Add client side pidfile functions: pidfile_read(), pidfile_signal().

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile

@@ -56,7 +56,8 @@ endif
 DISTFILES   = README LICENSE
 HEADERS     = lite.h
 OBJS       := chomp.o copyfile.o dir.o fexist.o fisdir.o fmode.o fsendfile.o
-OBJS       += makepath.o pidfile.o rsync.o strlcpy.o strlcat.o strtonum.o tempfile.o
+OBJS       += makepath.o pidfile.o pidfilefn.o rsync.o
+OBJS       += strlcpy.o strlcat.o strtonum.o tempfile.o
 DEPS       := $(OBJS:.o=.d)
 JUNK        = *~ *.bak *.map .*.d *.d DEADJOE semantic.cache *.gdb *.elf core core.*
 

README.md

@@ -116,6 +116,14 @@ Generic Functions
   may still exist even though the program is no longer running.  This
   is only a problem for clients.
 
+- `pidfile_read(pidfile)`
+
+  Read PID from pid file created by `pidfile()`.
+
+- `pidfile_signal(pidfile, signal)`
+
+  Send signal to PID found in pid file created by `pidfile()`.
+
 - `rsync(src, dst, delete, *filter())`
 
   Very simple `rsync()` to copy files files and directories

lite.h

@@ -51,7 +51,9 @@ int     makepath   (char *dir);
 int     dir        (const char *dir, const char *type, int (*filter) (const char *file), char ***list, int strip);
 int     rsync      (char *src, char *dst, int delete, int (*filter) (const char *file));
 
-int     pidfile    (const char *basename);
+int     pidfile       (const char *basename);
+int     pidfile_signal(const char *pidfile, int signal);
+int     pidfile_read  (const char *pidfile);
 
 #ifndef strlcpy
 size_t  strlcpy    (char *dst, const char *src, size_t siz);
@@ -126,7 +128,9 @@ static inline int string_case_compare (const char *a, const char *b)
 }
 
 /* Compat */
-#define copy_filep(src, dst) fcopyfile(src,dst);
+#define copy_filep(src, dst) fcopyfile(src,dst)
+#define pidfile_read_pid(file) pifile_read(file)
+#define signal_pidfile(file, signo) pidfile_signal(file,signo)
 
 #endif /* FINIT_LITE_H_ */
 

pidfilefn.c

@@ -0,0 +1,131 @@
+/* Functions for dealing with PID files (client side)
+ *
+ * Copyright (c) 2009-2015  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+
+extern char *chomp(char *str);
+
+/**
+ * pidfile_read - Reads a PID value from a pidfile.
+ * @pidfile: File containing PID, usually in /var/run/<PROC>.pid
+ *
+ * This function takes a @pidfile and returns the PID found therein.
+ *
+ * Returns:
+ * On invalid @pidfile -1 and errno set to %EINVAL, when @pidfile does not exist -1
+ * and errno set to %ENOENT.  When the pidfile is empty or when its contents cannot
+ * be translated this function returns zero (0), on success this function returns
+ * a PID value greater than one. PID 1 is reserved for the system init process.
+ */
+int pidfile_read(const char *pidfile)
+{
+	int pid = 0;
+	char buf[16];
+	FILE *fp;
+
+	if (!pidfile) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (access(pidfile, F_OK) < 0)
+		return -1;
+
+	fp = fopen(pidfile, "r");
+	if (!fp)
+		return -1;
+
+	if (fgets(buf, sizeof(buf), fp)) {
+                char *ptr = chomp(buf);
+
+                if (ptr) {
+                        errno = 0;
+                        pid = strtoul(ptr, NULL, 0);
+                        if (errno)
+                                pid = 0; /* Failed conversion. */
+                }
+	}
+	fclose(fp);
+
+	return pid;
+}
+
+/**
+ * pidfile_signal - Send signal to a PID and cleanup pidfile afterwards
+ * @pidfile: File containing PID, usually in /var/run/<PROC>.pid
+ * @signal: Signal to send to PID found in @pidfile.
+ *
+ * If @signal is any of %SIGTERM, %SIGKILL, or if kill() returns -1 the
+ * @pidfile is removed.
+ *
+ * Returns:
+ * POSIX OK(0) on success, non-zero otherwise.
+ */
+int pidfile_signal(const char *pidfile, int signal)
+{
+	int pid = -1, ret = -1;
+
+	pid = pidfile_read(pidfile);
+	if (pid <= 0)
+		return 1;
+
+	ret = kill(pid, signal);
+	if ((ret == -1) || (signal == SIGTERM) || (signal == SIGKILL))
+		remove(pidfile);
+
+	return 0;
+}
+
+
+/********************************* UNIT TESTS ************************************/
+#ifdef UTEST_PIDFN
+#define PIDFILE "/var/run/unittest.pid"
+
+static void sig_handler(int signo)
+{
+	fprintf(stderr, "Exiting ...\n");
+}
+
+int main(void)
+{
+	signal(SIGTERM, sig_handler);
+
+	fprintf(stderr, "Testing pidfile() ...\n");
+        pidfile(NULL);
+	system("ls -ld " PIDFILE);
+
+	fprintf(stderr, "Reading pid file, should be %d ...\n", getpid());
+        fprintf(stderr, "=> %d\n", pidfile_read(PIDFILE));
+
+        fprintf(stderr, "Signalling ourselves ...\n");
+
+	return pidfile_signal(PIDFILE, SIGTERM);
+}
+#endif  /* UTEST_PIDFN */
+
+/**
+ * Local Variables:
+ *  compile-command: "gcc -g -o unittest -DUTEST_PIDFN pidfile.c chomp.c pidfilefn.c && ./unittest"
+ *  version-control: t
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */