HAVE_GROUP_MEMBER = 0]
configure.ac:
gl_FUNC_GROUP_MEMBER
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