hex: add functions to parse hex object IDs in any algorithm

There are some places where we need to parse a hex object ID in any
algorithm without knowing beforehand which algorithm is in use. An
example is when parsing fast-import marks.

Add a get_oid_hex_any to parse an object ID and return the algorithm it
belongs to, and additionally add parse_oid_hex_any which is the
equivalent change for parse_oid_hex. If the object is not parseable, we
return GIT_HASH_UNKNOWN.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index 4c9c21a11da4c085a541d13258c0d309895613bc..158d7ccfd8854d1362ef925e4c0ecd1c88dcba32 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -1523,6 +1523,16 @@ int parse_oid_hex(const char *hex, struct object_id *oid, const char **end);
 int parse_oid_hex_algop(const char *hex, struct object_id *oid, const char **end,
                        const struct git_hash_algo *algo);
 
+
+/*
+ * These functions work like get_oid_hex and parse_oid_hex, but they will parse
+ * a hex value for any algorithm. The algorithm is detected based on the length
+ * and the algorithm in use is returned. If this is not a hex object ID in any
+ * algorithm, returns GIT_HASH_UNKNOWN.
+ */
+int get_oid_hex_any(const char *hex, struct object_id *oid);
+int parse_oid_hex_any(const char *hex, struct object_id *oid, const char **end);
+
 /*
  * This reads short-hand syntax that not only evaluates to a commit
  * object name, but also can act as if the end user spelled the name

diff --git a/hex.c b/hex.c
index 10e24dc2e4c2be41c91e2929881b91dc771c4677..da51e64929a4f4973406d001a66e5ec72e76e628 100644 (file)
--- a/hex.c
+++ b/hex.c
@@ -72,6 +72,20 @@ int get_oid_hex_algop(const char *hex, struct object_id *oid,
        return get_hash_hex_algop(hex, oid->hash, algop);
 }
 
+/*
+ * NOTE: This function relies on hash algorithms being in order from shortest
+ * length to longest length.
+ */
+int get_oid_hex_any(const char *hex, struct object_id *oid)
+{
+       int i;
+       for (i = GIT_HASH_NALGOS - 1; i > 0; i--) {
+               if (!get_hash_hex_algop(hex, oid->hash, &hash_algos[i]))
+                       return i;
+       }
+       return GIT_HASH_UNKNOWN;
+}
+
 int get_oid_hex(const char *hex, struct object_id *oid)
 {
        return get_oid_hex_algop(hex, oid, the_hash_algo);
@@ -87,6 +101,14 @@ int parse_oid_hex_algop(const char *hex, struct object_id *oid,
        return ret;
 }
 
+int parse_oid_hex_any(const char *hex, struct object_id *oid, const char **end)
+{
+       int ret = get_oid_hex_any(hex, oid);
+       if (ret)
+               *end = hex + hash_algos[ret].hexsz;
+       return ret;
+}
+
 int parse_oid_hex(const char *hex, struct object_id *oid, const char **end)
 {
        return parse_oid_hex_algop(hex, oid, end, the_hash_algo);