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-rw-r--r--replace_object.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/replace_object.c b/replace_object.c
new file mode 100644
index 0000000000..eb59604fd3
--- /dev/null
+++ b/replace_object.c
@@ -0,0 +1,114 @@
+#include "cache.h"
+#include "sha1-lookup.h"
+#include "refs.h"
+
+static struct replace_object {
+ unsigned char sha1[2][20];
+} **replace_object;
+
+static int replace_object_alloc, replace_object_nr;
+
+static const unsigned char *replace_sha1_access(size_t index, void *table)
+{
+ struct replace_object **replace = table;
+ return replace[index]->sha1[0];
+}
+
+static int replace_object_pos(const unsigned char *sha1)
+{
+ return sha1_pos(sha1, replace_object, replace_object_nr,
+ replace_sha1_access);
+}
+
+static int register_replace_object(struct replace_object *replace,
+ int ignore_dups)
+{
+ int pos = replace_object_pos(replace->sha1[0]);
+
+ if (0 <= pos) {
+ if (ignore_dups)
+ free(replace);
+ else {
+ free(replace_object[pos]);
+ replace_object[pos] = replace;
+ }
+ return 1;
+ }
+ pos = -pos - 1;
+ if (replace_object_alloc <= ++replace_object_nr) {
+ replace_object_alloc = alloc_nr(replace_object_alloc);
+ replace_object = xrealloc(replace_object,
+ sizeof(*replace_object) *
+ replace_object_alloc);
+ }
+ if (pos < replace_object_nr)
+ memmove(replace_object + pos + 1,
+ replace_object + pos,
+ (replace_object_nr - pos - 1) *
+ sizeof(*replace_object));
+ replace_object[pos] = replace;
+ return 0;
+}
+
+static int register_replace_ref(const char *refname,
+ const unsigned char *sha1,
+ int flag, void *cb_data)
+{
+ /* Get sha1 from refname */
+ const char *slash = strrchr(refname, '/');
+ const char *hash = slash ? slash + 1 : refname;
+ struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
+
+ if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->sha1[0])) {
+ free(repl_obj);
+ warning("bad replace ref name: %s", refname);
+ return 0;
+ }
+
+ /* Copy sha1 from the read ref */
+ hashcpy(repl_obj->sha1[1], sha1);
+
+ /* Register new object */
+ if (register_replace_object(repl_obj, 1))
+ die("duplicate replace ref: %s", refname);
+
+ return 0;
+}
+
+static void prepare_replace_object(void)
+{
+ static int replace_object_prepared;
+
+ if (replace_object_prepared)
+ return;
+
+ for_each_replace_ref(register_replace_ref, NULL);
+ replace_object_prepared = 1;
+}
+
+/* We allow "recursive" replacement. Only within reason, though */
+#define MAXREPLACEDEPTH 5
+
+const unsigned char *lookup_replace_object(const unsigned char *sha1)
+{
+ int pos, depth = MAXREPLACEDEPTH;
+ const unsigned char *cur = sha1;
+
+ if (!read_replace_refs)
+ return sha1;
+
+ prepare_replace_object();
+
+ /* Try to recursively replace the object */
+ do {
+ if (--depth < 0)
+ die("replace depth too high for object %s",
+ sha1_to_hex(sha1));
+
+ pos = replace_object_pos(cur);
+ if (0 <= pos)
+ cur = replace_object[pos]->sha1[1];
+ } while (0 <= pos);
+
+ return cur;
+}