config: do not ungetc EOF

When we are parsing a config value, if we see a carriage
return, we fgetc the next character to see if it is a
line feed (in which case we silently drop the CR). If it
isn't, we then ungetc the character, and take the literal
CR.

But we never check whether we in fact got a character at
all. If the config file ends in CR, we will get EOF here,
and try to ungetc EOF. This works OK for a real stdio
stream. The ungetc returns an error, and the next fgetc will
then return EOF again.

However, our custom buffer-based stream is not so fortunate.
It happily rewinds the position of the stream by one
character, ignoring the fact that we fed it EOF. The next
fgetc call returns the final CR again, over and over, and we
end up in an infinite loop.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.c b/config.c
index 61a9c296f48c929177835c6128133449a1e14a6b..5eca17b24264573a04eebe8be3b397ec1e804954 100644 (file)
--- a/config.c
+++ b/config.c
@@ -228,7 +228,8 @@ 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';
                }
        }

diff --git a/t/t1307-config-blob.sh b/t/t1307-config-blob.sh
index fdc257e66fdc121b9f125466bf38431e3233dd19..3c6791e6be705bc823ff180cd481fef3dc939734 100755 (executable)
--- a/t/t1307-config-blob.sh
+++ b/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