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https://github.com/morgan9e/systemd
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fd421c4adc
If the cleanup function returns the appropriate type, use that to reset the variable. For other functions (usually the foreign ones which return void), add an explicit value to reset to. This causes a bit of code churn, but I think it might be worth it. In a following patch static destructors will be called from a fuzzer, and this change allows them to be called multiple times. But I think such a change might help with detecting unitialized code reuse too. We hit various bugs like this, and things are more obvious when a pointer has been set to NULL. I was worried whether this change increases text size, but it doesn't seem to: -Dbuildtype=debug: before "tree-wide: return NULL from freeing functions": -rwxrwxr-x 1 zbyszek zbyszek 4117672 Feb 16 14:36 build/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 4494520 Feb 16 15:06 build/systemd* after "tree-wide: return NULL from freeing functions": -rwxrwxr-x 1 zbyszek zbyszek 4117672 Feb 16 14:36 build/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 4494576 Feb 16 15:10 build/systemd* now: -rwxrwxr-x 1 zbyszek zbyszek 4117672 Feb 16 14:36 build/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 4494640 Feb 16 15:15 build/systemd* -Dbuildtype=release: before "tree-wide: return NULL from freeing functions": -rwxrwxr-x 1 zbyszek zbyszek 5252256 Feb 14 14:47 build-rawhide/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 1834184 Feb 16 15:09 build-rawhide/systemd* after "tree-wide: return NULL from freeing functions": -rwxrwxr-x 1 zbyszek zbyszek 5252256 Feb 14 14:47 build-rawhide/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 1834184 Feb 16 15:10 build-rawhide/systemd* now: -rwxrwxr-x 1 zbyszek zbyszek 5252256 Feb 14 14:47 build-rawhide/libsystemd.so.0.30.0* -rwxrwxr-x 1 zbyszek zbyszek 1834184 Feb 16 15:16 build-rawhide/systemd* I would expect that the compiler would be able to elide the setting of a variable if the variable is never used again. And this seems to be the case: in optimized builds there is no change in size whatsoever. And the change in size in unoptimized build is negligible. Something strange is happening with size of libsystemd: it's bigger in optimized builds. Something to figure out, but unrelated to this patch.
109 lines
2.8 KiB
C
109 lines
2.8 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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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 <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[static 2]);
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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_FULL(FILE*, pclose, NULL);
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DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(DIR*, closedir, NULL);
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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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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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/* Like free_and_replace(), but for file descriptors */
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#define CLOSE_AND_REPLACE(a, b) \
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({ \
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int *_fdp_ = &(a); \
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safe_close(*_fdp_); \
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*_fdp_ = TAKE_FD(b); \
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0; \
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})
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int fd_reopen(int fd, int flags);
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int read_nr_open(void);
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