From bf87a2c8ea4487ca4448c9fe42a9c9858400acbd Mon Sep 17 00:00:00 2001 From: Pádraig Brady Date: Wed, 8 Apr 2009 10:43:15 +0100 Subject: id: fix infinite loop on some systems Steven Parkes reported that `id -G $USER` went into an infinite loop on Darwin systems for users in more than 10 groups: http://bugs.gentoo.org/show_bug.cgi?id=264007 * gl/lib/mgetgroups.c (mgetgroups): Work around buggy getgrouplist implementations that don't update the required size correctly, by doubling the result buffer and retrying. Also return the parameter updated by getgrouplist rather than its return value, as the documentation doesn't actually state the number of groups stored is returned by getgrouplist. * tests/misc/id-groups: Add test to exercise this logic * tests/Makefile.am: Reference new test * NEWS: Mention the fix * THANKS: Update --- gl/lib/mgetgroups.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'gl/lib') diff --git a/gl/lib/mgetgroups.c b/gl/lib/mgetgroups.c index e697013ef..736dd87f3 100644 --- a/gl/lib/mgetgroups.c +++ b/gl/lib/mgetgroups.c @@ -81,10 +81,16 @@ mgetgroups (char const *username, gid_t gid, GETGROUPS_T **groups) while (1) { GETGROUPS_T *h; + int last_n_groups = max_n_groups; /* getgrouplist updates max_n_groups to num required. */ ng = getgrouplist (username, gid, g, &max_n_groups); + /* Some systems (like Darwin) have a bug where they + never increase max_n_groups. */ + if (ng < 0 && last_n_groups == max_n_groups) + max_n_groups *= 2; + if ((h = realloc_groupbuf (g, max_n_groups)) == NULL) { int saved_errno = errno; @@ -97,7 +103,9 @@ mgetgroups (char const *username, gid_t gid, GETGROUPS_T **groups) if (0 <= ng) { *groups = g; - return ng; + /* On success some systems just return 0 from getgrouplist, + so return max_n_groups rather than ng. */ + return max_n_groups; } } } -- cgit v1.2.3-70-g09d2