src/basic/fd-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <dirent.h>
   5 #include <stdbool.h>
   6 #include <stdio.h>
   7 #include <sys/socket.h>
   8
   9 #include "macro.h"
  10 #include "stdio-util.h"
  11
  12 /* maximum length of fdname */
  13 #define FDNAME_MAX 255
  14
  15 /* Make sure we can distinguish fd 0 and NULL */
  16 #define FD_TO_PTR(fd) INT_TO_PTR((fd)+1)
  17 #define PTR_TO_FD(p) (PTR_TO_INT(p)-1)
  18
  19 int close_nointr(int fd);
  20 int safe_close(int fd);
  21 void safe_close_pair(int p[static 2]);
  22
  23 static inline int safe_close_above_stdio(int fd) {
  24         if (fd < 3) /* Don't close stdin/stdout/stderr, but still invalidate the fd by returning -1 */
  25                 return -1;
  26
  27         return safe_close(fd);
  28 }
  29
  30 void close_many(const int fds[], size_t n_fd);
  31
  32 int fclose_nointr(FILE *f);
  33 FILE* safe_fclose(FILE *f);
  34 DIR* safe_closedir(DIR *f);
  35
  36 static inline void closep(int *fd) {
  37         safe_close(*fd);
  38 }
  39
  40 static inline void close_pairp(int (*p)[2]) {
  41         safe_close_pair(*p);
  42 }
  43
  44 static inline void fclosep(FILE **f) {
  45         safe_fclose(*f);
  46 }
  47
  48 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, pclose, NULL);
  49 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(DIR*, closedir, NULL);
  50
  51 #define _cleanup_close_ _cleanup_(closep)
  52 #define _cleanup_fclose_ _cleanup_(fclosep)
  53 #define _cleanup_pclose_ _cleanup_(pclosep)
  54 #define _cleanup_closedir_ _cleanup_(closedirp)
  55 #define _cleanup_close_pair_ _cleanup_(close_pairp)
  56
  57 int fd_nonblock(int fd, bool nonblock);
  58 int fd_cloexec(int fd, bool cloexec);
  59
  60 int get_max_fd(void);
  61
  62 int close_all_fds(const int except[], size_t n_except);
  63 int close_all_fds_without_malloc(const int except[], size_t n_except);
  64
  65 int same_fd(int a, int b);
  66
  67 void cmsg_close_all(struct msghdr *mh);
  68
  69 bool fdname_is_valid(const char *s);
  70
  71 int fd_get_path(int fd, char **ret);
  72
  73 int move_fd(int from, int to, int cloexec);
  74
  75 enum {
  76         ACQUIRE_NO_DEV_NULL = 1 << 0,
  77         ACQUIRE_NO_MEMFD    = 1 << 1,
  78         ACQUIRE_NO_PIPE     = 1 << 2,
  79         ACQUIRE_NO_TMPFILE  = 1 << 3,
  80         ACQUIRE_NO_REGULAR  = 1 << 4,
  81 };
  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(-1, -1, -1);
  89 }
  90
  91 /* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
  92 #define TAKE_FD(fd)                             \
  93         ({                                      \
  94                 int *_fd_ = &(fd);              \
  95                 int _ret_ = *_fd_;              \
  96                 *_fd_ = -1;                     \
  97                 _ret_;                          \
  98         })
  99
 100 /* Like free_and_replace(), but for file descriptors */
 101 #define CLOSE_AND_REPLACE(a, b)                 \
 102         ({                                      \
 103                 int *_fdp_ = &(a);              \
 104                 safe_close(*_fdp_);             \
 105                 *_fdp_ = TAKE_FD(b);            \
 106                 0;                              \
 107         })
 108
 109 int fd_reopen(int fd, int flags);
 110 int read_nr_open(void);
 111 int btrfs_defrag_fd(int fd);
 112 int fd_get_diskseq(int fd, uint64_t *ret);
 113
 114 /* The maximum length a buffer for a /proc/self/fd/<fd> path needs */
 115 #define PROC_FD_PATH_MAX \
 116         (STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int))
 117
 118 static inline char *format_proc_fd_path(char buf[static PROC_FD_PATH_MAX], int fd) {
 119         assert(buf);
 120         assert(fd >= 0);
 121         assert_se(snprintf_ok(buf, PROC_FD_PATH_MAX, "/proc/self/fd/%i", fd));
 122         return buf;
 123 }
 124
 125 #define FORMAT_PROC_FD_PATH(fd) \
 126         format_proc_fd_path((char[PROC_FD_PATH_MAX]) {}, (fd))