| Message ID | 20250104-glib-v2-2-12013f3e5782@daynix.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tap: Use g_spawn_sync() and g_spawn_check_wait_status() | expand |
On Sat, Jan 04, 2025 at 05:04:08PM +0900, Akihiko Odaki wrote: > g_spawn_sync() gives an informative message if it fails to execute > the script instead of reporting exiting status 1. > > g_spawn_check_wait_status() also gives an message easier to understand > than the raw value returned by waitpid(). > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > --- > net/tap.c | 169 ++++++++++++++++++++++++-------------------------------------- > 1 file changed, 66 insertions(+), 103 deletions(-) > > diff --git a/net/tap.c b/net/tap.c > index ae1c7e398321..392a024f8ed9 100644 > --- a/net/tap.c > +++ b/net/tap.c > @@ -385,56 +385,30 @@ static TAPState *net_tap_fd_init(NetClientState *peer, > return s; > } > > -static void close_all_fds_after_fork(int excluded_fd) > +static void unset_cloexec(gpointer data) > { > - const int skip_fd[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, > - excluded_fd}; > - unsigned int nskip = ARRAY_SIZE(skip_fd); > - > - /* > - * skip_fd must be an ordered array of distinct fds, exclude > - * excluded_fd if already included in the [STDIN_FILENO - STDERR_FILENO] > - * range > - */ > - if (excluded_fd <= STDERR_FILENO) { > - nskip--; > - } > - > - qemu_close_all_open_fd(skip_fd, nskip); > + g_assert(!fcntl(GPOINTER_TO_INT(data), F_SETFD, 0)); > } > > static void launch_script(const char *setup_script, const char *ifname, > int fd, Error **errp) > { > - int pid, status; > - char *args[3]; > - char **parg; > + gint status; > + gchar *argv[] = { (gchar *)setup_script, (gchar *)ifname, NULL }; > + g_autoptr(GError) error = NULL; > > /* try to launch network script */ > - pid = fork(); > - if (pid < 0) { > - error_setg_errno(errp, errno, "could not launch network script %s", > - setup_script); > + if (!g_spawn_sync(NULL, argv, NULL, G_SPAWN_CHILD_INHERITS_STDIN, > + unset_cloexec, GINT_TO_POINTER(fd), > + NULL, NULL, &status, &error)) { This unset_cloexec callback is relying on knowledge of current internal impl details of g_spawn_sync. The API docs say that all file descriptors will be closed, except for stdin/out/err. We should not assume glib is doing this by setting O_CLOEXEC, as opposed to directly calling close(). If we need specific FDs to remain open, we neeed to be using the other g_spawn_async_with_pipes_and_fds API that accepts a list of FDs to remain open. With regards, Daniel
I tested this series of patches with virtio-net regression tests, everything works fine. Tested-by: Lei Yang <leiyang@redhat.com> On Sat, Jan 4, 2025 at 4:05 PM Akihiko Odaki <akihiko.odaki@daynix.com> wrote: > > g_spawn_sync() gives an informative message if it fails to execute > the script instead of reporting exiting status 1. > > g_spawn_check_wait_status() also gives an message easier to understand > than the raw value returned by waitpid(). > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > --- > net/tap.c | 169 ++++++++++++++++++++++++-------------------------------------- > 1 file changed, 66 insertions(+), 103 deletions(-) > > diff --git a/net/tap.c b/net/tap.c > index ae1c7e398321..392a024f8ed9 100644 > --- a/net/tap.c > +++ b/net/tap.c > @@ -385,56 +385,30 @@ static TAPState *net_tap_fd_init(NetClientState *peer, > return s; > } > > -static void close_all_fds_after_fork(int excluded_fd) > +static void unset_cloexec(gpointer data) > { > - const int skip_fd[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, > - excluded_fd}; > - unsigned int nskip = ARRAY_SIZE(skip_fd); > - > - /* > - * skip_fd must be an ordered array of distinct fds, exclude > - * excluded_fd if already included in the [STDIN_FILENO - STDERR_FILENO] > - * range > - */ > - if (excluded_fd <= STDERR_FILENO) { > - nskip--; > - } > - > - qemu_close_all_open_fd(skip_fd, nskip); > + g_assert(!fcntl(GPOINTER_TO_INT(data), F_SETFD, 0)); > } > > static void launch_script(const char *setup_script, const char *ifname, > int fd, Error **errp) > { > - int pid, status; > - char *args[3]; > - char **parg; > + gint status; > + gchar *argv[] = { (gchar *)setup_script, (gchar *)ifname, NULL }; > + g_autoptr(GError) error = NULL; > > /* try to launch network script */ > - pid = fork(); > - if (pid < 0) { > - error_setg_errno(errp, errno, "could not launch network script %s", > - setup_script); > + if (!g_spawn_sync(NULL, argv, NULL, G_SPAWN_CHILD_INHERITS_STDIN, > + unset_cloexec, GINT_TO_POINTER(fd), > + NULL, NULL, &status, &error)) { > + error_setg(errp, "could not launch network script %s: %s", > + setup_script, error->message); > return; > } > - if (pid == 0) { > - close_all_fds_after_fork(fd); > - parg = args; > - *parg++ = (char *)setup_script; > - *parg++ = (char *)ifname; > - *parg = NULL; > - execv(setup_script, args); > - _exit(1); > - } else { > - while (waitpid(pid, &status, 0) != pid) { > - /* loop */ > - } > > - if (WIFEXITED(status) && WEXITSTATUS(status) == 0) { > - return; > - } > - error_setg(errp, "network script %s failed with status %d", > - setup_script, status); > + if (!g_spawn_check_wait_status(status, &error)) { > + error_setg(errp, "network script %s failed: %s", > + setup_script, error->message); > } > } > > @@ -477,6 +451,12 @@ static int net_bridge_run_helper(const char *helper, const char *bridge, > { > sigset_t oldmask, mask; > g_autofree char *default_helper = NULL; > + g_autofree char *fd_buf = NULL; > + g_autofree char *br_buf = NULL; > + g_autofree char *helper_cmd = NULL; > + g_autoptr(GError) error = NULL; > + int fd; > + int saved_errno; > int pid, status; > char *args[5]; > char **parg; > @@ -495,82 +475,65 @@ static int net_bridge_run_helper(const char *helper, const char *bridge, > return -1; > } > > - /* try to launch bridge helper */ > - pid = fork(); > - if (pid < 0) { > - error_setg_errno(errp, errno, "Can't fork bridge helper"); > - return -1; > - } > - if (pid == 0) { > - char *fd_buf = NULL; > - char *br_buf = NULL; > - char *helper_cmd = NULL; > - > - close_all_fds_after_fork(sv[1]); > - fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]); > + fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]); > > - if (strrchr(helper, ' ') || strrchr(helper, '\t')) { > - /* assume helper is a command */ > + if (strrchr(helper, ' ') || strrchr(helper, '\t')) { > + /* assume helper is a command */ > > - if (strstr(helper, "--br=") == NULL) { > - br_buf = g_strdup_printf("%s%s", "--br=", bridge); > - } > - > - helper_cmd = g_strdup_printf("%s %s %s %s", helper, > - "--use-vnet", fd_buf, br_buf ? br_buf : ""); > - > - parg = args; > - *parg++ = (char *)"sh"; > - *parg++ = (char *)"-c"; > - *parg++ = helper_cmd; > - *parg++ = NULL; > + if (strstr(helper, "--br=") == NULL) { > + br_buf = g_strdup_printf("%s%s", "--br=", bridge); > + } > > - execv("/bin/sh", args); > - g_free(helper_cmd); > - } else { > - /* assume helper is just the executable path name */ > + helper_cmd = g_strdup_printf("%s %s %s %s", helper, > + "--use-vnet", fd_buf, br_buf ? br_buf : ""); > > - br_buf = g_strdup_printf("%s%s", "--br=", bridge); > + parg = args; > + *parg++ = (char *)"sh"; > + *parg++ = (char *)"-c"; > + *parg++ = helper_cmd; > + *parg++ = NULL; > + } else { > + /* assume helper is just the executable path name */ > > - parg = args; > - *parg++ = (char *)helper; > - *parg++ = (char *)"--use-vnet"; > - *parg++ = fd_buf; > - *parg++ = br_buf; > - *parg++ = NULL; > + br_buf = g_strdup_printf("%s%s", "--br=", bridge); > > - execv(helper, args); > - } > - g_free(fd_buf); > - g_free(br_buf); > - _exit(1); > + parg = args; > + *parg++ = (char *)helper; > + *parg++ = (char *)"--use-vnet"; > + *parg++ = fd_buf; > + *parg++ = br_buf; > + *parg++ = NULL; > + } > > - } else { > - int fd; > - int saved_errno; > + /* try to launch bridge helper */ > + if (!g_spawn_async(NULL, args, NULL, > + G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_CHILD_INHERITS_STDIN, > + unset_cloexec, GINT_TO_POINTER(sv[1]), &pid, &error)) { > + error_setg(errp, "could not launch bridge helper: %s", error->message); > + return -1; > + } > > - close(sv[1]); > + close(sv[1]); > > - fd = RETRY_ON_EINTR(recv_fd(sv[0])); > - saved_errno = errno; > + fd = RETRY_ON_EINTR(recv_fd(sv[0])); > + saved_errno = errno; > > - close(sv[0]); > + close(sv[0]); > > - while (waitpid(pid, &status, 0) != pid) { > - /* loop */ > - } > - sigprocmask(SIG_SETMASK, &oldmask, NULL); > - if (fd < 0) { > - error_setg_errno(errp, saved_errno, > - "failed to recv file descriptor"); > - return -1; > - } > - if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { > - error_setg(errp, "bridge helper failed"); > - return -1; > - } > - return fd; > + while (waitpid(pid, &status, 0) != pid) { > + /* loop */ > } > + sigprocmask(SIG_SETMASK, &oldmask, NULL); > + if (fd < 0) { > + error_setg_errno(errp, saved_errno, > + "failed to recv file descriptor"); > + return -1; > + } > + if (!g_spawn_check_wait_status(status, &error)) { > + error_setg(errp, "bridge helper failed: %s", error->message); > + return -1; > + } > + return fd; > } > > int net_init_bridge(const Netdev *netdev, const char *name, > > -- > 2.47.1 > >
diff --git a/net/tap.c b/net/tap.c index ae1c7e398321..392a024f8ed9 100644 --- a/net/tap.c +++ b/net/tap.c @@ -385,56 +385,30 @@ static TAPState *net_tap_fd_init(NetClientState *peer, return s; } -static void close_all_fds_after_fork(int excluded_fd) +static void unset_cloexec(gpointer data) { - const int skip_fd[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, - excluded_fd}; - unsigned int nskip = ARRAY_SIZE(skip_fd); - - /* - * skip_fd must be an ordered array of distinct fds, exclude - * excluded_fd if already included in the [STDIN_FILENO - STDERR_FILENO] - * range - */ - if (excluded_fd <= STDERR_FILENO) { - nskip--; - } - - qemu_close_all_open_fd(skip_fd, nskip); + g_assert(!fcntl(GPOINTER_TO_INT(data), F_SETFD, 0)); } static void launch_script(const char *setup_script, const char *ifname, int fd, Error **errp) { - int pid, status; - char *args[3]; - char **parg; + gint status; + gchar *argv[] = { (gchar *)setup_script, (gchar *)ifname, NULL }; + g_autoptr(GError) error = NULL; /* try to launch network script */ - pid = fork(); - if (pid < 0) { - error_setg_errno(errp, errno, "could not launch network script %s", - setup_script); + if (!g_spawn_sync(NULL, argv, NULL, G_SPAWN_CHILD_INHERITS_STDIN, + unset_cloexec, GINT_TO_POINTER(fd), + NULL, NULL, &status, &error)) { + error_setg(errp, "could not launch network script %s: %s", + setup_script, error->message); return; } - if (pid == 0) { - close_all_fds_after_fork(fd); - parg = args; - *parg++ = (char *)setup_script; - *parg++ = (char *)ifname; - *parg = NULL; - execv(setup_script, args); - _exit(1); - } else { - while (waitpid(pid, &status, 0) != pid) { - /* loop */ - } - if (WIFEXITED(status) && WEXITSTATUS(status) == 0) { - return; - } - error_setg(errp, "network script %s failed with status %d", - setup_script, status); + if (!g_spawn_check_wait_status(status, &error)) { + error_setg(errp, "network script %s failed: %s", + setup_script, error->message); } } @@ -477,6 +451,12 @@ static int net_bridge_run_helper(const char *helper, const char *bridge, { sigset_t oldmask, mask; g_autofree char *default_helper = NULL; + g_autofree char *fd_buf = NULL; + g_autofree char *br_buf = NULL; + g_autofree char *helper_cmd = NULL; + g_autoptr(GError) error = NULL; + int fd; + int saved_errno; int pid, status; char *args[5]; char **parg; @@ -495,82 +475,65 @@ static int net_bridge_run_helper(const char *helper, const char *bridge, return -1; } - /* try to launch bridge helper */ - pid = fork(); - if (pid < 0) { - error_setg_errno(errp, errno, "Can't fork bridge helper"); - return -1; - } - if (pid == 0) { - char *fd_buf = NULL; - char *br_buf = NULL; - char *helper_cmd = NULL; - - close_all_fds_after_fork(sv[1]); - fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]); + fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]); - if (strrchr(helper, ' ') || strrchr(helper, '\t')) { - /* assume helper is a command */ + if (strrchr(helper, ' ') || strrchr(helper, '\t')) { + /* assume helper is a command */ - if (strstr(helper, "--br=") == NULL) { - br_buf = g_strdup_printf("%s%s", "--br=", bridge); - } - - helper_cmd = g_strdup_printf("%s %s %s %s", helper, - "--use-vnet", fd_buf, br_buf ? br_buf : ""); - - parg = args; - *parg++ = (char *)"sh"; - *parg++ = (char *)"-c"; - *parg++ = helper_cmd; - *parg++ = NULL; + if (strstr(helper, "--br=") == NULL) { + br_buf = g_strdup_printf("%s%s", "--br=", bridge); + } - execv("/bin/sh", args); - g_free(helper_cmd); - } else { - /* assume helper is just the executable path name */ + helper_cmd = g_strdup_printf("%s %s %s %s", helper, + "--use-vnet", fd_buf, br_buf ? br_buf : ""); - br_buf = g_strdup_printf("%s%s", "--br=", bridge); + parg = args; + *parg++ = (char *)"sh"; + *parg++ = (char *)"-c"; + *parg++ = helper_cmd; + *parg++ = NULL; + } else { + /* assume helper is just the executable path name */ - parg = args; - *parg++ = (char *)helper; - *parg++ = (char *)"--use-vnet"; - *parg++ = fd_buf; - *parg++ = br_buf; - *parg++ = NULL; + br_buf = g_strdup_printf("%s%s", "--br=", bridge); - execv(helper, args); - } - g_free(fd_buf); - g_free(br_buf); - _exit(1); + parg = args; + *parg++ = (char *)helper; + *parg++ = (char *)"--use-vnet"; + *parg++ = fd_buf; + *parg++ = br_buf; + *parg++ = NULL; + } - } else { - int fd; - int saved_errno; + /* try to launch bridge helper */ + if (!g_spawn_async(NULL, args, NULL, + G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_CHILD_INHERITS_STDIN, + unset_cloexec, GINT_TO_POINTER(sv[1]), &pid, &error)) { + error_setg(errp, "could not launch bridge helper: %s", error->message); + return -1; + } - close(sv[1]); + close(sv[1]); - fd = RETRY_ON_EINTR(recv_fd(sv[0])); - saved_errno = errno; + fd = RETRY_ON_EINTR(recv_fd(sv[0])); + saved_errno = errno; - close(sv[0]); + close(sv[0]); - while (waitpid(pid, &status, 0) != pid) { - /* loop */ - } - sigprocmask(SIG_SETMASK, &oldmask, NULL); - if (fd < 0) { - error_setg_errno(errp, saved_errno, - "failed to recv file descriptor"); - return -1; - } - if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { - error_setg(errp, "bridge helper failed"); - return -1; - } - return fd; + while (waitpid(pid, &status, 0) != pid) { + /* loop */ } + sigprocmask(SIG_SETMASK, &oldmask, NULL); + if (fd < 0) { + error_setg_errno(errp, saved_errno, + "failed to recv file descriptor"); + return -1; + } + if (!g_spawn_check_wait_status(status, &error)) { + error_setg(errp, "bridge helper failed: %s", error->message); + return -1; + } + return fd; } int net_init_bridge(const Netdev *netdev, const char *name,
g_spawn_sync() gives an informative message if it fails to execute the script instead of reporting exiting status 1. g_spawn_check_wait_status() also gives an message easier to understand than the raw value returned by waitpid(). Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> --- net/tap.c | 169 ++++++++++++++++++++++++-------------------------------------- 1 file changed, 66 insertions(+), 103 deletions(-)