fs: getsize() on directories

2 files changed, 42 insertions, 24 deletions

diff --git a/src/user/lib/fs/dir.c b/src/user/lib/fs/dir.c
index 802dd61..4235ea6 100644
--- a/src/user/lib/fs/dir.c
+++ b/src/user/lib/fs/dir.c
@@ -33,9 +33,11 @@ bool dir_appendl(struct dirbuild *db, const char *name, size_t len) {
 		len  -= db->offset;
 		db->offset = 0;
 
-		// TODO no buffer overrun check
-		memcpy(db->buf + db->bpos, name, len - 1);
-		db->buf[db->bpos + len - 1] = '\0';
+		if (db->buf) {
+			// TODO no buffer overrun check
+			memcpy(db->buf + db->bpos, name, len - 1);
+			db->buf[db->bpos + len - 1] = '\0';
+		}
 		db->bpos += len;
 	} else {
 		db->offset -= len;
@@ -45,26 +47,35 @@ bool dir_appendl(struct dirbuild *db, const char *name, size_t len) {
 
 bool dir_append_from(struct dirbuild *db, handle_t h) {
 	if (db->error) return true;
+	if (db->buf && db->bpos == db->blen) return false;
 
-	if (db->bpos == db->blen)
-		return false;
+	int ret;
+	if (db->buf) {
+		ret = _syscall_read(h, db->buf + db->bpos, db->blen - db->bpos, db->offset);
+		if (ret < 0) {
+			db->error = ret;
+			return true;
+		} else if (ret > 0) {
+			/* not eof */
+			db->offset = 0;
+			db->bpos += ret;
+			return false;
+		} /* else ret == 0, EOF, need getsize */
+	}
 
-	int ret = _syscall_read(h, db->buf + db->bpos, db->blen - db->bpos, db->offset);
+	ret = _syscall_getsize(h);
 	if (ret < 0) {
 		db->error = ret;
 		return true;
 	}
-	if (ret == 0) {
-		// TODO no idea how much we've overread
-		// this messes up reading bind mounts of multiple directories
-		db->error = -ENOSYS;
-		return true;
+	if (db->offset < ret) {
+		/* should only occur when !buf, otherwise leaks previous data from buf.
+		 * TODO consider impact */
+		db->bpos += ret - db->offset;
+		db->offset = 0;
+	} else {
+		db->offset -= ret;
 	}
-
-	// TODO deduplicate entries
-
-	db->offset = 0;
-	db->bpos += ret;
 	return false;
 }
 
diff --git a/src/user/lib/fs/misc.c b/src/user/lib/fs/misc.c
index 54f54fd..16e95e7 100644
--- a/src/user/lib/fs/misc.c
+++ b/src/user/lib/fs/misc.c
@@ -74,9 +74,11 @@ void fs_whitelist(const char **list) {
 	char *buf = malloc(buf_len);
 	char *ipath;
 	bool passthru, inject;
+	struct dirbuild db;
 	if (!buf) exit(1);
 
 	while (!_syscall_fs_wait(buf, buf_len, &res)) {
+		size_t blen;
 		ipath = res.id;
 		switch (res.op) {
 			case VFSOP_OPEN:
@@ -110,16 +112,17 @@ void fs_whitelist(const char **list) {
 				break;
 
 			case VFSOP_READ:
-				struct dirbuild db;
-				dir_start(&db, res.offset, buf, buf_len);
-				size_t blen = strlen(ipath);
+			case VFSOP_GETSIZE:
+				blen = strlen(ipath);
+				char *target = res.op == VFSOP_READ ? buf : NULL;
+				dir_start(&db, res.offset, target, buf_len);
 				for (const char **iter = list; *iter; iter++) {
 					// TODO could be precomputed too
 					size_t len = strlen(*iter); // inefficient, whatever
 					if (blen < len && !memcmp(ipath, *iter, blen))
 						dir_appendl(&db, *iter + blen, dir_seglen(*iter + blen));
 				}
-				_syscall_fs_respond(buf, dir_finish(&db), 0);
+				_syscall_fs_respond(target, dir_finish(&db), 0);
 				break;
 
 			case VFSOP_CLOSE:
@@ -175,10 +178,12 @@ void fs_union(const char **list) {
 				break;
 
 		case VFSOP_READ:
+		case VFSOP_GETSIZE:
 			if (res.capacity > buflen)
 				res.capacity = buflen;
 			bool end = false;
-			dir_start(&db, res.offset, pre, res.capacity);
+			char *target = res.op == VFSOP_READ ? pre : NULL;
+			dir_start(&db, res.offset, target, res.capacity);
 			for (size_t i = 0; !end && list[i]; i++) {
 				const char *prefix = list[i];
 				size_t prefixlen = strlen(prefix);
@@ -189,7 +194,7 @@ void fs_union(const char **list) {
 				end = end || dir_append_from(&db, h);
 				_syscall_close(h);
 			}
-			_syscall_fs_respond(pre, dir_finish(&db), 0);
+			_syscall_fs_respond(target, dir_finish(&db), 0);
 			break;
 
 			default:
@@ -242,13 +247,15 @@ void fs_dir_inject(const char *path) {
 				break;
 
 			case VFSOP_READ:
+			case VFSOP_GETSIZE:
 				if (res.capacity > buf_len)
 					res.capacity = buf_len;
-				dir_start(&db, res.offset, buf, res.capacity);
+				char *target = res.op == VFSOP_READ ? buf : NULL;
+				dir_start(&db, res.offset, target, res.capacity);
 				dir_appendl(&db, data->inject, data->inject_len);
 				if (data->delegate >= 0)
 					dir_append_from(&db, data->delegate);
-				_syscall_fs_respond(buf, dir_finish(&db), 0);
+				_syscall_fs_respond(target, dir_finish(&db), 0);
 				break;
 
 			default: