#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,
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);
.\"
.\" $FreeBSD$
.\"
-.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
.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
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
.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
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
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;
}
/* 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) {
.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
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 ,
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 .
#include <sys/file.h>
#include <sys/stat.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libutil.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 <libutil.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;
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.
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);
+}
projects / thirdparty / libbsd.git / commitdiff
