remove clumsy strncpy use

strncpy isn't really safe because it doesn't guarantee null termination,
and we have had to work around it in several places.
strlcpy (from OpenBSD) isn't great, either because it often leaves
errors going unchecked (by truncating strings).

So we'll add the pathcpy_trunc() function with is basically strlcpy
with a hardcoded MAXPATHLEN as the limit, and we'll acknowledge
truncation since we only work on paths and MAXPATHLEN should be
set correctly by the system headers[1].

file-specific notes:

inputStream_http:
eyeballing the changes here, it seems to look alright but I
haven't actually tested it myself.

ls:
don't even bother printing a file if the filename is too long
(and when is it ever?) since we won't be able to read it anyways.

metadataChunk:
it's only metadata, and it's only for showin the user, so truncating
it here souldn't be a big issue.
memset to zero in init is unecessary, so lets not waste cycles

[1] - If the system headers are screwed up, then we're majorly
screwed regardless of what we do :x

git-svn-id: https://svn.musicpd.org/mpd/trunk@4491 09075e82-0dd4-0310-85a5-a0d7c8717e4f

8 files changed, 77 insertions, 60 deletions

diff --git a/src/decode.c b/src/decode.c
index 8eacddb07..144edd70f 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -112,9 +112,7 @@ static int calculateCrossFadeChunks(PlayerControl * pc, AudioFormat * af)
 		{ \
 			decodeWaitedOn = 0; \
 			if(openAudioDevice(&(cb->audioFormat))<0) { \
-				strncpy(pc->erroredUrl, pc->utf8url, \
-                                                MAXPATHLEN); \
-				pc->erroredUrl[MAXPATHLEN] = '\0'; \
+				pathcpy_trunc(pc->erroredUrl, pc->utf8url); \
 				pc->error = PLAYER_ERROR_AUDIO; \
 				ERROR("problems opening audio device while playing \"%s\"\n", pc->utf8url); \
 				quitDecode(pc,dc); \
@@ -129,8 +127,7 @@ static int calculateCrossFadeChunks(PlayerControl * pc, AudioFormat * af)
 					cb->audioFormat.sampleRate; \
                 } \
                 else if(dc->state!=DECODE_STATE_START || decode_pid <= 0) { \
-		        strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN); \
-		        pc->erroredUrl[MAXPATHLEN] = '\0'; \
+			pathcpy_trunc(pc->erroredUrl, pc->utf8url); \
 		        pc->error = PLAYER_ERROR_FILE; \
 		        quitDecode(pc,dc); \
 		        return; \
@@ -145,15 +142,13 @@ static int waitOnDecode(PlayerControl * pc, DecoderControl * dc,
 			OutputBuffer * cb, int *decodeWaitedOn)
 {
 	MpdTag *tag = NULL;
-	strncpy(pc->currentUrl, pc->utf8url, MAXPATHLEN);
-	pc->currentUrl[MAXPATHLEN] = '\0';
+	pathcpy_trunc(pc->currentUrl, pc->utf8url);
 
 	while (decode_pid > 0 && dc->start)
 		my_usleep(10000);
 
 	if (dc->start || dc->error != DECODE_ERROR_NOERROR) {
-		strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN);
-		pc->erroredUrl[MAXPATHLEN] = '\0';
+		pathcpy_trunc(pc->erroredUrl, pc->utf8url);
 		pc->error = PLAYER_ERROR_FILE;
 		quitDecode(pc, dc);
 		return -1;
@@ -229,9 +224,7 @@ static int decodeSeek(PlayerControl * pc, DecoderControl * dc,
 		if(pause) pc->state = PLAYER_STATE_PAUSE; \
 		else { \
 			if(openAudioDevice(NULL)<0) { \
-				strncpy(pc->erroredUrl, pc->utf8url, \
-                                                MAXPATHLEN); \
-				pc->erroredUrl[MAXPATHLEN] = '\0'; \
+				pathcpy_trunc(pc->erroredUrl, pc->utf8url); \
 				pc->error = PLAYER_ERROR_AUDIO; \
 				ERROR("problems opening audio device while playing \"%s\"\n", pc->utf8url); \
 				quitDecode(pc,dc); \
@@ -286,8 +279,7 @@ static void decodeStart(PlayerControl * pc, OutputBuffer * cb,
 
 	copyMpdTagToOutputBuffer(cb, NULL);
 
-	strncpy(dc->utf8url, pc->utf8url, MAXPATHLEN);
-	dc->utf8url[MAXPATHLEN] = '\0';
+	pathcpy_trunc(dc->utf8url, pc->utf8url);
 
 	if (openInputStream(&inStream, path) < 0) {
 		dc->error = DECODE_ERROR_FILE;
@@ -396,8 +388,7 @@ static void decodeStart(PlayerControl * pc, OutputBuffer * cb,
 	}
 
 	if (ret < 0 || ret == DECODE_ERROR_UNKTYPE) {
-		strncpy(pc->erroredUrl, dc->utf8url, MAXPATHLEN);
-		pc->erroredUrl[MAXPATHLEN] = '\0';
+		pathcpy_trunc(pc->erroredUrl, dc->utf8url);
 		if (ret != DECODE_ERROR_UNKTYPE)
 			dc->error = DECODE_ERROR_FILE;
 		else {
@@ -439,8 +430,7 @@ static int decoderInit(PlayerControl * pc, OutputBuffer * cb,
 		/* END OF CHILD */
 	} else if (decode_pid < 0) {
 		unblockSignals();
-		strncpy(pc->erroredUrl, pc->utf8url, MAXPATHLEN);
-		pc->erroredUrl[MAXPATHLEN] = '\0';
+		pathcpy_trunc(pc->erroredUrl, pc->utf8url);
 		pc->error = PLAYER_ERROR_SYSTEM;
 		return -1;
 	}
diff --git a/src/inputStream_http.c b/src/inputStream_http.c
index b4b6d04f2..969d2a0ea 100644
--- a/src/inputStream_http.c
+++ b/src/inputStream_http.c
@@ -306,15 +306,15 @@ static int parseUrl(InputStreamHTTPData * data, char *url)
 
 		if (colon && colon < at) {
 			user = malloc(colon - temp + 1);
-			strncpy(user, temp, colon - temp);
+			memcpy(user, temp, colon - temp);
 			user[colon - temp] = '\0';
 
 			passwd = malloc(at - colon);
-			strncpy(passwd, colon + 1, at - colon - 1);
+			memcpy(passwd, colon + 1, at - colon - 1);
 			passwd[at - colon - 1] = '\0';
 		} else {
 			user = malloc(at - temp + 1);
-			strncpy(user, temp, at - temp);
+			memcpy(user, temp, at - temp);
 			user[at - temp] = '\0';
 
 			passwd = strdup("");
@@ -346,7 +346,7 @@ static int parseUrl(InputStreamHTTPData * data, char *url)
 		return -1;
 
 	data->host = malloc(len);
-	strncpy(data->host, temp, len - 1);
+	memcpy(data->host, temp, len - 1);
 	data->host[len - 1] = '\0';
 	/* fetch the port */
 	if (colon && (!slash || slash != colon + 1)) {
@@ -354,7 +354,7 @@ static int parseUrl(InputStreamHTTPData * data, char *url)
 		if (slash)
 			len -= strlen(slash);
 		data->port = malloc(len + 1);
-		strncpy(data->port, colon + 1, len);
+		memcpy(data->port, colon + 1, len);
 		data->port[len] = '\0';
 		DEBUG(__FILE__ ": Port: %s\n", data->port);
 	} else {
diff --git a/src/ls.c b/src/ls.c
index 5cda6605e..376ebb058 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -128,12 +128,14 @@ int lsPlaylists(int fd, char *utf8path)
 	strcat(s, "/");
 
 	while ((ent = readdir(dir))) {
+		size_t len = strlen(ent->d_name) + 1;
 		dup = ent->d_name;
-		if (dup[0] != '.' &&
+		if (mpd_likely(len <= maxlen) &&
+		    dup[0] != '.' &&
 		    (suff = strlen(dup) - suflen) > 0 &&
 		    dup[suff] == '.' &&
 		    strcmp(dup + suff + 1, PLAYLIST_FILE_SUFFIX) == 0) {
-			strncpy(s + actlen, ent->d_name, maxlen);
+			memcpy(s + actlen, ent->d_name, len);
 			if (stat(s, &st) == 0) {
 				if (S_ISREG(st.st_mode)) {
 					if (list == NULL)
diff --git a/src/metadataChunk.c b/src/metadataChunk.c
index 7d57c00af..d11669857 100644
--- a/src/metadataChunk.c
+++ b/src/metadataChunk.c
@@ -17,13 +17,12 @@
  */
 
 #include "metadataChunk.h"
+#include "gcc.h"
 
 #include <string.h>
 
 static void initMetadataChunk(MetadataChunk * chunk)
 {
-	memset(chunk, 0, sizeof(MetadataChunk));
-
 	chunk->name = -1;
 	chunk->artist = -1;
 	chunk->album = -1;
@@ -54,8 +53,12 @@ MpdTag *metadataChunkToMpdTagDup(MetadataChunk * chunk)
 	if(element < 0 && string && (slen = strlen(string)) && \
                         pos < METADATA_BUFFER_LENGTH-1) \
         { \
-		strncpy(chunk->buffer+pos, string, \
-                                METADATA_BUFFER_LENGTH-1-pos); \
+		size_t len = slen; \
+		size_t max = METADATA_BUFFER_LENGTH - 1 - pos; \
+		if (mpd_unlikely(len > max)) \
+			len = max; \
+		memcpy(chunk->buffer+pos, string, len); \
+		*(chunk->buffer+pos+len) = '\0'; \
 		element = pos; \
 		pos += slen+1; \
 	} \
diff --git a/src/path.c b/src/path.c
index 3a6cce23b..69c86391b 100644
--- a/src/path.c
+++ b/src/path.c
@@ -37,10 +37,9 @@
 #endif
 #endif
 
-char *musicDir;
-char *playlistDir;
-
-char *fsCharset = NULL;
+const char *musicDir;
+static const char *playlistDir;
+static char *fsCharset = NULL;
 
 static char *pathConvCharset(char *to, char *from, char *str)
 {
@@ -205,39 +204,59 @@ void finishPaths(void)
 	fsCharset = NULL;
 }
 
-char *rmp2amp(char *relativePath)
+static char *pfx_path(const char *path, const char *pfx, const size_t pfx_len)
 {
-	static char absolutePath[MAXPATHLEN + 1];
-
-	memset(absolutePath, 0, MAXPATHLEN + 1);
+	static char ret[MAXPATHLEN+1];
+	size_t rp_len = strlen(path);
+
+	/* check for the likely condition first: */
+	if (mpd_likely((pfx_len + rp_len) < MAXPATHLEN)) {
+		memcpy(ret, pfx, pfx_len);
+		memcpy(ret + pfx_len, path, rp_len + 1);
+		return ret;
+	}
 
-	strncpy(absolutePath, musicDir, MAXPATHLEN);
-	strncat(absolutePath, relativePath, MAXPATHLEN - strlen(musicDir));
+	/* unlikely, return an empty string because truncating would
+	 * also be wrong... break early and break loudly (the system
+	 * headers are likely screwed, not mpd) */
+	ERROR("Cannot prefix '%s' to '%s', max: %d", pfx, path, MAXPATHLEN);
+	ret[0] = '\0';
+	return ret;
+}
 
-	return absolutePath;
+char *rmp2amp(char *relativePath)
+{
+	size_t pfx_len = strlen(musicDir);
+	return pfx_path(relativePath, musicDir, pfx_len);
 }
 
 char *rpp2app(char *relativePath)
 {
-	static char absolutePath[MAXPATHLEN + 1];
-
-	memset(absolutePath, 0, MAXPATHLEN + 1);
+	size_t pfx_len = strlen(playlistDir);
+	return pfx_path(relativePath, playlistDir, pfx_len);
+}
 
-	strncpy(absolutePath, playlistDir, MAXPATHLEN);
-	strncat(absolutePath, relativePath, MAXPATHLEN - strlen(musicDir));
+/* this is actually like strlcpy (OpenBSD), but we don't actually want to
+ * blindly use it everywhere, only for paths that are OK to truncate (for
+ * error reporting and such */
+void pathcpy_trunc(char *dest, const char *src)
+{
+	size_t len = strlen(src);
 
-	return absolutePath;
+	if (mpd_unlikely(len > MAXPATHLEN))
+		len = MAXPATHLEN;
+	memcpy(dest, src, len);
+	dest[len] = '\0';
 }
 
 char *parentPath(char *path)
 {
-	static char parentPath[MAXPATHLEN + 1];
+	static char parentPath[MAXPATHLEN+1];
 	char *c;
 
-	memset(parentPath, 0, MAXPATHLEN + 1);
-	strncpy(parentPath, path, MAXPATHLEN);
+	pathcpy_trunc(parentPath, path);
+	c = strrchr(parentPath,'/');
 
-	c = strrchr(parentPath, '/');
 	if (c == NULL)
 		parentPath[0] = '\0';
 	else {
diff --git a/src/path.h b/src/path.h
index 2e8cce241..222e145a5 100644
--- a/src/path.h
+++ b/src/path.h
@@ -23,7 +23,7 @@
 
 #include <sys/param.h>
 
-extern char *musicDir;
+extern const char *musicDir;
 
 void initPaths();
 
@@ -51,4 +51,10 @@ char *parentPath(char *path);
 /* strips extra "///" and leading "/" and trailing "/" */
 char *sanitizePathDup(char *path);
 
+/* this is actually like strlcpy (OpenBSD), but we don't actually want to
+ * blindly use it everywhere, only for paths that are OK to truncate (for
+ * error reporting and such.
+ * dest must be MAXPATHLEN+1 bytes large (which is standard in mpd) */
+void pathcpy_trunc(char *dest, const char *src);
+
 #endif
diff --git a/src/player.c b/src/player.c
index 2ffe66e76..c7ea14a86 100644
--- a/src/player.c
+++ b/src/player.c
@@ -17,6 +17,7 @@
  */
 
 #include "player.h"
+#include "path.h"
 #include "decode.h"
 #include "command.h"
 #include "interface.h"
@@ -170,8 +171,7 @@ int playerPlay(int fd, Song * song)
 
 	copyMpdTagToMetadataChunk(song->tag, &(pc->fileMetadataChunk));
 
-	strncpy(pc->utf8url, getSongUrl(song), MAXPATHLEN);
-	pc->utf8url[MAXPATHLEN] = '\0';
+	pathcpy_trunc(pc->utf8url, getSongUrl(song));
 
 	pc->play = 1;
 	if (getPlayerPid() == 0 && playerInit() < 0) {
@@ -337,8 +337,7 @@ int queueSong(Song * song)
 	PlayerControl *pc = &(getPlayerData()->playerControl);
 
 	if (pc->queueState == PLAYER_QUEUE_BLANK) {
-		strncpy(pc->utf8url, getSongUrl(song), MAXPATHLEN);
-		pc->utf8url[MAXPATHLEN] = '\0';
+		pathcpy_trunc(pc->utf8url, getSongUrl(song));
 
 		if (song->tag)
 			pc->fileTime = song->tag->time;
@@ -408,8 +407,7 @@ int playerSeek(int fd, Song * song, float time)
 
 		copyMpdTagToMetadataChunk(song->tag, &(pc->fileMetadataChunk));
 
-		strncpy(pc->utf8url, getSongUrl(song), MAXPATHLEN);
-		pc->utf8url[MAXPATHLEN] = '\0';
+		pathcpy_trunc(pc->utf8url, getSongUrl(song));
 	}
 
 	if (pc->error == PLAYER_ERROR_NOERROR) {
diff --git a/src/tag.c b/src/tag.c
index ae0c3c87c..8a6846d94 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -612,10 +612,9 @@ int mpdTagsAreEqual(MpdTag * tag1, MpdTag * tag2)
 static void appendToTagItems(MpdTag * tag, int type, char *value, int len)
 {
 	int i = tag->numOfItems;
+	char *dup = malloc(len + 1);
 
-	char *dup;
-	dup = malloc(len + 1);
-	strncpy(dup, value, len);
+	memcpy(dup, value, len);
 	dup[len] = '\0';
 
 	fixUtf8(dup);