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Remove (unused) locking related code from system_gate.

See merge request mer-core/scratchbox2!17
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Matti Kosola committed Mar 7, 2019
2 parents 9d24d0e + 28ab420 commit c52892d
Showing 1 changed file with 227 additions and 16 deletions.
243 changes: 227 additions & 16 deletions scratchbox2/preload/system.c
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@@ -1,26 +1,236 @@
/*
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
*/
/* copied from sources of glibc-2.8 and adapted for Scratchbox 2 by Lauri T. Aarnio */

/* Copyright (C) 1991-2000,2002,2003,2005,2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C 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.
The GNU C 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 the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */

#include <errno.h>
#include <signal.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

/* sb2 */
#include "libsb2.h"
#include "exported.h"

#define __sigaction sigaction
#define __sigaddset sigaddset
#define __sigprocmask sigprocmask
#define __set_errno(x) (errno=(x))
#define __fork fork
#define __execve execve
#define __waitpid waitpid

/* To handle locking the same way as glibc does we would need to include
* (now private) libc-lock.h, which would make things difficult. At the same
* time it seems scratchbox2 has always been compiled without the
* _LIBC_REENTRANT defined here, so we are not really changing any logic
* even though the locking related code is removed.
* #include <bits/libc-lock.h>
*/
#ifdef _LIBC_REENTRANT
#error _LIBC_REENTRANT related code removed. Check sources for explanation.
#endif

/* ------------ Start of glibc based code ------------ */

#define SHELL_PATH "/bin/sh" /* Path of the shell. */
#define SHELL_NAME "sh" /* Name to give it. */


#ifdef _LIBC_REENTRANT
static struct sigaction intr, quit;
static int sa_refcntr;
__libc_lock_define_initialized (static, lock);

# define DO_LOCK() __libc_lock_lock (lock)
# define DO_UNLOCK() __libc_lock_unlock (lock)
# define INIT_LOCK() ({ __libc_lock_init (lock); sa_refcntr = 0; })
# define ADD_REF() sa_refcntr++
# define SUB_REF() --sa_refcntr
#else
# define DO_LOCK()
# define DO_UNLOCK()
# define INIT_LOCK()
# define ADD_REF() 0
# define SUB_REF() 0
#endif


/* Execute LINE as a shell command, returning its status. */
static int
do_system (const char *line)
{
int status, save;
pid_t pid;
struct sigaction sa;
#ifndef _LIBC_REENTRANT
struct sigaction intr, quit;
#endif
sigset_t omask;

sa.sa_handler = SIG_IGN;
sa.sa_flags = 0;
__sigemptyset (&sa.sa_mask);

DO_LOCK ();
if (ADD_REF () == 0)
{
if (__sigaction (SIGINT, &sa, &intr) < 0)
{
SUB_REF ();
goto out;
}
if (__sigaction (SIGQUIT, &sa, &quit) < 0)
{
save = errno;
SUB_REF ();
goto out_restore_sigint;
}
}
DO_UNLOCK ();

/* We reuse the bitmap in the 'sa' structure. */
__sigaddset (&sa.sa_mask, SIGCHLD);
save = errno;
if (__sigprocmask (SIG_BLOCK, &sa.sa_mask, &omask) < 0)
{
#ifndef _LIBC
if (errno == ENOSYS)
__set_errno (save);
else
#endif
{
DO_LOCK ();
if (SUB_REF () == 0)
{
save = errno;
(void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);
out_restore_sigint:
(void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);
__set_errno (save);
}
out:
DO_UNLOCK ();
return -1;
}
}

#ifdef CLEANUP_HANDLER
CLEANUP_HANDLER;
#endif

#ifdef FORK
pid = FORK ();
#else
pid = __fork ();
#endif
if (pid == (pid_t) 0)
{
/* Child side. */
const char *new_argv[4];
new_argv[0] = SHELL_NAME;
new_argv[1] = "-c";
new_argv[2] = line;
new_argv[3] = NULL;

/* Restore the signals. */
(void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);
(void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);
(void) __sigprocmask (SIG_SETMASK, &omask, (sigset_t *) NULL);
INIT_LOCK ();

/* Exec the shell. */
SB_LOG(SB_LOGLEVEL_DEBUG, "system(%s)", line);
(void) __execve (SHELL_PATH, (char *const *) new_argv, __environ);
_exit (127);
}
else if (pid < (pid_t) 0)
/* The fork failed. */
status = -1;
else
/* Parent side. */
{
/* Note the system() is a cancellation point. But since we call
waitpid() which itself is a cancellation point we do not
have to do anything here. */
if (TEMP_FAILURE_RETRY (__waitpid (pid, &status, 0)) != pid)
status = -1;
SB_LOG(SB_LOGLEVEL_DEBUG, "system: waitpid => status=%d", status);
}

#ifdef CLEANUP_HANDLER
CLEANUP_RESET;
#endif

save = errno;
DO_LOCK ();
if ((SUB_REF () == 0
&& (__sigaction (SIGINT, &intr, (struct sigaction *) NULL)
| __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL)) != 0)
|| __sigprocmask (SIG_SETMASK, &omask, (sigset_t *) NULL) != 0)
{
#ifndef _LIBC
/* glibc cannot be used on systems without waitpid. */
if (errno == ENOSYS)
__set_errno (save);
else
#endif
status = -1;
}
DO_UNLOCK ();

return status;
}

static int
sb2_libc_system (const char *line)
{
if (line == NULL)
/* Check that we have a command processor available. It might
not be available after a chroot(), for example. */
return do_system ("exit 0") == 0;

#if 0
/* FIXME: sb2 now uses this as if the program
* was single-threaded always. this is of course
* false assumption.
*/
if (SINGLE_THREAD_P)
#endif
return do_system (line);

#if 0
int oldtype = LIBC_CANCEL_ASYNC ();

int result = do_system (line);

LIBC_CANCEL_RESET (oldtype);

return result;
#endif
}

/* ------------ End Of glibc-Based Code ------------ */

/* sb2: */
int system_gate(
int *result_errno_ptr,
int (*real_system_ptr)(const char *line),
Expand All @@ -32,7 +242,8 @@ int system_gate(
(void)realfnname;
SB_LOG(SB_LOGLEVEL_DEBUG, "system(%s)", line);
errno = *result_errno_ptr; /* restore to orig.value */
result = __libc_system(line);
result = sb2_libc_system(line);
*result_errno_ptr = errno;
return(result);
}

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