From 9697feabd63b19b4cbcebb8e6a369eb99e684a65 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Tue, 13 Mar 2012 02:29:27 +0100

Subject: [PATCH] util: add brute-force fallback for close_all_fds()

If /proc is not available (i.e. in chroot envs) let's fall back to brute

forcing our way through the fd table.

https://bugzilla.redhat.com/show_bug.cgi?id=784921

(cherry picked from commit b19be9eb9e231ccf350e0e051b687fc425c61904)

---

 src/util.c |   54 ++++++++++++++++++++++++++++++++++++++----------------

 1 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/src/util.c b/src/util.c

index 0c9537e..3a66c3b 100644

--- a/src/util.c

+++ b/src/util.c

@@ -2147,13 +2147,47 @@ int fd_cloexec(int fd, bool cloexec) {

         return 0;

 }

+static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) {

+        unsigned i;

+

+        assert(n_fdset == 0 || fdset);

+

+        for (i = 0; i < n_fdset; i++)

+                if (fdset[i] == fd)

+                        return true;

+

+        return false;

+}

+

 int close_all_fds(const int except[], unsigned n_except) {

         DIR *d;

         struct dirent *de;

         int r = 0;

-        if (!(d = opendir("/proc/self/fd")))

-                return -errno;

+        assert(n_except == 0 || except);

+

+        d = opendir("/proc/self/fd");

+        if (!d) {

+                int fd;

+                struct rlimit rl;

+

+                /* When /proc isn't available (for example in chroots)

+                 * the fallback is brute forcing through the fd

+                 * table */

+

+                assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0);

+                for (fd = 3; fd < (int) rl.rlim_max; fd ++) {

+

+                        if (fd_in_set(fd, except, n_except))

+                                continue;

+

+                        if (close_nointr(fd) < 0)

+                                if (errno != EBADF && r == 0)

+                                        r = -errno;

+                }

+

+                return r;

+        }

         while ((de = readdir(d))) {

                 int fd = -1;

@@ -2171,20 +2205,8 @@ int close_all_fds(const int except[], unsigned n_except) {

                 if (fd == dirfd(d))

                         continue;

-                if (except) {

-                        bool found;

-                        unsigned i;

-

-                        found = false;

-                        for (i = 0; i < n_except; i++)

-                                if (except[i] == fd) {

-                                        found = true;

-                                        break;

-                                }

-

-                        if (found)

-                                continue;

-                }

+                if (fd_in_set(fd, except, n_except))

+                        continue;

                 if (close_nointr(fd) < 0) {

                         /* Valgrind has its own FD and doesn't want to have it closed */