cat-file: handle NULL object_context.path

Commit dc944b65f1 (get_sha1_with_context: dynamically allocate oc->path, 2017-05-19) changed the rules that callers must follow for seeing if we parsed a path in the object name. The rules switched from "check if the oc.path buffer is empty" to "check if the oc.path pointer is NULL". But that commit forgot to update some sites in cat_one_file(), meaning we might dereference a NULL pointer. You can see this by making a path-aware request like --textconv without specifying --path, and giving an object name that doesn't have a path in it. Like: git cat-file --textconv HEAD which will reliably segfault. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Sep 21, 2017 at 02:21 UTC cc0ea7c9e5c3d3bf9623415737b595c9d26b9b6d
2 files changed +7 -2
builtin/cat-file.c
+2 -2
@@ -94,7 +94,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
94 return !has_object_file(&oid);
95
96 case 'w':
97 - if (!path[0])
97 + if (!path)
98 die("git cat-file --filters %s: <object> must be "
99 "<sha1:path>", obj_name);
100
@@ -104,7 +104,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
104 break;
105
106 case 'c':
107 - if (!path[0])
107 + if (!path)
108 die("git cat-file --textconv %s: <object> must be <sha1:path>",
109 obj_name);
110
t/t8010-cat-file-filters.sh
+5
@@ -51,6 +51,11 @@ test_expect_success '--path=<path> complains without --textconv/--filters' '
51 grep "path.*needs.*filters" err
52 '
53
54 +test_expect_success '--textconv/--filters complain without path' '
55 + test_must_fail git cat-file --textconv HEAD &&
56 + test_must_fail git cat-file --filters HEAD
57 +'
58 +
59 test_expect_success 'cat-file --textconv --batch works' '
60 sha1=$(git rev-parse -q --verify HEAD:world.txt) &&
61 test_config diff.txt.textconv "tr A-Za-z N-ZA-Mn-za-m <" &&