vfs: make vfs_path_normalize more robust and consistent

* Correctly process trailing . and .. without /
* Fix potential read past the input buffer
* Always strip trailing /

src/util/stringops.c

@@ -144,11 +144,6 @@ char* strftimealloc(const char *fmt, const struct tm *timeinfo) {
 	};
 }
 
-void strip_trailing_slashes(char *buf) {
-	for(char *c = buf + strlen(buf) - 1; c >= buf && (*c == '/' || *c == '\\'); c--)
-		*c = 0;
-}
-
 char* strappend(char **dst, char *src) {
 	if(!*dst) {
 		return *dst = strdup(src);

src/util/stringops.h

@@ -48,7 +48,6 @@ void stralloc(char **dest, const char *src);
 char* strjoin(const char *first, ...) attr_sentinel attr_returns_allocated;
 char* vstrfmt(const char *fmt, va_list args) attr_returns_allocated;
 char* strfmt(const char *fmt, ...) attr_printf(1,  2) attr_returns_allocated;
-void strip_trailing_slashes(char *buf);
 char* strtok_r(char *str, const char *delim, char **nextp);
 char* strappend(char **dst, char *src);
 char* strftimealloc(const char *fmt, const struct tm *timeinfo) attr_returns_allocated;

src/vfs/pathutil.c

@@ -17,6 +17,8 @@ char *vfs_path_normalize(const char *path, char *out) {
 	char *last_sep = out - 1;
 	char *path_end = strchr(path, 0);
 
+	#define IS_SEP_OR_NUL(chr) (VFS_IS_PATH_SEPARATOR(chr) || (chr == '\0'))
+
 	while(p < path_end) {
 		if(VFS_IS_PATH_SEPARATOR(*p)) {
 			if(o > out && !VFS_IS_PATH_SEPARATOR(o[-1])) {
@@ -27,13 +29,13 @@ char *vfs_path_normalize(const char *path, char *out) {
 			do {
 				++p;
 			} while(p < path_end && VFS_IS_PATH_SEPARATOR(*p));
-		} else if(*p == '.' && VFS_IS_PATH_SEPARATOR(p[1])) {
+		} else if(*p == '.' && IS_SEP_OR_NUL(p[1])) {
 			p += 2;
-		} else if(!strncmp(p, "..", 2) && VFS_IS_PATH_SEPARATOR(p[2])) {
+		} else if(p + 1 < path_end && !strncmp(p, "..", 2) && IS_SEP_OR_NUL(p[2])) {
 			if(last_sep >= out) {
 				do {
 					--last_sep;
-				} while(!VFS_IS_PATH_SEPARATOR(*last_sep) && last_sep >= out);
+				} while(last_sep >= out && !VFS_IS_PATH_SEPARATOR(*last_sep));
 
 				o = last_sep-- + 1;
 			}
@@ -44,9 +46,18 @@ char *vfs_path_normalize(const char *path, char *out) {
 		}
 	}
 
+	#undef IS_SEP_OR_NUL
+
+	// remove trailing slash
+	if(o > out && VFS_IS_PATH_SEPARATOR(o[-1])) {
+		--o;
+		assert(o == out || !VFS_IS_PATH_SEPARATOR(o[-1]));
+	}
+
 	*o = 0;
 
-	// log_debug("[%s] --> [%s]", path, out);
+// 	log_debug("[%s] --> [%s]", path, out);
+
 	return out;
 }
 
@@ -124,7 +135,7 @@ void vfs_path_root_prefix(char *path) {
 	}
 }
 
-char* vfs_syspath_normalize_inplace(char *path) {
+char *vfs_syspath_normalize_inplace(char *path) {
 	char buf[strlen(path)+1];
 	strcpy(buf, path);
 	vfs_syspath_normalize(buf, sizeof(buf), path);

src/vfs/pathutil.h

@@ -19,9 +19,9 @@
 
 static_assert(sizeof(VFS_PATH_SEPARATOR_STR) == 2, "No more than one VFS path separator, please");
 
-char* vfs_path_normalize(const char *path, char *out);
-char* vfs_path_normalize_alloc(const char *path);
-char* vfs_path_normalize_inplace(char *path);
+char *vfs_path_normalize(const char *path, char *out);
+char *vfs_path_normalize_alloc(const char *path);
+char *vfs_path_normalize_inplace(char *path);
 void vfs_path_split_left(char *path, char **lpath, char **rpath);
 void vfs_path_split_right(char *path, char **lpath, char **rpath);
 void vfs_path_root_prefix(char *path);

src/vfs/public.c

@@ -282,7 +282,6 @@ int vfs_dir_list_order_descending(const void *a, const void *b) {
 void* vfs_dir_walk(const char *path, void* (*visit)(const char *path, void *arg), void *arg) {
 	char npath[strlen(path) + 1];
 	vfs_path_normalize(path, npath);
-	strip_trailing_slashes(npath);
 
 	VFSDir *dir = vfs_dir_open(npath);
 	void *result = NULL;

src/vfs/zipfile.c

@@ -294,16 +294,8 @@ static void vfs_zipfile_init_pathmap(VFSNode *node) {
 	for(zip_int64_t i = 0; i < num; ++i) {
 		const char *original = zip_get_name(tls->zip, i, 0);
 		char normalized[strlen(original) + 1];
-
 		vfs_path_normalize(original, normalized);
 
-		if(*normalized) {
-			char *c = strchr(normalized, 0) - 1;
-			if(*c == '/') {
-				*c = 0;
-			}
-		}
-
 		if(strcmp(original, normalized)) {
 			ht_set(&zdata->pathmap, normalized, i);
 		}