diff options
Diffstat (limited to 'gdb/gdbsupport/filestuff.c')
| -rw-r--r-- | gdb/gdbsupport/filestuff.c | 503 |
1 files changed, 503 insertions, 0 deletions
diff --git a/gdb/gdbsupport/filestuff.c b/gdb/gdbsupport/filestuff.c new file mode 100644 index 00000000000..b8fca1552a4 --- /dev/null +++ b/gdb/gdbsupport/filestuff.c @@ -0,0 +1,503 @@ +/* Low-level file-handling. + Copyright (C) 2012-2019 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. */ + +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. */ + +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; + } +} |