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 "stdio-util.h"
  12
  13 /* maximum length of fdname */
  14 #define FDNAME_MAX 255
  15
  16 /* Make sure we can distinguish fd 0 and NULL */
  17 #define FD_TO_PTR(fd) INT_TO_PTR((fd)+1)
  18 #define PTR_TO_FD(p) (PTR_TO_INT(p)-1)
  19
  20 /* Useful helpers for initializing pipe(), socketpair() or stdio fd arrays */
  21 #define EBADF_PAIR { -EBADF, -EBADF }
  22 #define EBADF_TRIPLET { -EBADF, -EBADF, -EBADF }
  23
  24 int close_nointr(int fd);
  25 int safe_close(int fd);
  26 void safe_close_pair(int p[static 2]);
  27
  28 static inline int safe_close_above_stdio(int fd) {
  29         if (fd < 3) /* Don't close stdin/stdout/stderr, but still invalidate the fd by returning -EBADF. */
  30                 return -EBADF;
  31
  32         return safe_close(fd);
  33 }
  34
  35 void close_many(const int fds[], size_t n_fd);
  36 void close_many_unset(int fds[], size_t n_fd);
  37 void close_many_and_free(int *fds, size_t n_fds);
  38
  39 int fclose_nointr(FILE *f);
  40 FILE* safe_fclose(FILE *f);
  41 DIR* safe_closedir(DIR *f);
  42
  43 static inline void closep(int *fd) {
  44         safe_close(*fd);
  45 }
  46
  47 static inline void close_pairp(int (*p)[2]) {
  48         safe_close_pair(*p);
  49 }
  50
  51 static inline void fclosep(FILE **f) {
  52         safe_fclose(*f);
  53 }
  54
  55 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, pclose, NULL);
  56 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(DIR*, closedir, NULL);
  57
  58 #define _cleanup_close_ _cleanup_(closep)
  59 #define _cleanup_fclose_ _cleanup_(fclosep)
  60 #define _cleanup_pclose_ _cleanup_(pclosep)
  61 #define _cleanup_closedir_ _cleanup_(closedirp)
  62 #define _cleanup_close_pair_ _cleanup_(close_pairp)
  63
  64 int fd_nonblock(int fd, bool nonblock);
  65 int fd_cloexec(int fd, bool cloexec);
  66 int fd_cloexec_many(const int fds[], size_t n_fds, bool cloexec);
  67
  68 int get_max_fd(void);
  69
  70 int close_all_fds(const int except[], size_t n_except);
  71 int close_all_fds_without_malloc(const int except[], size_t n_except);
  72
  73 int same_fd(int a, int b);
  74
  75 void cmsg_close_all(struct msghdr *mh);
  76
  77 bool fdname_is_valid(const char *s);
  78
  79 int fd_get_path(int fd, char **ret);
  80
  81 int move_fd(int from, int to, int cloexec);
  82
  83 int fd_move_above_stdio(int fd);
  84
  85 int rearrange_stdio(int original_input_fd, int original_output_fd, int original_error_fd);
  86
  87 static inline int make_null_stdio(void) {
  88         return rearrange_stdio(-EBADF, -EBADF, -EBADF);
  89 }
  90
  91 /* Like TAKE_PTR() but for file descriptors, resetting them to -EBADF */
  92 #define TAKE_FD(fd) TAKE_GENERIC(fd, int, -EBADF)
  93
  94 /* Like free_and_replace(), but for file descriptors */
  95 #define close_and_replace(a, b)                 \
  96         ({                                      \
  97                 int *_fdp_ = &(a);              \
  98                 safe_close(*_fdp_);             \
  99                 *_fdp_ = TAKE_FD(b);            \
 100                 0;                              \
 101         })
 102
 103 int fd_reopen(int fd, int flags);
 104 int fd_reopen_condition(int fd, int flags, int mask, int *ret_new_fd);
 105 int fd_is_opath(int fd);
 106 int read_nr_open(void);
 107 int fd_get_diskseq(int fd, uint64_t *ret);
 108
 109 int path_is_root_at(int dir_fd, const char *path);
 110 static inline int path_is_root(const char *path) {
 111         return path_is_root_at(AT_FDCWD, path);
 112 }
 113 static inline int dir_fd_is_root(int dir_fd) {
 114         return path_is_root_at(dir_fd, NULL);
 115 }
 116 static inline int dir_fd_is_root_or_cwd(int dir_fd) {
 117         return dir_fd == AT_FDCWD ? true : path_is_root_at(dir_fd, NULL);
 118 }
 119
 120 /* The maximum length a buffer for a /proc/self/fd/<fd> path needs */
 121 #define PROC_FD_PATH_MAX \
 122         (STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int))
 123
 124 static inline char *format_proc_fd_path(char buf[static PROC_FD_PATH_MAX], int fd) {
 125         assert(buf);
 126         assert(fd >= 0);
 127         assert_se(snprintf_ok(buf, PROC_FD_PATH_MAX, "/proc/self/fd/%i", fd));
 128         return buf;
 129 }
 130
 131 #define FORMAT_PROC_FD_PATH(fd) \
 132         format_proc_fd_path((char[PROC_FD_PATH_MAX]) {}, (fd))
 133
 134 const char *accmode_to_string(int flags);
 135
 136 /* Like ASSERT_PTR, but for fds */
 137 #define ASSERT_FD(fd)                           \
 138         ({                                      \
 139                 int _fd_ = (fd);                \
 140                 assert(_fd_ >= 0);              \
 141                 _fd_;                           \
 142         })