Hi Stefan
Am 12.10.22 um 18:04 schrieb marcandre.lureau@redhat.com:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>
> Simplify qio_channel_command_new_spawn() with GSpawn API. This will
> allow to build for WIN32 in the following patches.
>
> As pointed out by Daniel Berrangé: there is a change in semantics here
> too. The current code only touches stdin/stdout/stderr. Any other FDs
> which do NOT have O_CLOEXEC set will be inherited. With the new code,
> all FDs except stdin/out/err will be explicitly closed, because we don't
> set the flag G_SPAWN_LEAVE_DESCRIPTORS_OPEN. The only place we use
> QIOChannelCommand today is the migration exec: protocol, and that is
> only declared to use stdin/stdout.
>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Message-Id: <20221006113657.2656108-5-marcandre.lureau@redhat.com" target="_blank">20221006113657.2656108-5-marcandre.lureau@redhat.com>
> ---
> include/io/channel-command.h | 2 +-
> io/channel-command.c | 105 ++++++-----------------------------
> 2 files changed, 19 insertions(+), 88 deletions(-)
>
> diff --git a/include/io/channel-command.h b/include/io/channel-command.h
> index 305ac1d280..8dc58273c0 100644
> --- a/include/io/channel-command.h
> +++ b/include/io/channel-command.h
> @@ -41,7 +41,7 @@ struct QIOChannelCommand {
> QIOChannel parent;
> int writefd;
> int readfd;
> - pid_t pid;
> + GPid pid;
GPid is a pointer for Windows now. Therefore code like pid > 0 is no
longer valid. As the new initial value is no longer -1, but 0 now, this
patch might fix the code for Windows:
diff --git a/io/channel-command.c b/io/channel-command.c
index 74516252ba..8850a374f1 100644
--- a/io/channel-command.c
+++ b/io/channel-command.c
@@ -175,7 +175,7 @@ static void qio_channel_command_finalize(Object *obj)
close(ioc->writefd);
}
ioc->writefd = ioc->readfd = -1;
- if (ioc->pid > 0) {
+ if (ioc->pid != 0) {
qio_channel_command_abort(ioc, NULL);
g_spawn_close_pid(ioc->pid);
}
Hmm, GPid is an "int" on unix, "void*" on windows. I think the current code should work fine. Do you see really an issue? Your change looks correct to me too, can you send a proper patch with details?
thanks
> };
>
>
> diff --git a/io/channel-command.c b/io/channel-command.c
> index 9f2f4a1793..f84d1f03a0 100644
> --- a/io/channel-command.c
> +++ b/io/channel-command.c
> @@ -31,7 +31,7 @@
> * qio_channel_command_new_pid:
> * @writefd: the FD connected to the command's stdin
> * @readfd: the FD connected to the command's stdout
> - * @pid: the PID of the running child command
> + * @pid: the PID/HANDLE of the running child command
> * @errp: pointer to a NULL-initialized error object
> *
> * Create a channel for performing I/O with the
> @@ -50,7 +50,7 @@
> static QIOChannelCommand *
> qio_channel_command_new_pid(int writefd,
> int readfd,
> - pid_t pid)
> + GPid pid)
> {
> QIOChannelCommand *ioc;
>
> @@ -69,94 +69,24 @@ qio_channel_command_new_spawn(const char *const argv[],
> int flags,
> Error **errp)
> {
> - pid_t pid = -1;
> - int stdinfd[2] = { -1, -1 };
> - int stdoutfd[2] = { -1, -1 };
> - int devnull = -1;
> - bool stdinnull = false, stdoutnull = false;
> - QIOChannelCommand *ioc;
> + g_autoptr(GError) err = NULL;
> + GPid pid = 0;
> + GSpawnFlags gflags = G_SPAWN_CLOEXEC_PIPES | G_SPAWN_DO_NOT_REAP_CHILD;
> + int stdinfd = -1, stdoutfd = -1;
>
> flags = flags & O_ACCMODE;
> -
> - if (flags == O_RDONLY) {
> - stdinnull = true;
> - }
> - if (flags == O_WRONLY) {
> - stdoutnull = true;
> - }
> -
> - if (stdinnull || stdoutnull) {
> - devnull = open("/dev/null", O_RDWR);
> - if (devnull < 0) {
> - error_setg_errno(errp, errno,
> - "Unable to open /dev/null");
> - goto error;
> - }
> - }
> -
> - if ((!stdinnull && !g_unix_open_pipe(stdinfd, FD_CLOEXEC, NULL)) ||
> - (!stdoutnull && !g_unix_open_pipe(stdoutfd, FD_CLOEXEC, NULL))) {
> - error_setg_errno(errp, errno,
> - "Unable to open pipe");
> - goto error;
> - }
> -
> - pid = qemu_fork(errp);
> - if (pid < 0) {
> - goto error;
> - }
> -
> - if (pid == 0) { /* child */
> - dup2(stdinnull ? devnull : stdinfd[0], STDIN_FILENO);
> - dup2(stdoutnull ? devnull : stdoutfd[1], STDOUT_FILENO);
> - /* Leave stderr connected to qemu's stderr */
> -
> - if (!stdinnull) {
> - close(stdinfd[0]);
> - close(stdinfd[1]);
> - }
> - if (!stdoutnull) {
> - close(stdoutfd[0]);
> - close(stdoutfd[1]);
> - }
> - if (devnull != -1) {
> - close(devnull);
> - }
> -
> - execv(argv[0], (char * const *)argv);
> - _exit(1);
> + gflags |= flags == O_WRONLY ? G_SPAWN_STDOUT_TO_DEV_NULL : 0;
> +
> + if (!g_spawn_async_with_pipes(NULL, (char **)argv, NULL, gflags, NULL, NULL,
> + &pid,
> + flags == O_RDONLY ? NULL : &stdinfd,
> + flags == O_WRONLY ? NULL : &stdoutfd,
> + NULL, &err)) {
> + error_setg(errp, "%s", err->message);
> + return NULL;
> }
>
> - if (!stdinnull) {
> - close(stdinfd[0]);
> - }
> - if (!stdoutnull) {
> - close(stdoutfd[1]);
> - }
> -
> - ioc = qio_channel_command_new_pid(stdinnull ? devnull : stdinfd[1],
> - stdoutnull ? devnull : stdoutfd[0],
> - pid);
> - trace_qio_channel_command_new_spawn(ioc, argv[0], flags);
> - return ioc;
> -
> - error:
> - if (devnull != -1) {
> - close(devnull);
> - }
> - if (stdinfd[0] != -1) {
> - close(stdinfd[0]);
> - }
> - if (stdinfd[1] != -1) {
> - close(stdinfd[1]);
> - }
> - if (stdoutfd[0] != -1) {
> - close(stdoutfd[0]);
> - }
> - if (stdoutfd[1] != -1) {
> - close(stdoutfd[1]);
> - }
> - return NULL;
> + return qio_channel_command_new_pid(stdinfd, stdoutfd, pid);
> }
>
> #else /* WIN32 */
> @@ -221,7 +151,7 @@ static void qio_channel_command_init(Object *obj)
> QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
> ioc->readfd = -1;
> ioc->writefd = -1;
> - ioc->pid = -1;
> + ioc->pid = 0;
> }
>
> static void qio_channel_command_finalize(Object *obj)
> @@ -239,6 +169,7 @@ static void qio_channel_command_finalize(Object *obj)
> #ifndef WIN32
> qio_channel_command_abort(ioc, NULL);
> #endif
> + g_spawn_close_pid(ioc->pid);
> }
> }
>