| /* Low-level file-handling. |
| Copyright (C) 2012-2024 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 "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. */ |
| |
| std::string |
| read_remainder_of_file (FILE *file) |
| { |
| std::string res; |
| for (;;) |
| { |
| std::string::size_type start_size = res.size (); |
| constexpr int chunk_size = 1024; |
| |
| /* Resize to accommodate CHUNK_SIZE bytes. */ |
| res.resize (start_size + chunk_size); |
| |
| int n = fread (&res[start_size], 1, chunk_size, file); |
| 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)) |
| return {}; |
| |
| /* Resize the string according to the data we read. */ |
| res.resize (start_size + n); |
| break; |
| } |
| |
| return res; |
| } |
| |
| /* See gdbsupport/filestuff.h. */ |
| |
| std::optional<std::string> |
| read_text_file_to_string (const char *path) |
| { |
| gdb_file_up file = gdb_fopen_cloexec (path, "r"); |
| if (file == nullptr) |
| return {}; |
| |
| return read_remainder_of_file (file.get ()); |
| } |