[src/trunk]: src Extend pidfile(3) to support creating pid files in arbitrary...

[jmmv <jmmv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f0a0121c663a
branches:  trunk
changeset: 763640:f0a0121c663a
user:      jmmv <jmmv%NetBSD.org@localhost>
date:      Tue Mar 29 13:55:37 2011 +0000

description:
Extend pidfile(3) to support creating pid files in arbitrary locations.

If the argument provided to pidfile(3) contains a '/', then the value is
considered to be an absolute/relative path and the pid file is created
in the given location.

Otherwise, pidfile(3) behaves as before and treats the provided value as
a basename to construct a pid file in /var/run/<basename>.pid.  This means
that to create a pid file named "foo.pid" in the current directory, one
must specify "./foo.pid".

diffstat:

 lib/libutil/pidfile.3         |   48 ++++++++----
 lib/libutil/pidfile.c         |  160 ++++++++++++++++++++++++++++-------------
 tests/lib/libutil/t_pidfile.c |  119 +++++++++++++++++++++++++++++--
 3 files changed, 250 insertions(+), 77 deletions(-)

diffs (truncated from 482 to 300 lines):

diff -r b7578d3f3fe5 -r f0a0121c663a lib/libutil/pidfile.3
--- a/lib/libutil/pidfile.3     Tue Mar 29 07:48:13 2011 +0000
+++ b/lib/libutil/pidfile.3     Tue Mar 29 13:55:37 2011 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: pidfile.3,v 1.12 2010/05/05 22:05:31 wiz Exp $
+.\"    $NetBSD: pidfile.3,v 1.13 2011/03/29 13:55:37 jmmv Exp $
 .\"
 .\" Copyright (c) 1999 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd May 4, 2010
+.Dd March 23, 2011
 .Dt PIDFILE 3
 .Os
 .Sh NAME
@@ -38,34 +38,48 @@
 .Sh SYNOPSIS
 .In util.h
 .Ft int
-.Fn pidfile "const char *basename"
+.Fn pidfile "const char *path"
 .Sh DESCRIPTION
 .Fn pidfile
-writes a file containing the process ID of the program to the
+creates a file containing the process ID of the caller program.
+The pid file can be used as a quick reference if
+the process needs to be sent a signal.
+When the program exits, the pid file is removed automatically, unless
+the program receives a fatal signal.
+.Pp
+If
+.Ar path
+is
+.Dv NULL
+or a plain basename (a name containing no directory components), the pid file
+is created in the
 .Pa /var/run
 directory.
 The file name has the form
 .Pa /var/run/basename.pid .
-If the
-.Ar basename
-argument is
+The basename part is either the value of
+.Ar path
+if it was not
 .Dv NULL ,
-.Fn pidfile
-will determine the program name and use that instead.
+or the program name as returned by
+.Xr getprogname 3
+otherwise.
 .Pp
-The pid file can be used as a quick reference if
-the process needs to be sent a signal.
-When the program exits, the pid file will be removed automatically, unless
-the program receives a fatal signal.
+If
+.Ar path
+is an absolute or relative path (i.e. it contains the
+.Sq /
+character),
+the pid file is created in the provided location.
 .Pp
 Note that only the first invocation of
 .Fn pidfile
 causes a pid file to be written; subsequent invocations have no effect
 unless a new
-.Ar basename
+.Ar path
 is supplied.
 If called with a new
-.Ar basename ,
+.Ar path ,
 .Fn pidfile
 will remove the old pid file and write the new one.
 .Sh RETURN VALUES
@@ -78,11 +92,13 @@
 .Fn pidfile
 function call appeared in
 .Nx 1.5 .
+Support for creating pid files in any arbitrary path was added in
+.Nx 6.0 .
 .Sh BUGS
 .Fn pidfile
 uses
 .Xr atexit 3
-to ensure the pidfile is unlinked at program exit.
+to ensure the pid file is unlinked at program exit.
 However, programs that use the
 .Xr _exit 2
 function (for example, in signal handlers)
diff -r b7578d3f3fe5 -r f0a0121c663a lib/libutil/pidfile.c
--- a/lib/libutil/pidfile.c     Tue Mar 29 07:48:13 2011 +0000
+++ b/lib/libutil/pidfile.c     Tue Mar 29 13:55:37 2011 +0000
@@ -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;
+
+       if ((pidfile_path != NULL) && (pidfile_pid == getpid()))
+               (void) unlink(pidfile_path);
+}
 
-       /*
-        * Register handler which will remove the pidfile later.
-        */
-       if (!pidfile_atexit_done) {
+/* 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);