Archipelago » qemu

/*

 * 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 <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>

#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)

{

    qemu_system_shutdown_request();

}

static void sigchld_handler(int signal)

{

    waitpid(-1, NULL, WNOHANG);

}

void os_setup_signal_handling(void)

{

    struct sigaction act;

    memset(&act, 0, sizeof(act));

    act.sa_handler = termsig_handler;

    sigaction(SIGINT,  &act, NULL);

    sigaction(SIGHUP,  &act, NULL);

    sigaction(SIGTERM, &act, NULL);

    act.sa_handler = sigchld_handler;

    act.sa_flags = SA_NOCLDSTOP;

    sigaction(SIGCHLD, &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 = qemu_mallocz(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)) {

            qemu_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 (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) {

        return -1;

    }

    len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());

    if (write(fd, buffer, len) != len) {

        return -1;

    }

    return 0;

}