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 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 src/test/test-tmpfiles.c (limited to 'src/test/test-tmpfiles.c') 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; +} -- cgit v1.2.3-54-g00ecf