21b40f1662
Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work with two sorts of virtual files. One sort uses "seq_file", and the results of the first read are buffered for the second read. The other sort uses "raw" reads which always go direct to the device. In the later case, the content of the virtual file must be retrieved with a single read otherwise subsequent read might get the new value instead of finding EOF immediately. That's the reason why the usage of fread(3) is prohibited in this case as it always performs a second call to read(2) looking for EOF which is subject to the race described previously. Fixes: #13585.
101 lines
4 KiB
C
101 lines
4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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#include <dirent.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include "macro.h"
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#include "time-util.h"
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#define LONG_LINE_MAX (1U*1024U*1024U)
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typedef enum {
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WRITE_STRING_FILE_CREATE = 1 << 0,
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WRITE_STRING_FILE_ATOMIC = 1 << 1,
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WRITE_STRING_FILE_AVOID_NEWLINE = 1 << 2,
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WRITE_STRING_FILE_VERIFY_ON_FAILURE = 1 << 3,
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WRITE_STRING_FILE_SYNC = 1 << 4,
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WRITE_STRING_FILE_DISABLE_BUFFER = 1 << 5,
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WRITE_STRING_FILE_NOFOLLOW = 1 << 6,
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WRITE_STRING_FILE_MKDIR_0755 = 1 << 7,
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/* And before you wonder, why write_string_file_atomic_label_ts() is a separate function instead of just one
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more flag here: it's about linking: we don't want to pull -lselinux into all users of write_string_file()
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and friends. */
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} WriteStringFileFlags;
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typedef enum {
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READ_FULL_FILE_SECURE = 1 << 0,
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READ_FULL_FILE_UNBASE64 = 1 << 1,
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READ_FULL_FILE_UNHEX = 1 << 2,
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} ReadFullFileFlags;
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int fopen_unlocked(const char *path, const char *options, FILE **ret);
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int fdopen_unlocked(int fd, const char *options, FILE **ret);
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FILE* open_memstream_unlocked(char **ptr, size_t *sizeloc);
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FILE* fmemopen_unlocked(void *buf, size_t size, const char *mode);
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int write_string_stream_ts(FILE *f, const char *line, WriteStringFileFlags flags, struct timespec *ts);
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static inline int write_string_stream(FILE *f, const char *line, WriteStringFileFlags flags) {
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return write_string_stream_ts(f, line, flags, NULL);
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}
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int write_string_file_ts(const char *fn, const char *line, WriteStringFileFlags flags, struct timespec *ts);
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static inline int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags) {
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return write_string_file_ts(fn, line, flags, NULL);
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}
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int write_string_filef(const char *fn, WriteStringFileFlags flags, const char *format, ...) _printf_(3, 4);
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int read_one_line_file(const char *filename, char **line);
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int read_full_file_full(const char *filename, ReadFullFileFlags flags, char **contents, size_t *size);
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static inline int read_full_file(const char *filename, char **contents, size_t *size) {
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return read_full_file_full(filename, 0, contents, size);
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}
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int read_full_virtual_file(const char *filename, char **ret_contents, size_t *ret_size);
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int read_full_stream_full(FILE *f, const char *filename, ReadFullFileFlags flags, char **contents, size_t *size);
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static inline int read_full_stream(FILE *f, char **contents, size_t *size) {
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return read_full_stream_full(f, NULL, 0, contents, size);
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}
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int verify_file(const char *fn, const char *blob, bool accept_extra_nl);
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int executable_is_script(const char *path, char **interpreter);
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int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field);
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DIR *xopendirat(int dirfd, const char *name, int flags);
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int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f);
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int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f);
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int fflush_and_check(FILE *f);
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int fflush_sync_and_check(FILE *f);
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int write_timestamp_file_atomic(const char *fn, usec_t n);
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int read_timestamp_file(const char *fn, usec_t *ret);
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int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space);
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typedef enum ReadLineFlags {
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READ_LINE_ONLY_NUL = 1 << 0,
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} ReadLineFlags;
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int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret);
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static inline int read_line(FILE *f, size_t limit, char **ret) {
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return read_line_full(f, limit, 0, ret);
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}
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static inline int read_nul_string(FILE *f, size_t limit, char **ret) {
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return read_line_full(f, limit, READ_LINE_ONLY_NUL, ret);
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}
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int safe_fgetc(FILE *f, char *ret);
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int warn_file_is_world_accessible(const char *filename, struct stat *st, const char *unit, unsigned line);
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