+/*
+ * Resolve a reference, recursively following symbolic refererences.
+ *
+ * Store the referred-to object's name in sha1 and return the name of
+ * the non-symbolic reference that ultimately pointed at it. The
+ * return value, if not NULL, is a pointer into either a static buffer
+ * or the input ref.
+ *
+ * If the reference cannot be resolved to an object, the behavior
+ * depends on the RESOLVE_REF_READING flag:
+ *
+ * - If RESOLVE_REF_READING is set, return NULL.
+ *
+ * - If RESOLVE_REF_READING is not set, clear sha1 and return the name of
+ * the last reference name in the chain, which will either be a non-symbolic
+ * reference or an undefined reference. If this is a prelude to
+ * "writing" to the ref, the return value is the name of the ref
+ * that will actually be created or changed.
+ *
+ * If the RESOLVE_REF_NO_RECURSE flag is passed, only resolves one
+ * level of symbolic reference. The value stored in sha1 for a symbolic
+ * reference will always be null_sha1 in this case, and the return
+ * value is the reference that the symref refers to directly.
+ *
+ * If flags is non-NULL, set the value that it points to the
+ * combination of REF_ISPACKED (if the reference was found among the
+ * packed references), REF_ISSYMREF (if the initial reference was a
+ * symbolic reference), REF_BAD_NAME (if the reference name is ill
+ * formed --- see RESOLVE_REF_ALLOW_BAD_NAME below), and REF_ISBROKEN
+ * (if the ref is malformed or has a bad name). See refs.h for more detail
+ * on each flag.
+ *
+ * If ref is not a properly-formatted, normalized reference, return
+ * NULL. If more than MAXDEPTH recursive symbolic lookups are needed,
+ * give up and return NULL.
+ *
+ * RESOLVE_REF_ALLOW_BAD_NAME allows resolving refs even when their
+ * name is invalid according to git-check-ref-format(1). If the name
+ * is bad then the value stored in sha1 will be null_sha1 and the two
+ * flags REF_ISBROKEN and REF_BAD_NAME will be set.
+ *
+ * Even with RESOLVE_REF_ALLOW_BAD_NAME, names that escape the refs/
+ * directory and do not consist of all caps and underscores cannot be
+ * resolved. The function returns NULL for such ref names.
+ * Caps and underscores refers to the special refs, such as HEAD,
+ * FETCH_HEAD and friends, that all live outside of the refs/ directory.
+ */
+#define RESOLVE_REF_READING 0x01
+#define RESOLVE_REF_NO_RECURSE 0x02
+#define RESOLVE_REF_ALLOW_BAD_NAME 0x04
+
+extern const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
+ unsigned char *sha1, int *flags);
+
+extern char *resolve_refdup(const char *refname, int resolve_flags,
+ unsigned char *sha1, int *flags);
+
+extern int read_ref_full(const char *refname, int resolve_flags,
+ unsigned char *sha1, int *flags);
+extern int read_ref(const char *refname, unsigned char *sha1);
+
+extern int ref_exists(const char *);
+
+extern int is_branch(const char *refname);
+
+/*
+ * If refname is a non-symbolic reference that refers to a tag object,
+ * and the tag can be (recursively) dereferenced to a non-tag object,
+ * store the SHA1 of the referred-to object to sha1 and return 0. If
+ * any of these conditions are not met, return a non-zero value.
+ * Symbolic references are considered unpeelable, even if they
+ * ultimately resolve to a peelable tag.
+ */
+extern int peel_ref(const char *refname, unsigned char *sha1);
+
+/**
+ * Resolve refname in the nested "gitlink" repository that is located
+ * at path. If the resolution is successful, return 0 and set sha1 to
+ * the name of the object; otherwise, return a non-zero value.
+ */
+extern int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1);
+
+/*
+ * Return true iff abbrev_name is a possible abbreviation for
+ * full_name according to the rules defined by ref_rev_parse_rules in
+ * refs.c.
+ */
+extern int refname_match(const char *abbrev_name, const char *full_name);
+
+extern int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref);
+extern int dwim_log(const char *str, int len, unsigned char *sha1, char **ref);
+