Update pidfile module from FreeBSD

Use EINVAL instead of EDOOFUS. Add a missing synopsis for
pidfile_fileno() in the man page. Move the definition of struct pidfh
from libutil.h into pidfile.c following upstream change.

include/bsd/libutil.h

@@ -48,13 +48,7 @@
 #include <stdint.h>
 #include <stdio.h>
 
-/* for pidfile.c */
-struct pidfh {
-	int	pf_fd;
-	char	*pf_path;
-	dev_t	pf_dev;
-	ino_t	pf_ino;
-};
+struct pidfh;
 
 __BEGIN_DECLS
 int humanize_number(char *buf, size_t len, int64_t bytes,
@@ -65,6 +59,7 @@ int flopen(const char *_path, int _flags, ...);
 int flopenat(int dirfd, const char *path, int flags, ...);
 
 struct pidfh *pidfile_open(const char *path, mode_t mode, pid_t *pidptr);
+int pidfile_fileno(const struct pidfh *pfh);
 int pidfile_write(struct pidfh *pfh);
 int pidfile_close(struct pidfh *pfh);
 int pidfile_remove(struct pidfh *pfh);

man/pidfile.3bsd

@@ -24,15 +24,16 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 20, 2008
+.Dd February 8, 2012
 .Dt PIDFILE 3bsd
 .Os
 .Sh NAME
 .Nm pidfile_open ,
 .Nm pidfile_write ,
 .Nm pidfile_close ,
-.Nm pidfile_remove
-.Nd library for PID files handling
+.Nm pidfile_remove ,
+.Nm pidfile_fileno
+.Nd "library for PID files handling"
 .Sh LIBRARY
 .ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
 .Lb libbsd
@@ -49,6 +50,8 @@ for include usage.)
 .Fn pidfile_close "struct pidfh *pfh"
 .Ft int
 .Fn pidfile_remove "struct pidfh *pfh"
+.Ft int
+.Fn pidfile_fileno "struct pidfh *pfh"
 .Sh DESCRIPTION
 The
 .Nm pidfile
@@ -62,11 +65,14 @@ The
 function opens (or creates) a file specified by the
 .Fa path
 argument and locks it.
-If a file can not be locked, a PID of an already running daemon is returned in
-the
+If
 .Fa pidptr
-argument (if it is not
-.Dv NULL ) .
+argument is not
+.Dv NULL
+and file can not be locked, the function will use it to store a PID of an
+already running daemon or
+.Li -1
+in case daemon did not write its PID yet.
 The function does not write process' PID into the file here, so it can be
 used before
 .Fn fork Ns ing
@@ -77,10 +83,16 @@ argument is
 .Dv NULL ,
 .Pa /var/run/ Ns Ao Va progname Ac Ns Pa .pid
 file will be used.
+The
+.Fn pidfile_open
+function sets the O_CLOEXEC close-on-exec flag when opening the pidfile.
 .Pp
 The
 .Fn pidfile_write
 function writes process' PID into a previously opened file.
+The file is truncated before write, so calling the
+.Fn pidfile_write
+function multiple times is supported.
 .Pp
 The
 .Fn pidfile_close
@@ -92,6 +104,10 @@ to start a child process.
 The
 .Fn pidfile_remove
 function closes and removes a pidfile.
+.Pp
+The
+.Fn pidfile_fileno
+function returns the file descriptor for the open pidfile.
 .Sh RETURN VALUES
 The
 .Fn pidfile_open
@@ -105,15 +121,27 @@ If an error occurs,
 will be set.
 .Pp
 .Rv -std pidfile_write pidfile_close pidfile_remove
+.Pp
+The
+.Fn pidfile_fileno
+function returns the low-level file descriptor.
+It returns
+.Li -1
+and sets
+.Va errno
+if a NULL
+.Vt pidfh
+is specified, or if the pidfile is no longer open.
 .Sh EXAMPLES
 The following example shows in which order these functions should be used.
 Note that it is safe to pass
 .Dv NULL
 to
 .Fn pidfile_write ,
-.Fn pidfile_remove
-and
+.Fn pidfile_remove ,
 .Fn pidfile_close
+and
+.Fn pidfile_fileno
 functions.
 .Bd -literal
 struct pidfh *pfh;
@@ -127,6 +155,11 @@ if (pfh == NULL) {
 	}
 	/* If we cannot create pidfile from other reasons, only warn. */
 	warn("Cannot open or create pidfile");
+	/*
+	 * Even though pfh is NULL we can continue, as the other pidfile_*
+	 * function can handle such situation by doing nothing except setting
+	 * errno to EINVAL.
+	 */
 }
 
 if (daemon(0, 0) == \-1) {
@@ -165,16 +198,18 @@ function will fail if:
 .It Bq Er EEXIST
 Some process already holds the lock on the given pidfile, meaning that a
 daemon is already running.
+If
+.Fa pidptr
+argument is not
+.Dv NULL
+the function will use it to store a PID of an already running daemon or
+.Li -1
+in case daemon did not write its PID yet.
 .It Bq Er ENAMETOOLONG
 Specified pidfile's name is too long.
 .It Bq Er EINVAL
 Some process already holds the lock on the given pidfile, but PID read
 from there is invalid.
-.It Bq Er EAGAIN
-Some process already holds the lock on the given pidfile, but the file
-is truncated.
-Most likely, the existing daemon is writing new PID into
-the file.
 .El
 .Pp
 The
@@ -242,6 +277,16 @@ and
 system calls and the
 .Xr flopen 3bsd
 library function.
+.Pp
+The
+.Fn pidfile_fileno
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+Improper function use.
+Probably called not from the process which used
+.Fn pidfile_open .
+.El
 .Sh SEE ALSO
 .Xr open 2 ,
 .Xr daemon 3 ,
@@ -251,7 +296,7 @@ library function.
 The
 .Nm pidfile
 functionality is based on ideas from
-.An John-Mark Gurney Aq jmg@FreeBSD.org .
+.An John-Mark Gurney Aq Mt jmg@FreeBSD.org .
 .Pp
 The code and manual page was written by
-.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .
+.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org .

src/libbsd.map

@@ -142,4 +142,6 @@ LIBBSD_0.8 {
 
 LIBBSD_0.9 {
     flopenat;
+
+    pidfile_fileno;
 } LIBBSD_0.8;

src/pidfile.c

@@ -29,20 +29,27 @@
 #include <sys/file.h>
 #include <sys/stat.h>
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <string.h>
-#include <time.h>
 #include <err.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <libutil.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+struct pidfh {
+	int	pf_fd;
+	char	*pf_path;
+	dev_t	pf_dev;
+	ino_t	pf_ino;
+};
 
 static int _pidfile_remove(struct pidfh *pfh, int freeit);
 
 static int
-pidfile_verify(struct pidfh *pfh)
+pidfile_verify(const struct pidfh *pfh)
 {
 	struct stat sb;
 
@@ -114,25 +121,33 @@ pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
 	fd = flopen(pfh->pf_path,
 	    O_WRONLY | O_CREAT | O_TRUNC | O_NONBLOCK, mode);
 	if (fd == -1) {
-		count = 0;
-		rqtp.tv_sec = 0;
-		rqtp.tv_nsec = 5000000;
-		if (errno == EWOULDBLOCK && pidptr != NULL) {
-		again:
-			errno = pidfile_read(pfh->pf_path, pidptr);
-			if (errno == 0)
+		if (errno == EWOULDBLOCK) {
+			if (pidptr == NULL) {
 				errno = EEXIST;
-			else if (errno == EAGAIN) {
-				if (++count <= 3) {
+			} else {
+				count = 20;
+				rqtp.tv_sec = 0;
+				rqtp.tv_nsec = 5000000;
+				for (;;) {
+					errno = pidfile_read(pfh->pf_path,
+					                     pidptr);
+					if (errno != EAGAIN || --count == 0)
+						break;
 					nanosleep(&rqtp, 0);
-					goto again;
 				}
+				if (errno == EAGAIN)
+					*pidptr = -1;
+				if (errno == 0 || errno == EAGAIN)
+					errno = EEXIST;
 			}
 		}
+		error = errno;
 		free(pfh->pf_path);
 		free(pfh);
+		errno = error;
 		return (NULL);
 	}
+
 	/*
 	 * Remember file information, so in pidfile_write() we are sure we write
 	 * to the proper descriptor.
@@ -251,3 +266,14 @@ pidfile_remove(struct pidfh *pfh)
 
 	return (_pidfile_remove(pfh, 1));
 }
+
+int
+pidfile_fileno(const struct pidfh *pfh)
+{
+
+	if (pfh == NULL || pfh->pf_fd == -1) {
+		errno = EINVAL;
+		return (-1);
+	}
+	return (pfh->pf_fd);
+}