7:52 a.m.
Direct access to an open file is so much simpler than passing
everything through a pipe!
* src/qemu/qemu_driver.c (qemudOpenAsUID)
(qemudDomainSaveImageClose): Delete.
(qemudDomainSaveImageOpen): Rename...
(qemuDomainSaveImageOpen): ...and drop read_pid argument. Use
virFileOpenAs instead of qemudOpenAsUID.
(qemudDomainSaveImageStartVM, qemudDomainRestore)
(qemudDomainObjRestore): Rename...
(qemuDomainSaveImageStartVM, qemuDomainRestore)
(qemDomainObjRestore): ...and simplify accordingly.
(qemudDomainObjStart, qemuDriver): Update callers.
---
v5: no major changes
src/qemu/qemu_driver.c | 265 ++++++++---------------------------------------
1 files changed, 45 insertions(+), 220 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 6ecfbd6..2c852c0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3048,183 +3048,32 @@ cleanup:
return ret;
}
-/* qemudOpenAsUID() - pipe/fork/setuid/open a file, and return the
- pipe fd to caller, so that it can read from the file. Also return
- the pid of the child process, so the caller can wait for it to exit
- after it's finished reading (to avoid a zombie, if nothing
- else). */
-
-static int
-qemudOpenAsUID(const char *path, uid_t uid, gid_t gid, pid_t *child_pid)
-{
- int pipefd[2];
- int fd = -1;
-
- *child_pid = -1;
-
- if (pipe(pipefd) < 0) {
- virReportSystemError(errno,
- _("failed to create pipe to read '%s'"),
- path);
- pipefd[0] = pipefd[1] = -1;
- goto parent_cleanup;
- }
-
- int forkRet = virFork(child_pid);
-
- if (*child_pid < 0) {
- virReportSystemError(errno,
- _("failed to fork child to read '%s'"),
- path);
- goto parent_cleanup;
- }
-
- if (*child_pid > 0) {
-
- /* parent */
-
- /* parent doesn't need the write side of the pipe */
- VIR_FORCE_CLOSE(pipefd[1]);
-
- if (forkRet < 0) {
- virReportSystemError(errno,
- _("failed in parent after forking child to read
'%s'"),
- path);
- goto parent_cleanup;
- }
- /* caller gets the read side of the pipe */
- fd = pipefd[0];
- pipefd[0] = -1;
-parent_cleanup:
- VIR_FORCE_CLOSE(pipefd[0]);
- VIR_FORCE_CLOSE(pipefd[1]);
- if ((fd < 0) && (*child_pid > 0)) {
- /* a child process was started and subsequently an error
- occurred in the parent, so we need to wait for it to
- exit, but its status is inconsequential. */
- while ((waitpid(*child_pid, NULL, 0) == -1)
- && (errno == EINTR)) {
- /* empty */
- }
- *child_pid = -1;
- }
- return fd;
- }
-
- /* child */
-
- /* setuid to the qemu user, then open the file, read it,
- and stuff it into the pipe for the parent process to
- read */
- int exit_code;
- char *buf = NULL;
- size_t bufsize = 1024 * 1024;
- int bytesread;
-
- /* child doesn't need the read side of the pipe */
- VIR_FORCE_CLOSE(pipefd[0]);
-
- if (forkRet < 0) {
- exit_code = errno;
- virReportSystemError(errno,
- _("failed in child after forking to read
'%s'"),
- path);
- goto child_cleanup;
- }
-
- if (virSetUIDGID(uid, gid) < 0) {
- exit_code = errno;
- goto child_cleanup;
- }
-
- if ((fd = open(path, O_RDONLY)) < 0) {
- exit_code = errno;
- virReportSystemError(errno,
- _("cannot open '%s' as uid %d"),
- path, uid);
- goto child_cleanup;
- }
-
- if (VIR_ALLOC_N(buf, bufsize) < 0) {
- exit_code = ENOMEM;
- virReportOOMError();
- goto child_cleanup;
- }
-
- /* read from fd and write to pipefd[1] until EOF */
- do {
- if ((bytesread = saferead(fd, buf, bufsize)) < 0) {
- exit_code = errno;
- virReportSystemError(errno,
- _("child failed reading from '%s'"),
- path);
- goto child_cleanup;
- }
- if (safewrite(pipefd[1], buf, bytesread) != bytesread) {
- exit_code = errno;
- virReportSystemError(errno, "%s",
- _("child failed writing to pipe"));
- goto child_cleanup;
- }
- } while (bytesread > 0);
- exit_code = 0;
-
-child_cleanup:
- VIR_FREE(buf);
- VIR_FORCE_CLOSE(fd);
- VIR_FORCE_CLOSE(pipefd[1]);
- _exit(exit_code);
-}
-
-static int qemudDomainSaveImageClose(int fd, pid_t read_pid, int *status)
-{
- int ret = 0;
-
- if (VIR_CLOSE(fd) < 0) {
- virReportSystemError(errno, "%s",
- _("cannot close file"));
- }
-
- if (read_pid != -1) {
- /* reap the process that read the file */
- while ((ret = waitpid(read_pid, status, 0)) == -1
- && errno == EINTR) {
- /* empty */
- }
- } else if (status) {
- *status = 0;
- }
-
- return ret;
-}
-
-static int ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4) ATTRIBUTE_NONNULL(5)
-qemudDomainSaveImageOpen(struct qemud_driver *driver,
- const char *path,
- virDomainDefPtr *ret_def,
- struct qemud_save_header *ret_header,
- pid_t *ret_read_pid)
+static int ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4)
+qemuDomainSaveImageOpen(struct qemud_driver *driver,
+ const char *path,
+ virDomainDefPtr *ret_def,
+ struct qemud_save_header *ret_header)
{
int fd;
- pid_t read_pid = -1;
struct qemud_save_header header;
char *xml = NULL;
virDomainDefPtr def = NULL;
- if ((fd = open(path, O_RDONLY)) < 0) {
- if ((driver->user == 0) || (getuid() != 0)) {
+ if ((fd = virFileOpenAs(path, O_RDONLY, 0, getuid(), getgid(), 0)) < 0) {
+ if ((fd != -EACCES && fd != -EPERM) ||
+ driver->user == getuid()) {
qemuReportError(VIR_ERR_OPERATION_FAILED,
"%s", _("cannot read domain image"));
goto error;
}
/* Opening as root failed, but qemu runs as a different user
- that might have better luck. Create a pipe, then fork a
- child process to run as the qemu user, which will hopefully
- have the necessary authority to read the file. */
- if ((fd = qemudOpenAsUID(path,
- driver->user, driver->group, &read_pid)) <
0) {
- /* error already reported */
+ * that might have better luck. */
+ if ((fd = virFileOpenAs(path, O_RDONLY, 0,
+ driver->user, driver->group,
+ VIR_FILE_OPEN_AS_UID)) < 0) {
+ qemuReportError(VIR_ERR_OPERATION_FAILED,
+ "%s", _("cannot read domain image"));
goto error;
}
}
@@ -3274,34 +3123,30 @@ qemudDomainSaveImageOpen(struct qemud_driver *driver,
*ret_def = def;
*ret_header = header;
- *ret_read_pid = read_pid;
return fd;
error:
virDomainDefFree(def);
VIR_FREE(xml);
- qemudDomainSaveImageClose(fd, read_pid, NULL);
+ VIR_FORCE_CLOSE(fd);
return -1;
}
-static int ATTRIBUTE_NONNULL(6)
-qemudDomainSaveImageStartVM(virConnectPtr conn,
- struct qemud_driver *driver,
- virDomainObjPtr vm,
- int *fd,
- pid_t *read_pid,
- const struct qemud_save_header *header,
- const char *path)
+static int ATTRIBUTE_NONNULL(4) ATTRIBUTE_NONNULL(5) ATTRIBUTE_NONNULL(6)
+qemuDomainSaveImageStartVM(virConnectPtr conn,
+ struct qemud_driver *driver,
+ virDomainObjPtr vm,
+ int *fd,
+ const struct qemud_save_header *header,
+ const char *path)
{
int ret = -1;
virDomainEventPtr event;
int intermediatefd = -1;
pid_t intermediate_pid = -1;
int childstat;
- int wait_ret;
- int status;
if (header->version == 2) {
const char *intermediate_argv[3] = { NULL, "-dc", NULL };
@@ -3334,8 +3179,9 @@ qemudDomainSaveImageStartVM(virConnectPtr conn,
if (intermediate_pid != -1) {
if (ret < 0) {
- /* if there was an error setting up qemu, the intermediate process will
- * wait forever to write to stdout, so we must manually kill it.
+ /* if there was an error setting up qemu, the intermediate
+ * process will wait forever to write to stdout, so we
+ * must manually kill it.
*/
VIR_FORCE_CLOSE(intermediatefd);
VIR_FORCE_CLOSE(*fd);
@@ -3350,30 +3196,10 @@ qemudDomainSaveImageStartVM(virConnectPtr conn,
}
VIR_FORCE_CLOSE(intermediatefd);
- wait_ret = qemudDomainSaveImageClose(*fd, *read_pid, &status);
- *fd = -1;
- if (*read_pid != -1) {
- if (wait_ret == -1) {
- virReportSystemError(errno,
- _("failed to wait for process reading
'%s'"),
- path);
- ret = -1;
- } else if (!WIFEXITED(status)) {
- qemuReportError(VIR_ERR_OPERATION_FAILED,
- _("child process exited abnormally reading
'%s'"),
- path);
- ret = -1;
- } else {
- int exit_status = WEXITSTATUS(status);
- if (exit_status != 0) {
- virReportSystemError(exit_status,
- _("child process returned error reading
'%s'"),
- path);
- ret = -1;
- }
- }
+ if (VIR_CLOSE(*fd) < 0) {
+ virReportSystemError(errno, _("cannot close file: %s"), path);
+ ret = -1;
}
- *read_pid = -1;
if (ret < 0) {
qemuAuditDomainStart(vm, "restored", false);
@@ -3412,19 +3238,20 @@ out:
return ret;
}
-static int qemudDomainRestore(virConnectPtr conn,
- const char *path) {
+static int
+qemuDomainRestore(virConnectPtr conn,
+ const char *path)
+{
struct qemud_driver *driver = conn->privateData;
virDomainDefPtr def = NULL;
virDomainObjPtr vm = NULL;
int fd = -1;
- pid_t read_pid = -1;
int ret = -1;
struct qemud_save_header header;
qemuDriverLock(driver);
- fd = qemudDomainSaveImageOpen(driver, path, &def, &header, &read_pid);
+ fd = qemuDomainSaveImageOpen(driver, path, &def, &header);
if (fd < 0)
goto cleanup;
@@ -3442,8 +3269,7 @@ static int qemudDomainRestore(virConnectPtr conn,
if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0)
goto cleanup;
- ret = qemudDomainSaveImageStartVM(conn, driver, vm, &fd,
- &read_pid, &header, path);
+ ret = qemuDomainSaveImageStartVM(conn, driver, vm, &fd, &header, path);
if (qemuDomainObjEndJob(vm) == 0)
vm = NULL;
@@ -3454,25 +3280,25 @@ static int qemudDomainRestore(virConnectPtr conn,
cleanup:
virDomainDefFree(def);
- qemudDomainSaveImageClose(fd, read_pid, NULL);
+ VIR_FORCE_CLOSE(fd);
if (vm)
virDomainObjUnlock(vm);
qemuDriverUnlock(driver);
return ret;
}
-static int qemudDomainObjRestore(virConnectPtr conn,
- struct qemud_driver *driver,
- virDomainObjPtr vm,
- const char *path)
+static int
+qemuDomainObjRestore(virConnectPtr conn,
+ struct qemud_driver *driver,
+ virDomainObjPtr vm,
+ const char *path)
{
virDomainDefPtr def = NULL;
int fd = -1;
- pid_t read_pid = -1;
int ret = -1;
struct qemud_save_header header;
- fd = qemudDomainSaveImageOpen(driver, path, &def, &header, &read_pid);
+ fd = qemuDomainSaveImageOpen(driver, path, &def, &header);
if (fd < 0)
goto cleanup;
@@ -3493,12 +3319,11 @@ static int qemudDomainObjRestore(virConnectPtr conn,
virDomainObjAssignDef(vm, def, true);
def = NULL;
- ret = qemudDomainSaveImageStartVM(conn, driver, vm, &fd,
- &read_pid, &header, path);
+ ret = qemuDomainSaveImageStartVM(conn, driver, vm, &fd, &header, path);
cleanup:
virDomainDefFree(def);
- qemudDomainSaveImageClose(fd, read_pid, NULL);
+ VIR_FORCE_CLOSE(fd);
return ret;
}
@@ -3709,7 +3534,7 @@ static int qemudDomainObjStart(virConnectPtr conn,
*/
managed_save = qemuDomainManagedSavePath(driver, vm);
if ((managed_save) && (virFileExists(managed_save))) {
- ret = qemudDomainObjRestore(conn, driver, vm, managed_save);
+ ret = qemuDomainObjRestore(conn, driver, vm, managed_save);
if (unlink(managed_save) < 0) {
VIR_WARN("Failed to remove the managed state %s", managed_save);
@@ -7126,7 +6951,7 @@ static virDriver qemuDriver = {
qemuDomainGetBlkioParameters, /* domainGetBlkioParameters */
qemudDomainGetInfo, /* domainGetInfo */
qemudDomainSave, /* domainSave */
- qemudDomainRestore, /* domainRestore */
+ qemuDomainRestore, /* domainRestore */
qemudDomainCoreDump, /* domainCoreDump */
qemudDomainSetVcpus, /* domainSetVcpus */
qemudDomainSetVcpusFlags, /* domainSetVcpusFlags */
--
1.7.4