mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-09 04:21:49 +08:00
7a283d9cf5
I would like to add more code to nat/linux-osdata.c that reads an entire file from /proc or /sys and processes it as a string afterwards. I would like to avoid duplicating the somewhat error-prone code that reads an entire file to a buffer. I think we should have a utility function that does that. Add read_file_to_string to gdbsupport/filestuff.{c,h}, and make linux_common_core_of_thread use it. I want to make the new function return an std::string, and because strtok doesn't play well with std::string (it requires a `char *`, std::string::c_str returns a `const char *`), change linux_common_core_of_thread to use std::string methods instead. Approved-By: Tom Tromey <tom@tromey.com> Change-Id: I1793fda72a82969c28b944a84acb953f74c9230a
541 lines
12 KiB
C++
541 lines
12 KiB
C++
/* Low-level file-handling.
|
||
Copyright (C) 2012-2022 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>
|
||
#include <algorithm>
|
||
|
||
#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_KINFO_GETFILE
|
||
#include <sys/user.h>
|
||
#include <libutil.h>
|
||
#endif
|
||
|
||
#ifdef HAVE_SYS_RESOURCE_H
|
||
#include <sys/resource.h>
|
||
#endif /* HAVE_SYS_RESOURCE_H */
|
||
|
||
#ifndef O_CLOEXEC
|
||
#define O_CLOEXEC 0
|
||
#endif
|
||
|
||
#ifndef O_NOINHERIT
|
||
#define O_NOINHERIT 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;
|
||
|
||
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
|
||
#ifdef HAVE_KINFO_GETFILE
|
||
int nfd;
|
||
gdb::unique_xmalloc_ptr<struct kinfo_file[]> fdtbl
|
||
(kinfo_getfile (getpid (), &nfd));
|
||
if (fdtbl != NULL)
|
||
{
|
||
for (int i = 0; i < nfd; i++)
|
||
{
|
||
if (fdtbl[i].kf_fd >= 0)
|
||
{
|
||
int result = func (arg, fdtbl[i].kf_fd);
|
||
if (result != 0)
|
||
return result;
|
||
}
|
||
}
|
||
return 0;
|
||
}
|
||
/* 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 vector holding all the fds open when notice_open_fds was called. We
|
||
don't use a hashtab because we don't expect there to be many open fds. */
|
||
|
||
static std::vector<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)
|
||
{
|
||
open_fds.push_back (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)
|
||
{
|
||
auto it = std::remove (open_fds.begin (), open_fds.end (), fd);
|
||
|
||
if (it != open_fds.end ())
|
||
open_fds.erase (it);
|
||
else
|
||
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)
|
||
{
|
||
for (int val : open_fds)
|
||
{
|
||
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. */
|
||
|
||
scoped_fd
|
||
gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
|
||
{
|
||
scoped_fd fd (open (filename, flags | O_CLOEXEC, mode));
|
||
|
||
if (fd.get () >= 0)
|
||
maybe_mark_cloexec (fd.get ());
|
||
|
||
return fd;
|
||
}
|
||
|
||
/* See filestuff.h. */
|
||
|
||
gdb_file_up
|
||
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. On MinGW, O_CLOEXEC is an alias of O_NOINHERIT, and
|
||
"e" isn't supported. */
|
||
static int fopen_e_ever_failed_einval =
|
||
O_CLOEXEC == 0 || O_CLOEXEC == O_NOINHERIT;
|
||
|
||
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 gdb_file_up (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;
|
||
}
|
||
|
||
/* See gdbsupport/filestuff.h. */
|
||
|
||
bool
|
||
is_regular_file (const char *name, int *errno_ptr)
|
||
{
|
||
struct stat st;
|
||
const int status = stat (name, &st);
|
||
|
||
/* Stat should never fail except when the file does not exist.
|
||
If stat fails, analyze the source of error and return true
|
||
unless the file does not exist, to avoid returning false results
|
||
on obscure systems where stat does not work as expected. */
|
||
|
||
if (status != 0)
|
||
{
|
||
if (errno != ENOENT)
|
||
return true;
|
||
*errno_ptr = ENOENT;
|
||
return false;
|
||
}
|
||
|
||
if (S_ISREG (st.st_mode))
|
||
return true;
|
||
|
||
if (S_ISDIR (st.st_mode))
|
||
*errno_ptr = EISDIR;
|
||
else
|
||
*errno_ptr = EINVAL;
|
||
return false;
|
||
}
|
||
|
||
/* See gdbsupport/filestuff.h. */
|
||
|
||
bool
|
||
mkdir_recursive (const char *dir)
|
||
{
|
||
auto holder = make_unique_xstrdup (dir);
|
||
char * const start = holder.get ();
|
||
char *component_start = start;
|
||
char *component_end = start;
|
||
|
||
while (1)
|
||
{
|
||
/* Find the beginning of the next component. */
|
||
while (*component_start == '/')
|
||
component_start++;
|
||
|
||
/* Are we done? */
|
||
if (*component_start == '\0')
|
||
return true;
|
||
|
||
/* Find the slash or null-terminator after this component. */
|
||
component_end = component_start;
|
||
while (*component_end != '/' && *component_end != '\0')
|
||
component_end++;
|
||
|
||
/* Temporarily replace the slash with a null terminator, so we can create
|
||
the directory up to this component. */
|
||
char saved_char = *component_end;
|
||
*component_end = '\0';
|
||
|
||
/* If we get EEXIST and the existing path is a directory, then we're
|
||
happy. If it exists, but it's a regular file and this is not the last
|
||
component, we'll fail at the next component. If this is the last
|
||
component, the caller will fail with ENOTDIR when trying to
|
||
open/create a file under that path. */
|
||
if (mkdir (start, 0700) != 0)
|
||
if (errno != EEXIST)
|
||
return false;
|
||
|
||
/* Restore the overwritten char. */
|
||
*component_end = saved_char;
|
||
component_start = component_end;
|
||
}
|
||
}
|
||
|
||
/* See gdbsupport/filestuff.h. */
|
||
|
||
gdb::optional<std::string>
|
||
read_text_file_to_string (const char *path)
|
||
{
|
||
gdb_file_up file = gdb_fopen_cloexec (path, "r");
|
||
if (file == nullptr)
|
||
return {};
|
||
|
||
std::string res;
|
||
for (;;)
|
||
{
|
||
std::string::size_type start_size = res.size ();
|
||
constexpr int chunk_size = 1024;
|
||
|
||
/* Resize to accomodate CHUNK_SIZE bytes. */
|
||
res.resize (start_size + chunk_size);
|
||
|
||
int n = fread (&res[start_size], 1, chunk_size, file.get ());
|
||
if (n == chunk_size)
|
||
continue;
|
||
|
||
gdb_assert (n < chunk_size);
|
||
|
||
/* Less than CHUNK means EOF or error. If it's an error, return
|
||
no value. */
|
||
if (ferror (file.get ()))
|
||
return {};
|
||
|
||
/* Resize the string according to the data we read. */
|
||
res.resize (start_size + n);
|
||
break;
|
||
}
|
||
|
||
return res;
|
||
}
|