From 411b7c87536a8639954bf1eb6876209abfb4e848 Mon Sep 17 00:00:00 2001
From: Martin Schwenke <martin@meltin.net>
Date: Mon, 31 Jul 2017 15:11:33 +1000
Subject: [PATCH] util: New functions pidfile_path_create(), pidfile_fd_close()

Uses the core of CTDB's create_pidfile_context() for
pidfile_path_create(). pidfile_fd_close() is a subset of CTDB's
pidfile_context_destructor().

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Volker Lendecke <vl@samba.org>
---
 lib/util/pidfile.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/util/pidfile.h |  3 ++
 2 files changed, 102 insertions(+)

diff --git a/lib/util/pidfile.c b/lib/util/pidfile.c
index ede146f560e8..2be61966e26d 100644
--- a/lib/util/pidfile.c
+++ b/lib/util/pidfile.c
@@ -2,6 +2,7 @@
    Unix SMB/CIFS implementation.
    pidfile handling
    Copyright (C) Andrew Tridgell 1998
+   Copyright (C) Amitay Isaccs  2016
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -31,6 +32,104 @@
  * @brief Pid file handling
  */
 
+int pidfile_path_create(const char *path, int *outfd)
+{
+	struct flock lck;
+	char tmp[64] = { 0 };
+	pid_t pid;
+	int fd, ret = 0;
+	int len;
+	ssize_t nwritten;
+
+	pid = getpid();
+
+	fd = open(path, O_CREAT|O_WRONLY|O_NONBLOCK, 0644);
+	if (fd == -1) {
+		return errno;
+	}
+
+	if (! set_close_on_exec(fd)) {
+		close(fd);
+		return EIO;
+	}
+
+	lck = (struct flock) {
+		.l_type = F_WRLCK,
+		.l_whence = SEEK_SET,
+	};
+
+	do {
+		ret = fcntl(fd, F_SETLK, &lck);
+	} while ((ret == -1) && (errno == EINTR));
+
+	if (ret != 0) {
+		ret = errno;
+		close(fd);
+		return ret;
+	}
+
+	/*
+	 * PID file is locked by us so from here on we should unlink
+	 * on failure
+	 */
+
+	do {
+		ret = ftruncate(fd, 0);
+	} while ((ret == -1) && (errno == EINTR));
+
+	if (ret == -1) {
+		ret = EIO;
+		goto fail_unlink;
+	}
+
+	len = snprintf(tmp, sizeof(tmp), "%u\n", pid);
+	if (len < 0) {
+		ret = errno;
+		goto fail_unlink;
+	}
+	if (len >= sizeof(tmp)) {
+		ret = ENOSPC;
+		goto fail_unlink;
+	}
+
+	do {
+		nwritten = write(fd, tmp, len);
+	} while ((nwritten == -1) && (errno == EINTR));
+
+	if ((nwritten == -1) || (nwritten != len)) {
+		ret = EIO;
+		goto fail_unlink;
+	}
+
+	if (outfd != NULL) {
+		*outfd = fd;
+	}
+	return 0;
+
+fail_unlink:
+	unlink(path);
+	close(fd);
+	return ret;
+}
+
+void pidfile_fd_close(int fd)
+{
+	struct flock lck = {
+		.l_type = F_UNLCK,
+		.l_whence = SEEK_SET,
+	};
+	int ret;
+
+	do {
+		ret = fcntl(fd, F_SETLK, &lck);
+	} while ((ret == -1) && (errno == EINTR));
+
+	do {
+		ret = close(fd);
+	} while ((ret == -1) && (errno == EINTR));
+}
+
+
 /**
  * return the pid in a pidfile. return 0 if the process (or pidfile)
  * does not exist
diff --git a/lib/util/pidfile.h b/lib/util/pidfile.h
index d504f526a5ce..d51161afc391 100644
--- a/lib/util/pidfile.h
+++ b/lib/util/pidfile.h
@@ -20,6 +20,9 @@
 #ifndef _SAMBA_PIDFILE_H_
 #define _SAMBA_PIDFILE_H_
 
+int pidfile_path_create(const char *path, int *outfd);
+void pidfile_fd_close(int fd);
+
 pid_t pidfile_pid(const char *piddir, const char *name);
 void pidfile_create(const char *piddir, const char *program_name);
 void pidfile_unlink(const char *piddir, const char *program_name);