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Implemented support for posix_spawn() and (main change): always use vfork() for starting external commands

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This commit is contained in:
Jean-Francois Dockes 2015-05-27 16:24:18 +02:00
parent 1de1b64c02
commit 5916f1a0e0
10 changed files with 203 additions and 38 deletions
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125
src/utils/execmd.cpp
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@ -15,7 +15,11 @@
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef TEST_EXECMD
#ifdef RECOLL_DATADIR
#include "autoconfig.h"
#else
#include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
@ -31,6 +35,16 @@
#include <vector>
#include <string>
#ifdef HAVE_SPAWN_H
#ifndef __USE_GNU
#define __USE_GNU
#define undef__USE_GNU
#endif
#include <spawn.h>
#ifdef undef__USE_GNU
#undef __USE_GNU
#endif
#endif
#include "execmd.h"
@ -150,7 +164,18 @@ bool ExecCmd::which(const string& cmd, string& exepath, const char* path)
return false;
}
void ExecCmd::putenv(const string &ea)
void ExecCmd::useVfork(bool on)
{
// Just in case: there are competent people who believe that the
// dynamic linker can sometimes deadlock if execve() is resolved
// inside the vfork/exec window. Make sure it's done now. If "/" is
// an executable file, we have a problem.
const char *argv[] = {"/", 0};
execve("/", (char *const *)argv, environ);
o_useVfork = on;
}
void ExecCmd::putenv(const string &ea)
{
m_env.push_back(ea);
}
@ -256,10 +281,17 @@ inline void ExecCmd::dochild(const string &cmd, const char **argv,
}
// Restore SIGTERM to default. Really, signal handling should be
// specified when creating the execmd. Help Recoll get rid of its
// filter children though. To be fixed one day... Not sure that
// all of this is needed. But an ignored sigterm and the masks are
// normally inherited.
// specified when creating the execmd, there might be other
// signals to reset. Resetting SIGTERM helps Recoll get rid of its
// filter children for now though. To be fixed one day...
// Note that resetting to SIG_DFL is a portable use of
// signal(). No need for sigaction() here.
// There is supposedely a risk of problems if another thread was
// calling a signal-affecting function when vfork was called. This
// seems acceptable though as no self-respecting thread is going
// to mess with the global process signal disposition.
if (signal(SIGTERM, SIG_DFL) == SIG_ERR) {
//LOGERR(("ExecCmd::DOCHILD: signal() failed, errno %d\n", errno));
}
@ -307,9 +339,9 @@ inline void ExecCmd::dochild(const string &cmd, const char **argv,
libclf_closefrom(3);
execve(cmd.c_str(), (char *const*)argv, (char *const*)envv);
// Hu ho. This should never happened as we checked the existence of the
// executable before calling dochild... Until we did this, this was
// the chief cause of LOG mutex deadlock
// Hu ho. This should never have happened as we checked the
// existence of the executable before calling dochild... Until we
// did this check, this was the chief cause of LOG mutex deadlock
LOGERR(("ExecCmd::DOCHILD: execve(%s) failed. errno %d\n", cmd.c_str(),
errno));
_exit(127);
@ -392,11 +424,85 @@ int ExecCmd::startExec(const string &cmd, const vector<string>& args,
free(envv);
return -1;
}
////////////////////////////////
//////////////////////////////// End vfork child prepare section.
#if HAVE_POSIX_SPAWN && USE_POSIX_SPAWN
{
posix_spawnattr_t attrs;
posix_spawnattr_init (&attrs);
short flags;
posix_spawnattr_getflags(&attrs, &flags);
flags |= POSIX_SPAWN_USEVFORK;
posix_spawnattr_setpgroup(&attrs, 0);
flags |= POSIX_SPAWN_SETPGROUP;
sigset_t sset;
sigemptyset(&sset);
posix_spawnattr_setsigmask (&attrs, &sset);
flags |= POSIX_SPAWN_SETSIGMASK;
sigemptyset(&sset);
sigaddset(&sset, SIGTERM);
posix_spawnattr_setsigdefault(&attrs, &sset);
flags |= POSIX_SPAWN_SETSIGDEF;
posix_spawnattr_setflags(&attrs, flags);
posix_spawn_file_actions_t facts;
posix_spawn_file_actions_init(&facts);
if (has_input) {
posix_spawn_file_actions_addclose(&facts, m_pipein[1]);
if (m_pipein[0] != 0) {
posix_spawn_file_actions_adddup2(&facts, m_pipein[0], 0);
posix_spawn_file_actions_addclose(&facts, m_pipein[0]);
}
}
if (has_output) {
posix_spawn_file_actions_addclose(&facts, m_pipeout[0]);
if (m_pipeout[1] != 1) {
posix_spawn_file_actions_adddup2(&facts, m_pipeout[1], 1);
posix_spawn_file_actions_addclose(&facts, m_pipeout[1]);
}
}
// Do we need to redirect stderr ?
if (!m_stderrFile.empty()) {
int oflags = O_WRONLY|O_CREAT;
#ifdef O_APPEND
oflags |= O_APPEND;
#endif
posix_spawn_file_actions_addopen(&facts, 2, m_stderrFile.c_str(),
oflags, 0600);
}
LOGDEB1(("using SPAWN\n"));
// posix_spawn() does not have any standard way to ask for
// calling closefrom(). Afaik there is a solaris extension for this,
// but let's just add all fds
for (int i = 3; i < libclf_maxfd(); i++) {
posix_spawn_file_actions_addclose(&facts, i);
}
int ret = posix_spawn(&m_pid, exe.c_str(), &facts, &attrs,
(char *const *)argv, (char *const *)envv);
posix_spawnattr_destroy(&attrs);
posix_spawn_file_actions_destroy(&facts);
if (ret) {
LOGERR(("ExecCmd::startExec: posix_spawn() failed. errno %d\n",
ret));
return -1;
}
}
#else
if (o_useVfork) {
LOGDEB1(("using VFORK\n"));
m_pid = vfork();
} else {
LOGDEB1(("using FORK\n"));
m_pid = fork();
}
if (m_pid < 0) {
@ -411,6 +517,7 @@ int ExecCmd::startExec(const string &cmd, const vector<string>& args,
// dochild does not return. Just in case...
_exit(1);
}
#endif
// Father process