setup: handle NULL value when parsing extensions

The "partialclone" extension config records a string, and hence it is an
error to have an implicit bool like:

  [extensions]
  partialclone

in your config. We should recognize and reject this, rather than
segfaulting (which is the current behavior). Note that it's OK to use
config_error_nonbool() here, even though the return value is an enum. We
explicitly document EXTENSION_ERROR as -1 for compatibility with
error(), etc.

This is the only extension value that has this problem. Most of the
others are bools that interpret this value naturally. The exception is
extensions.objectformat, which does correctly check for NULL.

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

diff --git a/setup.c b/setup.c
index fc592dc6dd5bf3f2ac7ac01ca0d72b7ce0129e77..50131be7cc6a374799263451d9f087dd366c4929 100644 (file)
--- a/setup.c
+++ b/setup.c
@@ -559,6 +559,8 @@ static enum extension_result handle_extension_v0(const char *var,
                        data->precious_objects = git_config_bool(var, value);
                        return EXTENSION_OK;
                } else if (!strcmp(ext, "partialclone")) {
+                       if (!value)
+                               return config_error_nonbool(var);
                        data->partial_clone = xstrdup(value);
                        return EXTENSION_OK;
                } else if (!strcmp(ext, "worktreeconfig")) {