prototype vfork exec-wrapper.

diff --git a/libs/pbd/system_exec.cc b/libs/pbd/system_exec.cc
index c3c0ace2d62492193a2697fc927bb4104db68eaa..ac0d37f0d0ef966e4bbbd43d0b7fd54a60f88c81 100644 (file)
--- a/libs/pbd/system_exec.cc
+++ b/libs/pbd/system_exec.cc
@@ -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

diff --git a/tools/exec_wrapper.c b/tools/exec_wrapper.c
new file mode 100644 (file)
index 0000000..ad7577b
--- /dev/null
+++ b/tools/exec_wrapper.c
@@ -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;
+}