]> git.proxmox.com Git - qemu.git/blobdiff - qga/commands-posix.c
qemu-ga: execute hook to quiesce the guest on fsfreeze-freeze/thaw
[qemu.git] / qga / commands-posix.c
index e448431c66e658068e9dc94b6337e83089c1d296..77f6ee7d5f6b5e053d5bb0868e7f21dab4aefb13 100644 (file)
 #include <glib.h>
 #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"
-#include "qemu-queue.h"
-#include "host-utils.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/queue.h"
+#include "qemu/host-utils.h"
+
+#ifndef CONFIG_HAS_ENVIRON
+#ifdef __APPLE__
+#include <crt_externs.h>
+#define environ (*_NSGetEnviron())
+#else
+extern char **environ;
+#endif
+#endif
 
 #if defined(__linux__)
 #include <mntent.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
 #include <net/if.h>
-#include <sys/wait.h>
 
-#if defined(__linux__) && defined(FIFREEZE)
+#ifdef FIFREEZE
 #define CONFIG_FSFREEZE
 #endif
+#ifdef FITRIM
+#define CONFIG_FSTRIM
+#endif
 #endif
 
-#if defined(__linux__)
-/* TODO: use this in place of all post-fork() fclose(std*) callers */
-static void reopen_fd_to_null(int fd)
+static void ga_wait_child(pid_t pid, int *status, Error **err)
 {
-    int nullfd;
+    pid_t rpid;
 
-    nullfd = open("/dev/null", O_RDWR);
-    if (nullfd < 0) {
-        return;
-    }
+    *status = 0;
 
-    dup2(nullfd, fd);
+    do {
+        rpid = waitpid(pid, status, 0);
+    } while (rpid == -1 && errno == EINTR);
 
-    if (nullfd != fd) {
-        close(nullfd);
+    if (rpid == -1) {
+        error_setg_errno(err, errno, "failed to wait for child (pid: %d)", pid);
+        return;
     }
+
+    g_assert(rpid == pid);
 }
-#endif /* defined(__linux__) */
 
 void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
 {
-    int ret;
     const char *shutdown_flag;
+    Error *local_err = NULL;
+    pid_t pid;
+    int status;
 
     slog("guest-shutdown called, mode: %s", mode);
     if (!has_mode || strcmp(mode, "powerdown") == 0) {
@@ -66,28 +79,44 @@ void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
     } else if (strcmp(mode, "reboot") == 0) {
         shutdown_flag = "-r";
     } else {
-        error_set(err, QERR_INVALID_PARAMETER_VALUE, "mode",
-                  "halt|powerdown|reboot");
+        error_setg(err,
+                   "mode is invalid (valid values are: halt|powerdown|reboot");
         return;
     }
 
-    ret = fork();
-    if (ret == 0) {
+    pid = fork();
+    if (pid == 0) {
         /* child, start the shutdown */
         setsid();
-        fclose(stdin);
-        fclose(stdout);
-        fclose(stderr);
-
-        ret = execl("/sbin/shutdown", "shutdown", shutdown_flag, "+0",
-                    "hypervisor initiated shutdown", (char*)NULL);
-        if (ret) {
-            slog("guest-shutdown failed: %s", strerror(errno));
-        }
-        exit(!!ret);
-    } else if (ret < 0) {
-        error_set(err, QERR_UNDEFINED_ERROR);
+        reopen_fd_to_null(0);
+        reopen_fd_to_null(1);
+        reopen_fd_to_null(2);
+
+        execle("/sbin/shutdown", "shutdown", shutdown_flag, "+0",
+               "hypervisor initiated shutdown", (char*)NULL, environ);
+        _exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        error_setg_errno(err, errno, "failed to create child process");
+        return;
     }
+
+    ga_wait_child(pid, &status, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return;
+    }
+
+    if (!WIFEXITED(status)) {
+        error_setg(err, "child process has terminated abnormally");
+        return;
+    }
+
+    if (WEXITSTATUS(status)) {
+        error_setg(err, "child process has failed to shutdown");
+        return;
+    }
+
+    /* succeded */
 }
 
 typedef struct GuestFileHandle {
@@ -110,7 +139,7 @@ static void guest_file_handle_add(FILE *fh)
     QTAILQ_INSERT_TAIL(&guest_file_state.filehandles, gfh, next);
 }
 
-static GuestFileHandle *guest_file_handle_find(int64_t id)
+static GuestFileHandle *guest_file_handle_find(int64_t id, Error **err)
 {
     GuestFileHandle *gfh;
 
@@ -121,6 +150,7 @@ static GuestFileHandle *guest_file_handle_find(int64_t id)
         }
     }
 
+    error_setg(err, "handle '%" PRId64 "' has not been found", id);
     return NULL;
 }
 
@@ -136,7 +166,8 @@ int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, E
     slog("guest-file-open called, filepath: %s, mode: %s", path, mode);
     fh = fopen(path, mode);
     if (!fh) {
-        error_set(err, QERR_OPEN_FILE_FAILED, path);
+        error_setg_errno(err, errno, "failed to open file '%s' (mode: '%s')",
+                         path, mode);
         return -1;
     }
 
@@ -147,7 +178,8 @@ int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, E
     ret = fcntl(fd, F_GETFL);
     ret = fcntl(fd, F_SETFL, ret | O_NONBLOCK);
     if (ret == -1) {
-        error_set(err, QERR_QGA_COMMAND_FAILED, "fcntl() failed");
+        error_setg_errno(err, errno, "failed to make file '%s' non-blocking",
+                         path);
         fclose(fh);
         return -1;
     }
@@ -159,18 +191,17 @@ int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, E
 
 void qmp_guest_file_close(int64_t handle, Error **err)
 {
-    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileHandle *gfh = guest_file_handle_find(handle, err);
     int ret;
 
     slog("guest-file-close called, handle: %ld", handle);
     if (!gfh) {
-        error_set(err, QERR_FD_NOT_FOUND, "handle");
         return;
     }
 
     ret = fclose(gfh->fh);
-    if (ret == -1) {
-        error_set(err, QERR_QGA_COMMAND_FAILED, "fclose() failed");
+    if (ret == EOF) {
+        error_setg_errno(err, errno, "failed to close handle");
         return;
     }
 
@@ -181,21 +212,21 @@ void qmp_guest_file_close(int64_t handle, Error **err)
 struct GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count,
                                           int64_t count, Error **err)
 {
-    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileHandle *gfh = guest_file_handle_find(handle, err);
     GuestFileRead *read_data = NULL;
     guchar *buf;
     FILE *fh;
     size_t read_count;
 
     if (!gfh) {
-        error_set(err, QERR_FD_NOT_FOUND, "handle");
         return NULL;
     }
 
     if (!has_count) {
         count = QGA_READ_COUNT_DEFAULT;
     } else if (count < 0) {
-        error_set(err, QERR_INVALID_PARAMETER, "count");
+        error_setg(err, "value '%" PRId64 "' is invalid for argument count",
+                   count);
         return NULL;
     }
 
@@ -203,8 +234,8 @@ struct GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count,
     buf = g_malloc0(count+1);
     read_count = fread(buf, 1, count, fh);
     if (ferror(fh)) {
+        error_setg_errno(err, errno, "failed to read file");
         slog("guest-file-read failed, handle: %ld", handle);
-        error_set(err, QERR_QGA_COMMAND_FAILED, "fread() failed");
     } else {
         buf[read_count] = 0;
         read_data = g_malloc0(sizeof(GuestFileRead));
@@ -227,11 +258,10 @@ GuestFileWrite *qmp_guest_file_write(int64_t handle, const char *buf_b64,
     guchar *buf;
     gsize buf_len;
     int write_count;
-    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileHandle *gfh = guest_file_handle_find(handle, err);
     FILE *fh;
 
     if (!gfh) {
-        error_set(err, QERR_FD_NOT_FOUND, "handle");
         return NULL;
     }
 
@@ -241,15 +271,16 @@ GuestFileWrite *qmp_guest_file_write(int64_t handle, const char *buf_b64,
     if (!has_count) {
         count = buf_len;
     } else if (count < 0 || count > buf_len) {
+        error_setg(err, "value '%" PRId64 "' is invalid for argument count",
+                   count);
         g_free(buf);
-        error_set(err, QERR_INVALID_PARAMETER, "count");
         return NULL;
     }
 
     write_count = fwrite(buf, 1, count, fh);
     if (ferror(fh)) {
+        error_setg_errno(err, errno, "failed to write to file");
         slog("guest-file-write failed, handle: %ld", handle);
-        error_set(err, QERR_QGA_COMMAND_FAILED, "fwrite() error");
     } else {
         write_data = g_malloc0(sizeof(GuestFileWrite));
         write_data->count = write_count;
@@ -264,20 +295,19 @@ GuestFileWrite *qmp_guest_file_write(int64_t handle, const char *buf_b64,
 struct GuestFileSeek *qmp_guest_file_seek(int64_t handle, int64_t offset,
                                           int64_t whence, Error **err)
 {
-    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileHandle *gfh = guest_file_handle_find(handle, err);
     GuestFileSeek *seek_data = NULL;
     FILE *fh;
     int ret;
 
     if (!gfh) {
-        error_set(err, QERR_FD_NOT_FOUND, "handle");
         return NULL;
     }
 
     fh = gfh->fh;
     ret = fseek(fh, offset, whence);
     if (ret == -1) {
-        error_set(err, QERR_QGA_COMMAND_FAILED, strerror(errno));
+        error_setg_errno(err, errno, "failed to seek file");
     } else {
         seek_data = g_malloc0(sizeof(GuestFileRead));
         seek_data->position = ftell(fh);
@@ -290,19 +320,18 @@ struct GuestFileSeek *qmp_guest_file_seek(int64_t handle, int64_t offset,
 
 void qmp_guest_file_flush(int64_t handle, Error **err)
 {
-    GuestFileHandle *gfh = guest_file_handle_find(handle);
+    GuestFileHandle *gfh = guest_file_handle_find(handle, err);
     FILE *fh;
     int ret;
 
     if (!gfh) {
-        error_set(err, QERR_FD_NOT_FOUND, "handle");
         return;
     }
 
     fh = gfh->fh;
     ret = fflush(fh);
     if (ret == EOF) {
-        error_set(err, QERR_QGA_COMMAND_FAILED, strerror(errno));
+        error_setg_errno(err, errno, "failed to flush file");
     }
 }
 
@@ -314,19 +343,18 @@ static void guest_file_init(void)
 /* linux-specific implementations. avoid this if at all possible. */
 #if defined(__linux__)
 
-#if defined(CONFIG_FSFREEZE)
-
-typedef struct GuestFsfreezeMount {
+#if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM)
+typedef struct FsMount {
     char *dirname;
     char *devtype;
-    QTAILQ_ENTRY(GuestFsfreezeMount) next;
-} GuestFsfreezeMount;
+    QTAILQ_ENTRY(FsMount) next;
+} FsMount;
 
-typedef QTAILQ_HEAD(, GuestFsfreezeMount) GuestFsfreezeMountList;
+typedef QTAILQ_HEAD(, FsMount) FsMountList;
 
-static void guest_fsfreeze_free_mount_list(GuestFsfreezeMountList *mounts)
+static void free_fs_mount_list(FsMountList *mounts)
 {
-     GuestFsfreezeMount *mount, *temp;
+     FsMount *mount, *temp;
 
      if (!mounts) {
          return;
@@ -343,17 +371,17 @@ static void guest_fsfreeze_free_mount_list(GuestFsfreezeMountList *mounts)
 /*
  * Walk the mount table and build a list of local file systems
  */
-static int guest_fsfreeze_build_mount_list(GuestFsfreezeMountList *mounts)
+static void build_fs_mount_list(FsMountList *mounts, Error **err)
 {
     struct mntent *ment;
-    GuestFsfreezeMount *mount;
-    char const *mtab = MOUNTED;
+    FsMount *mount;
+    char const *mtab = "/proc/self/mounts";
     FILE *fp;
 
     fp = setmntent(mtab, "r");
     if (!fp) {
-        g_warning("fsfreeze: unable to read mtab");
-        return -1;
+        error_setg(err, "failed to open mtab file: '%s'", mtab);
+        return;
     }
 
     while ((ment = getmntent(fp))) {
@@ -369,7 +397,7 @@ static int guest_fsfreeze_build_mount_list(GuestFsfreezeMountList *mounts)
             continue;
         }
 
-        mount = g_malloc0(sizeof(GuestFsfreezeMount));
+        mount = g_malloc0(sizeof(FsMount));
         mount->dirname = g_strdup(ment->mnt_dir);
         mount->devtype = g_strdup(ment->mnt_type);
 
@@ -377,8 +405,69 @@ static int guest_fsfreeze_build_mount_list(GuestFsfreezeMountList *mounts)
     }
 
     endmntent(fp);
+}
+#endif
 
-    return 0;
+#if defined(CONFIG_FSFREEZE)
+
+typedef enum {
+    FSFREEZE_HOOK_THAW = 0,
+    FSFREEZE_HOOK_FREEZE,
+} FsfreezeHookArg;
+
+const char *fsfreeze_hook_arg_string[] = {
+    "thaw",
+    "freeze",
+};
+
+static void execute_fsfreeze_hook(FsfreezeHookArg arg, Error **err)
+{
+    int status;
+    pid_t pid;
+    const char *hook;
+    const char *arg_str = fsfreeze_hook_arg_string[arg];
+    Error *local_err = NULL;
+
+    hook = ga_fsfreeze_hook(ga_state);
+    if (!hook) {
+        return;
+    }
+    if (access(hook, X_OK) != 0) {
+        error_setg_errno(err, errno, "can't access fsfreeze hook '%s'", hook);
+        return;
+    }
+
+    slog("executing fsfreeze hook with arg '%s'", arg_str);
+    pid = fork();
+    if (pid == 0) {
+        setsid();
+        reopen_fd_to_null(0);
+        reopen_fd_to_null(1);
+        reopen_fd_to_null(2);
+
+        execle(hook, hook, arg_str, NULL, environ);
+        _exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        error_setg_errno(err, errno, "failed to create child process");
+        return;
+    }
+
+    ga_wait_child(pid, &status, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return;
+    }
+
+    if (!WIFEXITED(status)) {
+        error_setg(err, "fsfreeze hook has terminated abnormally");
+        return;
+    }
+
+    status = WEXITSTATUS(status);
+    if (status) {
+        error_setg(err, "fsfreeze hook has failed with status %d", status);
+        return;
+    }
 }
 
 /*
@@ -400,17 +489,24 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
 int64_t qmp_guest_fsfreeze_freeze(Error **err)
 {
     int ret = 0, i = 0;
-    GuestFsfreezeMountList mounts;
-    struct GuestFsfreezeMount *mount;
+    FsMountList mounts;
+    struct FsMount *mount;
+    Error *local_err = NULL;
     int fd;
-    char err_msg[512];
 
     slog("guest-fsfreeze called");
 
+    execute_fsfreeze_hook(FSFREEZE_HOOK_FREEZE, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return -1;
+    }
+
     QTAILQ_INIT(&mounts);
-    ret = guest_fsfreeze_build_mount_list(&mounts);
-    if (ret < 0) {
-        return ret;
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return -1;
     }
 
     /* cannot risk guest agent blocking itself on a write in this state */
@@ -419,9 +515,7 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err)
     QTAILQ_FOREACH(mount, &mounts, next) {
         fd = qemu_open(mount->dirname, O_RDONLY);
         if (fd == -1) {
-            sprintf(err_msg, "failed to open %s, %s", mount->dirname,
-                    strerror(errno));
-            error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
+            error_setg_errno(err, errno, "failed to open %s", mount->dirname);
             goto error;
         }
 
@@ -437,9 +531,8 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err)
         ret = ioctl(fd, FIFREEZE);
         if (ret == -1) {
             if (errno != EOPNOTSUPP) {
-                sprintf(err_msg, "failed to freeze %s, %s",
-                        mount->dirname, strerror(errno));
-                error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(err, errno, "failed to freeze %s",
+                                 mount->dirname);
                 close(fd);
                 goto error;
             }
@@ -449,11 +542,11 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err)
         close(fd);
     }
 
-    guest_fsfreeze_free_mount_list(&mounts);
+    free_fs_mount_list(&mounts);
     return i;
 
 error:
-    guest_fsfreeze_free_mount_list(&mounts);
+    free_fs_mount_list(&mounts);
     qmp_guest_fsfreeze_thaw(NULL);
     return 0;
 }
@@ -464,15 +557,15 @@ error:
 int64_t qmp_guest_fsfreeze_thaw(Error **err)
 {
     int ret;
-    GuestFsfreezeMountList mounts;
-    GuestFsfreezeMount *mount;
+    FsMountList mounts;
+    FsMount *mount;
     int fd, i = 0, logged;
+    Error *local_err = NULL;
 
     QTAILQ_INIT(&mounts);
-    ret = guest_fsfreeze_build_mount_list(&mounts);
-    if (ret) {
-        error_set(err, QERR_QGA_COMMAND_FAILED,
-                  "failed to enumerate filesystems");
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
         return 0;
     }
 
@@ -509,7 +602,10 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
     }
 
     ga_unset_frozen(ga_state);
-    guest_fsfreeze_free_mount_list(&mounts);
+    free_fs_mount_list(&mounts);
+
+    execute_fsfreeze_hook(FSFREEZE_HOOK_THAW, err);
+
     return i;
 }
 
@@ -527,121 +623,158 @@ static void guest_fsfreeze_cleanup(void)
 }
 #endif /* CONFIG_FSFREEZE */
 
+#if defined(CONFIG_FSTRIM)
+/*
+ * Walk list of mounted file systems in the guest, and trim them.
+ */
+void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **err)
+{
+    int ret = 0;
+    FsMountList mounts;
+    struct FsMount *mount;
+    int fd;
+    Error *local_err = NULL;
+    struct fstrim_range r = {
+        .start = 0,
+        .len = -1,
+        .minlen = has_minimum ? minimum : 0,
+    };
+
+    slog("guest-fstrim called");
+
+    QTAILQ_INIT(&mounts);
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return;
+    }
+
+    QTAILQ_FOREACH(mount, &mounts, next) {
+        fd = qemu_open(mount->dirname, O_RDONLY);
+        if (fd == -1) {
+            error_setg_errno(err, errno, "failed to open %s", mount->dirname);
+            goto error;
+        }
+
+        /* We try to cull filesytems we know won't work in advance, but other
+         * filesytems may not implement fstrim for less obvious reasons.  These
+         * will report EOPNOTSUPP; we simply ignore these errors.  Any other
+         * error means an unexpected error, so return it in those cases.  In
+         * some other cases ENOTTY will be reported (e.g. CD-ROMs).
+         */
+        ret = ioctl(fd, FITRIM, &r);
+        if (ret == -1) {
+            if (errno != ENOTTY && errno != EOPNOTSUPP) {
+                error_setg_errno(err, errno, "failed to trim %s",
+                                 mount->dirname);
+                close(fd);
+                goto error;
+            }
+        }
+        close(fd);
+    }
+
+error:
+    free_fs_mount_list(&mounts);
+}
+#endif /* CONFIG_FSTRIM */
+
+
 #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;
+    Error *local_err = NULL;
     char *pmutils_path;
-    int status, pipefds[2];
-
-    if (pipe(pipefds) < 0) {
-        error_set(err, QERR_UNDEFINED_ERROR);
-        return;
-    }
+    pid_t pid;
+    int status;
 
     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);
+        char buf[32]; /* hopefully big enough */
+        ssize_t ret;
+        int fd;
 
         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);
-            }
+        if (pmutils_path) {
+            execle(pmutils_path, pmutils_bin, pmutils_arg, NULL, environ);
+        }
 
-            ret = read(fd, buf, sizeof(buf)-1);
-            if (ret <= 0) {
-                _exit(SUSPEND_NOT_SUPPORTED);
-            }
-            buf[ret] = '\0';
+        /*
+         * 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 (strstr(buf, sysfile_str)) {
-                _exit(SUSPEND_SUPPORTED);
-            }
+        if (!sysfile_str) {
+            _exit(SUSPEND_NOT_SUPPORTED);
+        }
 
+        fd = open(LINUX_SYS_STATE_FILE, O_RDONLY);
+        if (fd < 0) {
             _exit(SUSPEND_NOT_SUPPORTED);
         }
 
-        if (pid > 0) {
-            wait(&status);
-        } else {
-            status = SUSPEND_NOT_SUPPORTED;
+        ret = read(fd, buf, sizeof(buf)-1);
+        if (ret <= 0) {
+            _exit(SUSPEND_NOT_SUPPORTED);
         }
+        buf[ret] = '\0';
 
-        ret = write(pipefds[1], &status, sizeof(status));
-        if (ret != sizeof(status)) {
-            _exit(EXIT_FAILURE);
+        if (strstr(buf, sysfile_str)) {
+            _exit(SUSPEND_SUPPORTED);
         }
 
-        _exit(EXIT_SUCCESS);
+        _exit(SUSPEND_NOT_SUPPORTED);
+    } else if (pid < 0) {
+        error_setg_errno(err, errno, "failed to create child process");
+        goto out;
     }
 
-    close(pipefds[1]);
-    g_free(pmutils_path);
-
-    if (pid < 0) {
-        error_set(err, QERR_UNDEFINED_ERROR);
+    ga_wait_child(pid, &status, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
         goto out;
     }
 
-    ret = read(pipefds[0], &status, sizeof(status));
-    if (ret == sizeof(status) && WIFEXITED(status) &&
-        WEXITSTATUS(status) == SUSPEND_SUPPORTED) {
-            goto out;
+    if (!WIFEXITED(status)) {
+        error_setg(err, "child process has terminated abnormally");
+        goto out;
     }
 
-    error_set(err, QERR_UNSUPPORTED);
+    switch (WEXITSTATUS(status)) {
+    case SUSPEND_SUPPORTED:
+        goto out;
+    case SUSPEND_NOT_SUPPORTED:
+        error_setg(err,
+                   "the requested suspend mode is not supported by the guest");
+        goto out;
+    default:
+        error_setg(err,
+                   "the helper program '%s' returned an unexpected exit status"
+                   " code (%d)", pmutils_path, WEXITSTATUS(status));
+        goto out;
+    }
 
 out:
-    close(pipefds[0]);
+    g_free(pmutils_path);
 }
 
 static void guest_suspend(const char *pmutils_bin, const char *sysfile_str,
                           Error **err)
 {
-    pid_t pid;
+    Error *local_err = NULL;
     char *pmutils_path;
+    pid_t pid;
+    int status;
 
     pmutils_path = g_find_program_in_path(pmutils_bin);
 
@@ -678,14 +811,29 @@ static void guest_suspend(const char *pmutils_bin, const char *sysfile_str,
         }
 
         _exit(EXIT_SUCCESS);
+    } else if (pid < 0) {
+        error_setg_errno(err, errno, "failed to create child process");
+        goto out;
     }
 
-    g_free(pmutils_path);
+    ga_wait_child(pid, &status, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        goto out;
+    }
 
-    if (pid < 0) {
-        error_set(err, QERR_UNDEFINED_ERROR);
-        return;
+    if (!WIFEXITED(status)) {
+        error_setg(err, "child process has terminated abnormally");
+        goto out;
     }
+
+    if (WEXITSTATUS(status)) {
+        error_setg(err, "child process has failed to suspend");
+        goto out;
+    }
+
+out:
+    g_free(pmutils_path);
 }
 
 void qmp_guest_suspend_disk(Error **err)
@@ -738,12 +886,9 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
 {
     GuestNetworkInterfaceList *head = NULL, *cur_item = NULL;
     struct ifaddrs *ifap, *ifa;
-    char err_msg[512];
 
     if (getifaddrs(&ifap) < 0) {
-        snprintf(err_msg, sizeof(err_msg),
-                 "getifaddrs failed: %s", strerror(errno));
-        error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+        error_setg_errno(errp, errno, "getifaddrs failed");
         goto error;
     }
 
@@ -779,20 +924,16 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
             /* we haven't obtained HW address yet */
             sock = socket(PF_INET, SOCK_STREAM, 0);
             if (sock == -1) {
-                snprintf(err_msg, sizeof(err_msg),
-                         "failed to create socket: %s", strerror(errno));
-                error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(errp, errno, "failed to create socket");
                 goto error;
             }
 
             memset(&ifr, 0, sizeof(ifr));
-            strncpy(ifr.ifr_name,  info->value->name, IF_NAMESIZE);
+            pstrcpy(ifr.ifr_name, IF_NAMESIZE, info->value->name);
             if (ioctl(sock, SIOCGIFHWADDR, &ifr) == -1) {
-                snprintf(err_msg, sizeof(err_msg),
-                         "failed to get MAC address of %s: %s",
-                         ifa->ifa_name,
-                         strerror(errno));
-                error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(errp, errno,
+                                 "failed to get MAC address of %s",
+                                 ifa->ifa_name);
                 goto error;
             }
 
@@ -803,9 +944,7 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
                          (int) mac_addr[0], (int) mac_addr[1],
                          (int) mac_addr[2], (int) mac_addr[3],
                          (int) mac_addr[4], (int) mac_addr[5]) == -1) {
-                snprintf(err_msg, sizeof(err_msg),
-                         "failed to format MAC: %s", strerror(errno));
-                error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(errp, errno, "failed to format MAC");
                 goto error;
             }
 
@@ -820,9 +959,7 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
             address_item->value = g_malloc0(sizeof(*address_item->value));
             p = &((struct sockaddr_in *)ifa->ifa_addr)->sin_addr;
             if (!inet_ntop(AF_INET, p, addr4, sizeof(addr4))) {
-                snprintf(err_msg, sizeof(err_msg),
-                         "inet_ntop failed : %s", strerror(errno));
-                error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(errp, errno, "inet_ntop failed");
                 goto error;
             }
 
@@ -842,9 +979,7 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
             address_item->value = g_malloc0(sizeof(*address_item->value));
             p = &((struct sockaddr_in6 *)ifa->ifa_addr)->sin6_addr;
             if (!inet_ntop(AF_INET6, p, addr6, sizeof(addr6))) {
-                snprintf(err_msg, sizeof(err_msg),
-                         "inet_ntop failed : %s", strerror(errno));
-                error_set(errp, QERR_QGA_COMMAND_FAILED, err_msg);
+                error_setg_errno(errp, errno, "inet_ntop failed");
                 goto error;
             }
 
@@ -940,7 +1075,13 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
 
     return 0;
 }
+#endif /* CONFIG_FSFREEZE */
 
+#if !defined(CONFIG_FSTRIM)
+void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+}
 #endif
 
 /* register init/cleanup routines for stateful command groups */