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Re: [Qemu-devel] [PATCH 2/2] qemu-ga: Add the guest-suspend command
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] qemu-ga: Add the guest-suspend command |
Date: |
Mon, 16 Jan 2012 21:06:27 +0000 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Jan 16, 2012 at 06:09:52PM -0200, Luiz Capitulino wrote:
> +/* Try to find executable file 'file'. If it's found, its absolute path is
> + returned in 'abs_path' and the function returns true. If it's not found,
> + the function will return false and 'abs_path' will contain zeros */
> +static bool find_executable_file(const char *file, char *abs_path, size_t
> len)
> +{
> + char *path, *saveptr;
> + const char *token, *delim = ":";
> +
> + if (!getenv("PATH")) {
> + return false;
> + }
> +
> + path = g_strdup(getenv("PATH"));
> + if (!path) {
> + return false;
> + }
> +
> + for (token = strtok_r(path, delim, &saveptr); token;
> + token = strtok_r(NULL, delim, &saveptr)) {
> + snprintf(abs_path, len, "%s/%s", token, file);
> + if (access(abs_path, X_OK) == 0) {
> + g_free(path);
> + return true;
> + }
> + }
> +
> + g_free(path);
> + memset(abs_path, 0, len);
> +
> + return false;
> +}
I hope you don't hate me for now pointing out...
g_find_program_in_path()
http://developer.gnome.org/glib/stable/glib-Miscellaneous-Utility-Functions.html#g-find-program-in-path
> +
> int64_t qmp_guest_sync(int64_t id, Error **errp)
> {
> return id;
> @@ -574,6 +623,220 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
> }
> #endif
>
> +#define LINUX_SYS_STATE_FILE "/sys/power/state"
> +#define SUS_MODE_SUPPORTED 0
> +#define SUS_MODE_NOT_SUPPORTED 1
> +
> +/**
> + * This function forks twice and the information about the mode support
> + * status is passed to the qemu-ga process via a pipe.
> + *
> + * This approach allows us to keep the way we reap terminated children
> + * in qemu-ga quite simple.
> + */
> +static bool bios_supports_mode(const char *mode, Error **err)
> +{
> + pid_t pid;
> + ssize_t ret;
> + bool has_pmutils;
> + int status, pipefds[2];
> + char pmutils_path[PATH_MAX];
> + const char *pmutils_bin = "pm-is-supported";
> +
> + if (pipe(pipefds) < 0) {
> + error_set(err, QERR_UNDEFINED_ERROR);
> + return false;
> + }
> +
> + has_pmutils = find_executable_file(pmutils_bin, pmutils_path,
> + sizeof(pmutils_path));
> +
> + pid = fork();
> + if (!pid) {
> + struct sigaction act;
> +
> + memset(&act, 0, sizeof(act));
> + act.sa_handler = SIG_DFL;
> + sigaction(SIGCHLD, &act, NULL);
> +
> + setsid();
> + close(pipefds[0]);
> + reopen_fd_to_null(0);
> + reopen_fd_to_null(1);
> + reopen_fd_to_null(2);
> +
> + pid = fork();
> + if (!pid) {
> + int fd;
> + char buf[32]; /* hopefully big enough */
> + const char *arg;
> +
> + if (strcmp(mode, "hibernate") == 0) {
> + arg = "--hibernate";
> + } else if (strcmp(mode, "sleep") == 0) {
> + arg = "--suspend";
> + } else if (strcmp(mode, "hybrid") == 0) {
> + arg = "--suspend-hybrid";
> + } else {
> + _exit(SUS_MODE_NOT_SUPPORTED);
> + }
> +
> + if (has_pmutils) {
> + execle(pmutils_path, pmutils_bin, arg, NULL, environ);
> + }
> +
> + /*
> + * If we get here either pm-utils is not installed or execle()
> has
> + * failed. Let's try the manual approach if mode is not hybrid
> (as
> + * it's only supported by pm-utils)
> + */
> +
> + if (strcmp(mode, "hybrid") == 0) {
> + _exit(SUS_MODE_NOT_SUPPORTED);
> + }
> +
> + fd = open(LINUX_SYS_STATE_FILE, O_RDONLY);
> + if (fd < 0) {
> + _exit(SUS_MODE_NOT_SUPPORTED);
> + }
> +
> + ret = read(fd, buf, sizeof(buf));
You want "sizeof(buf)-1" here, otherwise if read return 'ret'
set to exactly sizeof(buf)...
> + if (ret <= 0) {
> + _exit(SUS_MODE_NOT_SUPPORTED);
> + }
> +
> + buf[ret] = '\0';
...this becomes a stack overflow.
> + has_pmutils = find_executable_file(pmutils_bin, pmutils_path,
> + sizeof(pmutils_path));
> +
> + pid = fork();
> + if (pid == 0) {
> + /* child */
> + int fd;
> + const char *cmd;
> +
> + setsid();
> + reopen_fd_to_null(0);
> + reopen_fd_to_null(1);
> + reopen_fd_to_null(2);
> +
> + if (has_pmutils) {
> + execle(pmutils_path, pmutils_bin, NULL, environ);
You could just use execl() and drop the trailing 'environ' here,
since that is the default anyway.
> + }
> +
> + /*
> + * If we get here either pm-utils is not installed or execle() has
> + * failed. Let's try the manual approach if mode is not hybrid (as
> + * it's only supported by pm-utils)
> + */
> +
> + slog("could not execute %s\n", pmutils_bin);
> + if (strcmp(mode, "hybrid") == 0) {
> + _exit(EXIT_FAILURE);
> + }
> +
> + slog("trying to suspend using the manual method...\n");
> +
> + fd = open(LINUX_SYS_STATE_FILE, O_WRONLY);
> + if (fd < 0) {
> + slog("can't open file %s: %s\n", LINUX_SYS_STATE_FILE,
> + strerror(errno));
> + _exit(EXIT_FAILURE);
> + }
> +
> + cmd = strcmp(mode, "sleep") == 0 ? "mem" : "disk";
> + if (write(fd, cmd, strlen(cmd)) < 0) {
> + slog("failued to write to %s\n", LINUX_SYS_STATE_FILE);
> + _exit(EXIT_FAILURE);
> + }
> +
> + _exit(EXIT_SUCCESS);
> + } else if (pid < 0) {
> + error_set(err, QERR_UNDEFINED_ERROR);
> + return;
> + }
> +}
> +
> /* register init/cleanup routines for stateful command groups */
> void ga_command_state_init(GAState *s, GACommandState *cs)
> {
Regards,
Daniel
--
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