- add initial library structure and Makefile

Makefile

@@ -0,0 +1,20 @@
+PREFIX?=/usr/local
+INC=-I$(PREFIX)/include
+LIB=-L$(PREFIX)/lib
+CFLAGS=-Wall -Wextra -g -O2 -pipe -funroll-loops -ffast-math -fno-strict-aliasing
+CC?=cc
+AR?=ar
+RANLIB?=ranlib
+
+LIBPIDUTIL = libpidutil.a
+OBJS = pidutil.o
+
+all: $(LIBPIDUTIL) $(PROGS)
+
+$(LIBPIDUTIL) : $(OBJS)
+	$(AR) rv $(LIBPIDUTIL) $?
+	$(RANLIB) $(LIBPIDUTIL)
+
+clean:
+	rm -f *.o *.a a.out core temp.* $(LIBPIDUTIL)
+	rm -fr *.dSYM

pidutil.c

@@ -0,0 +1,288 @@
+#include "pidutil.h"
+
+struct pidfh {
+	int	pf_fd;
+	char	pf_path[MAXPATHLEN + 1];
+	dev_t	pf_dev;
+	ino_t	pf_ino;
+};
+
+static int _pidfile_remove(struct pidfh *pfh, int freeit);
+
+static int
+pidfile_verify(const struct pidfh *pfh)
+{
+	struct stat sb;
+
+	if (pfh == NULL || pfh->pf_fd == -1)
+		return (EINVAL);
+	/*
+	 * Check remembered descriptor.
+	 */
+	if (fstat(pfh->pf_fd, &sb) == -1)
+		return (errno);
+	if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
+		return (EINVAL);
+	return (0);
+}
+
+int
+flopen(const char *path, int flags,...)
+{
+	int fd, operation, serrno, trunc;
+	struct stat sb, fsb;
+	int mode;
+
+#ifdef O_EXLOCK
+	flags &= ~O_EXLOCK;
+#endif
+
+	mode = 0;
+	if (flags & O_CREAT) {
+		va_list ap;
+
+		va_start(ap, flags);
+		mode = (int)va_arg(ap, int);
+		va_end(ap);
+	}
+	operation = LOCK_EX;
+	if (flags & O_NONBLOCK)
+		operation |= LOCK_NB;
+
+	trunc = (flags & O_TRUNC);
+	flags &= ~O_TRUNC;
+
+	for (;;) {
+		if ((fd = open(path, flags, mode)) == -1)
+			/* non-existent or no access */
+			return (-1);
+		if (flock(fd, operation) == -1) {
+			/* unsupported or interrupted */
+			serrno = errno;
+			(void)close(fd);
+			errno = serrno;
+			return (-1);
+		}
+		if (stat(path, &sb) == -1) {
+			/* disappeared from under our feet */
+			(void)close(fd);
+			continue;
+		}
+		if (fstat(fd, &fsb) == -1) {
+			/* can't happen [tm] */
+			serrno = errno;
+			(void)close(fd);
+			errno = serrno;
+			return (-1);
+		}
+		if (sb.st_dev != fsb.st_dev ||
+		    sb.st_ino != fsb.st_ino) {
+			/* changed under our feet */
+			(void)close(fd);
+			continue;
+		}
+		if (trunc && ftruncate(fd, 0) != 0) {
+			/* can't happen [tm] */
+			serrno = errno;
+			(void)close(fd);
+			errno = serrno;
+			return (-1);
+		}
+		return (fd);
+	}
+}
+
+static int
+pidfile_read(const char *path, pid_t *pidptr)
+{
+	char buf[16], *endptr;
+	int error, fd, i;
+
+	fd = open(path, O_RDONLY | O_CLOEXEC);
+	if (fd == -1)
+		return (errno);
+
+	i = read(fd, buf, sizeof(buf) - 1);
+	error = errno;			/* Remember errno in case close()
+					 * wants to change it. */
+	close(fd);
+	if (i == -1)
+		return (error);
+	else if (i == 0)
+		return (EAGAIN);
+	buf[i] = '\0';
+
+	*pidptr = strtol(buf, &endptr, 10);
+	if (endptr != &buf[i])
+		return (EINVAL);
+
+	return (0);
+}
+
+struct pidfh *
+pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
+{
+	struct pidfh *pfh;
+	struct timespec rqtp;
+	struct stat sb;
+	size_t len;
+	int fd, error, count;
+
+	pfh = malloc(sizeof(*pfh));
+	if (pfh == NULL)
+		return NULL;
+
+	if (path == NULL)
+		len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), "/var/run/%s.pid", getprogname());
+	else
+		len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), "%s", path);
+
+	if (len >= sizeof(pfh->pf_path)) {
+		free(pfh);
+		errno = ENAMETOOLONG;
+		return (NULL);
+	}
+	fd = flopen(pfh->pf_path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
+
+	if (fd == -1) {
+		if (errno == EWOULDBLOCK) {
+			if (pidptr == NULL) {
+				errno = EEXIST;
+			} 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);
+				}
+				if (errno == EAGAIN)
+					*pidptr = -1;
+				if (errno == 0 || errno == EAGAIN)
+					errno = EEXIST;
+			}
+		}
+		free(pfh);
+		return (NULL);
+	}
+	if (fstat(fd, &sb) == -1) {
+		error = errno;
+		unlink(pfh->pf_path);
+		close(fd);
+		free(pfh);
+		errno = error;
+		return (NULL);
+	}
+	pfh->pf_fd = fd;
+	pfh->pf_dev = sb.st_dev;
+	pfh->pf_ino = sb.st_ino;
+
+	return (pfh);
+}
+
+static int
+_pidfile_remove(struct pidfh *pfh, int freeit)
+{
+	int error;
+
+	error = pidfile_verify(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	if (unlink(pfh->pf_path) == -1)
+		error = errno;
+	if (close(pfh->pf_fd) == -1) {
+		if (error == 0)
+			error = errno;
+	}
+	if (freeit)
+		free(pfh);
+	else
+		pfh->pf_fd = -1;
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	return (0);
+}
+
+int
+pidfile_remove(struct pidfh *pfh)
+{
+
+	return (_pidfile_remove(pfh, 1));
+}
+
+int
+pidfile_write(struct pidfh *pfh)
+{
+	char pidstr[16];
+	int error, fd;
+
+	/*
+	 * Check remembered descriptor, so we don't overwrite some other file
+	 * if pidfile was closed and descriptor reused.
+	 */
+	errno = pidfile_verify(pfh);
+	if (errno != 0) {
+		/*
+		 * Don't close descriptor, because we are not sure if it's
+		 * ours.
+		 */
+		return (-1);
+	}
+	fd = pfh->pf_fd;
+
+	/*
+	 * Truncate PID file, so multiple calls of pidfile_write() are
+	 * allowed.
+	 */
+	if (ftruncate(fd, 0) == -1) {
+		error = errno;
+		_pidfile_remove(pfh, 0);
+		errno = error;
+		return (-1);
+	}
+	snprintf(pidstr, sizeof(pidstr), "%u", getpid());
+	if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
+		error = errno;
+		_pidfile_remove(pfh, 0);
+		errno = error;
+		return (-1);
+	}
+	return (0);
+}
+
+int
+pidfile_close(struct pidfh *pfh)
+{
+	int error;
+
+	error = pidfile_verify(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	if (close(pfh->pf_fd) == -1)
+		error = errno;
+	free(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	return (0);
+}
+
+int
+pidfile_fileno(const struct pidfh *pfh)
+{
+
+	if (pfh == NULL || pfh->pf_fd == -1) {
+		errno = EINVAL;
+		return (-1);
+	}
+	return (pfh->pf_fd);
+}

pidutil.h

@@ -0,0 +1,30 @@
+#ifndef _PIDUTIL_H
+#define _PIDUTIL_H
+
+#include <sys/file.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <time.h>
+#include <string.h>
+
+struct pidfh;
+
+int	flopen(const char *_path, int _flags, ...);
+
+struct pidfh *pidfile_open(const char *path, mode_t mode, pid_t *pidptr);
+int pidfile_write(struct pidfh	*pfh);
+int pidfile_close(struct pidfh	*pfh);
+int pidfile_remove(struct pidfh *pfh);
+int pidfile_fileno(const struct pidfh *pfh);
+
+#endif /* _PIDUTIL_H */