src/basic/fd-util.h

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once

#include <dirent.h>
#include <stdbool.h>
#include <stdio.h>
#include <sys/socket.h>

#include "macro.h"

/* Make sure we can distinguish fd 0 and NULL */
#define FD_TO_PTR(fd) INT_TO_PTR((fd)+1)
#define PTR_TO_FD(p) (PTR_TO_INT(p)-1)

int close_nointr(int fd);
int safe_close(int fd);
void safe_close_pair(int p[static 2]);

static inline int safe_close_above_stdio(int fd) {
        if (fd < 3) /* Don't close stdin/stdout/stderr, but still invalidate the fd by returning -1 */
                return -1;

        return safe_close(fd);
}

void close_many(const int fds[], size_t n_fd);

int fclose_nointr(FILE *f);
FILE* safe_fclose(FILE *f);
DIR* safe_closedir(DIR *f);

static inline void closep(int *fd) {
        safe_close(*fd);
}

static inline void close_pairp(int (*p)[2]) {
        safe_close_pair(*p);
}

static inline void fclosep(FILE **f) {
        safe_fclose(*f);
}

DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, pclose);
DEFINE_TRIVIAL_CLEANUP_FUNC(DIR*, closedir);

#define _cleanup_close_ _cleanup_(closep)
#define _cleanup_fclose_ _cleanup_(fclosep)
#define _cleanup_pclose_ _cleanup_(pclosep)
#define _cleanup_closedir_ _cleanup_(closedirp)
#define _cleanup_close_pair_ _cleanup_(close_pairp)

int fd_nonblock(int fd, bool nonblock);
int fd_cloexec(int fd, bool cloexec);

int close_all_fds(const int except[], size_t n_except);

int same_fd(int a, int b);

void cmsg_close_all(struct msghdr *mh);

bool fdname_is_valid(const char *s);

int fd_get_path(int fd, char **ret);

int move_fd(int from, int to, int cloexec);

enum {
        ACQUIRE_NO_DEV_NULL = 1 << 0,
        ACQUIRE_NO_MEMFD    = 1 << 1,
        ACQUIRE_NO_PIPE     = 1 << 2,
        ACQUIRE_NO_TMPFILE  = 1 << 3,
        ACQUIRE_NO_REGULAR  = 1 << 4,
};

int acquire_data_fd(const void *data, size_t size, unsigned flags);

int fd_duplicate_data_fd(int fd);

/* Hint: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5 */
/* The kernel sends e.g., EHOSTUNREACH or ENONET to userspace in some ICMP error cases.
 * See the icmp_err_convert[] in net/ipv4/icmp.c in the kernel sources */
#define ERRNO_IS_DISCONNECT(r)                                          \
        IN_SET(r,                                                       \
               ENOTCONN, ECONNRESET, ECONNREFUSED, ECONNABORTED, EPIPE, \
               ENETUNREACH, EHOSTUNREACH, ENOPROTOOPT, EHOSTDOWN, ENONET)

/* Resource exhaustion, could be our fault or general system trouble */
#define ERRNO_IS_RESOURCE(r) \
        IN_SET(r, ENOMEM, EMFILE, ENFILE)

int fd_move_above_stdio(int fd);

int rearrange_stdio(int original_input_fd, int original_output_fd, int original_error_fd);

static inline int make_null_stdio(void) {
        return rearrange_stdio(-1, -1, -1);
}

/* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
#define TAKE_FD(fd)                             \
        ({                                      \
                int _fd_ = (fd);                \
                (fd) = -1;                      \
                _fd_;                           \
        })

int fd_reopen(int fd, int flags);

int read_nr_open(void);