From 65b3903ff576488eaabb51d3c4fbf9c73d867d7c Mon Sep 17 00:00:00 2001 From: Zbigniew Jędrzejewski-Szmek Date: Sat, 25 Jan 2014 23:35:28 -0500 Subject: journal: guarantee async-signal-safety in sd_journald_sendv signal(7) provides a list of functions which may be called from a signal handler. Other functions, which only call those functions and don't access global memory and are reentrant are also safe. sd_j_sendv was mostly OK, but would call mkostemp and writev in a fallback path, which are unsafe. Being able to call sd_j_sendv in a async-signal-safe way is important because it allows it be used in signal handlers. Safety is achieved by replacing mkostemp with open(O_TMPFILE) and an open-coded writev replacement which uses write. Unfortunately, O_TMPFILE is only available on kernels >= 3.11. When O_TMPFILE is unavailable, an open-coded mkostemp is used. https://bugzilla.gnome.org/show_bug.cgi?id=722889 --- src/test/test-tmpfiles.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++ src/test/test-util.c | 26 ++++++++++++++++++++++++ 2 files changed, 77 insertions(+) create mode 100644 src/test/test-tmpfiles.c (limited to 'src/test') diff --git a/src/test/test-tmpfiles.c b/src/test/test-tmpfiles.c new file mode 100644 index 0000000000..f25a0dca52 --- /dev/null +++ b/src/test/test-tmpfiles.c @@ -0,0 +1,51 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2014 Zbigniew Jędrzejewski-Szmek + + 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 . +***/ + +#include +#include +#include +#include +#include +#include + +#include "util.h" + +int main(int argc, char** argv) { + const char *p = argv[1] ?: "/tmp"; + char *pattern = strappenda(p, "/systemd-test-XXXXXX"); + _cleanup_close_ int fd, fd2; + _cleanup_free_ char *cmd, *cmd2; + + fd = open_tmpfile(p, O_RDWR); + assert(fd >= 0); + + assert_se(asprintf(&cmd, "ls -l /proc/"PID_FMT"/fd/%d", getpid(), fd) > 0); + system(cmd); + + fd2 = mkostemp_safe(pattern, O_RDWR); + assert(fd >= 0); + assert_se(unlink(pattern) == 0); + + assert_se(asprintf(&cmd2, "ls -l /proc/"PID_FMT"/fd/%d", getpid(), fd2) > 0); + system(cmd2); + + return 0; +} diff --git a/src/test/test-util.c b/src/test/test-util.c index 05b2294e24..f819589b52 100644 --- a/src/test/test-util.c +++ b/src/test/test-util.c @@ -28,6 +28,8 @@ #include "util.h" #include "strv.h" +#include "def.h" +#include "fileio.h" static void test_streq_ptr(void) { assert_se(streq_ptr(NULL, NULL)); @@ -578,6 +580,29 @@ static void test_in_set(void) { assert_se(!IN_SET(0, 1, 2, 3, 4)); } +static void test_writev_safe(void) { + char name[] = "/tmp/test-writev_safe.XXXXXX"; + _cleanup_free_ char *contents; + size_t size; + int fd, r; + + struct iovec iov[3]; + IOVEC_SET_STRING(iov[0], "abc\n"); + IOVEC_SET_STRING(iov[1], ALPHANUMERICAL "\n"); + IOVEC_SET_STRING(iov[2], ""); + + fd = mkstemp(name); + printf("test_writev_safe: %s", name); + + r = writev_safe(fd, iov, 3); + assert(r == 0); + + r = read_full_file(name, &contents, &size); + assert(r == 0); + printf("contents: %s", contents); + assert(streq(contents, "abc\n" ALPHANUMERICAL "\n")); +} + int main(int argc, char *argv[]) { test_streq_ptr(); test_first_word(); @@ -615,6 +640,7 @@ int main(int argc, char *argv[]) { test_fstab_node_to_udev_node(); test_get_files_in_directory(); test_in_set(); + test_writev_safe(); return 0; } -- cgit v1.2.3-54-g00ecf