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rework SystemExec - use vfork wrapper (and lots of related stuff)

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This commit is contained in:
Robin Gareus 2014-03-13 16:50:44 +01:00
parent f48b556888
commit 543099afba
16 changed files with 240 additions and 40 deletions
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50
libs/ardour/ardour/system_exec.h Normal file
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@ -0,0 +1,50 @@
/*
Copyright (C) 2010 Paul Davis
Copyright (C) 2010-2014 Robin Gareus <robin@gareus.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef _ardour_system_exec_h_
#define _ardour_system_exec_h_
#include "ardour/libardour_visibility.h"
#include "pbd/system_exec.h"
namespace ARDOUR {
class LIBARDOUR_API SystemExec
: public PBD::SystemExec
{
public:
SystemExec (std::string c, std::string a = "");
SystemExec (std::string c, char ** a);
~SystemExec ();
int start (int stderr_mode = 1) {
return PBD::SystemExec::start(stderr_mode, _vfork_exec_wrapper);
}
private:
static char * _vfork_exec_wrapper;
}; /* end class */
}; /* end namespace */
#endif /* _libpbd_system_exec_h_ */

60
libs/ardour/system_exec.cc Normal file
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@ -0,0 +1,60 @@
/*
Copyright (C) 2010 Paul Davis
Copyright (C) 2010-2014 Robin Gareus <robin@gareus.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <glibmm/miscutils.h>
#include "pbd/pathscanner.h"
#include "pbd/file_utils.h"
#include "pbd/error.h"
#include "ardour/filesystem_paths.h"
#include "ardour/system_exec.h"
using namespace ARDOUR;
char * SystemExec::_vfork_exec_wrapper = NULL;
static char *vfork_exec_wrapper_path() {
std::string vfork_exec_wrapper;
if (!PBD::find_file_in_search_path (
PBD::Searchpath(Glib::build_filename(ARDOUR::ardour_dll_directory(), "vfork")),
"ardour-exec-wrapper", vfork_exec_wrapper)) {
PBD::warning << "vfork exec wrapper not found..'" << endmsg;
return NULL;
}
return strdup(vfork_exec_wrapper.c_str());
}
SystemExec::SystemExec (std::string c, char ** a)
: PBD::SystemExec(c, a)
{
if (!_vfork_exec_wrapper) {
_vfork_exec_wrapper = vfork_exec_wrapper_path();
}
}
SystemExec::SystemExec (std::string c, std::string a)
: PBD::SystemExec(c, a)
{
if (!_vfork_exec_wrapper) {
_vfork_exec_wrapper = vfork_exec_wrapper_path();
}
}
SystemExec::~SystemExec() { }

40
libs/ardour/vst_info_file.cc
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@ -40,12 +40,18 @@
#include <glib/gstdio.h>
#include <glibmm.h>
#include "pbd/error.h"
#ifndef VST_SCANNER_APP
#include "pbd/system_exec.h"
#ifdef VST_SCANNER_APP
#define errormsg cerr
#define warningmsg cerr
#define endmsg endl
#else
#include "ardour/plugin_manager.h" // scanner_bin_path
#include "ardour/rc_configuration.h"
#include "ardour/system_exec.h"
#include "pbd/error.h"
#define errormsg PBD::error
#define warningmsg PBD::warning
#endif
#include "ardour/filesystem_paths.h"
@ -324,7 +330,7 @@ vstfx_write_info_file (FILE* fp, vector<VSTInfo *> *infos)
} else if (infos->size() == 1) {
vstfx_write_info_block(fp, infos->front());
} else {
PBD::error << "Zero plugins in VST." << endmsg; // XXX here? rather make this impossible before if it ain't already.
errormsg << "Zero plugins in VST." << endmsg; // XXX here? rather make this impossible before if it ain't already.
}
}
@ -508,7 +514,7 @@ vstfx_get_info_from_file(const char* dllpath, vector<VSTInfo*> *infos)
rv = vstfx_load_info_file(infofile, infos);
fclose (infofile);
if (!rv) {
PBD::warning << "Cannot get VST information form " << dllpath << ": info file load failed." << endmsg;
warningmsg << "Cannot get VST information form " << dllpath << ": info file load failed." << endmsg;
}
}
return rv;
@ -774,7 +780,7 @@ vstfx_instantiate_and_get_info_lx (
VSTHandle* h;
VSTState* vstfx;
if (!(h = vstfx_load(dllpath))) {
PBD::warning << "Cannot get LinuxVST information from " << dllpath << ": load failed." << endmsg;
warningmsg << "Cannot get LinuxVST information from " << dllpath << ": load failed." << endmsg;
return false;
}
@ -782,7 +788,7 @@ vstfx_instantiate_and_get_info_lx (
if (!(vstfx = vstfx_instantiate(h, simple_master_callback, 0))) {
vstfx_unload(h);
PBD::warning << "Cannot get LinuxVST information from " << dllpath << ": instantiation failed." << endmsg;
warningmsg << "Cannot get LinuxVST information from " << dllpath << ": instantiation failed." << endmsg;
return false;
}
@ -803,7 +809,7 @@ vstfx_instantiate_and_get_info_fst (
VSTHandle* h;
VSTState* vstfx;
if(!(h = fst_load(dllpath))) {
PBD::warning << "Cannot get Windows VST information from " << dllpath << ": load failed." << endmsg;
warningmsg << "Cannot get Windows VST information from " << dllpath << ": load failed." << endmsg;
return false;
}
@ -812,7 +818,7 @@ vstfx_instantiate_and_get_info_fst (
if(!(vstfx = fst_instantiate(h, simple_master_callback, 0))) {
fst_unload(&h);
vstfx_current_loading_id = 0;
PBD::warning << "Cannot get Windows VST information from " << dllpath << ": instantiation failed." << endmsg;
warningmsg << "Cannot get Windows VST information from " << dllpath << ": instantiation failed." << endmsg;
return false;
}
vstfx_current_loading_id = 0;
@ -834,14 +840,14 @@ static char * _errorlog_dll = 0;
static void parse_scanner_output (std::string msg, size_t /*len*/)
{
if (!_errorlog_fd && !_errorlog_dll) {
PBD::error << "VST scanner: " << msg;
errormsg << "VST scanner: " << msg;
return;
}
if (!_errorlog_fd) {
if (!(_errorlog_fd = fopen(vstfx_errorfile_path(_errorlog_dll, 0).c_str(), "w"))) {
if (!(_errorlog_fd = fopen(vstfx_errorfile_path(_errorlog_dll, 1).c_str(), "w"))) {
PBD::error << "Cannot create plugin error-log for plugin " << _errorlog_dll;
errormsg << "Cannot create plugin error-log for plugin " << _errorlog_dll;
free(_errorlog_dll);
_errorlog_dll = NULL;
}
@ -851,7 +857,7 @@ static void parse_scanner_output (std::string msg, size_t /*len*/)
if (_errorlog_fd) {
fprintf (_errorlog_fd, "%s\n", msg.c_str());
} else {
PBD::error << "VST scanner: " << msg;
errormsg << "VST scanner: " << msg;
}
}
@ -907,11 +913,11 @@ vstfx_get_info (const char* dllpath, enum ARDOUR::PluginType type, enum VSTScanM
argp[2] = 0;
set_error_log(dllpath);
PBD::SystemExec scanner (scanner_bin_path, argp);
ARDOUR::SystemExec scanner (scanner_bin_path, argp);
PBD::ScopedConnectionList cons;
scanner.ReadStdout.connect_same_thread (cons, boost::bind (&parse_scanner_output, _1 ,_2));
if (scanner.start (2 /* send stderr&stdout via signal */)) {
PBD::error << "Cannot launch VST scanner app '" << scanner_bin_path << "': "<< strerror(errno) << endmsg;
errormsg << "Cannot launch VST scanner app '" << scanner_bin_path << "': "<< strerror(errno) << endmsg;
close_error_log();
return infos;
} else {
@ -977,7 +983,7 @@ vstfx_get_info (const char* dllpath, enum ARDOUR::PluginType type, enum VSTScanM
/* crate cache/whitelist */
infofile = vstfx_infofile_for_write (dllpath);
if (!infofile) {
PBD::warning << "Cannot cache VST information for " << dllpath << ": cannot create new FST info file." << endmsg;
warningmsg << "Cannot cache VST information for " << dllpath << ": cannot create new FST info file." << endmsg;
return infos;
} else {
vstfx_write_info_file (infofile, infos);
@ -1005,7 +1011,7 @@ get_personal_vst_blacklist_dir() {
/* if the directory doesn't exist, try to create it */
if (!Glib::file_test (dir, Glib::FILE_TEST_IS_DIR)) {
if (g_mkdir (dir.c_str (), 0700)) {
PBD::error << "Cannot create VST blacklist folder '" << dir << "'" << endmsg;
errormsg << "Cannot create VST blacklist folder '" << dir << "'" << endmsg;
//exit(1);
}
}
@ -1018,7 +1024,7 @@ get_personal_vst_info_cache_dir() {
/* if the directory doesn't exist, try to create it */
if (!Glib::file_test (dir, Glib::FILE_TEST_IS_DIR)) {
if (g_mkdir (dir.c_str (), 0700)) {
PBD::error << "Cannot create VST info folder '" << dir << "'" << endmsg;
errormsg << "Cannot create VST info folder '" << dir << "'" << endmsg;
//exit(1);
}
}

1
libs/ardour/wscript
View file

@ -197,6 +197,7 @@ libardour_sources = [
'speakers.cc',
'srcfilesource.cc',
'strip_silence.cc',
'system_exec.cc',
'revision.cc',
'tape_file_matcher.cc',
'template_utils.cc',

2
libs/pbd/pbd/system_exec.h
View file

@ -107,7 +107,7 @@ class LIBPBD_API SystemExec
* @return If the process is already running or was launched successfully
* the function returns zero (0). A negative number indicates an error.
*/
int start (int stderr_mode = 1);
int start (int stderr_mode, const char *_vfork_exec_wrapper);
/** kill running child-process
*
* if a child process exists trt to shut it down by closing its STDIN.

20
libs/pbd/system_exec.cc
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@ -43,6 +43,8 @@
#endif
#define USE_VFORK
#include "pbd/system_exec.h"
using namespace std;
@ -51,7 +53,7 @@ using namespace PBD;
static void * interposer_thread (void *arg);
static void close_fd (int& fd) { if (fd >= 0) ::close (fd); fd = -1; }
#ifndef PLATFORM_WINDOWS
#if (!defined PLATFORM_WINDOWS && defined NO_VFORK)
/*
* This function was part of libasyncns.
* LGPL v2.1
@ -146,7 +148,7 @@ static int close_allv(const int except_fds[]) {
return 0;
}
#endif /* not on windows */
#endif /* not on windows, nor vfork */
SystemExec::SystemExec (std::string c, std::string a)
@ -324,7 +326,7 @@ SystemExec::is_running ()
}
int
SystemExec::start (int stderr_mode)
SystemExec::start (int stderr_mode, const char * /*vfork_exec_wrapper*/)
{
char* working_dir = 0;
@ -596,7 +598,7 @@ SystemExec::is_running ()
}
int
SystemExec::start (int stderr_mode)
SystemExec::start (int stderr_mode, const char *vfork_exec_wrapper)
{
if (is_running()) {
return 0; // mmh what to return here?
@ -608,7 +610,7 @@ SystemExec::start (int stderr_mode)
return -1;
}
#ifdef USE_VFORK
#ifndef NO_VFORK
r = ::vfork();
#else
r = ::fork();
@ -631,11 +633,11 @@ SystemExec::start (int stderr_mode)
/* child process returned from execve */
pid=0;
close_fd(pok[0]);
close_fd(pok[1]);
close_fd(pin[1]);
close_fd(pin[0]);
close_fd(pout[1]);
close_fd(pout[0]);
pin[1] = -1;
return -3;
} else if ( n==-1 ) {
if ( errno==EAGAIN || errno==EINTR )
@ -659,7 +661,7 @@ SystemExec::start (int stderr_mode)
return 0; /* all systems go - return to main */
}
#ifndef USE_VFORK
#ifdef NO_VFORK
/* child process - exec external process */
close_fd(pok[0]);
::fcntl(pok[1], F_SETFD, FD_CLOEXEC);
@ -713,12 +715,12 @@ SystemExec::start (int stderr_mode)
#else
/* XXX this should be done before vfork()
* calling malloc here only increases the time we vfork() blocks
* calling malloc here only increases the time 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
argx[0] = strdup(vfork_exec_wrapper); // XXX
#define FDARG(NUM, FDN) \
argx[NUM] = (char*) calloc(6, sizeof(char)); snprintf(argx[NUM], 6, "%d", FDN);

44
libs/vfork/README Normal file
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@ -0,0 +1,44 @@
vfork-exec-wrapper
==================
A tiny tool that redirects stdio file-descriptors and executes a program.
Motivation
----------
Ardour can start external helper applications for various purposes
(e.g. video-server, video-monitor, plugin-scanner, post-export scripts,...)
and has the need to bidirectionally communicate with the external app.
On POSIX platforms (OSX, GNU/Linux, BSD,..) launching an external app is a
combination of fork() and execve(2). The problem with that is that fork(2)
duplicates the complete page-table (incl. allocated locked memory, and
file-descriptors) which - even if fork(2) is done from a non-realtime
thread - may cause audio I/O glitches or worse out-of-memory errors if
the mlock(2) limit is reached.
vfork(2) on the other hand "is a special case of clone(2). It is used to
create new processes without copying the page tables of the parent process.
It may be useful in performance-sensitive applications where a child is
created which then immediately issues an execve(2)." [vfork man page].
The problem with vfork(2) is that file-descriptors are not cloned, which
makes bi-directional communication impossible without additional work.
This is exactly what this vfork-exec-wrapper does: It takes a list of
file-descriptors, re-directs them to stdio and calls execve(2) again.
This code was previously in pbd/system_exec.cc (done after fork(2),
which become a NOOP with vfork(2)).
Usage
-----
ardour-exec-wrapper <file-des> <mode> <nice> <command> [args]
ardour-exec-wrapper takes three pairs of file-descriptors, stderr mode,
nice-level followed by the command to execute and optional arguments.
The first set FDs is used to communicate failure back to the parent process.
They are closed if execve(2) succeeds. The following two FDs are stdin and
stdout. The mode specifies handling of stderr: 0: keep stderr, 1: close and
ignore, 2: merge stderr into stdout.

101
libs/vfork/exec_wrapper.c Normal file
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@ -0,0 +1,101 @@
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <signal.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;
#ifdef HAVE_SIGSET
sigset(SIGPIPE, SIG_DFL);
#else
signal(SIGPIPE, SIG_DFL);
#endif
/* 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;
}

28
libs/vfork/wscript Normal file
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@ -0,0 +1,28 @@
#!/usr/bin/env python
from waflib.extras import autowaf as autowaf
from waflib import TaskGen
import os
import sys
# Mandatory variables
top = '.'
out = 'build'
def options(opt):
autowaf.set_options(opt)
def configure(conf):
conf.load('compiler_c')
autowaf.configure(conf)
def build(bld):
if bld.env['build_target'] == 'mingw':
return
obj = bld (features = 'c cprogram')
obj.source = 'exec_wrapper.c'
obj.target = 'ardour-exec-wrapper'
obj.install_path = os.path.join(bld.env['LIBDIR'], 'ardour3/vfork')
obj.defines = [
'_POSIX_SOURCE',
'_XOPEN_SOURCE=700',
]