apply: fix uninitialized hash function

"git apply" can work outside a repository as a better "GNU patch",
but when it does so, it still assumed that it can access
the_hash_algo, which is no longer true in the new world order.

Make sure we explicitly fall back to SHA-1 algorithm for backward
compatibility.

It is of dubious value to make this configurable to other hash
algorithms, as the code does not use the_hash_algo for hashing
purposes when working outside a repository (which is how
the_hash_algo is left to NULL)---it is only used to learn the max
length of the hash when parsing the object names on the "index"
line, but failing to parse the "index" line is not a hard failure,
and the program does not support operations like applying binary
patches and --3way fallback that requires object access outside a
repository.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/apply.c b/builtin/apply.c
index 861a01910ca20bcb9bd18279ebd10f9d94032fe1..d623c52f78fc6d1a7b8064b48b7f13eb5fd1b73a 100644 (file)
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -1,6 +1,7 @@
 #include "builtin.h"
 #include "gettext.h"
 #include "repository.h"
+#include "hash.h"
 #include "apply.h"
 
 static const char * const apply_usage[] = {
@@ -18,6 +19,15 @@ int cmd_apply(int argc, const char **argv, const char *prefix)
        if (init_apply_state(&state, the_repository, prefix))
                exit(128);
 
+       /*
+        * We could to redo the "apply.c" machinery to make this
+        * arbitrary fallback unnecessary, but it is dubious that it
+        * is worth the effort.
+        * cf. https://lore.kernel.org/git/xmqqcypfcmn4.fsf@gitster.g/
+        */
+       if (!the_hash_algo)
+               repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
+
        argc = apply_parse_options(argc, argv,
                                   &state, &force_apply, &options,
                                   apply_usage);

diff --git a/t/t1517-outside-repo.sh b/t/t1517-outside-repo.sh
index 2d8982d61a2373bff1127ecd4181f854e0137f7a..557808ffa7383441091b54456170473486e9c92b 100755 (executable)
--- a/t/t1517-outside-repo.sh
+++ b/t/t1517-outside-repo.sh
@@ -37,7 +37,7 @@ test_expect_success 'hash-object outside repository (uses SHA-1)' '
        test_cmp hash.expect hash.actual
 '
 
-test_expect_failure 'apply a patch outside repository' '
+test_expect_success 'apply a patch outside repository' '
        (
                cd non-repo &&
                cp ../nums.old nums &&