(I was out all month.) Thank you for the additional fixes.


On Thu, Dec 21, 2023 at 4:07 AM Junio C Hamano [off-list ref] wrote:

Junio C Hamano [off-list ref] writes:

quoted

The attached is one possible way to plug the leak; I am not sure if
it is the best one, though.  One thing I like about the solution is
that the approach makes sure that the mode attributes we would ever
return are very tightly controlled and does not allow a buggy code
to come up with "mode" to be passed to this new helper function to
pass random and unsupported mode bits without triggering the BUG().

 attr.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

Anybody who want to propose a better leakfix (we cannot afford to do
with UNLEAK() as the number of leaked mode string will be unbounded)?

Otherwise, I'll squash it in to Jonanna's patch and merge it down to
'next'.

Thanks.

quoted

diff --git c/attr.c w/attr.c
index b03c20f768..679e42258c 100644
--- c/attr.c
+++ w/attr.c

@@ -1250,10 +1250,34 @@ static struct object_id *default_attr_source(void)
      return &attr_source;
 }

+static const char *interned_mode_string(unsigned int mode)
+{
+     static struct {
+             unsigned int val;
+             char str[7];
+     } mode_string[] = {
+             { .val = 0040000 },
+             { .val = 0100644 },
+             { .val = 0100755 },
+             { .val = 0120000 },
+             { .val = 0160000 },
+     };
+     int i;
+
+     for (i = 0; i < ARRAY_SIZE(mode_string); i++) {
+             if (mode_string[i].val != mode)
+                     continue;
+             if (!*mode_string[i].str)
+                     snprintf(mode_string[i].str, sizeof(mode_string[i].str),
+                              "%06o", mode);
+             return mode_string[i].str;
+     }
+     BUG("Unsupported mode 0%o", mode);
+}
+
 static const char *builtin_object_mode_attr(struct index_state *istate, const char *path)
 {
      unsigned int mode;
-     struct strbuf sb = STRBUF_INIT;

      if (direction == GIT_ATTR_CHECKIN) {
              struct object_id oid;

@@ -1287,8 +1311,8 @@ static const char *builtin_object_mode_attr(struct index_state *istate, const ch
              else
                      return ATTR__UNSET;
      }
-     strbuf_addf(&sb, "%06o", mode);
-     return strbuf_detach(&sb, NULL);
+
+     return interned_mode_string(mode);
 }