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authorYu Watanabe <watanabe.yu+github@gmail.com>2019-11-03 22:54:32 +0900
committerGitHub <noreply@github.com>2019-11-03 22:54:32 +0900
commitf4dad55b8b2861426a7b9e7104dec33acb770894 (patch)
tree193667d60c5d857dbc4fa3f9a81edd575efc6366 /src
parent5e467d74ad0c87f1f5e1a1e58bdce7b1971dd7a3 (diff)
parenteb2cfa81b005264693cc15d156995f9c31034196 (diff)
downloadsystemd-f4dad55b8b2861426a7b9e7104dec33acb770894.tar.gz
Merge pull request #13899 from poettering/in-gid-tweak
user-util: tweak to in_gid()
Diffstat (limited to 'src')
-rw-r--r--src/basic/user-util.c50
-rw-r--r--src/test/test-user-util.c11
2 files changed, 45 insertions, 16 deletions
diff --git a/src/basic/user-util.c b/src/basic/user-util.c
index 7a31a69e36..b5fdfafd61 100644
--- a/src/basic/user-util.c
+++ b/src/basic/user-util.c
@@ -409,8 +409,10 @@ char* gid_to_name(gid_t gid) {
}
int in_gid(gid_t gid) {
- gid_t *gids;
- int ngroups, r, i;
+ _cleanup_free_ gid_t *allocated = NULL;
+ gid_t local[16], *p = local;
+ int ngroups = ELEMENTSOF(local);
+ unsigned attempt = 0;
if (getgid() == gid)
return 1;
@@ -421,23 +423,39 @@ int in_gid(gid_t gid) {
if (!gid_is_valid(gid))
return -EINVAL;
- ngroups = getgroups(0, NULL);
- if (ngroups < 0)
- return -errno;
- if (ngroups == 0)
- return 0;
-
- gids = newa(gid_t, ngroups);
+ for (;;) {
+ ngroups = getgroups(ngroups, p);
+ if (ngroups >= 0)
+ break;
+ if (errno != EINVAL)
+ return -errno;
+
+ /* Give up eventually */
+ if (attempt++ > 10)
+ return -EINVAL;
+
+ /* Get actual size needed, and size the array explicitly. Note that this is potentially racy
+ * to use (in multi-threaded programs), hence let's call this in a loop. */
+ ngroups = getgroups(0, NULL);
+ if (ngroups < 0)
+ return -errno;
+ if (ngroups == 0)
+ return false;
+
+ free(allocated);
+
+ allocated = new(gid_t, ngroups);
+ if (!allocated)
+ return -ENOMEM;
- r = getgroups(ngroups, gids);
- if (r < 0)
- return -errno;
+ p = allocated;
+ }
- for (i = 0; i < r; i++)
- if (gids[i] == gid)
- return 1;
+ for (int i = 0; i < ngroups; i++)
+ if (p[i] == gid)
+ return true;
- return 0;
+ return false;
}
int in_group(const char *name) {
diff --git a/src/test/test-user-util.c b/src/test/test-user-util.c
index 9475b99c28..47baacb518 100644
--- a/src/test/test-user-util.c
+++ b/src/test/test-user-util.c
@@ -286,6 +286,15 @@ static void test_make_salt(void) {
assert(!streq(s, t));
}
+static void test_in_gid(void) {
+
+ assert(in_gid(getgid()) >= 0);
+ assert(in_gid(getegid()) >= 0);
+
+ assert(in_gid(GID_INVALID) < 0);
+ assert(in_gid(TTY_GID) == 0); /* The TTY gid is for owning ttys, it would be really really weird if we were in it. */
+}
+
int main(int argc, char *argv[]) {
test_uid_to_name_one(0, "root");
test_uid_to_name_one(UID_NOBODY, NOBODY_USER_NAME);
@@ -320,5 +329,7 @@ int main(int argc, char *argv[]) {
test_make_salt();
+ test_in_gid();
+
return 0;
}