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match-trees: use hashcpy to splice trees

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When we splice trees together, we operate in place on the tree buffer.
If we're using SHA-1 for the hash algorithm, we may not have a full
GIT_MAX_RAWSZ (32) bytes to copy. Consequently, it doesn't logically
make sense for us to use a struct object_id to represent this type,
since it isn't a complete object.

Represent this value as a unsigned char pointer instead and copy it when
necessary.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson 2019-01-15 00:39:43 +00:00 committed by Junio C Hamano
parent 36775ab524
commit f55ac4311a
1 changed files with 18 additions and 6 deletions
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24
match-trees.c
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@ -179,7 +179,7 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,
char *buf;
unsigned long sz;
struct tree_desc desc;
struct object_id *rewrite_here;
unsigned char *rewrite_here;
const struct object_id *rewrite_with;
struct object_id subtree;
enum object_type type;
@ -206,9 +206,19 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,
if (!S_ISDIR(mode))
die("entry %s in tree %s is not a tree", name,
oid_to_hex(oid1));
rewrite_here = (struct object_id *)(desc.entry.path +
strlen(desc.entry.path) +
1);
/*
* We cast here for two reasons:
*
* - to flip the "char *" (for the path) to "unsigned
* char *" (for the hash stored after it)
*
* - to discard the "const"; this is OK because we
* know it points into our non-const "buf"
*/
rewrite_here = (unsigned char *)(desc.entry.path +
strlen(desc.entry.path) +
1);
break;
}
update_tree_entry(&desc);
@ -217,14 +227,16 @@ static int splice_tree(const struct object_id *oid1, const char *prefix,
die("entry %.*s not found in tree %s", toplen, prefix,
oid_to_hex(oid1));
if (*subpath) {
status = splice_tree(rewrite_here, subpath, oid2, &subtree);
struct object_id tree_oid;
hashcpy(tree_oid.hash, rewrite_here);
status = splice_tree(&tree_oid, subpath, oid2, &subtree);
if (status)
return status;
rewrite_with = &subtree;
} else {
rewrite_with = oid2;
}
oidcpy(rewrite_here, rewrite_with);
hashcpy(rewrite_here, rewrite_with->hash);
status = write_object_file(buf, sz, tree_type, result);
free(buf);
return status;