Expose git_reference_dwim

Extract this function out of the rev-parse code to be able to DWIM a
reference instead of its target.

include/git2/refs.h

@@ -55,6 +55,19 @@ GIT_EXTERN(int) git_reference_name_to_id(
 	git_oid *out, git_repository *repo, const char *name);
 
 /**
+ * Lookup a reference by DWIMing its short name
+ *
+ * Apply the git precendence rules to the given shorthand to determine
+ * which reference the user is refering to.
+ *
+ * @param out pointer in which to store the reference
+ * @param repo the repository in which to look
+ * @param shrothand the short name for the reference
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_reference_dwim(git_reference **out, git_repository *repo, const char *shorthand);
+
+/**
  * Create a new symbolic reference.
  *
  * A symbolic reference is a reference name that refers to another

src/refs.c

@@ -290,6 +290,67 @@ int git_reference_lookup_resolved(
 	return 0;
 }
 
+int git_reference_dwim(git_reference **out, git_repository *repo, const char *refname)
+{
+	int error = 0, i;
+	bool fallbackmode = true, foundvalid = false;
+	git_reference *ref;
+	git_buf refnamebuf = GIT_BUF_INIT, name = GIT_BUF_INIT;
+
+	static const char* formatters[] = {
+		"%s",
+		GIT_REFS_DIR "%s",
+		GIT_REFS_TAGS_DIR "%s",
+		GIT_REFS_HEADS_DIR "%s",
+		GIT_REFS_REMOTES_DIR "%s",
+		GIT_REFS_REMOTES_DIR "%s/" GIT_HEAD_FILE,
+		NULL
+	};
+
+	if (*refname)
+		git_buf_puts(&name, refname);
+	else {
+		git_buf_puts(&name, GIT_HEAD_FILE);
+		fallbackmode = false;
+	}
+
+	for (i = 0; formatters[i] && (fallbackmode || i == 0); i++) {
+
+		git_buf_clear(&refnamebuf);
+
+		if ((error = git_buf_printf(&refnamebuf, formatters[i], git_buf_cstr(&name))) < 0)
+			goto cleanup;
+
+		if (!git_reference_is_valid_name(git_buf_cstr(&refnamebuf))) {
+			error = GIT_EINVALIDSPEC;
+			continue;
+		}
+		foundvalid = true;
+
+		error = git_reference_lookup_resolved(&ref, repo, git_buf_cstr(&refnamebuf), -1);
+
+		if (!error) {
+			*out = ref;
+			error = 0;
+			goto cleanup;
+		}
+
+		if (error != GIT_ENOTFOUND)
+			goto cleanup;
+	}
+
+cleanup:
+	if (error && !foundvalid) {
+		/* never found a valid reference name */
+		giterr_set(GITERR_REFERENCE,
+			"Could not use '%s' as valid reference name", git_buf_cstr(&name));
+	}
+
+	git_buf_free(&name);
+	git_buf_free(&refnamebuf);
+	return error;
+}
+
 /**
  * Getters
  */

src/revparse.c

@@ -14,67 +14,6 @@
 
 #include "git2.h"
 
-static int disambiguate_refname(git_reference **out, git_repository *repo, const char *refname)
-{
-	int error = 0, i;
-	bool fallbackmode = true, foundvalid = false;
-	git_reference *ref;
-	git_buf refnamebuf = GIT_BUF_INIT, name = GIT_BUF_INIT;
-
-	static const char* formatters[] = {
-		"%s",
-		GIT_REFS_DIR "%s",
-		GIT_REFS_TAGS_DIR "%s",
-		GIT_REFS_HEADS_DIR "%s",
-		GIT_REFS_REMOTES_DIR "%s",
-		GIT_REFS_REMOTES_DIR "%s/" GIT_HEAD_FILE,
-		NULL
-	};
-
-	if (*refname)
-		git_buf_puts(&name, refname);
-	else {
-		git_buf_puts(&name, GIT_HEAD_FILE);
-		fallbackmode = false;
-	}
-
-	for (i = 0; formatters[i] && (fallbackmode || i == 0); i++) {
-
-		git_buf_clear(&refnamebuf);
-
-		if ((error = git_buf_printf(&refnamebuf, formatters[i], git_buf_cstr(&name))) < 0)
-			goto cleanup;
-
-		if (!git_reference_is_valid_name(git_buf_cstr(&refnamebuf))) {
-			error = GIT_EINVALIDSPEC;
-			continue;
-		}
-		foundvalid = true;
-
-		error = git_reference_lookup_resolved(&ref, repo, git_buf_cstr(&refnamebuf), -1);
-
-		if (!error) {
-			*out = ref;
-			error = 0;
-			goto cleanup;
-		}
-
-		if (error != GIT_ENOTFOUND)
-			goto cleanup;
-	}
-
-cleanup:
-	if (error && !foundvalid) {
-		/* never found a valid reference name */
-		giterr_set(GITERR_REFERENCE,
-			"Could not use '%s' as valid reference name", git_buf_cstr(&name));
-	}
-
-	git_buf_free(&name);
-	git_buf_free(&refnamebuf);
-	return error;
-}
-
 static int maybe_sha_or_abbrev(git_object** out, git_repository *repo, const char *spec, size_t speclen)
 {
 	git_oid oid;
@@ -157,7 +96,7 @@ static int revparse_lookup_object(git_object **out, git_repository *repo, const
 	if (error < 0 && error != GIT_ENOTFOUND)
 		return error;
 
-	error = disambiguate_refname(&ref, repo, spec);
+	error = git_reference_dwim(&ref, repo, spec);
 	if (!error) {
 		error = git_object_lookup(out, repo, git_reference_target(ref), GIT_OBJ_ANY);
 		git_reference_free(ref);
@@ -242,7 +181,7 @@ static int retrieve_previously_checked_out_branch_or_revision(git_object **out,
 
 		git_buf_put(&buf, msg+regexmatches[1].rm_so, regexmatches[1].rm_eo - regexmatches[1].rm_so);
 
-		if ((error = disambiguate_refname(base_ref, repo, git_buf_cstr(&buf))) == 0)
+		if ((error = git_reference_dwim(base_ref, repo, git_buf_cstr(&buf))) == 0)
 			goto cleanup;
 
 		if (error < 0 && error != GIT_ENOTFOUND)
@@ -323,7 +262,7 @@ static int retrieve_revobject_from_reflog(git_object **out, git_reference **base
 	int error = -1;
 
 	if (*base_ref == NULL) {
-		if ((error = disambiguate_refname(&ref, repo, identifier)) < 0)
+		if ((error = git_reference_dwim(&ref, repo, identifier)) < 0)
 			return error;
 	} else {
 		ref = *base_ref;
@@ -351,7 +290,7 @@ static int retrieve_remote_tracking_reference(git_reference **base_ref, const ch
 	int error = -1;
 
 	if (*base_ref == NULL) {
-		if ((error = disambiguate_refname(&ref, repo, identifier)) < 0)
+		if ((error = git_reference_dwim(&ref, repo, identifier)) < 0)
 			return error;
 	} else {
 		ref = *base_ref;