Add support for writing PID files

NEWS

@@ -12,6 +12,8 @@ Changes in 1.0.0, released on XXXX-XX-XX:
  * The configuration file structure has changed.
  * TagLib (its C wrapper library) is now a mandatory dependency
  * Support the new '@b@' placeholder for separate album metadata.
+ * The command line option -p has been added, causing ezstream to write a
+   locked PID file to a given location
 
 
 Changes in 0.6.0, released on 2015-01-18:

doc/ezstream.1.in.in

@@ -20,6 +20,7 @@
 .Bk -words
 .Op Fl hqrVv
 .Fl c Ar configfile
+.Op Fl p Ar pidfile
 .Ek
 .Nm
 .Bk -words
@@ -45,6 +46,20 @@ Use the XML configuration in
 .It Fl h
 Print a summary of available command line arguments with short descriptions
 and exit.
+.It Fl p Ar pidfile
+Write the
+.Nm
+process ID
+.Pq a single number
+to
+.Ar pidfile .
+The file will be written even when it already exists.
+A file lock is maintained until the main
+.Nm
+process terminates.
+If the file cannot be written for any reason,
+.Nm
+will log this, but not consider it a fatal error.
 .It Fl q
 Be more quiet.
 Suppress the output that external programs send to standard error.

src/cfg.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Moritz Grimm <mgrimm@mrsserver.net>
+ * Copyright (c) 2015, 2017 Moritz Grimm <mgrimm@mrsserver.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -277,6 +277,13 @@ cfg_set_program_config_file(const char *file, const char **errstrp)
 	return (0);
 }
 
+int
+cfg_set_program_pid_file(const char *file, const char **errstrp)
+{
+	SET_STRLCPY(cfg.program.pid_file, file, errstrp);
+	return (0);
+}
+
 int
 cfg_set_program_quiet_stderr(int quiet_stderr, const char **not_used)
 {
@@ -642,6 +649,12 @@ cfg_get_program_config_file(void)
 	return (cfg.program.config_file[0] ? cfg.program.config_file : NULL);
 }
 
+const char *
+cfg_get_program_pid_file(void)
+{
+	return (cfg.program.pid_file[0] ? cfg.program.pid_file : NULL);
+}
+
 int
 cfg_get_program_quiet_stderr(void)
 {

src/cfg.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Moritz Grimm <mgrimm@mrsserver.net>
+ * Copyright (c) 2015, 2017 Moritz Grimm <mgrimm@mrsserver.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -91,6 +91,7 @@ int	cfg_file_check(const char *);
 int	cfg_set_program_name(const char *, const char **);
 int	cfg_set_program_config_type(enum cfg_config_type, const char **);
 int	cfg_set_program_config_file(const char *, const char **);
+int	cfg_set_program_pid_file(const char *, const char **);
 int	cfg_set_program_quiet_stderr(int, const char **);
 int	cfg_set_program_rtstatus_output(int, const char **);
 int	cfg_set_program_verbosity(unsigned int, const char **);
@@ -137,6 +138,8 @@ enum cfg_config_type
 	cfg_get_program_config_type(void);
 const char *
 	cfg_get_program_config_file(void);
+const char *
+	cfg_get_program_pid_file(void);
 int	cfg_get_program_quiet_stderr(void);
 int	cfg_get_program_rtstatus_output(void);
 unsigned int

src/cfg_private.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Moritz Grimm <mgrimm@mrsserver.net>
+ * Copyright (c) 2015, 2017 Moritz Grimm <mgrimm@mrsserver.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -37,6 +37,7 @@ struct cfg {
 		char			 name[PATH_MAX];
 		enum cfg_config_type	 config_type;
 		char			 config_file[PATH_MAX];
+		char			 pid_file[PATH_MAX];
 		int			 quiet_stderr;
 		int			 rtstatus_output;
 		unsigned int		 verbosity;

src/cmdline.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Moritz Grimm <mgrimm@mrsserver.net>
+ * Copyright (c) 2015, 2017 Moritz Grimm <mgrimm@mrsserver.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -32,10 +32,11 @@
 #include "cmdline.h"
 #include "playlist.h"
 
-#define OPTSTRING	"c:hqrs:Vv"
+#define OPTSTRING	"c:hp:qrs:Vv"
 enum opt_vals {
 	OPT_CONFIGFILE		= 'c',
 	OPT_HELP		= 'h',
+	OPT_PIDFILE		= 'p',
 	OPT_QUIETSTDERR 	= 'q',
 	OPT_RTSTATUS		= 'r',
 	OPT_SHUFFLEFILE 	= 's',
@@ -51,7 +52,7 @@ static void	_set_program_name(const char *);
 static void
 _usage(void)
 {
-	fprintf(stderr, "usage: %s [-hqrVv] -c cfgfile\n",
+	fprintf(stderr, "usage: %s [-hqrVv] -c cfgfile [-p pidfile]\n",
 	    cfg_get_program_name());
 	fprintf(stderr, "       %s -s file\n",
 	    cfg_get_program_name());
@@ -63,6 +64,7 @@ _usage_help(void)
 	fprintf(stderr, "\n");
 	fprintf(stderr, "    -c cfgfile  use XML configuration in cfgfile\n");
 	fprintf(stderr, "    -h          print this help and exit\n");
+	fprintf(stderr, "    -p pidfile  write PID to pidfile\n");
 	fprintf(stderr, "    -q          suppress STDERR output from external en-/decoders\n");
 	fprintf(stderr, "    -r          show real-time stream information on stdout\n");
 	fprintf(stderr, "    -s file     read lines from file, shuffle, print to STDOUT, then exit\n");
@@ -125,6 +127,15 @@ cmdline_parse(int argc, char *argv[], int *ret_p)
 			_usage_help();
 			*ret_p = 0;
 			return (-1);
+		case OPT_PIDFILE:
+			if (0 > cfg_set_program_pid_file(optarg, &err_str)) {
+				fprintf(stderr, "-%c: argument %s\n",
+				    OPT_PIDFILE, err_str);
+				_usage();
+				*ret_p = 2;
+				return (-1);
+			}
+			break;
 		case OPT_RTSTATUS:
 			cfg_set_program_rtstatus_output(1, NULL);
 			/* FALLTHROUGH */

src/ezstream.c

@@ -1,7 +1,7 @@
 /*
  *  ezstream - source client for Icecast with external en-/decoder support
  *  Copyright (C) 2003, 2004, 2005, 2006  Ed Zaleski <oddsock@oddsock.org>
- *  Copyright (C) 2007, 2009, 2015        Moritz Grimm <mgrimm@mrsserver.net>
+ *  Copyright (C) 2007, 2009, 2015, 2017  Moritz Grimm <mgrimm@mrsserver.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 as
@@ -801,6 +801,9 @@ main(int argc, char *argv[])
 		return (ez_shutdown(1));
 	}
 
+	if (0 > writePidfile(cfg_get_program_pid_file()))
+		log_syserr(WARNING, errno, cfg_get_program_pid_file());
+
 	if (0 > stream_connect(stream)) {
 		log_error("initial server connection failed");
 		return (ez_shutdown(1));

src/util.c

@@ -1,7 +1,7 @@
 /*
  *  ezstream - source client for Icecast with external en-/decoder support
  *  Copyright (C) 2003, 2004, 2005, 2006  Ed Zaleski <oddsock@oddsock.org>
- *  Copyright (C) 2007, 2009              Moritz Grimm <mgrimm@mrsserver.net>
+ *  Copyright (C) 2007, 2009, 2017        Moritz Grimm <mgrimm@mrsserver.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 as
@@ -24,6 +24,9 @@
 
 #include "compat.h"
 
+#include <sys/types.h>
+#include <sys/file.h>
+
 #include <ctype.h>
 #include <errno.h>
 #include <langinfo.h>
@@ -31,12 +34,12 @@
 #include <locale.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
 #ifdef HAVE_ICONV
 # include <iconv.h>
 #endif
 
-#include "cfg.h"
 #include "log.h"
 #include "util.h"
 #include "xalloc.h"
@@ -45,7 +48,13 @@
 # define BUFSIZ 1024
 #endif
 
-char *	iconvert(const char *, const char *, const char *, int);
+static char		*pidfile_path;
+static FILE		*pidfile_file;
+static pid_t		 pidfile_pid;
+static unsigned int	 pidfile_numlocks;
+
+static char *	iconvert(const char *, const char *, const char *, int);
+static void	cleanupPidfile(void);
 
 int
 strrcmp(const char *s, const char *sub)
@@ -105,7 +114,7 @@ UTF8toCHAR(const char *in_str, int mode)
 	return (iconvert(in_str, "UTF-8", codeset, mode));
 }
 
-char *
+static char *
 iconvert(const char *in_str, const char *from, const char *to, int mode)
 {
 #ifdef HAVE_ICONV
@@ -205,6 +214,64 @@ iconvert(const char *in_str, const char *from, const char *to, int mode)
 #endif /* HAVE_ICONV */
 }
 
+static void
+cleanupPidfile(void)
+{
+	if (NULL != pidfile_path && getpid() == pidfile_pid) {
+		(void)unlink(pidfile_path);
+		(void)fclose(pidfile_file);
+	}
+}
+
+int
+writePidfile(const char *path)
+{
+	int	 save_errno = 0;
+	pid_t	 pid;
+
+	if (NULL == path)
+		return (0);
+
+	xfree(pidfile_path);
+	pidfile_path = xstrdup(path);
+
+	if (NULL != pidfile_file)
+		fclose(pidfile_file);
+	if (NULL == (pidfile_file = fopen(pidfile_path, "w"))) {
+		save_errno = errno;
+		xfree(pidfile_path);
+		pidfile_path = NULL;
+		return (-1);
+	}
+
+	pid = getpid();
+	if (0 >= fprintf(pidfile_file, "%ld\n", (long)pid) ||
+	    0 > fflush(pidfile_file) ||
+	    0 > flock(fileno(pidfile_file), LOCK_EX))
+		goto error;
+
+	if (0 == pidfile_numlocks) {
+		pidfile_pid = pid;
+		if (0 != atexit(cleanupPidfile))
+			goto error;
+		pidfile_numlocks++;
+	}
+
+	return (0);
+
+error:
+	save_errno = errno;
+	(void)unlink(pidfile_path);
+	xfree(pidfile_path);
+	pidfile_path = NULL;
+	(void)fclose(pidfile_file);
+	pidfile_file = NULL;
+	pidfile_pid = 0;
+	errno = save_errno;
+
+	return (-1);
+}
+
 char *
 replaceString(const char *source, const char *from, const char *to)
 {

src/util.h

@@ -1,7 +1,7 @@
 /*
  *  ezstream - source client for Icecast with external en-/decoder support
  *  Copyright (C) 2003, 2004, 2005, 2006  Ed Zaleski <oddsock@oddsock.org>
- *  Copyright (C) 2007                    Moritz Grimm <mgrimm@mrsserver.net>
+ *  Copyright (C) 2007, 2017              Moritz Grimm <mgrimm@mrsserver.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 as
@@ -20,12 +20,13 @@
 #define ICONV_TRANSLIT		1
 #define ICONV_IGNORE		2
 
-int		strrcmp(const char *, const char *);
+int	writePidfile(const char *);
-int		strrcasecmp(const char *, const char *);
+int	strrcmp(const char *, const char *);
-char *		CHARtoUTF8(const char *, int);
+int	strrcasecmp(const char *, const char *);
-char *		UTF8toCHAR(const char *, int);
+char *	CHARtoUTF8(const char *, int);
-char *		replaceString(const char *, const char *, const char *);
+char *	UTF8toCHAR(const char *, int);
-char *		shellQuote(const char *);
+char *	replaceString(const char *, const char *, const char *);
-int		urlParse(const char *, char **, unsigned short *, char **);
+char *	shellQuote(const char *);
+int	urlParse(const char *, char **, unsigned short *, char **);
 
 #endif /* __UTIL_H__ */

tests/check_cfg.c

@@ -207,6 +207,14 @@ START_TEST(test_program_config_file)
 }
 END_TEST
 
+START_TEST(test_program_pid_file)
+{
+	ck_assert_ptr_eq(cfg_get_program_pid_file(), NULL);
+	TEST_STRLCPY(cfg_set_program_pid_file, cfg_get_program_pid_file,
+	    PATH_MAX);
+}
+END_TEST
+
 START_TEST(test_program_quiet_stderr)
 {
 	ck_assert_int_eq(cfg_set_program_quiet_stderr(-1, NULL), 0);
@@ -808,6 +816,7 @@ cfg_suite(void)
 	tcase_add_test(tc_program, test_program_name);
 	tcase_add_test(tc_program, test_program_config_type);
 	tcase_add_test(tc_program, test_program_config_file);
+	tcase_add_test(tc_program, test_program_pid_file);
 	tcase_add_test(tc_program, test_program_quiet_stderr);
 	tcase_add_test(tc_program, test_program_rtstatus_output);
 	tcase_add_test(tc_program, test_program_verbosity);

tests/check_cmdline.c

@@ -33,6 +33,22 @@ START_TEST(test_help)
 }
 END_TEST
 
+START_TEST(test_pidfile)
+{
+	char	*argv[] =
+	{
+		"check_cmdline", "-p", "PIDFILE-TEST" , NULL
+	};
+	int	 argc = (int)(sizeof(argv) / sizeof(argv[0])) - 1;
+	int	 ret;
+
+	ck_assert_ptr_eq(cfg_get_program_pid_file(), NULL);
+	ck_assert_int_ne(cmdline_parse(argc, argv, &ret), 0);
+	ck_assert_int_eq(ret, 2);
+	ck_assert_str_eq(cfg_get_program_pid_file(), "PIDFILE-TEST");
+}
+END_TEST
+
 START_TEST(test_quiet_stderr)
 {
 	char	*argv[] = { "check_cmdline", "-q", NULL };
@@ -133,6 +149,7 @@ cmdline_suite(void)
 	tcase_add_checked_fixture(tc_cmdline, setup_checked, teardown_checked);
 	tcase_add_test(tc_cmdline, test_configfile);
 	tcase_add_test(tc_cmdline, test_help);
+	tcase_add_test(tc_cmdline, test_pidfile);
 	tcase_add_test(tc_cmdline, test_quiet_stderr);
 	tcase_add_test(tc_cmdline, test_rtstatus_output);
 	tcase_add_test(tc_cmdline, test_shuffle);