Mitigate segfault during getting file locations

When environment was misconfigured (or properly configured but in a very
strange way) segfault might occur due to fixed memory constraints.

README.md

@@ -52,8 +52,8 @@ Exemplary configuration might be as follows:
 * `format-coverfile = "^(cover|folder)\.jpg$"`
 
 
-Instalation
------------
+Installation
+------------
 
 	$ autoreconf --install
 	$ mkdir build && cd build

src/cache.c

@@ -1,6 +1,6 @@
 /*
  * cmusfm - cache.c
- * Copyright (c) 2014 Arkadiusz Bokowy
+ * Copyright (c) 2014-2015 Arkadiusz Bokowy
  *
  * This file is a part of a cmusfm.
  *
@@ -104,7 +104,7 @@ void cmusfm_cache_update(const scrobbler_trackinfo_t *sb_tinf) {
 			sb_tinf->artist, sb_tinf->album, sb_tinf->album_artist,
 			sb_tinf->track_number, sb_tinf->track, sb_tinf->duration);
 
-	if ((f = fopen(get_cmusfm_cache_file(), "a")) == NULL)
+	if ((f = fopen(cmusfm_cache_file, "a")) == NULL)
 		return;
 
 	record = get_cache_record(sb_tinf);
@@ -118,7 +118,6 @@ void cmusfm_cache_update(const scrobbler_trackinfo_t *sb_tinf) {
 void cmusfm_cache_submit(scrobbler_session_t *sbs) {
 
 	char rd_buff[4096];
-	char *fname;
 	FILE *f;
 	scrobbler_trackinfo_t sb_tinf;
 	struct cmusfm_cache_record *record;
@@ -127,8 +126,7 @@ void cmusfm_cache_submit(scrobbler_session_t *sbs) {
 
 	debug("cache submit");
 
-	fname = get_cmusfm_cache_file();
-	if ((f = fopen(fname, "r")) == NULL)
+	if ((f = fopen(cmusfm_cache_file, "r")) == NULL)
 		return;
 
 	// read file until EOF
@@ -200,12 +198,10 @@ void cmusfm_cache_submit(scrobbler_session_t *sbs) {
 	fclose(f);
 
 	// remove cache file
-	unlink(fname);
+	unlink(cmusfm_cache_file);
 }
 
-// Helper function for retrieving cmusfm cache file.
+/* Helper function for retrieving cmusfm cache file. */
 char *get_cmusfm_cache_file(void) {
-	static char fname[128];
-	sprintf(fname, "%s/" CACHE_FNAME, get_cmus_home_dir());
-	return fname;
+	return get_cmus_home_file(CACHE_FNAME);
 }

src/cmusfm.h

@@ -1,6 +1,6 @@
 /*
  * cmusfm - cmusfm.h
- * Copyright (c) 2010-2014 Arkadiusz Bokowy
+ * Copyright (c) 2010-2015 Arkadiusz Bokowy
  *
  * This file is a part of a cmusfm.
  *
@@ -30,14 +30,17 @@
 #define CACHE_FNAME  "cmusfm.cache"
 
 
-// time delay (in seconds) between login attempts to the Last.fm
-// scrobbling service after a submit failure
+/* time delay (in seconds) between login attempts to the Last.fm
+ * scrobbling service after a submit failure */
 #define SERVICE_RETRY_DELAY 60 * 30
 
 
-// global variable definitions
+/* global variable definitions */
 extern unsigned char SC_api_key[16];
 extern unsigned char SC_secret[16];
+extern const char *cmusfm_cache_file;
+extern const char *cmusfm_config_file;
+extern const char *cmusfm_socket_file;
 extern struct cmusfm_config config;
 
 
@@ -71,6 +74,7 @@ struct format_match {
 
 
 char *get_cmus_home_dir(void);
+char *get_cmus_home_file(const char *file);
 #ifdef ENABLE_LIBNOTIFY
 char *get_album_cover_file(const char *location, const char *format);
 #endif

src/config.c

@@ -1,6 +1,6 @@
 /*
  * cmusfm - config.c
- * Copyright (c) 2014 Arkadiusz Bokowy
+ * Copyright (c) 2014-2015 Arkadiusz Bokowy
  *
  * This file is a part of a cmusfm.
  *
@@ -24,10 +24,10 @@
 
 #include "config.h"
 
-#include <stdio.h>
-#include <string.h>
 #include <ctype.h>
 #include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
 #include <sys/stat.h>
 #ifdef HAVE_SYS_INOTIFY_H
 #include <sys/inotify.h>
@@ -156,17 +156,15 @@ int cmusfm_config_write(const char *fname, struct cmusfm_config *conf) {
 }
 
 #ifdef HAVE_SYS_INOTIFY_H
-// Add the cmusfm configuration file into the inotify watch stack. File
-// is watched for modification, and after event is triggered it will be
-// automatically removed from the stack.
+/* Add the cmusfm configuration file into the inotify watch stack. File
+ * is watched for modification, and after event is triggered it will be
+ * automatically removed from the stack. */
 int cmusfm_config_add_watch(int fd) {
-	return inotify_add_watch(fd, get_cmusfm_config_file(), IN_MODIFY | IN_ONESHOT);
+	return inotify_add_watch(fd, cmusfm_config_file, IN_MODIFY | IN_ONESHOT);
 }
 #endif
 
-// Helper function for retrieving cmusfm configuration file.
+/* Helper function for retrieving cmusfm configuration file. */
 char *get_cmusfm_config_file(void) {
-	static char fname[128];
-	sprintf(fname, "%s/" CONFIG_FNAME, get_cmus_home_dir());
-	return fname;
+	return get_cmus_home_file(CONFIG_FNAME);
 }

src/main.c

@@ -1,6 +1,6 @@
 /*
  * cmusfm - main.c
- * Copyright (c) 2010-2014 Arkadiusz Bokowy
+ * Copyright (c) 2010-2015 Arkadiusz Bokowy
  *
  * This file is a part of a cmusfm.
  *
@@ -22,23 +22,29 @@
 #include "../config.h"
 #endif
 
+#include "cmusfm.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "cmusfm.h"
+#include "cache.h"
 #include "config.h"
 #include "debug.h"
 #include "server.h"
 
 
-// Last.fm API key for cmusfm
+/* Last.fm API key for cmusfm */
 unsigned char SC_api_key[16] = {0x67, 0x08, 0x2e, 0x45, 0xda, 0xb1,
 		0xf6, 0x43, 0x3d, 0xa7, 0x2a, 0x00, 0xe3, 0xbc, 0x03, 0x7a};
 unsigned char SC_secret[16] = {0x02, 0xfc, 0xbc, 0x90, 0x34, 0x1a,
 		0x01, 0xf2, 0x1c, 0x3b, 0xfc, 0x05, 0xb6, 0x36, 0xe3, 0xae};
 
-// Global configuration structure
+/* Global cmusfm file location variables */
+const char *cmusfm_cache_file = NULL;
+const char *cmusfm_config_file = NULL;
+const char *cmusfm_socket_file = NULL;
+
+/* Global configuration structure */
 struct cmusfm_config config;
 
 
@@ -102,15 +108,13 @@ static int cmusfm_initialization() {
 	scrobbler_session_t *sbs;
 	struct cmusfm_config conf;
 	int fetch_session_key;
-	char *conf_fname;
 	char yesno[8], *ptr;
 
 	fetch_session_key = 1;
-	conf_fname = get_cmusfm_config_file();
 	sbs = scrobbler_initialize(SC_api_key, SC_secret);
 
 	// try to read previous configuration
-	if (cmusfm_config_read(conf_fname, &conf) == 0) {
+	if (cmusfm_config_read(cmusfm_config_file, &conf) == 0) {
 		printf("Checking previous session (user: %s) ...", conf.user_name);
 		fflush(stdout);
 		scrobbler_set_session_key_str(sbs, conf.session_key);
@@ -135,8 +139,8 @@ static int cmusfm_initialization() {
 	}
 	scrobbler_free(sbs);
 
-	if (cmusfm_config_write(conf_fname, &conf) != 0)
-		printf("Error: unable to write file: %s\n", conf_fname);
+	if (cmusfm_config_write(cmusfm_config_file, &conf) != 0)
+		printf("Error: unable to write file: %s\n", cmusfm_config_file);
 
 	return 0;
 }
@@ -153,11 +157,16 @@ int main(int argc, char *argv[]) {
 		return EXIT_SUCCESS;
 	}
 
+	/* setup global variables - file locations */
+	cmusfm_cache_file = get_cmusfm_cache_file();
+	cmusfm_config_file = get_cmusfm_config_file();
+	cmusfm_socket_file = get_cmusfm_socket_file();
+
 	if (argc == 2 && strcmp(argv[1], "init") == 0)
 		return cmusfm_initialization();
 
-	if (cmusfm_config_read(get_cmusfm_config_file(), &config) == -1) {
-		perror("error: unable to read config file");
+	if (cmusfm_config_read(cmusfm_config_file, &config) == -1) {
+		perror("error: config read");
 		return EXIT_FAILURE;
 	}
 

src/server.c

@@ -1,6 +1,6 @@
 /*
  * cmusfm - server.c
- * Copyright (c) 2010-2014 Arkadiusz Bokowy
+ * Copyright (c) 2010-2015 Arkadiusz Bokowy
  *
  * This file is a part of a cmusfm.
  *
@@ -24,14 +24,14 @@
 
 #include "server.h"
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <poll.h>
 #include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #ifdef HAVE_SYS_INOTIFY_H
@@ -47,22 +47,22 @@
 #endif
 
 
-// Helper function for artist name retrieval.
+/* Helper function for artist name retrieval. */
 static char *get_sock_data_artist(struct sock_data_tag *dt) {
 	return (char *)(dt + 1);
 }
 
-// Helper function for album name retrieval.
+/* Helper function for album name retrieval. */
 static char *get_sock_data_album(struct sock_data_tag *dt) {
 	return &((char *)(dt + 1))[dt->alboff];
 }
 
-// Helper function for track name retrieval.
+/* Helper function for track name retrieval. */
 static char *get_sock_data_track(struct sock_data_tag *dt) {
 	return &((char *)(dt + 1))[dt->titoff];
 }
 
-// Helper function for location retrieval.
+/* Helper function for location retrieval. */
 static char *get_sock_data_location(struct sock_data_tag *dt) {
 	return &((char *)(dt + 1))[dt->locoff];
 }
@@ -270,7 +270,7 @@ void cmusfm_server_start(void) {
 
 	memset(&sock_a, 0, sizeof(sock_a));
 	sock_a.sun_family = AF_UNIX;
-	strcpy(sock_a.sun_path, get_cmusfm_socket_file());
+	strcpy(sock_a.sun_path, cmusfm_socket_file);
 	pfds[0].fd = socket(PF_UNIX, SOCK_STREAM, 0);
 
 	// check if behind the socket there is already an active server instance
@@ -329,7 +329,7 @@ void cmusfm_server_start(void) {
 			// to us, simply read out the inotify file descriptor
 			read(pfds[2].fd, &inot_even, sizeof(inot_even));
 			debug("inotify event occurred: %x", inot_even.mask);
-			cmusfm_config_read(get_cmusfm_config_file(), &config);
+			cmusfm_config_read(cmusfm_config_file, &config);
 			cmusfm_config_add_watch(pfds[2].fd);
 		}
 #endif
@@ -435,7 +435,7 @@ int cmusfm_server_send_track(struct cmtrack_info *tinfo) {
 
 	// connect to the communication socket
 	memset(&sock_a, 0, sizeof(sock_a));
-	strcpy(sock_a.sun_path, get_cmusfm_socket_file());
+	strcpy(sock_a.sun_path, cmusfm_socket_file);
 	sock_a.sun_family = AF_UNIX;
 	sock = socket(PF_UNIX, SOCK_STREAM, 0);
 	if (connect(sock, (struct sockaddr *)(&sock_a), sizeof(sock_a)) == -1) {
@@ -450,9 +450,7 @@ int cmusfm_server_send_track(struct cmtrack_info *tinfo) {
 	return close(sock);
 }
 
-// Helper function for retrieving cmusfm server socket file.
+/* Helper function for retrieving cmusfm server socket file. */
 char *get_cmusfm_socket_file(void) {
-	static char fname[128];
-	sprintf(fname, "%s/" SOCKET_FNAME, get_cmus_home_dir());
-	return fname;
+	return get_cmus_home_file(SOCKET_FNAME);
 }