1 files changed, 87 insertions, 0 deletions
diff --git a/src/lib/file-lock.h b/src/lib/file-lock.h
new file mode 100644
index 0000000..0939adc
--- /dev/null
+++ b/src/lib/file-lock.h
@@ -0,0 +1,87 @@
+#ifndef FILE_LOCK_H
+#define FILE_LOCK_H
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#define DEFAULT_LOCK_TIMEOUT 120
+
+struct file_lock;
+struct dotlock;
+
+enum file_lock_method {
+	FILE_LOCK_METHOD_FCNTL,
+	FILE_LOCK_METHOD_FLOCK,
+	FILE_LOCK_METHOD_DOTLOCK
+};
+
+struct file_lock_settings {
+	enum file_lock_method lock_method;
+
+	/* When the lock is freed, close the fd automatically. This can
+	   be useful for files that are only created to exist as lock files. */
+	bool unlink_on_free:1;
+	/* When the lock is freed, unlink() the file automatically, unless other
+	   processes are already waiting on the lock. This can be useful for
+	   files that are only created to exist as lock files. */
+	bool close_on_free:1;
+	/* Do not panic when the kernel returns EDEADLK while acquiring the
+	   lock. */
+	bool allow_deadlock:1;
+};
+
+/* Parse lock method from given string. Returns TRUE if ok,
+   FALSE if name is unknown. */
+bool file_lock_method_parse(const char *name, enum file_lock_method *method_r);
+/* Convert lock method to string. */
+const char *file_lock_method_to_str(enum file_lock_method method);
+
+/* Lock the file. Returns 1 if successful, 0 if file is already locked,
+   or -1 if error. lock_type is F_WRLCK or F_RDLCK. */
+int file_try_lock(int fd, const char *path, int lock_type,
+		  const struct file_lock_settings *set,
+		  struct file_lock **lock_r, const char **error_r);
+/* Like lock_try_lock(), but return 0 only after having tried to lock for
+   timeout_secs. */
+int file_wait_lock(int fd, const char *path, int lock_type,
+		   const struct file_lock_settings *set,
+		   unsigned int timeout_secs,
+		   struct file_lock **lock_r, const char **error_r);
+/* Change the lock type. WARNING: This isn't an atomic operation!
+   The result is the same as file_unlock() + file_try_lock(). */
+int file_lock_try_update(struct file_lock *lock, int lock_type);
+/* When the lock is freed, unlink() the file automatically, unless other
+   processes are already waiting on the lock. This can be useful for files that
+   are only created to exist as lock files. */
+void file_lock_set_unlink_on_free(struct file_lock *lock, bool set);
+/* When the lock is freed, close the fd automatically. This can
+   be useful for files that are only created to exist as lock files. */
+void file_lock_set_close_on_free(struct file_lock *lock, bool set);
+
+/* Convert dotlock into file_lock, which can be deleted with either
+   file_unlock() or file_lock_free(). */
+struct file_lock *file_lock_from_dotlock(struct dotlock **dotlock);
+
+/* Unlock and free the lock. */
+void file_unlock(struct file_lock **lock);
+/* Free the lock without unlocking it (because you're closing the fd anyway). */
+void file_lock_free(struct file_lock **lock);
+
+/* Returns the path given as parameter to file_*lock*(). */
+const char *file_lock_get_path(struct file_lock *lock);
+/* Update lock file's path (after it gets renamed by the caller). This is
+   useful mainly together with file_lock_set_unlink_on_free(). */
+void file_lock_set_path(struct file_lock *lock, const char *path);
+
+/* Returns human-readable string containing the process that has the file
+   currently locked. Returns "" if unknown, otherwise " (string)". */
+const char *file_lock_find(int lock_fd, enum file_lock_method lock_method,
+			   int lock_type);
+
+/* Track the duration of a lock wait. */
+void file_lock_wait_start(void);
+void file_lock_wait_end(const char *lock_name);
+/* Return how many microseconds has been spent on lock waiting. */
+uint64_t file_lock_wait_get_total_usecs(void);
+
+#endif