Handle failure reading a file (such as a key file)

--HG--
extra : convert_revision : 3219ab5642c86615c6ffb30eb93f573a73415d2f

dbutil.c

@@ -527,26 +527,36 @@ char * stripcontrol(const char * text) {
  * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
 int buf_readfile(buffer* buf, const char* filename) {
 
-	int fd;
+	int fd = -1;
 	int len;
 	int maxlen;
+	ret = DROPBEAR_FAILURE;
 
 	fd = open(filename, O_RDONLY);
 
 	if (fd < 0) {
-		close(fd);
-		return DROPBEAR_FAILURE;
+		goto out;
 	}
 	
 	do {
 		maxlen = buf->size - buf->pos;
-		len = read(fd, buf_getwriteptr(buf, maxlen),
-				maxlen);
+		len = read(fd, buf_getwriteptr(buf, maxlen), maxlen);
+		if (len < 0) {
+			if (errno == EINTR || errno == EAGAIN) {
+				continue;
+			}
+			goto out;
+		}
 		buf_incrwritepos(buf, len);
 	} while (len < maxlen && len > 0);
 
-	close(fd);
-	return DROPBEAR_SUCCESS;
+	ret = DROPBEAR_SUCCESS;
+
+out:
+	if (fd >= 0) {
+		m_close(fd);
+	}
+	return ret;
 }
 
 /* get a line from the file into buffer in the style expected for an