Updating libutil from netbsd

lib/libutil/pidfile.c

@@ -1,11 +1,11 @@
-/*	$NetBSD: pidfile.c,v 1.8 2008/04/28 20:23:03 martin Exp $	*/
+/*	$NetBSD: pidfile.c,v 1.9 2011/03/29 13:55:37 jmmv Exp $	*/
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
- * by Jason R. Thorpe and Matthias Scheler.
+ * by Jason R. Thorpe, Matthias Scheler and Julio Merino.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,90 +31,144 @@
 
 #include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: pidfile.c,v 1.8 2008/04/28 20:23:03 martin Exp $");
+__RCSID("$NetBSD: pidfile.c,v 1.9 2011/03/29 13:55:37 jmmv Exp $");
 #endif
 
 #include <sys/param.h>
+
 #include <paths.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <util.h>
 
-static int   pidfile_atexit_done;
 static pid_t pidfile_pid;
-static char *pidfile_basename;
 static char *pidfile_path;
 
-static void pidfile_cleanup(void);
-
-int
-pidfile(const char *basename)
+/* Deletes an existent pidfile iff it was created by this process. */
+static void
+pidfile_cleanup(void)
 {
-	FILE *f;
 
-	/*
-	 * Register handler which will remove the pidfile later.
-	 */
-	if (!pidfile_atexit_done) {
+	if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
+		(void) unlink(pidfile_path);
+}
+
+/* Registers an atexit(3) handler to delete the pidfile we have generated.
+ * We only register the handler when we create a pidfile, so we can assume
+ * that the pidfile exists.
+ *
+ * Returns 0 on success or -1 if the handler could not be registered. */
+static int
+register_atexit_handler(void)
+{
+	static bool done = false;
+
+	if (!done) {
 		if (atexit(pidfile_cleanup) < 0)
 			return -1;
-		pidfile_atexit_done = 1;
+		done = true;
 	}
 
+	return 0;
+}
+
+/* Given a new pidfile name in 'path', deletes any previously-created pidfile
+ * if the previous file differs to the new one.
+ *
+ * If a previous file is deleted, returns 1, which means that a new pidfile
+ * must be created.  Otherwise, this returns 0, which means that the existing
+ * file does not need to be touched. */
+static int
+cleanup_old_pidfile(const char* path)
+{
+	if (pidfile_path != NULL) {
+		if (strcmp(pidfile_path, path) != 0) {
+			pidfile_cleanup();
+
+			free(pidfile_path);
+			pidfile_path = NULL;
+
+			return 1;
+		} else
+			return 0;
+	} else
+		return 1;
+}
+
+/* Constructs a name for a pidfile in the default location (/var/run).  If
+ * 'basename' is NULL, uses the name of the current program for the name of
+ * the pidfile.
+ *
+ * Returns a pointer to a dynamically-allocatd string containing the absolute
+ * path to the pidfile; NULL on failure. */
+static char *
+generate_varrun_path(const char *basename)
+{
+	char *path;
+
 	if (basename == NULL)
 		basename = getprogname();
 
-	/*
-	 * If pidfile has already been created for the supplied basename
-	 * we don't need to create a pidfile again.
-	 */
-	if (pidfile_path != NULL) {
-		if (strcmp(pidfile_basename, basename) == 0)
-			return 0;
-		/*
-		 * Remove existing pidfile if it was created by this process.
-		 */
-		pidfile_cleanup();
+	/* _PATH_VARRUN includes trailing / */
+	(void) asprintf(&path, "%s%s.pid", _PATH_VARRUN, basename);
+	return path;
+}
 
+/* Creates a pidfile with the provided name.  The new pidfile is "registered"
+ * in the global variables pidfile_path and pidfile_pid so that any further
+ * call to pidfile(3) can check if we are recreating the same file or a new
+ * one.
+ *
+ * Returns 0 on success or -1 if there is any error. */
+static int
+create_pidfile(const char* path)
+{
+	FILE *f;
+
+	if (register_atexit_handler() == -1)
+		return -1;
+
+	if (cleanup_old_pidfile(path) == 0)
+		return 0;
+
+	pidfile_path = strdup(path);
+	if (pidfile_path == NULL)
+		return -1;
+
+	if ((f = fopen(path, "w")) == NULL) {
 		free(pidfile_path);
 		pidfile_path = NULL;
-		free(pidfile_basename);
-		pidfile_basename = NULL;
+		return -1;
 	}
 
 	pidfile_pid = getpid();
 
-	pidfile_basename = strdup(basename);
-	if (pidfile_basename == NULL)
-		return -1;
-
-	/* _PATH_VARRUN includes trailing / */
-	(void) asprintf(&pidfile_path, "%s%s.pid", _PATH_VARRUN, basename);
-	if (pidfile_path == NULL) {
-		free(pidfile_basename);
-		pidfile_basename = NULL;
-		return -1;
-	}
-
-	if ((f = fopen(pidfile_path, "w")) == NULL) {
-		free(pidfile_path);
-		pidfile_path = NULL;
-		free(pidfile_basename);
-		pidfile_basename = NULL;
-		return -1;
-	}
-
 	(void) fprintf(f, "%d\n", pidfile_pid);
 	(void) fclose(f);
+
 	return 0;
 }
 
-static void
-pidfile_cleanup(void)
+int
+pidfile(const char *path)
 {
-	/* Only remove the pidfile if it was created by this process. */
-	if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
-		(void) unlink(pidfile_path);
+
+	if (path == NULL || strchr(path, '/') == NULL) {
+		char *default_path;
+
+		if ((default_path = generate_varrun_path(path)) == NULL)
+			return -1;
+
+		if (create_pidfile(default_path) == -1) {
+			free(default_path);
+			return -1;
+		}
+
+		free(default_path);
+		return 0;
+	} else
+		return create_pidfile(path);
 }