4960ce43ff
This call creates an fd from another fd containing the same data. Specifically, repeated read() on the returned fd should return the same data as the original fd. This call is useful when we want to copy data out of disk images and suchlike, and want to be pass fds with the data around without having to keep the disk image continously mounted. The implementation tries to be somewhat smart and tries to prefer memfds/pipes over files in /tmp or /var/tmp based on the size of the data, but has appropropriate fallbacks in place.
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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***/
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#include <dirent.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <sys/socket.h>
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#include "macro.h"
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/* Make sure we can distinguish fd 0 and NULL */
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#define FD_TO_PTR(fd) INT_TO_PTR((fd)+1)
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#define PTR_TO_FD(p) (PTR_TO_INT(p)-1)
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int close_nointr(int fd);
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int safe_close(int fd);
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void safe_close_pair(int p[]);
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static inline int safe_close_above_stdio(int fd) {
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if (fd < 3) /* Don't close stdin/stdout/stderr, but still invalidate the fd by returning -1 */
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return -1;
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return safe_close(fd);
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}
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void close_many(const int fds[], size_t n_fd);
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int fclose_nointr(FILE *f);
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FILE* safe_fclose(FILE *f);
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DIR* safe_closedir(DIR *f);
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static inline void closep(int *fd) {
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safe_close(*fd);
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}
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static inline void close_pairp(int (*p)[2]) {
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safe_close_pair(*p);
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}
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static inline void fclosep(FILE **f) {
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safe_fclose(*f);
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}
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DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, pclose);
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DEFINE_TRIVIAL_CLEANUP_FUNC(DIR*, closedir);
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#define _cleanup_close_ _cleanup_(closep)
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#define _cleanup_fclose_ _cleanup_(fclosep)
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#define _cleanup_pclose_ _cleanup_(pclosep)
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#define _cleanup_closedir_ _cleanup_(closedirp)
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#define _cleanup_close_pair_ _cleanup_(close_pairp)
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int fd_nonblock(int fd, bool nonblock);
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int fd_cloexec(int fd, bool cloexec);
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int close_all_fds(const int except[], size_t n_except);
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int same_fd(int a, int b);
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void cmsg_close_all(struct msghdr *mh);
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bool fdname_is_valid(const char *s);
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int fd_get_path(int fd, char **ret);
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int move_fd(int from, int to, int cloexec);
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enum {
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ACQUIRE_NO_DEV_NULL = 1 << 0,
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ACQUIRE_NO_MEMFD = 1 << 1,
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ACQUIRE_NO_PIPE = 1 << 2,
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ACQUIRE_NO_TMPFILE = 1 << 3,
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ACQUIRE_NO_REGULAR = 1 << 4,
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};
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int acquire_data_fd(const void *data, size_t size, unsigned flags);
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int fd_duplicate_data_fd(int fd);
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/* Hint: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5 */
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#define ERRNO_IS_DISCONNECT(r) \
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IN_SET(r, ENOTCONN, ECONNRESET, ECONNREFUSED, ECONNABORTED, EPIPE, ENETUNREACH)
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/* Resource exhaustion, could be our fault or general system trouble */
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#define ERRNO_IS_RESOURCE(r) \
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IN_SET(r, ENOMEM, EMFILE, ENFILE)
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int fd_move_above_stdio(int fd);
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int rearrange_stdio(int original_input_fd, int original_output_fd, int original_error_fd);
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static inline int make_null_stdio(void) {
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return rearrange_stdio(-1, -1, -1);
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}
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/* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
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#define TAKE_FD(fd) \
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({ \
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int _fd_ = (fd); \
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(fd) = -1; \
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_fd_; \
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})
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int fd_reopen(int fd, int flags);
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