file.c/__ast_file_read_dirs: Fix issues on filesystems without d_type

One of the code paths in __ast_file_read_dirs will only get executed if
the OS doesn't support dirent->d_type OR if the filesystem the
particular file is on doesn't support it.  So, while standard Linux
systems support the field, some filesystems like XFS do not.  In this
case, we need to call stat() to determine whether the directory entry
is a file or directory so we append the filename to the supplied
directory path and call stat.  We forgot to truncate path back to just
the directory afterwards though so we were passing a complete file name
to the callback in the dir_name parameter instead of just the directory
name.

The logic has been re-written to only create a full_path if we need to
call stat() or if we need to descend into another directory.

Change-Id: I54e4228bd8355fad65200c6df3ec4c9c8a98dfba

main/file.c

@@ -1095,27 +1095,27 @@ int ast_filecopy(const char *filename, const char *filename2, const char *fmt)
 	return filehelper(filename, filename2, fmt, ACTION_COPY);
 }
 
-static int __ast_file_read_dirs(struct ast_str **path, ast_file_on_file on_file,
+static int __ast_file_read_dirs(const char *path, ast_file_on_file on_file,
 				void *obj, int max_depth)
 {
 	DIR *dir;
 	struct dirent *entry;
-	size_t size;
 	int res;
 
-	if (!(dir = opendir(ast_str_buffer(*path)))) {
+	if (!(dir = opendir(path))) {
 		ast_log(LOG_ERROR, "Error opening directory - %s: %s\n",
-			ast_str_buffer(*path), strerror(errno));
+			path, strerror(errno));
 		return -1;
 	}
-	size = ast_str_strlen(*path);
 
 	--max_depth;
 
 	res = 0;
 
 	while ((entry = readdir(dir)) != NULL && !errno) {
-		int is_file, is_dir, used_stat = 0;
+		int is_file = 0;
+		int is_dir = 0;
+		RAII_VAR(char *, full_path, NULL, ast_free);
 
 		if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..")) {
 			continue;
@@ -1136,16 +1136,18 @@ static int __ast_file_read_dirs(struct ast_str **path, ast_file_on_file on_file,
 			struct stat statbuf;
 
 			/*
-			 * If using the stat function the file needs to be appended to the
-			 * path so it can be found. However, before appending make sure the
-			 * path contains only the directory for this depth level.
+			 * Don't use alloca or we risk blowing out the stack if recursing
+			 * into subdirectories.
 			 */
-			ast_str_truncate(*path, size);
-			ast_str_append(path, 0, "/%s", entry->d_name);
+			full_path = ast_malloc(strlen(path) + strlen(entry->d_name) + 2);
+			if (!full_path) {
+				return -1;
+			}
+			sprintf(full_path, "%s/%s", path, entry->d_name);
 
-			if (stat(ast_str_buffer(*path), &statbuf)) {
+			if (stat(full_path, &statbuf)) {
 				ast_log(LOG_ERROR, "Error reading path stats - %s: %s\n",
-					ast_str_buffer(*path), strerror(errno));
+					full_path, strerror(errno));
 				/*
 				 * Output an error, but keep going. It could just be
 				 * a broken link and other files could be fine.
@@ -1155,12 +1157,11 @@ static int __ast_file_read_dirs(struct ast_str **path, ast_file_on_file on_file,
 
 			is_file = S_ISREG(statbuf.st_mode);
 			is_dir = S_ISDIR(statbuf.st_mode);
-			used_stat = 1;
 		}
 
 		if (is_file) {
 			/* If the handler returns non-zero then stop */
-			if ((res = on_file(ast_str_buffer(*path), entry->d_name, obj))) {
+			if ((res = on_file(path, entry->d_name, obj))) {
 				break;
 			}
 			/* Otherwise move on to next item in directory */
@@ -1168,23 +1169,22 @@ static int __ast_file_read_dirs(struct ast_str **path, ast_file_on_file on_file,
 		}
 
 		if (!is_dir) {
-			ast_debug(5, "Skipping %s: not a regular file or directory\n",
-				  ast_str_buffer(*path));
+			ast_debug(5, "Skipping %s: not a regular file or directory\n", full_path);
 			continue;
 		}
 
 		/* Only re-curse into sub-directories if not at the max depth */
 		if (max_depth != 0) {
-			/*
-			 * If the stat function was used then the sub-directory has
-			 * already been appended, otherwise append it.
-			 */
-			if (!used_stat) {
-				ast_str_truncate(*path, size);
-				ast_str_append(path, 0, "/%s", entry->d_name);
+			if (!full_path) {
+				/* Don't use alloca.  See note above. */
+				full_path = ast_malloc(strlen(path) + strlen(entry->d_name) + 2);
+				if (!full_path) {
+					return -1;
+				}
+				sprintf(full_path, "%s/%s", path, entry->d_name);
 			}
 
-			if ((res = __ast_file_read_dirs(path, on_file, obj, max_depth))) {
+			if ((res = __ast_file_read_dirs(full_path, on_file, obj, max_depth))) {
 				break;
 			}
 		}
@@ -1194,7 +1194,7 @@ static int __ast_file_read_dirs(struct ast_str **path, ast_file_on_file on_file,
 
 	if (!res && errno) {
 		ast_log(LOG_ERROR, "Error while reading directories - %s: %s\n",
-			ast_str_buffer(*path), strerror(errno));
+			path, strerror(errno));
 		res = -1;
 	}
 
@@ -1215,27 +1215,20 @@ AST_MUTEX_DEFINE_STATIC(read_dirs_lock);
 
 int ast_file_read_dirs(const char *dir_name, ast_file_on_file on_file, void *obj, int max_depth)
 {
-	struct ast_str *path;
 	int res;
 
-	if (!(path = ast_str_create(256))) {
-		return -1;
-	}
-
-	ast_str_set(&path, 0, "%s", dir_name);
 	errno = 0;
 
 #if !defined(__GLIBC__)
 	ast_mutex_lock(&read_dirs_lock);
 #endif
 
-	res = __ast_file_read_dirs(&path, on_file, obj, max_depth);
+	res = __ast_file_read_dirs(dir_name, on_file, obj, max_depth);
 
 #if !defined(__GLIBC__)
 	ast_mutex_unlock(&read_dirs_lock);
 #endif
 
-	ast_free(path);
 	return res;
 }
 

tests/test_file.c

@@ -21,7 +21,10 @@
 	<support_level>core</support_level>
  ***/
 
+
 #include "asterisk.h"
+#include <sys/stat.h>
+#include <stdio.h>
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
@@ -117,6 +120,17 @@ static char *test_files_get_one(struct _filenames *filenames, int num)
 
 static int handle_find_file(const char *dir_name, const char *filename, void *obj)
 {
+	struct stat statbuf;
+	char *full_path = ast_alloca(strlen(dir_name) + strlen(filename) + 2);
+
+	sprintf(full_path, "%s/%s", dir_name, filename);
+
+	errno = 0;
+	if (stat(full_path, &statbuf)) {
+		ast_log(LOG_ERROR, "Error reading path stats - %s: %s\n",
+			full_path, strerror(errno));
+		return 0;
+	}
 	/* obj contains the name of the file we are looking for */
 	return strcmp(obj, filename) ? 0 : FOUND;
 }