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qemu/os-posix.c

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/*
* os-posix.c
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2010 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
/*needed for MAP_POPULATE before including qemu-options.h */
#include <sys/mman.h>
#include <pwd.h>
#include <grp.h>
#include <libgen.h>
/* Needed early for CONFIG_BSD etc. */
#include "config-host.h"
#include "sysemu.h"
#include "net/slirp.h"
#include "qemu-options.h"
#ifdef CONFIG_LINUX
#include <sys/prctl.h>
#include <sys/syscall.h>
#endif
#ifdef CONFIG_EVENTFD
#include <sys/eventfd.h>
#endif
static struct passwd *user_pwd;
static const char *chroot_dir;
static int daemonize;
static int fds[2];
void os_setup_early_signal_handling(void)
{
struct sigaction act;
sigfillset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = SIG_IGN;
sigaction(SIGPIPE, &act, NULL);
}
static void termsig_handler(int signal, siginfo_t *info, void *c)
{
qemu_system_killed(info->si_signo, info->si_pid);
}
void os_setup_signal_handling(void)
{
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_sigaction = termsig_handler;
act.sa_flags = SA_SIGINFO;
sigaction(SIGINT, &act, NULL);
sigaction(SIGHUP, &act, NULL);
sigaction(SIGTERM, &act, NULL);
}
/* Find a likely location for support files using the location of the binary.
For installed binaries this will be "$bindir/../share/qemu". When
running from the build tree this will be "$bindir/../pc-bios". */
#define SHARE_SUFFIX "/share/qemu"
#define BUILD_SUFFIX "/pc-bios"
char *os_find_datadir(const char *argv0)
{
char *dir;
char *p = NULL;
char *res;
char buf[PATH_MAX];
size_t max_len;
#if defined(__linux__)
{
int len;
len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
if (len > 0) {
buf[len] = 0;
p = buf;
}
}
#elif defined(__FreeBSD__)
{
static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
size_t len = sizeof(buf) - 1;
*buf = '\0';
if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
*buf) {
buf[sizeof(buf) - 1] = '\0';
p = buf;
}
}
#endif
/* If we don't have any way of figuring out the actual executable
location then try argv[0]. */
if (!p) {
p = realpath(argv0, buf);
if (!p) {
return NULL;
}
}
dir = dirname(p);
dir = dirname(dir);
max_len = strlen(dir) +
MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
res = g_malloc0(max_len);
snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
if (access(res, R_OK)) {
snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
if (access(res, R_OK)) {
g_free(res);
res = NULL;
}
}
return res;
}
#undef SHARE_SUFFIX
#undef BUILD_SUFFIX
void os_set_proc_name(const char *s)
{
#if defined(PR_SET_NAME)
char name[16];
if (!s)
return;
name[sizeof(name) - 1] = 0;
strncpy(name, s, sizeof(name));
/* Could rewrite argv[0] too, but that's a bit more complicated.
This simple way is enough for `top'. */
if (prctl(PR_SET_NAME, name)) {
perror("unable to change process name");
exit(1);
}
#else
fprintf(stderr, "Change of process name not supported by your OS\n");
exit(1);
#endif
}
/*
* Parse OS specific command line options.
* return 0 if option handled, -1 otherwise
*/
void os_parse_cmd_args(int index, const char *optarg)
{
switch (index) {
#ifdef CONFIG_SLIRP
case QEMU_OPTION_smb:
if (net_slirp_smb(optarg) < 0)
exit(1);
break;
#endif
case QEMU_OPTION_runas:
user_pwd = getpwnam(optarg);
if (!user_pwd) {
fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
exit(1);
}
break;
case QEMU_OPTION_chroot:
chroot_dir = optarg;
break;
case QEMU_OPTION_daemonize:
daemonize = 1;
break;
}
return;
}
static void change_process_uid(void)
{
if (user_pwd) {
if (setgid(user_pwd->pw_gid) < 0) {
fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
exit(1);
}
if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
user_pwd->pw_name, user_pwd->pw_gid);
exit(1);
}
if (setuid(user_pwd->pw_uid) < 0) {
fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
exit(1);
}
if (setuid(0) != -1) {
fprintf(stderr, "Dropping privileges failed\n");
exit(1);
}
}
}
static void change_root(void)
{
if (chroot_dir) {
if (chroot(chroot_dir) < 0) {
fprintf(stderr, "chroot failed\n");
exit(1);
}
if (chdir("/")) {
perror("not able to chdir to /");
exit(1);
}
}
}
void os_daemonize(void)
{
if (daemonize) {
pid_t pid;
if (pipe(fds) == -1)
exit(1);
pid = fork();
if (pid > 0) {
uint8_t status;
ssize_t len;
close(fds[1]);
again:
len = read(fds[0], &status, 1);
if (len == -1 && (errno == EINTR))
goto again;
if (len != 1)
exit(1);
else if (status == 1) {
fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
exit(1);
} else
exit(0);
} else if (pid < 0)
exit(1);
close(fds[0]);
qemu_set_cloexec(fds[1]);
setsid();
pid = fork();
if (pid > 0)
exit(0);
else if (pid < 0)
exit(1);
umask(027);
signal(SIGTSTP, SIG_IGN);
signal(SIGTTOU, SIG_IGN);
signal(SIGTTIN, SIG_IGN);
}
}
void os_setup_post(void)
{
int fd = 0;
if (daemonize) {
uint8_t status = 0;
ssize_t len;
again1:
len = write(fds[1], &status, 1);
if (len == -1 && (errno == EINTR))
goto again1;
if (len != 1)
exit(1);
if (chdir("/")) {
perror("not able to chdir to /");
exit(1);
}
TFR(fd = qemu_open("/dev/null", O_RDWR));
if (fd == -1)
exit(1);
}
change_root();
change_process_uid();
if (daemonize) {
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
close(fd);
}
}
void os_pidfile_error(void)
{
if (daemonize) {
uint8_t status = 1;
if (write(fds[1], &status, 1) != 1) {
perror("daemonize. Writing to pipe\n");
}
} else
fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
}
void os_set_line_buffering(void)
{
setvbuf(stdout, NULL, _IOLBF, 0);
}
/*
* Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
*/
int qemu_eventfd(int fds[2])
{
#ifdef CONFIG_EVENTFD
int ret;
ret = eventfd(0, 0);
if (ret >= 0) {
fds[0] = ret;
qemu_set_cloexec(ret);
if ((fds[1] = dup(ret)) == -1) {
close(ret);
return -1;
}
qemu_set_cloexec(fds[1]);
return 0;
}
if (errno != ENOSYS) {
return -1;
}
#endif
return qemu_pipe(fds);
}
int qemu_create_pidfile(const char *filename)
{
char buffer[128];
int len;
int fd;
fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
if (fd == -1) {
return -1;
}
if (lockf(fd, F_TLOCK, 0) == -1) {
close(fd);
return -1;
}
len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
if (write(fd, buffer, len) != len) {
close(fd);
return -1;
}
close(fd);
return 0;
}
int qemu_get_thread_id(void)
{
#if defined (__linux__)
return syscall(SYS_gettid);
#else
return getpid();
#endif
}
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