Merge branch 'jk/config-no-ungetc-eof' into maint

Reading configuration from a blob object, when it ends with a lone
CR, use to confuse the configuration parser.

* jk/config-no-ungetc-eof:
  config_buf_ungetc: warn when pushing back a random character
  config: do not ungetc EOF

config.c

@@ -73,8 +73,12 @@ static int config_buf_fgetc(struct config_source *conf)
 
 static int config_buf_ungetc(int c, struct config_source *conf)
 {
-	if (conf->u.buf.pos > 0)
-		return conf->u.buf.buf[--conf->u.buf.pos];
+	if (conf->u.buf.pos > 0) {
+		conf->u.buf.pos--;
+		if (conf->u.buf.buf[conf->u.buf.pos] != c)
+			die("BUG: config_buf can only ungetc the same character");
+		return c;
+	}
 
 	return EOF;
 }
@@ -235,7 +239,8 @@ static int get_next_char(void)
 		/* DOS like systems */
 		c = cf->do_fgetc(cf);
 		if (c != '\n') {
-			cf->do_ungetc(c, cf);
+			if (c != EOF)
+				cf->do_ungetc(c, cf);
 			c = '\r';
 		}
 	}

t/t1307-config-blob.sh

@@ -67,4 +67,13 @@ test_expect_success 'parse errors in blobs are properly attributed' '
 	grep "HEAD:config" err
 '
 
+test_expect_success 'can parse blob ending with CR' '
+	printf "[some]key = value\\r" >config &&
+	git add config &&
+	git commit -m CR &&
+	echo value >expect &&
+	git config --blob=HEAD:config some.key >actual &&
+	test_cmp expect actual
+'
+
 test_done