1 files changed, 84 insertions, 0 deletions
diff --git a/src/libc/fs/dir.c b/src/libc/fs/dir.c
new file mode 100644
index 0000000..b7f840d
--- /dev/null
+++ b/src/libc/fs/dir.c
@@ -0,0 +1,84 @@
+#include <camellia/syscalls.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include <camellia/fs/dir.h>
+
+void dir_start(struct dirbuild *db, long offset, char *buf, size_t buflen) {
+	db->offset = offset;
+	db->buf = buf;
+	db->bpos = 0;
+	db->blen = buflen;
+	db->error = 0;
+
+	// TODO decide how negative directory offsets should be handled
+	if (offset < 0) db->error = -ENOSYS;
+}
+
+bool dir_append(struct dirbuild *db, const char *name) {
+	return dir_appendl(db, name, strlen(name));
+}
+
+bool dir_appendl(struct dirbuild *db, const char *name, size_t len) {
+	if (db->error) return true;
+	if (len > (size_t)LONG_MAX) {
+		db->error = -1;
+		return true;
+	}
+
+	len++; // account for the null byte
+
+	if (db->offset < (long)len) {
+		name += db->offset;
+		len  -= db->offset;
+		db->offset = 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;
+	}
+	return false;
+}
+
+bool dir_append_from(struct dirbuild *db, hid_t h) {
+	if (db->error) return true;
+	if (db->buf && db->bpos == db->blen) return false;
+
+	int ret;
+	if (db->buf) {
+		ret = _sys_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 */
+	}
+
+	ret = _sys_getsize(h);
+	if (ret < 0) {
+		db->error = ret;
+		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;
+	}
+	return false;
+}
+
+long dir_finish(struct dirbuild *db) {
+	return db->error ? db->error : db->bpos;
+}