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,
--
2.47.1I 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
>
>
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
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 2025/01/06 18:34, Daniel P. Berrangé wrote:
> 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.
g_spawn_async_with_pipes_and_fds() is not available for 2.66 so we
cannot use it.
An upstream developer says unsetting FD_CLOEXEC in the setup function is
fine in such a scenario. They are not documenting that because new glib
versions they are developing has g_spawn_async_with_pipes_and_fds(),
which is a better alternative:
https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4452
Regards,
Akihiko Odaki
On Wed, Jan 15, 2025 at 03:04:19PM +0900, Akihiko Odaki wrote:
> On 2025/01/06 18:34, Daniel P. Berrangé wrote:
> > 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.
>
> g_spawn_async_with_pipes_and_fds() is not available for 2.66 so we cannot
> use it.
>
> An upstream developer says unsetting FD_CLOEXEC in the setup function is
> fine in such a scenario. They are not documenting that because new glib
> versions they are developing has g_spawn_async_with_pipes_and_fds(), which
> is a better alternative:
> https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4452
That comment only says we're fine to unset FD_CLOEXEC on *historical*
releases of GLib. ie they're not going to break this in a bug fix on
a stable branch of 2.66.x. For anything >= 2.68 they say we need to
be using g_spawn_async_with_pipes_and_fds
IOW, we need to support both code paths today, and in future when we
drop 2.66 compat, we can eliminate the FD_CLOEXEC codepath, leaving
us with only g_spawn_async_with_pipes_and_fds
With regards,
Daniel
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