| File: | build-scan/../src/basic/lockfile-util.c |
| Warning: | line 71, column 17 Value stored to 'fd' is never read |
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| 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
| 2 | |
| 3 | #include <errno(*__errno_location ()).h> |
| 4 | #include <fcntl.h> |
| 5 | #include <stdio.h> |
| 6 | #include <string.h> |
| 7 | #include <sys/file.h> |
| 8 | #include <sys/stat.h> |
| 9 | |
| 10 | #include "alloc-util.h" |
| 11 | #include "fd-util.h" |
| 12 | #include "fs-util.h" |
| 13 | #include "lockfile-util.h" |
| 14 | #include "macro.h" |
| 15 | #include "path-util.h" |
| 16 | |
| 17 | int make_lock_file(const char *p, int operation, LockFile *ret) { |
| 18 | _cleanup_close___attribute__((cleanup(closep))) int fd = -1; |
| 19 | _cleanup_free___attribute__((cleanup(freep))) char *t = NULL((void*)0); |
| 20 | int r; |
| 21 | |
| 22 | /* |
| 23 | * We use UNPOSIX locks if they are available. They have nice |
| 24 | * semantics, and are mostly compatible with NFS. However, |
| 25 | * they are only available on new kernels. When we detect we |
| 26 | * are running on an older kernel, then we fall back to good |
| 27 | * old BSD locks. They also have nice semantics, but are |
| 28 | * slightly problematic on NFS, where they are upgraded to |
| 29 | * POSIX locks, even though locally they are orthogonal to |
| 30 | * POSIX locks. |
| 31 | */ |
| 32 | |
| 33 | t = strdup(p); |
| 34 | if (!t) |
| 35 | return -ENOMEM12; |
| 36 | |
| 37 | for (;;) { |
| 38 | struct flock fl = { |
| 39 | .l_type = (operation & ~LOCK_NB4) == LOCK_EX2 ? F_WRLCK1 : F_RDLCK0, |
| 40 | .l_whence = SEEK_SET0, |
| 41 | }; |
| 42 | struct stat st; |
| 43 | |
| 44 | fd = open(p, O_CREAT0100|O_RDWR02|O_NOFOLLOW0400000|O_CLOEXEC02000000|O_NOCTTY0400, 0600); |
| 45 | if (fd < 0) |
| 46 | return -errno(*__errno_location ()); |
| 47 | |
| 48 | r = fcntl(fd, (operation & LOCK_NB4) ? F_OFD_SETLK37 : F_OFD_SETLKW38, &fl); |
| 49 | if (r < 0) { |
| 50 | |
| 51 | /* If the kernel is too old, use good old BSD locks */ |
| 52 | if (errno(*__errno_location ()) == EINVAL22) |
| 53 | r = flock(fd, operation); |
| 54 | |
| 55 | if (r < 0) |
| 56 | return errno(*__errno_location ()) == EAGAIN11 ? -EBUSY16 : -errno(*__errno_location ()); |
| 57 | } |
| 58 | |
| 59 | /* If we acquired the lock, let's check if the file |
| 60 | * still exists in the file system. If not, then the |
| 61 | * previous exclusive owner removed it and then closed |
| 62 | * it. In such a case our acquired lock is worthless, |
| 63 | * hence try again. */ |
| 64 | |
| 65 | r = fstat(fd, &st); |
| 66 | if (r < 0) |
| 67 | return -errno(*__errno_location ()); |
| 68 | if (st.st_nlink > 0) |
| 69 | break; |
| 70 | |
| 71 | fd = safe_close(fd); |
Value stored to 'fd' is never read | |
| 72 | } |
| 73 | |
| 74 | ret->path = t; |
| 75 | ret->fd = fd; |
| 76 | ret->operation = operation; |
| 77 | |
| 78 | fd = -1; |
| 79 | t = NULL((void*)0); |
| 80 | |
| 81 | return r; |
| 82 | } |
| 83 | |
| 84 | int make_lock_file_for(const char *p, int operation, LockFile *ret) { |
| 85 | const char *fn; |
| 86 | char *t; |
| 87 | |
| 88 | assert(p)do { if ((__builtin_expect(!!(!(p)),0))) log_assert_failed_realm (LOG_REALM_SYSTEMD, ("p"), "../src/basic/lockfile-util.c", 88 , __PRETTY_FUNCTION__); } while (0); |
| 89 | assert(ret)do { if ((__builtin_expect(!!(!(ret)),0))) log_assert_failed_realm (LOG_REALM_SYSTEMD, ("ret"), "../src/basic/lockfile-util.c", 89 , __PRETTY_FUNCTION__); } while (0); |
| 90 | |
| 91 | fn = basename(p); |
| 92 | if (!filename_is_valid(fn)) |
| 93 | return -EINVAL22; |
| 94 | |
| 95 | t = newa(char, strlen(p) + 2 + 4 + 1)({ do { if ((__builtin_expect(!!(!(!size_multiply_overflow(sizeof (char), strlen(p) + 2 + 4 + 1))),0))) log_assert_failed_realm (LOG_REALM_SYSTEMD, ("!size_multiply_overflow(sizeof(char), strlen(p) + 2 + 4 + 1)" ), "../src/basic/lockfile-util.c", 95, __PRETTY_FUNCTION__); } while (0); (char*) __builtin_alloca (sizeof(char)*(strlen(p) + 2 + 4 + 1)); }); |
| 96 | stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), fn), ".lck"); |
| 97 | |
| 98 | return make_lock_file(t, operation, ret); |
| 99 | } |
| 100 | |
| 101 | void release_lock_file(LockFile *f) { |
| 102 | int r; |
| 103 | |
| 104 | if (!f) |
| 105 | return; |
| 106 | |
| 107 | if (f->path) { |
| 108 | |
| 109 | /* If we are the exclusive owner we can safely delete |
| 110 | * the lock file itself. If we are not the exclusive |
| 111 | * owner, we can try becoming it. */ |
| 112 | |
| 113 | if (f->fd >= 0 && |
| 114 | (f->operation & ~LOCK_NB4) == LOCK_SH1) { |
| 115 | static const struct flock fl = { |
| 116 | .l_type = F_WRLCK1, |
| 117 | .l_whence = SEEK_SET0, |
| 118 | }; |
| 119 | |
| 120 | r = fcntl(f->fd, F_OFD_SETLK37, &fl); |
| 121 | if (r < 0 && errno(*__errno_location ()) == EINVAL22) |
| 122 | r = flock(f->fd, LOCK_EX2|LOCK_NB4); |
| 123 | |
| 124 | if (r >= 0) |
| 125 | f->operation = LOCK_EX2|LOCK_NB4; |
| 126 | } |
| 127 | |
| 128 | if ((f->operation & ~LOCK_NB4) == LOCK_EX2) |
| 129 | unlink_noerrno(f->path); |
| 130 | |
| 131 | f->path = mfree(f->path); |
| 132 | } |
| 133 | |
| 134 | f->fd = safe_close(f->fd); |
| 135 | f->operation = 0; |
| 136 | } |