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285c2fdf0f
libvirt/src/util/command.c
Daniel P. Berrange 285c2fdf0f Allow handshake with child process during startup 
Allow the parent process to perform a bi-directional handshake
with the child process during fork/exec. The child process
will fork and do its initial setup. Immediately prior to the
exec(), it will stop & wait for a handshake from the parent
process. The parent process will spawn the child and wait
until the child reaches the handshake point. It will do
whatever extra setup work is required, before signalling the
child to continue.

The implementation of this is done using two pairs of blocking
pipes. The first pair is used to block the parent, until the
child writes a single byte. Then the second pair pair is used
to block the child, until the parent confirms with another
single byte.

* src/util/command.c, src/util/command.h,
  src/libvirt_private.syms: Add APIs to perform a handshake
2011-06-02 10:53:58 +01:00

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/*
* command.c: Child command execution
*
* Copyright (C) 2010-2011 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <config.h>
#include <poll.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "command.h"
#include "memory.h"
#include "virterror_internal.h"
#include "util.h"
#include "logging.h"
#include "files.h"
#include "buf.h"
#include <stdlib.h>
#define VIR_FROM_THIS VIR_FROM_NONE
#define virCommandError(code, ...) \
virReportErrorHelper(VIR_FROM_NONE, code, __FILE__, \
__FUNCTION__, __LINE__, __VA_ARGS__)
enum {
/* Internal-use extension beyond public VIR_EXEC_ flags */
VIR_EXEC_RUN_SYNC = 0x40000000,
};
struct _virCommand {
int has_error; /* ENOMEM on allocation failure, -1 for anything else. */
char **args;
size_t nargs;
size_t maxargs;
char **env;
size_t nenv;
size_t maxenv;
char *pwd;
/* XXX Use int[] if we ever need to support more than FD_SETSIZE fd's. */
fd_set preserve; /* FDs to pass to child. */
fd_set transfer; /* FDs to close in parent. */
unsigned int flags;
char *inbuf;
char **outbuf;
char **errbuf;
int infd;
int inpipe;
int outfd;
int errfd;
int *outfdptr;
int *errfdptr;
bool handshake;
int handshakeWait[2];
int handshakeNotify[2];
virExecHook hook;
void *opaque;
pid_t pid;
char *pidfile;
bool reap;
};
/*
* Create a new command for named binary
*/
virCommandPtr
virCommandNew(const char *binary)
{
const char *const args[] = { binary, NULL };
return virCommandNewArgs(args);
}
/*
* Create a new command with a NULL terminated
* set of args, taking binary from args[0]
*/
virCommandPtr
virCommandNewArgs(const char *const*args)
{
virCommandPtr cmd;
if (VIR_ALLOC(cmd) < 0)
return NULL;
cmd->handshakeWait[0] = -1;
cmd->handshakeWait[1] = -1;
cmd->handshakeNotify[0] = -1;
cmd->handshakeNotify[1] = -1;
FD_ZERO(&cmd->preserve);
FD_ZERO(&cmd->transfer);
cmd->infd = cmd->outfd = cmd->errfd = -1;
cmd->inpipe = -1;
cmd->pid = -1;
virCommandAddArgSet(cmd, args);
return cmd;
}
/*
* Create a new command with a NULL terminated
* list of args, starting with the binary to run
*/
virCommandPtr
virCommandNewArgList(const char *binary, ...)
{
virCommandPtr cmd = virCommandNew(binary);
va_list list;
const char *arg;
if (!cmd || cmd->has_error)
return NULL;
va_start(list, binary);
while ((arg = va_arg(list, const char *)) != NULL)
virCommandAddArg(cmd, arg);
va_end(list);
return cmd;
}
/*
* Preserve the specified file descriptor in the child, instead of
* closing it. FD must not be one of the three standard streams. If
* transfer is true, then fd will be closed in the parent after a call
* to Run/RunAsync/Free, otherwise caller is still responsible for fd.
*/
static void
virCommandKeepFD(virCommandPtr cmd, int fd, bool transfer)
{
if (!cmd)
return;
if (fd <= STDERR_FILENO || FD_SETSIZE <= fd) {
if (!cmd->has_error)
cmd->has_error = -1;
VIR_DEBUG("cannot preserve %d", fd);
return;
}
FD_SET(fd, &cmd->preserve);
if (transfer)
FD_SET(fd, &cmd->transfer);
}
/*
* Preserve the specified file descriptor
* in the child, instead of closing it.
* The parent is still responsible for managing fd.
*/
void
virCommandPreserveFD(virCommandPtr cmd, int fd)
{
return virCommandKeepFD(cmd, fd, false);
}
/*
* Transfer the specified file descriptor
* to the child, instead of closing it.
* Close the fd in the parent during Run/RunAsync/Free.
*/
void
virCommandTransferFD(virCommandPtr cmd, int fd)
{
return virCommandKeepFD(cmd, fd, true);
}
/*
* Save the child PID in a pidfile
*/
void
virCommandSetPidFile(virCommandPtr cmd, const char *pidfile)
{
if (!cmd || cmd->has_error)
return;
VIR_FREE(cmd->pidfile);
if (!(cmd->pidfile = strdup(pidfile))) {
cmd->has_error = ENOMEM;
}
}
/*
* Remove all capabilities from the child
*/
void
virCommandClearCaps(virCommandPtr cmd)
{
if (!cmd || cmd->has_error)
return;
cmd->flags |= VIR_EXEC_CLEAR_CAPS;
}
#if 0 /* XXX Enable if we have a need for capability management. */
/*
* Re-allow a specific capability
*/
void
virCommandAllowCap(virCommandPtr cmd,
int capability ATTRIBUTE_UNUSED)
{
if (!cmd || cmd->has_error)
return;
/* XXX ? */
}
#endif /* 0 */
/*
* Daemonize the child process
*/
void
virCommandDaemonize(virCommandPtr cmd)
{
if (!cmd || cmd->has_error)
return;
cmd->flags |= VIR_EXEC_DAEMON;
}
/*
* Set FDs created by virCommandSetOutputFD and virCommandSetErrorFD
* as non-blocking in the parent.
*/
void
virCommandNonblockingFDs(virCommandPtr cmd)
{
if (!cmd || cmd->has_error)
return;
cmd->flags |= VIR_EXEC_NONBLOCK;
}
/*
* Add an environment variable to the child created by a printf-style format
*/
void
virCommandAddEnvFormat(virCommandPtr cmd, const char *format, ...)
{
char *env;
va_list list;
if (!cmd || cmd->has_error)
return;
va_start(list, format);
if (virVasprintf(&env, format, list) < 0) {
cmd->has_error = ENOMEM;
va_end(list);
return;
}
va_end(list);
/* Arg plus trailing NULL. */
if (VIR_RESIZE_N(cmd->env, cmd->maxenv, cmd->nenv, 1 + 1) < 0) {
VIR_FREE(env);
cmd->has_error = ENOMEM;
return;
}
cmd->env[cmd->nenv++] = env;
}
/*
* Add an environment variable to the child
* using separate name & value strings
*/
void
virCommandAddEnvPair(virCommandPtr cmd, const char *name, const char *value)
{
virCommandAddEnvFormat(cmd, "%s=%s", name, value);
}
/*
* Add an environment variable to the child
* using a preformatted env string FOO=BAR
*/
void
virCommandAddEnvString(virCommandPtr cmd, const char *str)
{
char *env;
if (!cmd || cmd->has_error)
return;
if (!(env = strdup(str))) {
cmd->has_error = ENOMEM;
return;
}
/* env plus trailing NULL */
if (VIR_RESIZE_N(cmd->env, cmd->maxenv, cmd->nenv, 1 + 1) < 0) {
VIR_FREE(env);
cmd->has_error = ENOMEM;
return;
}
cmd->env[cmd->nenv++] = env;
}
/*
* Convert a buffer containing preformatted name=value into an
* environment variable of the child.
* Correctly transfers memory errors or contents from buf to cmd.
*/
void
virCommandAddEnvBuffer(virCommandPtr cmd, virBufferPtr buf)
{
if (!cmd || cmd->has_error) {
virBufferFreeAndReset(buf);
return;
}
/* env plus trailing NULL. */
if (virBufferError(buf) ||
VIR_RESIZE_N(cmd->env, cmd->maxenv, cmd->nenv, 1 + 1) < 0) {
cmd->has_error = ENOMEM;
virBufferFreeAndReset(buf);
return;
}
cmd->env[cmd->nenv++] = virBufferContentAndReset(buf);
}
/*
* Pass an environment variable to the child
* using current process' value
*/
void
virCommandAddEnvPass(virCommandPtr cmd, const char *name)
{
char *value;
if (!cmd || cmd->has_error)
return;
value = getenv(name);
if (value)
virCommandAddEnvPair(cmd, name, value);
}
/*
* Set LC_ALL to C, and propagate other essential environment
* variables from the parent process.
*/
void
virCommandAddEnvPassCommon(virCommandPtr cmd)
{
if (!cmd || cmd->has_error)
return;
/* Attempt to Pre-allocate; allocation failure will be detected
* later during virCommandAdd*. */
ignore_value(VIR_RESIZE_N(cmd->env, cmd->maxenv, cmd->nenv, 9));
virCommandAddEnvPair(cmd, "LC_ALL", "C");
virCommandAddEnvPass(cmd, "LD_PRELOAD");
virCommandAddEnvPass(cmd, "LD_LIBRARY_PATH");
virCommandAddEnvPass(cmd, "PATH");
virCommandAddEnvPass(cmd, "HOME");
virCommandAddEnvPass(cmd, "USER");
virCommandAddEnvPass(cmd, "LOGNAME");
virCommandAddEnvPass(cmd, "TMPDIR");
}
/*
* Add a command line argument to the child
*/
void
virCommandAddArg(virCommandPtr cmd, const char *val)
{
char *arg;
if (!cmd || cmd->has_error)
return;
if (!(arg = strdup(val))) {
cmd->has_error = ENOMEM;
return;
}
/* Arg plus trailing NULL. */
if (VIR_RESIZE_N(cmd->args, cmd->maxargs, cmd->nargs, 1 + 1) < 0) {
VIR_FREE(arg);
cmd->has_error = ENOMEM;
return;
}
cmd->args[cmd->nargs++] = arg;
}
/*
* Convert a buffer into a command line argument to the child.
* Correctly transfers memory errors or contents from buf to cmd.
*/
void
virCommandAddArgBuffer(virCommandPtr cmd, virBufferPtr buf)
{
if (!cmd || cmd->has_error) {
virBufferFreeAndReset(buf);
return;
}
/* Arg plus trailing NULL. */
if (virBufferError(buf) ||
VIR_RESIZE_N(cmd->args, cmd->maxargs, cmd->nargs, 1 + 1) < 0) {
cmd->has_error = ENOMEM;
virBufferFreeAndReset(buf);
return;
}
cmd->args[cmd->nargs++] = virBufferContentAndReset(buf);
}
/*
* Add a command line argument created by a printf-style format
*/
void
virCommandAddArgFormat(virCommandPtr cmd, const char *format, ...)
{
char *arg;
va_list list;
if (!cmd || cmd->has_error)
return;
va_start(list, format);
if (virVasprintf(&arg, format, list) < 0) {
cmd->has_error = ENOMEM;
va_end(list);
return;
}
va_end(list);
/* Arg plus trailing NULL. */
if (VIR_RESIZE_N(cmd->args, cmd->maxargs, cmd->nargs, 1 + 1) < 0) {
VIR_FREE(arg);
cmd->has_error = ENOMEM;
return;
}
cmd->args[cmd->nargs++] = arg;
}
/*
* Add "NAME=VAL" as a single command line argument to the child
*/
void
virCommandAddArgPair(virCommandPtr cmd, const char *name, const char *val)
{
virCommandAddArgFormat(cmd, "%s=%s", name, val);
}
/*
* Add a NULL terminated list of args
*/
void
virCommandAddArgSet(virCommandPtr cmd, const char *const*vals)
{
int narg = 0;
if (!cmd || cmd->has_error)
return;
if (vals[0] == NULL) {
cmd->has_error = EINVAL;
return;
}
while (vals[narg] != NULL)
narg++;
/* narg plus trailing NULL. */
if (VIR_RESIZE_N(cmd->args, cmd->maxargs, cmd->nargs, narg + 1) < 0) {
cmd->has_error = ENOMEM;
return;
}
narg = 0;
while (vals[narg] != NULL) {
char *arg = strdup(vals[narg++]);
if (!arg) {
cmd->has_error = ENOMEM;
return;
}
cmd->args[cmd->nargs++] = arg;
}
}
/*
* Add a NULL terminated list of args
*/
void
virCommandAddArgList(virCommandPtr cmd, ...)
{
va_list list;
int narg = 0;
if (!cmd || cmd->has_error)
return;
va_start(list, cmd);
while (va_arg(list, const char *) != NULL)
narg++;
va_end(list);
/* narg plus trailing NULL. */
if (VIR_RESIZE_N(cmd->args, cmd->maxargs, cmd->nargs, narg + 1) < 0) {
cmd->has_error = ENOMEM;
return;
}
va_start(list, cmd);
while (1) {
char *arg = va_arg(list, char *);
if (!arg)
break;
arg = strdup(arg);
if (!arg) {
cmd->has_error = ENOMEM;
va_end(list);
return;
}
cmd->args[cmd->nargs++] = arg;
}
va_end(list);
}
/*
* Set the working directory of a non-daemon child process, rather
* than the parent's working directory. Daemons automatically get /
* without using this call.
*/
void
virCommandSetWorkingDirectory(virCommandPtr cmd, const char *pwd)
{
if (!cmd || cmd->has_error)
return;
if (cmd->pwd) {
cmd->has_error = -1;
VIR_DEBUG("cannot set directory twice");
} else {
cmd->pwd = strdup(pwd);
if (!cmd->pwd)
cmd->has_error = ENOMEM;
}
}
/*
* Feed the child's stdin from a string buffer
*/
void
virCommandSetInputBuffer(virCommandPtr cmd, const char *inbuf)
{
if (!cmd || cmd->has_error)
return;
if (cmd->infd != -1 || cmd->inbuf) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify input twice");
return;
}
cmd->inbuf = strdup(inbuf);
if (!cmd->inbuf)
cmd->has_error = ENOMEM;
}
/*
* Capture the child's stdout to a string buffer. *outbuf is
* guaranteed to be allocated after successful virCommandRun or
* virCommandWait, and is best-effort allocated after failed
* virCommandRun; caller is responsible for freeing *outbuf.
*/
void
virCommandSetOutputBuffer(virCommandPtr cmd, char **outbuf)
{
*outbuf = NULL;
if (!cmd || cmd->has_error)
return;
if (cmd->outfdptr) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify output twice");
return;
}
cmd->outbuf = outbuf;
cmd->outfdptr = &cmd->outfd;
}
/*
* Capture the child's stderr to a string buffer. *errbuf is
* guaranteed to be allocated after successful virCommandRun or
* virCommandWait, and is best-effort allocated after failed
* virCommandRun; caller is responsible for freeing *errbuf.
*/
void
virCommandSetErrorBuffer(virCommandPtr cmd, char **errbuf)
{
*errbuf = NULL;
if (!cmd || cmd->has_error)
return;
if (cmd->errfdptr) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify stderr twice");
return;
}
cmd->errbuf = errbuf;
cmd->errfdptr = &cmd->errfd;
}
/*
* Attach a file descriptor to the child's stdin
*/
void
virCommandSetInputFD(virCommandPtr cmd, int infd)
{
if (!cmd || cmd->has_error)
return;
if (cmd->infd != -1 || cmd->inbuf) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify input twice");
return;
}
if (infd < 0) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify invalid input fd");
return;
}
cmd->infd = infd;
}
/*
* Attach a file descriptor to the child's stdout
*/
void
virCommandSetOutputFD(virCommandPtr cmd, int *outfd)
{
if (!cmd || cmd->has_error)
return;
if (cmd->outfdptr) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify output twice");
return;
}
cmd->outfdptr = outfd;
}
/*
* Attach a file descriptor to the child's stderr
*/
void
virCommandSetErrorFD(virCommandPtr cmd, int *errfd)
{
if (!cmd || cmd->has_error)
return;
if (cmd->errfdptr) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify stderr twice");
return;
}
cmd->errfdptr = errfd;
}
/*
* Run HOOK(OPAQUE) in the child as the last thing before changing
* directories, dropping capabilities, and executing the new process.
* Force the child to fail if HOOK does not return zero.
*/
void
virCommandSetPreExecHook(virCommandPtr cmd, virExecHook hook, void *opaque)
{
if (!cmd || cmd->has_error)
return;
if (cmd->hook) {
cmd->has_error = -1;
VIR_DEBUG("cannot specify hook twice");
return;
}
cmd->hook = hook;
cmd->opaque = opaque;
}
/*
* Call after adding all arguments and environment settings, but before
* Run/RunAsync, to immediately output the environment and arguments of
* cmd to logfd. If virCommandRun cannot succeed (because of an
* out-of-memory condition while building cmd), nothing will be logged.
*/
void
virCommandWriteArgLog(virCommandPtr cmd, int logfd)
{
int ioError = 0;
size_t i;
/* Any errors will be reported later by virCommandRun, which means
* no command will be run, so there is nothing to log. */
if (!cmd || cmd->has_error)
return;
for (i = 0 ; i < cmd->nenv ; i++) {
if (safewrite(logfd, cmd->env[i], strlen(cmd->env[i])) < 0)
ioError = errno;
if (safewrite(logfd, " ", 1) < 0)
ioError = errno;
}
for (i = 0 ; i < cmd->nargs ; i++) {
if (safewrite(logfd, cmd->args[i], strlen(cmd->args[i])) < 0)
ioError = errno;
if (safewrite(logfd, i == cmd->nargs - 1 ? "\n" : " ", 1) < 0)
ioError = errno;
}
if (ioError) {
char ebuf[1024];
VIR_WARN("Unable to write command %s args to logfile: %s",
cmd->args[0], virStrerror(ioError, ebuf, sizeof ebuf));
}
}
/*
* Call after adding all arguments and environment settings, but before
* Run/RunAsync, to return a string representation of the environment and
* arguments of cmd. If virCommandRun cannot succeed (because of an
* out-of-memory condition while building cmd), NULL will be returned.
* Caller is responsible for freeing the resulting string.
*/
char *
virCommandToString(virCommandPtr cmd)
{
size_t i;
virBuffer buf = VIR_BUFFER_INITIALIZER;
/* Cannot assume virCommandRun will be called; so report the error
* now. If virCommandRun is called, it will report the same error. */
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return NULL;
}
if (cmd->has_error) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return NULL;
}
for (i = 0; i < cmd->nenv; i++) {
virBufferAdd(&buf, cmd->env[i], strlen(cmd->env[i]));
virBufferAddChar(&buf, ' ');
}
virBufferAdd(&buf, cmd->args[0], strlen(cmd->args[0]));
for (i = 1; i < cmd->nargs; i++) {
virBufferAddChar(&buf, ' ');
virBufferAdd(&buf, cmd->args[i], strlen(cmd->args[i]));
}
if (virBufferError(&buf)) {
virBufferFreeAndReset(&buf);
virReportOOMError();
return NULL;
}
return virBufferContentAndReset(&buf);
}
/*
* Translate an exit status into a malloc'd string. Generic helper
* for virCommandRun and virCommandWait status argument, as well as
* raw waitpid and older virRun status.
*/
char *
virCommandTranslateStatus(int status)
{
char *buf;
if (WIFEXITED(status)) {
virAsprintf(&buf, _("exit status %d"), WEXITSTATUS(status));
} else if (WIFSIGNALED(status)) {
virAsprintf(&buf, _("fatal signal %d"), WTERMSIG(status));
} else {
virAsprintf(&buf, _("invalid value %d"), status);
}
return buf;
}
/*
* Manage input and output to the child process.
*/
static int
virCommandProcessIO(virCommandPtr cmd)
{
int infd = -1, outfd = -1, errfd = -1;
size_t inlen = 0, outlen = 0, errlen = 0;
size_t inoff = 0;
int ret = 0;
/* With an input buffer, feed data to child
* via pipe */
if (cmd->inbuf) {
inlen = strlen(cmd->inbuf);
infd = cmd->inpipe;
}
/* With out/err buffer, the outfd/errfd have been filled with an
* FD for us. Guarantee an allocated string with partial results
* even if we encounter a later failure, as well as freeing any
* results accumulated over a prior run of the same command. */
if (cmd->outbuf) {
outfd = cmd->outfd;
if (VIR_REALLOC_N(*cmd->outbuf, 1) < 0) {
virReportOOMError();
ret = -1;
}
}
if (cmd->errbuf) {
errfd = cmd->errfd;
if (VIR_REALLOC_N(*cmd->errbuf, 1) < 0) {
virReportOOMError();
ret = -1;
}
}
if (ret == -1)
goto cleanup;
ret = -1;
for (;;) {
int i;
struct pollfd fds[3];
int nfds = 0;
if (infd != -1) {
fds[nfds].fd = infd;
fds[nfds].events = POLLOUT;
nfds++;
}
if (outfd != -1) {
fds[nfds].fd = outfd;
fds[nfds].events = POLLIN;
nfds++;
}
if (errfd != -1) {
fds[nfds].fd = errfd;
fds[nfds].events = POLLIN;
nfds++;
}
if (nfds == 0)
break;
if (poll(fds, nfds, -1) < 0) {
if ((errno == EAGAIN) || (errno == EINTR))
continue;
virReportSystemError(errno, "%s",
_("unable to poll on child"));
goto cleanup;
}
for (i = 0; i < nfds ; i++) {
if (fds[i].fd == errfd ||
fds[i].fd == outfd) {
char data[1024];
char **buf;
size_t *len;
int done;
if (fds[i].fd == outfd) {
buf = cmd->outbuf;
len = &outlen;
} else {
buf = cmd->errbuf;
len = &errlen;
}
/* Silence a false positive from clang. */
sa_assert(buf);
done = read(fds[i].fd, data, sizeof(data));
if (done < 0) {
if (errno != EINTR &&
errno != EAGAIN) {
virReportSystemError(errno, "%s",
_("unable to write to child input"));
goto cleanup;
}
} else if (done == 0) {
if (fds[i].fd == outfd)
outfd = -1;
else
errfd = -1;
} else {
if (VIR_REALLOC_N(*buf, *len + done + 1) < 0) {
virReportOOMError();
goto cleanup;
}
memcpy(*buf + *len, data, done);
*len += done;
}
} else {
int done;
done = write(infd, cmd->inbuf + inoff,
inlen - inoff);
if (done < 0) {
if (errno != EINTR &&
errno != EAGAIN) {
virReportSystemError(errno, "%s",
_("unable to write to child input"));
goto cleanup;
}
} else {
inoff += done;
if (inoff == inlen) {
int tmpfd = infd;
if (VIR_CLOSE(infd) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
}
}
}
}
}
ret = 0;
cleanup:
if (cmd->outbuf && *cmd->outbuf)
(*cmd->outbuf)[outlen] = '\0';
if (cmd->errbuf && *cmd->errbuf)
(*cmd->errbuf)[errlen] = '\0';
return ret;
}
/*
* Exec the command, replacing the current process. Meant to be called
* after already forking / cloning, so does not attempt to daemonize or
* preserve any FDs.
*
* Returns -1 on any error executing the command.
* Will not return on success.
*/
#ifndef WIN32
int virCommandExec(virCommandPtr cmd)
{
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
return execve(cmd->args[0], cmd->args, cmd->env);
}
#else
int virCommandExec(virCommandPtr cmd ATTRIBUTE_UNUSED)
{
/* Mingw execve() has a broken signature. Disable this
* function until gnulib fixes the signature, since we
* don't really need this on Win32 anyway.
*/
virReportSystemError(ENOSYS, "%s",
_("Executing new processes is not supported on Win32 platform"));
return -1;
}
#endif
/*
* Run the command and wait for completion.
* Returns -1 on any error executing the
* command. Returns 0 if the command executed,
* with the exit status set
*/
int
virCommandRun(virCommandPtr cmd, int *exitstatus)
{
int ret = 0;
char *outbuf = NULL;
char *errbuf = NULL;
int infd[2] = { -1, -1 };
struct stat st;
bool string_io;
bool async_io = false;
char *str;
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
/* Avoid deadlock, by requiring that any open fd not under our
* control must be visiting a regular file, or that we are
* daemonized and no string io is required. */
string_io = cmd->inbuf || cmd->outbuf || cmd->errbuf;
if (cmd->infd != -1 &&
(fstat(cmd->infd, &st) < 0 || !S_ISREG(st.st_mode)))
async_io = true;
if (cmd->outfdptr && cmd->outfdptr != &cmd->outfd &&
(*cmd->outfdptr == -1 ||
fstat(*cmd->outfdptr, &st) < 0 || !S_ISREG(st.st_mode)))
async_io = true;
if (cmd->errfdptr && cmd->errfdptr != &cmd->errfd &&
(*cmd->errfdptr == -1 ||
fstat(*cmd->errfdptr, &st) < 0 || !S_ISREG(st.st_mode)))
async_io = true;
if (async_io) {
if (!(cmd->flags & VIR_EXEC_DAEMON) || string_io) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("cannot mix caller fds with blocking execution"));
return -1;
}
} else {
if ((cmd->flags & VIR_EXEC_DAEMON) && string_io) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("cannot mix string I/O with daemon"));
return -1;
}
}
/* If we have an input buffer, we need
* a pipe to feed the data to the child */
if (cmd->inbuf) {
if (pipe(infd) < 0) {
virReportSystemError(errno, "%s",
_("unable to open pipe"));
cmd->has_error = -1;
return -1;
}
cmd->infd = infd[0];
cmd->inpipe = infd[1];
}
/* If caller hasn't requested capture of stdout/err, then capture
* it ourselves so we can log it. But the intermediate child for
* a daemon has no expected output, and we don't want our
* capturing pipes passed on to the daemon grandchild.
*/
if (!(cmd->flags & VIR_EXEC_DAEMON)) {
if (!cmd->outfdptr) {
cmd->outfdptr = &cmd->outfd;
cmd->outbuf = &outbuf;
string_io = true;
}
if (!cmd->errfdptr) {
cmd->errfdptr = &cmd->errfd;
cmd->errbuf = &errbuf;
string_io = true;
}
}
cmd->flags |= VIR_EXEC_RUN_SYNC;
if (virCommandRunAsync(cmd, NULL) < 0) {
if (cmd->inbuf) {
int tmpfd = infd[0];
if (VIR_CLOSE(infd[0]) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
tmpfd = infd[1];
if (VIR_CLOSE(infd[1]) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
}
cmd->has_error = -1;
return -1;
}
if (string_io)
ret = virCommandProcessIO(cmd);
if (virCommandWait(cmd, exitstatus) < 0)
ret = -1;
str = (exitstatus ? virCommandTranslateStatus(*exitstatus)
: (char *) "status 0");
VIR_DEBUG("Result %s, stdout: '%s' stderr: '%s'",
NULLSTR(str),
cmd->outbuf ? NULLSTR(*cmd->outbuf) : "(null)",
cmd->errbuf ? NULLSTR(*cmd->errbuf) : "(null)");
if (exitstatus)
VIR_FREE(str);
/* Reset any capturing, in case caller runs
* this identical command again */
if (cmd->inbuf) {
int tmpfd = infd[0];
if (VIR_CLOSE(infd[0]) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
tmpfd = infd[1];
if (VIR_CLOSE(infd[1]) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
}
if (cmd->outbuf == &outbuf) {
int tmpfd = cmd->outfd;
if (VIR_CLOSE(cmd->outfd) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
cmd->outfdptr = NULL;
cmd->outbuf = NULL;
VIR_FREE(outbuf);
}
if (cmd->errbuf == &errbuf) {
int tmpfd = cmd->errfd;
if (VIR_CLOSE(cmd->errfd) < 0)
VIR_DEBUG("ignoring failed close on fd %d", tmpfd);
cmd->errfdptr = NULL;
cmd->errbuf = NULL;
VIR_FREE(errbuf);
}
return ret;
}
/*
* Perform all virCommand-specific actions, along with the user hook.
*/
static int
virCommandHook(void *data)
{
virCommandPtr cmd = data;
int res = 0;
if (cmd->hook) {
VIR_DEBUG("Run hook %p %p", cmd->hook, cmd->opaque);
res = cmd->hook(cmd->opaque);
VIR_DEBUG("Done hook %d", res);
}
if (res == 0 && cmd->pwd) {
VIR_DEBUG("Running child in %s", cmd->pwd);
res = chdir(cmd->pwd);
if (res < 0) {
virReportSystemError(errno,
_("Unable to change to %s"), cmd->pwd);
}
}
if (cmd->handshake) {
char c = res < 0 ? '0' : '1';
int rv;
VIR_DEBUG("Notifying parent for handshake start on %d", cmd->handshakeWait[1]);
if (safewrite(cmd->handshakeWait[1], &c, sizeof(c)) != sizeof(c)) {
virReportSystemError(errno, "%s", _("Unable to notify parent process"));
return -1;
}
/* On failure we pass the error message back to parent,
* so they don't have to dig through stderr logs
*/
if (res < 0) {
virErrorPtr err = virGetLastError();
const char *msg = err ? err->message :
_("Unknown failure during hook execution");
size_t len = strlen(msg) + 1;
if (safewrite(cmd->handshakeWait[1], msg, len) != len) {
virReportSystemError(errno, "%s", _("Unable to send error to parent process"));
return -1;
}
return -1;
}
VIR_DEBUG("Waiting on parent for handshake complete on %d", cmd->handshakeNotify[0]);
if ((rv = saferead(cmd->handshakeNotify[0], &c, sizeof(c))) != sizeof(c)) {
if (rv < 0)
virReportSystemError(errno, "%s", _("Unable to wait on parent process"));
else
virReportSystemError(EIO, "%s", _("libvirtd quit during handshake"));
return -1;
}
if (c != '1') {
virReportSystemError(EINVAL, _("Unexpected confirm code '%c' from parent process"), c);
return -1;
}
VIR_FORCE_CLOSE(cmd->handshakeWait[1]);
VIR_FORCE_CLOSE(cmd->handshakeNotify[0]);
}
VIR_DEBUG("Hook is done %d", res);
return res;
}
/*
* Run the command asynchronously
* Returns -1 on any error executing the
* command. Returns 0 if the command executed.
*/
int
virCommandRunAsync(virCommandPtr cmd, pid_t *pid)
{
int ret;
char *str;
int i;
bool synchronous = false;
if (!cmd || cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
synchronous = cmd->flags & VIR_EXEC_RUN_SYNC;
cmd->flags &= ~VIR_EXEC_RUN_SYNC;
/* Buffer management can only be requested via virCommandRun. */
if ((cmd->inbuf && cmd->infd == -1) ||
(cmd->outbuf && cmd->outfdptr != &cmd->outfd) ||
(cmd->errbuf && cmd->errfdptr != &cmd->errfd)) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("cannot mix string I/O with asynchronous command"));
return -1;
}
if (cmd->pid != -1) {
virCommandError(VIR_ERR_INTERNAL_ERROR,
_("command is already running as pid %d"),
cmd->pid);
return -1;
}
if (!synchronous && (cmd->flags & VIR_EXEC_DAEMON)) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("daemonized command cannot use virCommandRunAsync"));
return -1;
}
if (cmd->pwd && (cmd->flags & VIR_EXEC_DAEMON)) {
virCommandError(VIR_ERR_INTERNAL_ERROR,
_("daemonized command cannot set working directory %s"),
cmd->pwd);
return -1;
}
if (cmd->pidfile && !(cmd->flags & VIR_EXEC_DAEMON)) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("creation of pid file requires daemonized command"));
return -1;
}
str = virCommandToString(cmd);
VIR_DEBUG("About to run %s", str ? str : cmd->args[0]);
VIR_FREE(str);
ret = virExecWithHook((const char *const *)cmd->args,
(const char *const *)cmd->env,
&cmd->preserve,
&cmd->pid,
cmd->infd,
cmd->outfdptr,
cmd->errfdptr,
cmd->flags,
virCommandHook,
cmd,
cmd->pidfile);
VIR_DEBUG("Command result %d, with PID %d",
ret, (int)cmd->pid);
for (i = STDERR_FILENO + 1; i < FD_SETSIZE; i++) {
if (FD_ISSET(i, &cmd->transfer)) {
int tmpfd = i;
VIR_FORCE_CLOSE(tmpfd);
FD_CLR(i, &cmd->transfer);
}
}
if (ret == 0 && pid)
*pid = cmd->pid;
else
cmd->reap = true;
return ret;
}
/*
* Wait for the async command to complete.
* Return -1 on any error waiting for
* completion. Returns 0 if the command
* finished with the exit status set
*/
int
virCommandWait(virCommandPtr cmd, int *exitstatus)
{
int ret;
int status;
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
if (cmd->pid == -1) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("command is not yet running"));
return -1;
}
/* Wait for intermediate process to exit */
while ((ret = waitpid(cmd->pid, &status, 0)) == -1 &&
errno == EINTR);
if (ret == -1) {
virReportSystemError(errno, _("unable to wait for process %d"),
cmd->pid);
return -1;
}
cmd->pid = -1;
cmd->reap = false;
if (exitstatus == NULL) {
if (status != 0) {
char *str = virCommandToString(cmd);
char *st = virCommandTranslateStatus(status);
virCommandError(VIR_ERR_INTERNAL_ERROR,
_("Child process (%s) status unexpected: %s"),
str ? str : cmd->args[0], NULLSTR(st));
VIR_FREE(str);
VIR_FREE(st);
return -1;
}
} else {
*exitstatus = status;
}
return 0;
}
#ifndef WIN32
/*
* Abort an async command if it is running, without issuing
* any errors or affecting errno. Designed for error paths
* where some but not all paths to the cleanup code might
* have started the child process.
*/
void
virCommandAbort(virCommandPtr cmd)
{
int saved_errno;
int ret;
int status;
char *tmp = NULL;
if (!cmd || cmd->pid == -1)
return;
/* See if intermediate process has exited; if not, try a nice
* SIGTERM followed by a more severe SIGKILL.
*/
saved_errno = errno;
VIR_DEBUG("aborting child process %d", cmd->pid);
while ((ret = waitpid(cmd->pid, &status, WNOHANG)) == -1 &&
errno == EINTR);
if (ret == cmd->pid) {
tmp = virCommandTranslateStatus(status);
VIR_DEBUG("process has ended: %s", tmp);
goto cleanup;
} else if (ret == 0) {
VIR_DEBUG("trying SIGTERM to child process %d", cmd->pid);
kill(cmd->pid, SIGTERM);
usleep(10 * 1000);
while ((ret = waitpid(cmd->pid, &status, WNOHANG)) == -1 &&
errno == EINTR);
if (ret == cmd->pid) {
tmp = virCommandTranslateStatus(status);
VIR_DEBUG("process has ended: %s", tmp);
goto cleanup;
} else if (ret == 0) {
VIR_DEBUG("trying SIGKILL to child process %d", cmd->pid);
kill(cmd->pid, SIGKILL);
while ((ret = waitpid(cmd->pid, &status, 0)) == -1 &&
errno == EINTR);
if (ret == cmd->pid) {
tmp = virCommandTranslateStatus(status);
VIR_DEBUG("process has ended: %s", tmp);
goto cleanup;
}
}
}
VIR_DEBUG("failed to reap child %d, abandoning it", cmd->pid);
cleanup:
VIR_FREE(tmp);
cmd->pid = -1;
cmd->reap = false;
errno = saved_errno;
}
#else /* WIN32 */
void
virCommandAbort(virCommandPtr cmd ATTRIBUTE_UNUSED)
{
/* Mingw lacks WNOHANG and kill(). But since we haven't ported
* virExecWithHook to mingw yet, there's no process to be killed,
* making this implementation trivially correct for now :) */
}
#endif
void virCommandRequireHandshake(virCommandPtr cmd)
{
if (!cmd || cmd->has_error)
return;
if (cmd->handshake) {
cmd->has_error = -1;
VIR_DEBUG("Cannot require handshake twice");
return;
}
if (pipe(cmd->handshakeWait) < 0) {
cmd->has_error = errno;
return;
}
if (pipe(cmd->handshakeNotify) < 0) {
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
VIR_FORCE_CLOSE(cmd->handshakeWait[1]);
cmd->has_error = errno;
return;
}
VIR_DEBUG("Transfer handshake wait=%d notify=%d",
cmd->handshakeWait[1], cmd->handshakeNotify[0]);
virCommandTransferFD(cmd, cmd->handshakeWait[1]);
virCommandTransferFD(cmd, cmd->handshakeNotify[0]);
cmd->handshake = true;
}
int virCommandHandshakeWait(virCommandPtr cmd)
{
char c;
int rv;
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error || !cmd->handshake) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
if (cmd->handshakeWait[0] == -1) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Handshake is already complete"));
return -1;
}
VIR_DEBUG("Wait for handshake on %d", cmd->handshakeWait[0]);
if ((rv = saferead(cmd->handshakeWait[0], &c, sizeof(c))) != sizeof(c)) {
if (rv < 0)
virReportSystemError(errno, "%s", _("Unable to wait for child process"));
else
virReportSystemError(EIO, "%s", _("Child process quit during startup handshake"));
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
return -1;
}
if (c != '1') {
char *msg;
ssize_t len;
if (VIR_ALLOC_N(msg, 1024) < 0) {
virReportOOMError();
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
return -1;
}
if ((len = saferead(cmd->handshakeWait[0], msg, 1024)) < 0) {
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
VIR_FREE(msg);
virReportSystemError(errno, "%s", _("No error message from child failure"));
return -1;
}
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
msg[len-1] = '\0';
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s", msg);
VIR_FREE(msg);
return -1;
}
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
return 0;
}
int virCommandHandshakeNotify(virCommandPtr cmd)
{
char c = '1';
if (!cmd ||cmd->has_error == ENOMEM) {
virReportOOMError();
return -1;
}
if (cmd->has_error || !cmd->handshake) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("invalid use of command API"));
return -1;
}
if (cmd->handshakeNotify[1] == -1) {
virCommandError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Handshake is already complete"));
return -1;
}
VIR_DEBUG("Notify handshake on %d", cmd->handshakeWait[0]);
if (safewrite(cmd->handshakeNotify[1], &c, sizeof(c)) != sizeof(c)) {
virReportSystemError(errno, "%s", _("Unable to notify child process"));
VIR_FORCE_CLOSE(cmd->handshakeNotify[1]);
return -1;
}
VIR_FORCE_CLOSE(cmd->handshakeNotify[1]);
return 0;
}
/*
* Release all resources
*/
void
virCommandFree(virCommandPtr cmd)
{
int i;
if (!cmd)
return;
for (i = STDERR_FILENO + 1; i < FD_SETSIZE; i++) {
if (FD_ISSET(i, &cmd->transfer)) {
int tmpfd = i;
VIR_FORCE_CLOSE(tmpfd);
}
}
VIR_FREE(cmd->inbuf);
VIR_FORCE_CLOSE(cmd->outfd);
VIR_FORCE_CLOSE(cmd->errfd);
for (i = 0 ; i < cmd->nargs ; i++)
VIR_FREE(cmd->args[i]);
VIR_FREE(cmd->args);
for (i = 0 ; i < cmd->nenv ; i++)
VIR_FREE(cmd->env[i]);
VIR_FREE(cmd->env);
VIR_FREE(cmd->pwd);
if (cmd->handshake) {
/* The other 2 fds in these arrays are closed
* due to use with virCommandTransferFD
*/
VIR_FORCE_CLOSE(cmd->handshakeWait[0]);
VIR_FORCE_CLOSE(cmd->handshakeNotify[1]);
}
VIR_FREE(cmd->pidfile);
if (cmd->reap)
virCommandAbort(cmd);
VIR_FREE(cmd);
}
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