Commit 01b7ba6b7375d24a087d44aa48c0b78d66a6187e
2019-03-11T11:36:40
add a lockfile API
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153
diff --git a/include/got_error.h b/include/got_error.h
index 106fa01..f6f99ad 100644
--- a/include/got_error.h
+++ b/include/got_error.h
@@ -77,6 +77,7 @@
#define GOT_ERR_UUID_VERSION 61
#define GOT_ERR_UUID_INVALID 62
#define GOT_ERR_UUID 63
+#define GOT_ERR_LOCKFILE_TIMEOUT 64
static const struct got_error {
int code;
@@ -144,6 +145,7 @@ static const struct got_error {
{ GOT_ERR_UUID_VERSION, "bad uuid version" },
{ GOT_ERR_UUID_INVALID, "uuid invalid" },
{ GOT_ERR_UUID, "uuid error" },
+ { GOT_ERR_LOCKFILE_TIMEOUT,"lockfile timeout" },
};
/*
diff --git a/lib/got_lib_lockfile.h b/lib/got_lib_lockfile.h
new file mode 100644
index 0000000..379232f
--- /dev/null
+++ b/lib/got_lib_lockfile.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Git-compatible lock file implementation. Lock files are used to
+ * ensure exclusive access when files in a GIt repository are modified.
+ */
+
+#define GOT_LOCKFILE_SUFFIX ".lock"
+
+struct got_lockfile {
+ char *path;
+ char *locked_path;
+ int fd;
+};
+
+const struct got_error *got_lockfile_lock(struct got_lockfile **, const char *);
+const struct got_error *got_lockfile_unlock(struct got_lockfile *);
diff --git a/lib/lockfile.c b/lib/lockfile.c
new file mode 100644
index 0000000..2ea32df
--- /dev/null
+++ b/lib/lockfile.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/stat.h>
+#include <sys/queue.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <time.h>
+
+#include "got_error.h"
+
+#include "got_lib_lockfile.h"
+#include "got_lib_path.h"
+
+const struct got_error *
+got_lockfile_lock(struct got_lockfile **lf, const char *path)
+{
+ const struct got_error *err = NULL;
+ const int flags = O_RDONLY | O_CREAT | O_EXCL | O_EXLOCK;
+ int attempts = 5;
+
+ *lf = calloc(1, sizeof(*lf));
+ if (*lf == NULL)
+ return got_error_from_errno();
+ (*lf)->fd = -1;
+
+ (*lf)->locked_path = strdup(path);
+ if ((*lf)->locked_path == NULL) {
+ err = got_error_from_errno();
+ goto done;
+ }
+
+ if (asprintf(&(*lf)->path, "%s%s", path, GOT_LOCKFILE_SUFFIX) == -1) {
+ err = got_error_from_errno();
+ goto done;
+ }
+
+ do {
+ (*lf)->fd = open((*lf)->path, flags, GOT_DEFAULT_FILE_MODE);
+ if ((*lf)->fd == -1) {
+ if (errno != EEXIST) {
+ err = got_error_from_errno();
+ goto done;
+ }
+ sleep(1);
+ }
+ } while (--attempts > 0);
+
+ if ((*lf)->fd == -1)
+ err = got_error(GOT_ERR_LOCKFILE_TIMEOUT);
+done:
+ if (err) {
+ got_lockfile_unlock(*lf);
+ *lf = NULL;
+ }
+ return err;
+}
+
+const struct got_error *
+got_lockfile_unlock(struct got_lockfile *lf)
+{
+ const struct got_error *err = NULL;
+
+ if (lf->path && lf->fd != -1 && unlink(lf->path) != 0)
+ err = got_error_from_errno();
+ if (lf->fd != -1 && close(lf->fd) != 0 && err == NULL)
+ err = got_error_from_errno();
+ free(lf->path);
+ free(lf->locked_path);
+ free(lf);
+ return err;
+}