qemu-ga: add guest-suspend-disk

[qemu.git] / qga / commands-posix.c

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 126127aae418e1ce87d224449d26156fa5229e27..af785f5e5d3245afbbc6e3ba33a8bd7a40c5af64 100644 (file)
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -23,6 +23,7 @@
 
 #include <sys/types.h>
 #include <sys/ioctl.h>
+#include <sys/wait.h>
 #include "qga/guest-agent-core.h"
 #include "qga-qmp-commands.h"
 #include "qerror.h"
@@ -30,6 +31,22 @@
 
 static GAState *ga_state;
 
+static void reopen_fd_to_null(int fd)
+{
+    int nullfd;
+
+    nullfd = open("/dev/null", O_RDWR);
+    if (nullfd < 0) {
+        return;
+    }
+
+    dup2(nullfd, fd);
+
+    if (nullfd != fd) {
+        close(nullfd);
+    }
+}
+
 void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
 {
     int ret;
@@ -517,6 +534,177 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
 }
 #endif
 
+#define LINUX_SYS_STATE_FILE "/sys/power/state"
+#define SUSPEND_SUPPORTED 0
+#define SUSPEND_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 void bios_supports_mode(const char *pmutils_bin, const char *pmutils_arg,
+                               const char *sysfile_str, Error **err)
+{
+    pid_t pid;
+    ssize_t ret;
+    char *pmutils_path;
+    int status, pipefds[2];
+
+    if (pipe(pipefds) < 0) {
+        error_set(err, QERR_UNDEFINED_ERROR);
+        return;
+    }
+
+    pmutils_path = g_find_program_in_path(pmutils_bin);
+
+    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 */
+
+            if (pmutils_path) {
+                execle(pmutils_path, pmutils_bin, pmutils_arg, NULL, environ);
+            }
+
+            /*
+             * If we get here either pm-utils is not installed or execle() has
+             * failed. Let's try the manual method if the caller wants it.
+             */
+
+            if (!sysfile_str) {
+                _exit(SUSPEND_NOT_SUPPORTED);
+            }
+
+            fd = open(LINUX_SYS_STATE_FILE, O_RDONLY);
+            if (fd < 0) {
+                _exit(SUSPEND_NOT_SUPPORTED);
+            }
+
+            ret = read(fd, buf, sizeof(buf)-1);
+            if (ret <= 0) {
+                _exit(SUSPEND_NOT_SUPPORTED);
+            }
+            buf[ret] = '\0';
+
+            if (strstr(buf, sysfile_str)) {
+                _exit(SUSPEND_SUPPORTED);
+            }
+
+            _exit(SUSPEND_NOT_SUPPORTED);
+        }
+
+        if (pid > 0) {
+            wait(&status);
+        } else {
+            status = SUSPEND_NOT_SUPPORTED;
+        }
+
+        ret = write(pipefds[1], &status, sizeof(status));
+        if (ret != sizeof(status)) {
+            _exit(EXIT_FAILURE);
+        }
+
+        _exit(EXIT_SUCCESS);
+    }
+
+    close(pipefds[1]);
+    g_free(pmutils_path);
+
+    if (pid < 0) {
+        error_set(err, QERR_UNDEFINED_ERROR);
+        goto out;
+    }
+
+    ret = read(pipefds[0], &status, sizeof(status));
+    if (ret == sizeof(status) && WIFEXITED(status) &&
+        WEXITSTATUS(status) == SUSPEND_SUPPORTED) {
+            goto out;
+    }
+
+    error_set(err, QERR_UNSUPPORTED);
+
+out:
+    close(pipefds[0]);
+}
+
+static void guest_suspend(const char *pmutils_bin, const char *sysfile_str,
+                          Error **err)
+{
+    pid_t pid;
+    char *pmutils_path;
+
+    pmutils_path = g_find_program_in_path(pmutils_bin);
+
+    pid = fork();
+    if (pid == 0) {
+        /* child */
+        int fd;
+
+        setsid();
+        reopen_fd_to_null(0);
+        reopen_fd_to_null(1);
+        reopen_fd_to_null(2);
+
+        if (pmutils_path) {
+            execle(pmutils_path, pmutils_bin, NULL, environ);
+        }
+
+        /*
+         * If we get here either pm-utils is not installed or execle() has
+         * failed. Let's try the manual method if the caller wants it.
+         */
+
+        if (!sysfile_str) {
+            _exit(EXIT_FAILURE);
+        }
+
+        fd = open(LINUX_SYS_STATE_FILE, O_WRONLY);
+        if (fd < 0) {
+            _exit(EXIT_FAILURE);
+        }
+
+        if (write(fd, sysfile_str, strlen(sysfile_str)) < 0) {
+            _exit(EXIT_FAILURE);
+        }
+
+        _exit(EXIT_SUCCESS);
+    }
+
+    g_free(pmutils_path);
+
+    if (pid < 0) {
+        error_set(err, QERR_UNDEFINED_ERROR);
+        return;
+    }
+}
+
+void qmp_guest_suspend_disk(Error **err)
+{
+    bios_supports_mode("pm-is-supported", "--hibernate", "disk", err);
+    if (error_is_set(err)) {
+        return;
+    }
+
+    guest_suspend("pm-hibernate", "disk", err);
+}
+
 /* register init/cleanup routines for stateful command groups */
 void ga_command_state_init(GAState *s, GACommandState *cs)
 {