src/basic/fd-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <dirent.h>
   5 #include <fcntl.h>
   6 #include <stdbool.h>
   7 #include <stdio.h>
   8 #include <sys/socket.h>
   9
  10 #include "macro.h"
  11 #include "missing_fcntl.h"
  12 #include "stdio-util.h"
  13
  14 /* maximum length of fdname */
  15 #define FDNAME_MAX 255
  16
  17 /* Make sure we can distinguish fd 0 and NULL */
  18 #define FD_TO_PTR(fd) INT_TO_PTR((fd)+1)
  19 #define PTR_TO_FD(p) (PTR_TO_INT(p)-1)
  20
  21 /* Useful helpers for initializing pipe(), socketpair() or stdio fd arrays */
  22 #define EBADF_PAIR { -EBADF, -EBADF }
  23 #define EBADF_TRIPLET { -EBADF, -EBADF, -EBADF }
  24
  25 int close_nointr(int fd);
  26 int safe_close(int fd);
  27 void safe_close_pair(int p[static 2]);
  28
  29 static inline int safe_close_above_stdio(int fd) {
  30         if (fd < 3) /* Don't close stdin/stdout/stderr, but still invalidate the fd by returning -EBADF. */
  31                 return -EBADF;
  32
  33         return safe_close(fd);
  34 }
  35
  36 void close_many(const int fds[], size_t n_fds);
  37 void close_many_unset(int fds[], size_t n_fds);
  38 void close_many_and_free(int *fds, size_t n_fds);
  39
  40 int fclose_nointr(FILE *f);
  41 FILE* safe_fclose(FILE *f);
  42 DIR* safe_closedir(DIR *f);
  43
  44 static inline void closep(int *fd) {
  45         safe_close(*fd);
  46 }
  47
  48 static inline void close_pairp(int (*p)[2]) {
  49         safe_close_pair(*p);
  50 }
  51
  52 static inline void fclosep(FILE **f) {
  53         safe_fclose(*f);
  54 }
  55
  56 static inline void* close_fd_ptr(void *p) {
  57         safe_close(PTR_TO_FD(p));
  58         return NULL;
  59 }
  60
  61 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, pclose, NULL);
  62 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(DIR*, closedir, NULL);
  63
  64 #define _cleanup_close_ _cleanup_(closep)
  65 #define _cleanup_fclose_ _cleanup_(fclosep)
  66 #define _cleanup_pclose_ _cleanup_(pclosep)
  67 #define _cleanup_closedir_ _cleanup_(closedirp)
  68 #define _cleanup_close_pair_ _cleanup_(close_pairp)
  69
  70 int fd_nonblock(int fd, bool nonblock);
  71 int stdio_disable_nonblock(void);
  72
  73 int fd_cloexec(int fd, bool cloexec);
  74 int fd_cloexec_many(const int fds[], size_t n_fds, bool cloexec);
  75
  76 int get_max_fd(void);
  77
  78 int close_all_fds(const int except[], size_t n_except);
  79 int close_all_fds_without_malloc(const int except[], size_t n_except);
  80
  81 int pack_fds(int fds[], size_t n);
  82
  83 int same_fd(int a, int b);
  84
  85 void cmsg_close_all(struct msghdr *mh);
  86
  87 bool fdname_is_valid(const char *s);
  88
  89 int fd_get_path(int fd, char **ret);
  90
  91 int move_fd(int from, int to, int cloexec);
  92
  93 int fd_move_above_stdio(int fd);
  94
  95 int rearrange_stdio(int original_input_fd, int original_output_fd, int original_error_fd);
  96
  97 static inline int make_null_stdio(void) {
  98         return rearrange_stdio(-EBADF, -EBADF, -EBADF);
  99 }
 100
 101 /* Like TAKE_PTR() but for file descriptors, resetting them to -EBADF */
 102 #define TAKE_FD(fd) TAKE_GENERIC(fd, int, -EBADF)
 103
 104 /* Like free_and_replace(), but for file descriptors */
 105 #define close_and_replace(a, b)                 \
 106         ({                                      \
 107                 int *_fdp_ = &(a);              \
 108                 safe_close(*_fdp_);             \
 109                 *_fdp_ = TAKE_FD(b);            \
 110                 0;                              \
 111         })
 112
 113 int fd_reopen(int fd, int flags);
 114 int fd_reopen_propagate_append_and_position(int fd, int flags);
 115 int fd_reopen_condition(int fd, int flags, int mask, int *ret_new_fd);
 116
 117 int fd_is_opath(int fd);
 118
 119 int fd_verify_safe_flags_full(int fd, int extra_flags);
 120 static inline int fd_verify_safe_flags(int fd) {
 121         return fd_verify_safe_flags_full(fd, 0);
 122 }
 123
 124 int read_nr_open(void);
 125 int fd_get_diskseq(int fd, uint64_t *ret);
 126
 127 int path_is_root_at(int dir_fd, const char *path);
 128 static inline int path_is_root(const char *path) {
 129         return path_is_root_at(AT_FDCWD, path);
 130 }
 131 static inline int dir_fd_is_root(int dir_fd) {
 132         return path_is_root_at(dir_fd, NULL);
 133 }
 134 static inline int dir_fd_is_root_or_cwd(int dir_fd) {
 135         return dir_fd == AT_FDCWD ? true : path_is_root_at(dir_fd, NULL);
 136 }
 137
 138 int fds_are_same_mount(int fd1, int fd2);
 139
 140 /* The maximum length a buffer for a /proc/self/fd/<fd> path needs */
 141 #define PROC_FD_PATH_MAX \
 142         (STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int))
 143
 144 static inline char *format_proc_fd_path(char buf[static PROC_FD_PATH_MAX], int fd) {
 145         assert(buf);
 146         assert(fd >= 0);
 147         assert_se(snprintf_ok(buf, PROC_FD_PATH_MAX, "/proc/self/fd/%i", fd));
 148         return buf;
 149 }
 150
 151 #define FORMAT_PROC_FD_PATH(fd) \
 152         format_proc_fd_path((char[PROC_FD_PATH_MAX]) {}, (fd))
 153
 154 /* The maximum length a buffer for a /proc/<pid>/fd/<fd> path needs */
 155 #define PROC_PID_FD_PATH_MAX \
 156         (STRLEN("/proc//fd/") + DECIMAL_STR_MAX(pid_t) + DECIMAL_STR_MAX(int))
 157
 158 char *format_proc_pid_fd_path(char buf[static PROC_PID_FD_PATH_MAX], pid_t pid, int fd);
 159
 160 /* Kinda the same as FORMAT_PROC_FD_PATH(), but goes by PID rather than "self" symlink */
 161 #define FORMAT_PROC_PID_FD_PATH(pid, fd)                                \
 162         format_proc_pid_fd_path((char[PROC_PID_FD_PATH_MAX]) {}, (pid), (fd))
 163
 164 int proc_fd_enoent_errno(void);
 165
 166 const char *accmode_to_string(int flags);
 167
 168 /* Like ASSERT_PTR, but for fds */
 169 #define ASSERT_FD(fd)                           \
 170         ({                                      \
 171                 int _fd_ = (fd);                \
 172                 assert(_fd_ >= 0);              \
 173                 _fd_;                           \
 174         })