428 lines
8.5 KiB
C
428 lines
8.5 KiB
C
/* Low-level file-handling.
|
||
Copyright (C) 2012-2016 Free Software Foundation, Inc.
|
||
|
||
This file is part of GDB.
|
||
|
||
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 3 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, see <http://www.gnu.org/licenses/>. */
|
||
|
||
#include "common-defs.h"
|
||
#include "filestuff.h"
|
||
#include "gdb_vecs.h"
|
||
#include <fcntl.h>
|
||
#include <unistd.h>
|
||
#include <sys/types.h>
|
||
#include <sys/stat.h>
|
||
|
||
#ifdef USE_WIN32API
|
||
#include <winsock2.h>
|
||
#include <windows.h>
|
||
#define HAVE_SOCKETS 1
|
||
#elif defined HAVE_SYS_SOCKET_H
|
||
#include <sys/socket.h>
|
||
/* Define HAVE_F_GETFD if we plan to use F_GETFD. */
|
||
#define HAVE_F_GETFD F_GETFD
|
||
#define HAVE_SOCKETS 1
|
||
#endif
|
||
|
||
#ifdef HAVE_SYS_RESOURCE_H
|
||
#include <sys/resource.h>
|
||
#endif /* HAVE_SYS_RESOURCE_H */
|
||
|
||
#ifndef O_CLOEXEC
|
||
#define O_CLOEXEC 0
|
||
#endif
|
||
|
||
#ifndef SOCK_CLOEXEC
|
||
#define SOCK_CLOEXEC 0
|
||
#endif
|
||
|
||
|
||
|
||
#ifndef HAVE_FDWALK
|
||
|
||
#include <dirent.h>
|
||
|
||
/* Replacement for fdwalk, if the system doesn't define it. Walks all
|
||
open file descriptors (though this implementation may walk closed
|
||
ones as well, depending on the host platform's capabilities) and
|
||
call FUNC with ARG. If FUNC returns non-zero, stops immediately
|
||
and returns the same value. Otherwise, returns zero when
|
||
finished. */
|
||
|
||
static int
|
||
fdwalk (int (*func) (void *, int), void *arg)
|
||
{
|
||
/* Checking __linux__ isn't great but it isn't clear what would be
|
||
better. There doesn't seem to be a good way to check for this in
|
||
configure. */
|
||
#ifdef __linux__
|
||
DIR *dir;
|
||
|
||
dir = opendir ("/proc/self/fd");
|
||
if (dir != NULL)
|
||
{
|
||
struct dirent *entry;
|
||
int result = 0;
|
||
|
||
for (entry = readdir (dir); entry != NULL; entry = readdir (dir))
|
||
{
|
||
long fd;
|
||
char *tail;
|
||
int result;
|
||
|
||
errno = 0;
|
||
fd = strtol (entry->d_name, &tail, 10);
|
||
if (*tail != '\0' || errno != 0)
|
||
continue;
|
||
if ((int) fd != fd)
|
||
{
|
||
/* What can we do here really? */
|
||
continue;
|
||
}
|
||
|
||
if (fd == dirfd (dir))
|
||
continue;
|
||
|
||
result = func (arg, fd);
|
||
if (result != 0)
|
||
break;
|
||
}
|
||
|
||
closedir (dir);
|
||
return result;
|
||
}
|
||
/* We may fall through to the next case. */
|
||
#endif
|
||
|
||
{
|
||
int max, fd;
|
||
|
||
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
|
||
struct rlimit rlim;
|
||
|
||
if (getrlimit (RLIMIT_NOFILE, &rlim) == 0 && rlim.rlim_max != RLIM_INFINITY)
|
||
max = rlim.rlim_max;
|
||
else
|
||
#endif
|
||
{
|
||
#ifdef _SC_OPEN_MAX
|
||
max = sysconf (_SC_OPEN_MAX);
|
||
#else
|
||
/* Whoops. */
|
||
return 0;
|
||
#endif /* _SC_OPEN_MAX */
|
||
}
|
||
|
||
for (fd = 0; fd < max; ++fd)
|
||
{
|
||
struct stat sb;
|
||
int result;
|
||
|
||
/* Only call FUNC for open fds. */
|
||
if (fstat (fd, &sb) == -1)
|
||
continue;
|
||
|
||
result = func (arg, fd);
|
||
if (result != 0)
|
||
return result;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
#endif /* HAVE_FDWALK */
|
||
|
||
|
||
|
||
/* A VEC holding all the fds open when notice_open_fds was called. We
|
||
don't use a hashtab because libiberty isn't linked into gdbserver;
|
||
and anyway we don't expect there to be many open fds. */
|
||
|
||
static VEC (int) *open_fds;
|
||
|
||
/* An fdwalk callback function used by notice_open_fds. It puts the
|
||
given file descriptor into the vec. */
|
||
|
||
static int
|
||
do_mark_open_fd (void *ignore, int fd)
|
||
{
|
||
VEC_safe_push (int, open_fds, fd);
|
||
return 0;
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
void
|
||
notice_open_fds (void)
|
||
{
|
||
fdwalk (do_mark_open_fd, NULL);
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
void
|
||
mark_fd_no_cloexec (int fd)
|
||
{
|
||
do_mark_open_fd (NULL, fd);
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
void
|
||
unmark_fd_no_cloexec (int fd)
|
||
{
|
||
int i, val;
|
||
|
||
for (i = 0; VEC_iterate (int, open_fds, i, val); ++i)
|
||
{
|
||
if (fd == val)
|
||
{
|
||
VEC_unordered_remove (int, open_fds, i);
|
||
return;
|
||
}
|
||
}
|
||
|
||
gdb_assert_not_reached (_("fd not found in open_fds"));
|
||
}
|
||
|
||
/* Helper function for close_most_fds that closes the file descriptor
|
||
if appropriate. */
|
||
|
||
static int
|
||
do_close (void *ignore, int fd)
|
||
{
|
||
int i, val;
|
||
|
||
for (i = 0; VEC_iterate (int, open_fds, i, val); ++i)
|
||
{
|
||
if (fd == val)
|
||
{
|
||
/* Keep this one open. */
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
close (fd);
|
||
return 0;
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
void
|
||
close_most_fds (void)
|
||
{
|
||
fdwalk (do_close, NULL);
|
||
}
|
||
|
||
|
||
|
||
/* This is a tri-state flag. When zero it means we haven't yet tried
|
||
O_CLOEXEC. When positive it means that O_CLOEXEC works on this
|
||
host. When negative, it means that O_CLOEXEC doesn't work. We
|
||
track this state because, while gdb might have been compiled
|
||
against a libc that supplies O_CLOEXEC, there is no guarantee that
|
||
the kernel supports it. */
|
||
|
||
static int trust_o_cloexec;
|
||
|
||
/* Mark FD as close-on-exec, ignoring errors. Update
|
||
TRUST_O_CLOEXEC. */
|
||
|
||
static void
|
||
mark_cloexec (int fd)
|
||
{
|
||
#ifdef HAVE_F_GETFD
|
||
int old = fcntl (fd, F_GETFD, 0);
|
||
|
||
if (old != -1)
|
||
{
|
||
fcntl (fd, F_SETFD, old | FD_CLOEXEC);
|
||
|
||
if (trust_o_cloexec == 0)
|
||
{
|
||
if ((old & FD_CLOEXEC) != 0)
|
||
trust_o_cloexec = 1;
|
||
else
|
||
trust_o_cloexec = -1;
|
||
}
|
||
}
|
||
#endif /* HAVE_F_GETFD */
|
||
}
|
||
|
||
/* Depending on TRUST_O_CLOEXEC, mark FD as close-on-exec. */
|
||
|
||
static void
|
||
maybe_mark_cloexec (int fd)
|
||
{
|
||
if (trust_o_cloexec <= 0)
|
||
mark_cloexec (fd);
|
||
}
|
||
|
||
#ifdef HAVE_SOCKETS
|
||
|
||
/* Like maybe_mark_cloexec, but for callers that use SOCK_CLOEXEC. */
|
||
|
||
static void
|
||
socket_mark_cloexec (int fd)
|
||
{
|
||
if (SOCK_CLOEXEC == 0 || trust_o_cloexec <= 0)
|
||
mark_cloexec (fd);
|
||
}
|
||
|
||
#endif
|
||
|
||
|
||
|
||
/* See filestuff.h. */
|
||
|
||
int
|
||
gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
|
||
{
|
||
int fd = open (filename, flags | O_CLOEXEC, mode);
|
||
|
||
if (fd >= 0)
|
||
maybe_mark_cloexec (fd);
|
||
|
||
return fd;
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
FILE *
|
||
gdb_fopen_cloexec (const char *filename, const char *opentype)
|
||
{
|
||
FILE *result;
|
||
/* Probe for "e" support once. But, if we can tell the operating
|
||
system doesn't know about close on exec mode "e" without probing,
|
||
skip it. E.g., the Windows runtime issues an "Invalid parameter
|
||
passed to C runtime function" OutputDebugString warning for
|
||
unknown modes. Assume that if O_CLOEXEC is zero, then "e" isn't
|
||
supported. */
|
||
static int fopen_e_ever_failed_einval = O_CLOEXEC == 0;
|
||
|
||
if (!fopen_e_ever_failed_einval)
|
||
{
|
||
char *copy;
|
||
|
||
copy = (char *) alloca (strlen (opentype) + 2);
|
||
strcpy (copy, opentype);
|
||
/* This is a glibc extension but we try it unconditionally on
|
||
this path. */
|
||
strcat (copy, "e");
|
||
result = fopen (filename, copy);
|
||
|
||
if (result == NULL && errno == EINVAL)
|
||
{
|
||
result = fopen (filename, opentype);
|
||
if (result != NULL)
|
||
fopen_e_ever_failed_einval = 1;
|
||
}
|
||
}
|
||
else
|
||
result = fopen (filename, opentype);
|
||
|
||
if (result != NULL)
|
||
maybe_mark_cloexec (fileno (result));
|
||
|
||
return result;
|
||
}
|
||
|
||
#ifdef HAVE_SOCKETS
|
||
/* See filestuff.h. */
|
||
|
||
int
|
||
gdb_socketpair_cloexec (int domain, int style, int protocol,
|
||
int filedes[2])
|
||
{
|
||
#ifdef HAVE_SOCKETPAIR
|
||
int result = socketpair (domain, style | SOCK_CLOEXEC, protocol, filedes);
|
||
|
||
if (result != -1)
|
||
{
|
||
socket_mark_cloexec (filedes[0]);
|
||
socket_mark_cloexec (filedes[1]);
|
||
}
|
||
|
||
return result;
|
||
#else
|
||
gdb_assert_not_reached (_("socketpair not available on this host"));
|
||
#endif
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
int
|
||
gdb_socket_cloexec (int domain, int style, int protocol)
|
||
{
|
||
int result = socket (domain, style | SOCK_CLOEXEC, protocol);
|
||
|
||
if (result != -1)
|
||
socket_mark_cloexec (result);
|
||
|
||
return result;
|
||
}
|
||
#endif
|
||
|
||
/* See filestuff.h. */
|
||
|
||
int
|
||
gdb_pipe_cloexec (int filedes[2])
|
||
{
|
||
int result;
|
||
|
||
#ifdef HAVE_PIPE2
|
||
result = pipe2 (filedes, O_CLOEXEC);
|
||
if (result != -1)
|
||
{
|
||
maybe_mark_cloexec (filedes[0]);
|
||
maybe_mark_cloexec (filedes[1]);
|
||
}
|
||
#else
|
||
#ifdef HAVE_PIPE
|
||
result = pipe (filedes);
|
||
if (result != -1)
|
||
{
|
||
mark_cloexec (filedes[0]);
|
||
mark_cloexec (filedes[1]);
|
||
}
|
||
#else /* HAVE_PIPE */
|
||
gdb_assert_not_reached (_("pipe not available on this host"));
|
||
#endif /* HAVE_PIPE */
|
||
#endif /* HAVE_PIPE2 */
|
||
|
||
return result;
|
||
}
|
||
|
||
/* Helper function which does the work for make_cleanup_close. */
|
||
|
||
static void
|
||
do_close_cleanup (void *arg)
|
||
{
|
||
int *fd = (int *) arg;
|
||
|
||
close (*fd);
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
struct cleanup *
|
||
make_cleanup_close (int fd)
|
||
{
|
||
int *saved_fd = XNEW (int);
|
||
|
||
*saved_fd = fd;
|
||
return make_cleanup_dtor (do_close_cleanup, saved_fd, xfree);
|
||
}
|