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提交 80449b32 编写于 作者: E Eric Blake
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qemu: use common API for reading difficult files 

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.
上级 1a369dfb
隐藏空白更改
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Showing with 45 addition and 220 deletion
src/qemu/qemu_driver.c
浏览文件 @ 80449b32
......@@ -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 */
......
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