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prototype vfork exec-wrapper.

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This commit is contained in:
Robin Gareus
2014-03-11 15:48:13 +01:00
parent 279aefc60e
commit f6129ed0f4
2 changed files with 135 additions and 33 deletions
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74
libs/pbd/system_exec.cc
View File

@@ -608,7 +608,11 @@ SystemExec::start (int stderr_mode)
return -1;
}
#ifdef USE_VFORK
r = ::vfork();
#else
r = ::fork();
#endif
if (r < 0) {
/* failed to fork */
return -2;
@@ -642,28 +646,6 @@ SystemExec::start (int stderr_mode)
close_fd(pok[0]);
/* child started successfully */
#if 0
/* use fork for output-interposer
* it will run in a separated process
*/
/* catch stdout thread */
r = ::fork();
if (r < 0) {
// failed to fork
terminate();
return -2;
}
if (r == 0) {
/* 2nd child process - catch stdout */
close_fd(pin[1]);
close_fd(pout[1]);
output_interposer();
exit(0);
}
close_fd(pout[1]);
close_fd(pin[0]);
close_fd(pout[0]);
#else /* use pthread */
close_fd(pout[1]);
close_fd(pin[0]);
int rv = pthread_create(&thread_id_tt, NULL, interposer_thread, this);
@@ -674,10 +656,10 @@ SystemExec::start (int stderr_mode)
terminate();
return -2;
}
#endif
return 0; /* all systems go - return to main */
}
#ifndef USE_VFORK
/* child process - exec external process */
close_fd(pok[0]);
::fcntl(pok[1], F_SETFD, FD_CLOEXEC);
@@ -712,16 +694,6 @@ SystemExec::start (int stderr_mode)
::nice(nicelevel);
}
#if 0
/* chdir to executable dir */
char *directory;
directory = strdup(cmd.c_str());
if (strrchr(directory, '/') != (char *) 0) {
::chdir(directory);
}
free(directory);
#endif
#ifdef HAVE_SIGSET
sigset(SIGPIPE, SIG_DFL);
#else
@@ -738,6 +710,42 @@ SystemExec::start (int stderr_mode)
close_fd(pok[1]);
exit(-1);
return -1;
#else
/* XXX this should be done before vfork()
* calling malloc here only increases the time we vfork() blocks
*/
int argn = 0;
for (int i=0;argp[i];++i) { argn++; }
char **argx = (char **) malloc((argn + 10) * sizeof(char *));
argx[0] = strdup("/home/rgareus/src/git/ardourCairoCanvas/tools/exec_wrapper"); // XXX TODO
#define FDARG(NUM, FDN) \
argx[NUM] = (char*) calloc(6, sizeof(char)); snprintf(argx[NUM], 6, "%d", FDN);
FDARG(1, pok[0])
FDARG(2, pok[1])
FDARG(3, pin[0])
FDARG(4, pin[1])
FDARG(5, pout[0])
FDARG(6, pout[1])
FDARG(7, stderr_mode)
FDARG(8, nicelevel)
for (int i=0;argp[i];++i) {
argx[9+i] = argp[i];
}
argx[argn+9] = NULL;
::execve(argx[0], argx, envp);
/* if we reach here something went wrong.. */
char buf = 0;
(void) ::write(pok[1], &buf, 1 );
close_fd(pok[1]);
exit(-1);
return -1;
#endif
}
void

94
tools/exec_wrapper.c Normal file
View File

@@ -0,0 +1,94 @@
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#ifndef STDIN_FILENO
#define STDIN_FILENO 0
#endif
#ifndef STDOUT_FILENO
#define STDOUT_FILENO 1
#endif
#ifndef STDERR_FILENO
#define STDERR_FILENO 2
#endif
extern char **environ;
static void close_fd (int *fd) { if ((*fd) >= 0) close (*fd); *fd = -1; }
int main(int argc, char *argv[]) {
if (argc < 10) {
// TODO: if argv > 3, assume pok[] is given, notifify parent.
// usage() and a man-page (help2man) would not be bad, either :)
return -1;
}
int pok[2];
int pin[2];
int pout[2];
pok[0] = atoi(argv[1]);
pok[1] = atoi(argv[2]);
pin[0] = atoi(argv[3]);
pin[1] = atoi(argv[4]);
pout[0] = atoi(argv[5]);
pout[1] = atoi(argv[6]);
int stderr_mode = atoi(argv[7]);
int nicelevel = atoi(argv[8]);
/* vfork()ed child process - exec external process */
close_fd(&pok[0]);
fcntl(pok[1], F_SETFD, FD_CLOEXEC);
close_fd(&pin[1]);
if (pin[0] != STDIN_FILENO) {
dup2(pin[0], STDIN_FILENO);
}
close_fd(&pin[0]);
close_fd(&pout[0]);
if (pout[1] != STDOUT_FILENO) {
dup2(pout[1], STDOUT_FILENO);
}
if (stderr_mode == 2) {
/* merge STDERR into output */
if (pout[1] != STDERR_FILENO) {
dup2(pout[1], STDERR_FILENO);
}
} else if (stderr_mode == 1) {
/* ignore STDERR */
close(STDERR_FILENO);
} else {
/* keep STDERR */
}
if (pout[1] != STDOUT_FILENO && pout[1] != STDERR_FILENO) {
close_fd(&pout[1]);
}
if (nicelevel !=0) {
nice(nicelevel);
}
/* copy current environment */
char **envp = NULL;
int i=0;
envp = (char **) calloc(1, sizeof(char*));
for (i=0;environ[i];++i) {
envp[i] = strdup(environ[i]);
envp = (char **) realloc(envp, (i+2) * sizeof(char*));
}
envp[i] = 0;
/* all systems go */
execve(argv[9], &argv[9], envp);
/* if we reach here something went wrong.. */
char buf = 0;
(void) write(pok[1], &buf, 1 );
close_fd(&pok[1]);
exit(-1);
return -1;
}