71 lines
2.7 KiB
Diff
71 lines
2.7 KiB
Diff
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From 1b547e500207a469a533d819db5b7c6c22516ec3 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Thu, 17 Jan 2019 12:23:21 +0100
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Subject: [PATCH] fd-util: rework how we determine highest possible fd
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(cherry picked from commit 498e265df1c63212ec1a0991c135877a23f1ba4f)
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Related: RHEL-18302
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---
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src/basic/fd-util.c | 37 ++++++++++++++++++++++++++-----------
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1 file changed, 26 insertions(+), 11 deletions(-)
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diff --git a/src/basic/fd-util.c b/src/basic/fd-util.c
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index e085dc23b4..fea93d2039 100644
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--- a/src/basic/fd-util.c
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+++ b/src/basic/fd-util.c
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@@ -188,6 +188,27 @@ _pure_ static bool fd_in_set(int fd, const int fdset[], size_t n_fdset) {
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return false;
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}
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+static int get_max_fd(void) {
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+ struct rlimit rl;
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+ rlim_t m;
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+
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+ /* Return the highest possible fd, based RLIMIT_NOFILE, but enforcing FD_SETSIZE-1 as lower boundary
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+ * and INT_MAX as upper boundary. */
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+
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+ if (getrlimit(RLIMIT_NOFILE, &rl) < 0)
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+ return -errno;
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+
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+ m = MAX(rl.rlim_cur, rl.rlim_max);
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+ if (m < FD_SETSIZE) /* Let's always cover at least 1024 fds */
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+ return FD_SETSIZE-1;
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+
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+ if (m == RLIM_INFINITY || m > INT_MAX) /* Saturate on overflow. After all fds are "int", hence can
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+ * never be above INT_MAX */
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+ return INT_MAX;
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+
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+ return (int) (m - 1);
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+}
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+
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int close_all_fds(const int except[], size_t n_except) {
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_cleanup_closedir_ DIR *d = NULL;
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struct dirent *de;
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@@ -197,20 +218,14 @@ int close_all_fds(const int except[], size_t n_except) {
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d = opendir("/proc/self/fd");
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if (!d) {
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- struct rlimit rl;
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int fd, max_fd;
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- /* When /proc isn't available (for example in chroots) the fallback is brute forcing through the fd
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- * table */
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-
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- assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0);
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-
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- if (rl.rlim_max == 0)
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- return -EINVAL;
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+ /* When /proc isn't available (for example in chroots) the fallback is brute forcing through
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+ * the fd table */
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- /* Let's take special care if the resource limit is set to unlimited, or actually larger than the range
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- * of 'int'. Let's avoid implicit overflows. */
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- max_fd = (rl.rlim_max == RLIM_INFINITY || rl.rlim_max > INT_MAX) ? INT_MAX : (int) (rl.rlim_max - 1);
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+ max_fd = get_max_fd();
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+ if (max_fd < 0)
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+ return max_fd;
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for (fd = 3; fd >= 0; fd = fd < max_fd ? fd + 1 : -1) {
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int q;
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