Merge pull request #1654 from poettering/util-lib

Various changes to src/basic/

1 files changed, 321 insertions, 0 deletions

diff --git a/src/basic/fd-util.c b/src/basic/fd-util.c
new file mode 100644
index 0000000000..e54c104597
--- /dev/null
+++ b/src/basic/fd-util.c
@@ -0,0 +1,321 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "fd-util.h"
+#include "util.h"
+
+int close_nointr(int fd) {
+        assert(fd >= 0);
+
+        if (close(fd) >= 0)
+                return 0;
+
+        /*
+         * Just ignore EINTR; a retry loop is the wrong thing to do on
+         * Linux.
+         *
+         * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
+         * https://bugzilla.gnome.org/show_bug.cgi?id=682819
+         * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR
+         * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
+         */
+        if (errno == EINTR)
+                return 0;
+
+        return -errno;
+}
+
+int safe_close(int fd) {
+
+        /*
+         * Like close_nointr() but cannot fail. Guarantees errno is
+         * unchanged. Is a NOP with negative fds passed, and returns
+         * -1, so that it can be used in this syntax:
+         *
+         * fd = safe_close(fd);
+         */
+
+        if (fd >= 0) {
+                PROTECT_ERRNO;
+
+                /* The kernel might return pretty much any error code
+                 * via close(), but the fd will be closed anyway. The
+                 * only condition we want to check for here is whether
+                 * the fd was invalid at all... */
+
+                assert_se(close_nointr(fd) != -EBADF);
+        }
+
+        return -1;
+}
+
+void safe_close_pair(int p[]) {
+        assert(p);
+
+        if (p[0] == p[1]) {
+                /* Special case pairs which use the same fd in both
+                 * directions... */
+                p[0] = p[1] = safe_close(p[0]);
+                return;
+        }
+
+        p[0] = safe_close(p[0]);
+        p[1] = safe_close(p[1]);
+}
+
+void close_many(const int fds[], unsigned n_fd) {
+        unsigned i;
+
+        assert(fds || n_fd <= 0);
+
+        for (i = 0; i < n_fd; i++)
+                safe_close(fds[i]);
+}
+
+int fclose_nointr(FILE *f) {
+        assert(f);
+
+        /* Same as close_nointr(), but for fclose() */
+
+        if (fclose(f) == 0)
+                return 0;
+
+        if (errno == EINTR)
+                return 0;
+
+        return -errno;
+}
+
+FILE* safe_fclose(FILE *f) {
+
+        /* Same as safe_close(), but for fclose() */
+
+        if (f) {
+                PROTECT_ERRNO;
+
+                assert_se(fclose_nointr(f) != EBADF);
+        }
+
+        return NULL;
+}
+
+DIR* safe_closedir(DIR *d) {
+
+        if (d) {
+                PROTECT_ERRNO;
+
+                assert_se(closedir(d) >= 0 || errno != EBADF);
+        }
+
+        return NULL;
+}
+
+int fd_nonblock(int fd, bool nonblock) {
+        int flags, nflags;
+
+        assert(fd >= 0);
+
+        flags = fcntl(fd, F_GETFL, 0);
+        if (flags < 0)
+                return -errno;
+
+        if (nonblock)
+                nflags = flags | O_NONBLOCK;
+        else
+                nflags = flags & ~O_NONBLOCK;
+
+        if (nflags == flags)
+                return 0;
+
+        if (fcntl(fd, F_SETFL, nflags) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int fd_cloexec(int fd, bool cloexec) {
+        int flags, nflags;
+
+        assert(fd >= 0);
+
+        flags = fcntl(fd, F_GETFD, 0);
+        if (flags < 0)
+                return -errno;
+
+        if (cloexec)
+                nflags = flags | FD_CLOEXEC;
+        else
+                nflags = flags & ~FD_CLOEXEC;
+
+        if (nflags == flags)
+                return 0;
+
+        if (fcntl(fd, F_SETFD, nflags) < 0)
+                return -errno;
+
+        return 0;
+}
+
+_pure_ 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) {
+        _cleanup_closedir_ DIR *d = NULL;
+        struct dirent *de;
+        int r = 0;
+
+        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;
+
+                if (hidden_file(de->d_name))
+                        continue;
+
+                if (safe_atoi(de->d_name, &fd) < 0)
+                        /* Let's better ignore this, just in case */
+                        continue;
+
+                if (fd < 3)
+                        continue;
+
+                if (fd == dirfd(d))
+                        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 */
+                        if (errno != EBADF && r == 0)
+                                r = -errno;
+                }
+        }
+
+        return r;
+}
+
+int same_fd(int a, int b) {
+        struct stat sta, stb;
+        pid_t pid;
+        int r, fa, fb;
+
+        assert(a >= 0);
+        assert(b >= 0);
+
+        /* Compares two file descriptors. Note that semantics are
+         * quite different depending on whether we have kcmp() or we
+         * don't. If we have kcmp() this will only return true for
+         * dup()ed file descriptors, but not otherwise. If we don't
+         * have kcmp() this will also return true for two fds of the same
+         * file, created by separate open() calls. Since we use this
+         * call mostly for filtering out duplicates in the fd store
+         * this difference hopefully doesn't matter too much. */
+
+        if (a == b)
+                return true;
+
+        /* Try to use kcmp() if we have it. */
+        pid = getpid();
+        r = kcmp(pid, pid, KCMP_FILE, a, b);
+        if (r == 0)
+                return true;
+        if (r > 0)
+                return false;
+        if (errno != ENOSYS)
+                return -errno;
+
+        /* We don't have kcmp(), use fstat() instead. */
+        if (fstat(a, &sta) < 0)
+                return -errno;
+
+        if (fstat(b, &stb) < 0)
+                return -errno;
+
+        if ((sta.st_mode & S_IFMT) != (stb.st_mode & S_IFMT))
+                return false;
+
+        /* We consider all device fds different, since two device fds
+         * might refer to quite different device contexts even though
+         * they share the same inode and backing dev_t. */
+
+        if (S_ISCHR(sta.st_mode) || S_ISBLK(sta.st_mode))
+                return false;
+
+        if (sta.st_dev != stb.st_dev || sta.st_ino != stb.st_ino)
+                return false;
+
+        /* The fds refer to the same inode on disk, let's also check
+         * if they have the same fd flags. This is useful to
+         * distinguish the read and write side of a pipe created with
+         * pipe(). */
+        fa = fcntl(a, F_GETFL);
+        if (fa < 0)
+                return -errno;
+
+        fb = fcntl(b, F_GETFL);
+        if (fb < 0)
+                return -errno;
+
+        return fa == fb;
+}
+
+void cmsg_close_all(struct msghdr *mh) {
+        struct cmsghdr *cmsg;
+
+        assert(mh);
+
+        CMSG_FOREACH(cmsg, mh)
+                if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
+                        close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int));
+}