thodg/libgit2/src/revparse.c

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• Hash : 12595ab8
  Author :
  Date : 2012-07-12T00:52:01
  

  revparse: deploy git_reference_remote_tracking_from_branch()

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• src/revparse.c

• /*
   * Copyright (C) 2009-2012 the libgit2 contributors
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include <assert.h>
  
  #include "common.h"
  #include "buffer.h"
  #include "tree.h"
  
  #include "git2.h"
  
  typedef enum {
  	REVPARSE_STATE_INIT,
  	REVPARSE_STATE_CARET,
  	REVPARSE_STATE_LINEAR,
  	REVPARSE_STATE_COLON,
  	REVPARSE_STATE_DONE,
  } revparse_state;
  
  static int revspec_error(const char *revspec)
  {
  	giterr_set(GITERR_INVALID, "Failed to parse revision specifier - Invalid pattern '%s'", revspec);
  	return -1;
  }
  
  static int revparse_lookup_fully_qualifed_ref(git_object **out, git_repository *repo, const char*spec)
  {
  	git_oid resolved;
  	int error;
  
  	if ((error = git_reference_name_to_oid(&resolved, repo, spec)) < 0)
  		return error;
  
  	return git_object_lookup(out, repo, &resolved, GIT_OBJ_ANY);
  }
  
  /* Returns non-zero if yes */
  static int spec_looks_like_describe_output(const char *spec)
  {
  	regex_t regex;
  	int regex_error, retcode;
  
  	regex_error = regcomp(&regex, ".+-[0-9]+-g[0-9a-fA-F]+", REG_EXTENDED);
  	if (regex_error != 0) {
  		giterr_set_regex(&regex, regex_error);
  		return regex_error;
  	}
  
  	retcode = regexec(&regex, spec, 0, NULL, 0);
  	regfree(&regex);
  	return retcode == 0;
  }
  
  static int disambiguate_refname(git_reference **out, git_repository *repo, const char *refname)
  {
  	int error, i;
  	bool fallbackmode = true;
  	git_reference *ref;
  	git_buf refnamebuf = GIT_BUF_INIT, name = GIT_BUF_INIT;
  
  	static const char* formatters[] = {
  		"%s",
  		"refs/%s",
  		"refs/tags/%s",
  		"refs/heads/%s",
  		"refs/remotes/%s",
  		"refs/remotes/%s/HEAD",
  		NULL
  	};
  
  	if (*refname)
  		git_buf_puts(&name, refname);
  	else {
  		git_buf_puts(&name, "HEAD");
  		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;
  
  		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:
  	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)
  {
  	git_oid oid;
  	size_t speclen = strlen(spec);
  
  	if (git_oid_fromstrn(&oid, spec, speclen) < 0)
  		return GIT_ENOTFOUND;
  
  	return git_object_lookup_prefix(out, repo, &oid, speclen, GIT_OBJ_ANY);
  }
  
  static int maybe_describe(git_object**out, git_repository *repo, const char *spec)
  {
  	const char *substr;
  	int match;
  
  	/* "git describe" output; snip everything before/including "-g" */
  	substr = strstr(spec, "-g");
  
  	if (substr == NULL)
  		return GIT_ENOTFOUND;
  	
  	if ((match = spec_looks_like_describe_output(spec)) < 0)
  		return match;
  
  	if (!match)
  		return GIT_ENOTFOUND;
  
  	return maybe_sha_or_abbrev(out, repo, substr+2);
  }
  
  static int revparse_lookup_object(git_object **out, git_repository *repo, const char *spec)
  {
  	int error;
  	git_reference *ref;
  
  	error = maybe_describe(out, repo, spec);
  	if (!error)
  		return 0;
  
  	if (error < 0 && error != GIT_ENOTFOUND)
  		return error;
  
  	error = maybe_sha_or_abbrev(out, repo, spec);
  	if (!error)
  		return 0;
  
  	if (error < 0 && error != GIT_ENOTFOUND)
  		return error;
  
  	error = disambiguate_refname(&ref, repo, spec);
  	if (!error) {
  		error = git_object_lookup(out, repo, git_reference_oid(ref), GIT_OBJ_ANY);
  		git_reference_free(ref);
  		return 0;
  	}
  
  	if (error < 0 && error != GIT_ENOTFOUND)
  		return error;
  
  	giterr_set(GITERR_REFERENCE, "Refspec '%s' not found.", spec);
  	return GIT_ENOTFOUND;
  }
  
  static int all_chars_are_digits(const char *str, size_t len)
  {
  	size_t i = 0;
  
  	for (i = 0; i < len; i++)
  		if (!git__isdigit(str[i])) return 0;
  
  	return 1;
  }
  
  static int walk_ref_history(git_object **out, git_repository *repo, const char *refspec, const char *reflogspec)
  {
  	git_reference *disambiguated = NULL;
  	git_reflog *reflog = NULL;
  	int n, retcode = GIT_ERROR;
  	int i, refloglen;
  	const git_reflog_entry *entry;
  	git_buf buf = GIT_BUF_INIT;
  	size_t refspeclen = strlen(refspec);
  	size_t reflogspeclen = strlen(reflogspec);
  
  	if (git__prefixcmp(reflogspec, "@{") != 0 ||
  		git__suffixcmp(reflogspec, "}") != 0)
  		return revspec_error(reflogspec);
  
  	/* "@{-N}" form means walk back N checkouts. That means the HEAD log. */
  	if (!git__prefixcmp(reflogspec, "@{-")) {
  		regex_t regex;
  		int regex_error;
  
  		if (refspeclen > 0)
  			return revspec_error(reflogspec);
  
  		if (git__strtol32(&n, reflogspec+3, NULL, 10) < 0 || n < 1)
  			return revspec_error(reflogspec);
  
  		if (!git_reference_lookup(&disambiguated, repo, "HEAD")) {
  			if (!git_reflog_read(&reflog, disambiguated)) {
  				regex_error = regcomp(&regex, "checkout: moving from (.*) to .*", REG_EXTENDED);
  				if (regex_error != 0) {
  					giterr_set_regex(&regex, regex_error);
  				} else {
  					regmatch_t regexmatches[2];
  
  					retcode = GIT_ENOTFOUND;
  
  					refloglen = git_reflog_entrycount(reflog);
  					for (i=refloglen-1; i >= 0; i--) {
  						const char *msg;
  						entry = git_reflog_entry_byindex(reflog, i);
  
  						msg = git_reflog_entry_msg(entry);
  						if (!regexec(&regex, msg, 2, regexmatches, 0)) {
  							n--;
  							if (!n) {
  								git_buf_put(&buf, msg+regexmatches[1].rm_so, regexmatches[1].rm_eo - regexmatches[1].rm_so);
  								retcode = revparse_lookup_object(out, repo, git_buf_cstr(&buf));
  								break;
  							}
  						}
  					}
  					regfree(&regex);
  				}
  			}
  		}
  	} else {
  		int date_error = 0, result;
  		git_time_t timestamp;
  		git_buf datebuf = GIT_BUF_INIT;
  
  		result = disambiguate_refname(&disambiguated, repo, refspec);
  
  		if (result < 0) {
  			retcode = result;
  			goto cleanup;
  		}
  
  		git_buf_put(&datebuf, reflogspec+2, reflogspeclen-3);
  		date_error = git__date_parse(&timestamp, git_buf_cstr(&datebuf));
  
  		/* @{u} or @{upstream} -> upstream branch, for a tracking branch. This is stored in the config. */
  		if (!strcmp(reflogspec, "@{u}") || !strcmp(reflogspec, "@{upstream}")) {
  			git_reference *tracking;
  			
  			if (!(retcode = git_reference_remote_tracking_from_branch(&tracking, disambiguated))) {
  				retcode = revparse_lookup_fully_qualifed_ref(out, repo, git_reference_name(tracking));
  				git_reference_free(tracking);
  			}
  		}
  
  		/* @{N} -> Nth prior value for the ref (from reflog) */
  		else if (all_chars_are_digits(reflogspec+2, reflogspeclen-3) &&
  			!git__strtol32(&n, reflogspec+2, NULL, 10) &&
  			n <= 100000000) { /* Allow integer time */
  
  				git_buf_puts(&buf, git_reference_name(disambiguated));
  
  				if (n == 0)
  					retcode = revparse_lookup_fully_qualifed_ref(out, repo, git_buf_cstr(&buf));
  				else if (!git_reflog_read(&reflog, disambiguated)) {
  						int numentries = git_reflog_entrycount(reflog);
  						if (numentries < n + 1) {
  							giterr_set(GITERR_REFERENCE, "Reflog for '%s' has only %d entries, asked for %d",
  								git_buf_cstr(&buf), numentries, n);
  							retcode = GIT_ENOTFOUND;
  						} else {
  							const git_reflog_entry *entry = git_reflog_entry_byindex(reflog, n);
  							const git_oid *oid = git_reflog_entry_oidold(entry);
  							retcode = git_object_lookup(out, repo, oid, GIT_OBJ_ANY);
  						}
  				}
  		}
  
  		else if (!date_error) {
  			/* Ref as it was on a certain date */
  			git_reflog *reflog;
  			if (!git_reflog_read(&reflog, disambiguated)) {
  				/* Keep walking until we find an entry older than the given date */
  				int numentries = git_reflog_entrycount(reflog);
  				int i;
  
  				for (i = numentries - 1; i >= 0; i--) {
  					const git_reflog_entry *entry = git_reflog_entry_byindex(reflog, i);
  					git_time commit_time = git_reflog_entry_committer(entry)->when;
  					if (commit_time.time - timestamp <= 0) {
  						retcode = git_object_lookup(out, repo, git_reflog_entry_oidnew(entry), GIT_OBJ_ANY);
  						break;
  					}
  				}
  
  				if (i ==  -1) {
  					/* Didn't find a match */
  					retcode = GIT_ENOTFOUND;
  				}
  
  				git_reflog_free(reflog);
  			}
  		}
  
  		git_buf_free(&datebuf);
  	}
  
  cleanup:
  	if (reflog)
  		git_reflog_free(reflog);
  	git_buf_free(&buf);
  	git_reference_free(disambiguated);
  	return retcode;
  }
  
  static git_object* dereference_object(git_object *obj)
  {
  	git_otype type = git_object_type(obj);
  
  	switch (type) {
  	case GIT_OBJ_COMMIT:
  		{
  			git_tree *tree = NULL;
  			if (0 == git_commit_tree(&tree, (git_commit*)obj)) {
  				return (git_object*)tree;
  			}
  		}
  		break;
  	case GIT_OBJ_TAG:
  		{
  			git_object *newobj = NULL;
  			if (0 == git_tag_target(&newobj, (git_tag*)obj)) {
  				return newobj;
  			}
  		}
  		break;
  
  	default:
  	case GIT_OBJ_TREE:
  	case GIT_OBJ_BLOB:
  	case GIT_OBJ_OFS_DELTA:
  	case GIT_OBJ_REF_DELTA:
  		break;
  	}
  
  	/* Can't dereference some types */
  	return NULL;
  }
  
  static int dereference_to_type(git_object **out, git_object *obj, git_otype target_type)
  {
  	int retcode = 1;
  	git_object *obj1 = obj, *obj2 = obj;
  
  	while (retcode > 0) {
  		git_otype this_type = git_object_type(obj1);
  
  		if (this_type == target_type) {
  			*out = obj1;
  			retcode = 0;
  		} else {
  			/* Dereference once, if possible. */
  			obj2 = dereference_object(obj1);
  			if (!obj2) {
  				giterr_set(GITERR_REFERENCE, "Can't dereference to type");
  				retcode = GIT_ERROR;
  			}
  		}
  		if (obj1 != obj && obj1 != obj2) {
  			git_object_free(obj1);
  		}
  		obj1 = obj2;
  	}
  	return retcode;
  }
  
  static git_otype parse_obj_type(const char *str)
  {
  	if (!strcmp(str, "{commit}")) return GIT_OBJ_COMMIT;
  	if (!strcmp(str, "{tree}")) return GIT_OBJ_TREE;
  	if (!strcmp(str, "{blob}")) return GIT_OBJ_BLOB;
  	if (!strcmp(str, "{tag}")) return GIT_OBJ_TAG;
  	return GIT_OBJ_BAD;
  }
  
  static int handle_caret_syntax(git_object **out, git_repository *repo, git_object *obj, const char *movement)
  {
  	git_commit *commit;
  	size_t movementlen = strlen(movement);
  	int n;
  
  	if (*movement == '{') {
  		if (movement[movementlen-1] != '}')
  			return revspec_error(movement);
  
  		/* {} -> Dereference until we reach an object that isn't a tag. */
  		if (movementlen == 2) {
  			git_object *newobj = obj;
  			git_object *newobj2 = newobj;
  			while (git_object_type(newobj2) == GIT_OBJ_TAG) {
  				newobj2 = dereference_object(newobj);
  				if (newobj != obj) git_object_free(newobj);
  				if (!newobj2) {
  					giterr_set(GITERR_REFERENCE, "Couldn't find object of target type.");
  					return GIT_ERROR;
  				}
  				newobj = newobj2;
  			}
  			*out = newobj2;
  			return 0;
  		}
  
  		/* {/...} -> Walk all commits until we see a commit msg that matches the phrase. */
  		if (movement[1] == '/') {
  			int retcode = GIT_ERROR;
  			git_revwalk *walk;
  			if (!git_revwalk_new(&walk, repo)) {
  				git_oid oid;
  				regex_t preg;
  				int reg_error;
  				git_buf buf = GIT_BUF_INIT;
  
  				git_revwalk_sorting(walk, GIT_SORT_TIME);
  				git_revwalk_push(walk, git_object_id(obj));
  
  				/* Extract the regex from the movement string */
  				git_buf_put(&buf, movement+2, strlen(movement)-3);
  
  				reg_error = regcomp(&preg, git_buf_cstr(&buf), REG_EXTENDED);
  				if (reg_error != 0) {
  					giterr_set_regex(&preg, reg_error);
  				} else {
  					while(!git_revwalk_next(&oid, walk)) {
  						git_object *walkobj;
  
  						/* Fetch the commit object, and check for matches in the message */
  						if (!git_object_lookup(&walkobj, repo, &oid, GIT_OBJ_COMMIT)) {
  							if (!regexec(&preg, git_commit_message((git_commit*)walkobj), 0, NULL, 0)) {
  								/* Found it! */
  								retcode = 0;
  								*out = walkobj;
  								if (obj == walkobj) {
  									/* Avoid leaking an object */
  									git_object_free(walkobj);
  								}
  								break;
  							}
  							git_object_free(walkobj);
  						}
  					}
  					if (retcode < 0) {
  						giterr_set(GITERR_REFERENCE, "Couldn't find a match for %s", movement);
  					}
  					regfree(&preg);
  				}
  
  				git_buf_free(&buf);
  				git_revwalk_free(walk);
  			}
  			return retcode;
  		}
  
  		/* {...} -> Dereference until we reach an object of a certain type. */
  		if (dereference_to_type(out, obj, parse_obj_type(movement)) < 0) {
  			return GIT_ERROR;
  		}
  		return 0;
  	}
  
  	/* Dereference until we reach a commit. */
  	if (dereference_to_type(&obj, obj, GIT_OBJ_COMMIT) < 0) {
  		/* Can't dereference to a commit; fail */
  		return GIT_ERROR;
  	}
  
  	/* "^" is the same as "^1" */
  	if (movementlen == 0) {
  		n = 1;
  	} else {
  		git__strtol32(&n, movement, NULL, 0);
  	}
  	commit = (git_commit*)obj;
  
  	/* "^0" just returns the input */
  	if (n == 0) {
  		*out = obj;
  		return 0;
  	}
  
  	if (git_commit_parent(&commit, commit, n-1) < 0) {
  		return GIT_ENOTFOUND;
  	}
  
  	*out = (git_object*)commit;
  	return 0;
  }
  
  static int handle_linear_syntax(git_object **out, git_object *obj, const char *movement)
  {
  	int n;
  
  	/* Dereference until we reach a commit. */
  	if (dereference_to_type(&obj, obj, GIT_OBJ_COMMIT) < 0) {
  		/* Can't dereference to a commit; fail */
  		return GIT_ERROR;
  	}
  
  	/* "~" is the same as "~1" */
  	if (*movement == '\0') {
  		n = 1;
  	} else if (git__strtol32(&n, movement, NULL, 0) < 0) {
  		return GIT_ERROR;
  	}
  
  	return git_commit_nth_gen_ancestor((git_commit **)out, (git_commit*)obj, n);
  }
  
  static int oid_for_tree_path(git_oid *out, git_tree *tree, git_repository *repo, const char *path)
  {
  	char *str, *tok;
  	void *alloc;
  	git_tree *tree2 = tree;
  	const git_tree_entry *entry = NULL;
  	git_otype type;
  
  	if (*path == '\0') {
  		git_oid_cpy(out, git_object_id((git_object *)tree));
  		return 0;
  	}
  
  	alloc = str = git__strdup(path);
  
  	while ((tok = git__strtok(&str, "/\\")) != NULL) {
  		entry = git_tree_entry_byname(tree2, tok);
  		if (tree2 != tree) git_tree_free(tree2);
  
  		if (entry == NULL)
  			break;
  
  		type = git_tree_entry_type(entry);
  
  		switch (type) {
  		case GIT_OBJ_TREE:
  			if (*str == '\0')
  				break;
  			if (git_tree_lookup(&tree2, repo, &entry->oid) < 0) {
  				git__free(alloc);
  				return GIT_ERROR;
  			}
  			break;
  		case GIT_OBJ_BLOB:
  			if (*str != '\0') {
  				entry = NULL;
  				goto out;
  			}
  			break;
  		default:
  			/* TODO: support submodules? */
  			giterr_set(GITERR_INVALID, "Unimplemented");
  			git__free(alloc);
  			return GIT_ERROR;
  		}
  	}
  
  out:
  	if (!entry) {
  		giterr_set(GITERR_INVALID, "Invalid tree path '%s'", path);
  		git__free(alloc);
  		return GIT_ENOTFOUND;
  	}
  
  	git_oid_cpy(out, git_tree_entry_id(entry));
  	git__free(alloc);
  	return 0;
  }
  
  static int handle_colon_syntax(git_object **out,
  	git_repository *repo,
  	git_object *obj,
  	const char *path)
  {
  	git_tree *tree;
  	git_oid oid;
  	int error;
  
  	/* Dereference until we reach a tree. */
  	if (dereference_to_type(&obj, obj, GIT_OBJ_TREE) < 0) {
  		return GIT_ERROR;
  	}
  	tree = (git_tree*)obj;
  
  	/* Find the blob or tree at the given path. */
  	error = oid_for_tree_path(&oid, tree, repo, path);
  	git_tree_free(tree);
  
  	if (error < 0)
  		return error;
  
  	return git_object_lookup(out, repo, &oid, GIT_OBJ_ANY);
  }
  
  static int revparse_global_grep(git_object **out, git_repository *repo, const char *pattern)
  {
  	git_revwalk *walk;
  	int retcode = GIT_ERROR;
  
  	if (!pattern[0]) {
  		giterr_set(GITERR_REGEX, "Empty pattern");
  		return GIT_ERROR;
  	}
  
  	if (!git_revwalk_new(&walk, repo)) {
  		regex_t preg;
  		int reg_error;
  		git_oid oid;
  
  		git_revwalk_sorting(walk, GIT_SORT_TIME);
  		git_revwalk_push_glob(walk, "refs/heads/*");
  
  		reg_error = regcomp(&preg, pattern, REG_EXTENDED);
  		if (reg_error != 0) {
  			giterr_set_regex(&preg, reg_error);
  		} else {
  			git_object *walkobj = NULL, *resultobj = NULL;
  			while(!git_revwalk_next(&oid, walk)) {
  				/* Fetch the commit object, and check for matches in the message */
  				if (walkobj != resultobj) git_object_free(walkobj);
  				if (!git_object_lookup(&walkobj, repo, &oid, GIT_OBJ_COMMIT)) {
  					if (!regexec(&preg, git_commit_message((git_commit*)walkobj), 0, NULL, 0)) {
  						/* Match! */
  						resultobj = walkobj;
  						retcode = 0;
  						break;
  					}
  				}
  			}
  			if (!resultobj) {
  				giterr_set(GITERR_REFERENCE, "Couldn't find a match for %s", pattern);
  				retcode = GIT_ENOTFOUND;
  				git_object_free(walkobj);
  			} else {
  				*out = resultobj;
  			}
  			regfree(&preg);
  			git_revwalk_free(walk);
  		}
  	}
  
  	return retcode;
  }
  
  int git_revparse_single(git_object **out, git_repository *repo, const char *spec)
  {
  	revparse_state current_state = REVPARSE_STATE_INIT,  next_state = REVPARSE_STATE_INIT;
  	const char *spec_cur = spec;
  	git_object *cur_obj = NULL,  *next_obj = NULL;
  	git_buf specbuffer = GIT_BUF_INIT,  stepbuffer = GIT_BUF_INIT;
  	int retcode = 0;
  
  	assert(out && repo && spec);
  
  	if (spec[0] == ':') {
  		if (spec[1] == '/') {
  			return revparse_global_grep(out, repo, spec+2);
  		}
  		/* TODO: support merge-stage path lookup (":2:Makefile"). */
  		giterr_set(GITERR_INVALID, "Unimplemented");
  		return GIT_ERROR;
  	}
  
  	while (current_state != REVPARSE_STATE_DONE) {
  		switch (current_state) {
  		case REVPARSE_STATE_INIT:
  			if (!*spec_cur) {
  				/* No operators, just a name. Find it and return. */
  				retcode = revparse_lookup_object(out, repo, spec);
  				next_state = REVPARSE_STATE_DONE;
  			} else if (*spec_cur == '@') {
  				/* '@' syntax doesn't allow chaining */
  				git_buf_puts(&stepbuffer, spec_cur);
  				retcode = walk_ref_history(out, repo, git_buf_cstr(&specbuffer), git_buf_cstr(&stepbuffer));
  				next_state = REVPARSE_STATE_DONE;
  			} else if (*spec_cur == '^') {
  				next_state = REVPARSE_STATE_CARET;
  			} else if (*spec_cur == '~') {
  				next_state = REVPARSE_STATE_LINEAR;
  			} else if (*spec_cur == ':') {
  				next_state = REVPARSE_STATE_COLON;
  			} else {
  				git_buf_putc(&specbuffer, *spec_cur);
  			}
  			spec_cur++;
  
  			if (current_state != next_state && next_state != REVPARSE_STATE_DONE) {
  				/* Leaving INIT state, find the object specified, in case that state needs it */
  				if ((retcode = revparse_lookup_object(&next_obj, repo, git_buf_cstr(&specbuffer))) < 0)
  					next_state = REVPARSE_STATE_DONE;
  			}
  			break;
  
  
  		case REVPARSE_STATE_CARET:
  			/* Gather characters until NULL, '~', or '^' */
  			if (!*spec_cur) {
  				retcode = handle_caret_syntax(out, repo, cur_obj, git_buf_cstr(&stepbuffer));
  				next_state = REVPARSE_STATE_DONE;
  			} else if (*spec_cur == '~') {
  				retcode = handle_caret_syntax(&next_obj, repo, cur_obj, git_buf_cstr(&stepbuffer));
  				git_buf_clear(&stepbuffer);
  				next_state = !retcode ? REVPARSE_STATE_LINEAR : REVPARSE_STATE_DONE;
  			} else if (*spec_cur == '^') {
  				retcode = handle_caret_syntax(&next_obj, repo, cur_obj, git_buf_cstr(&stepbuffer));
  				git_buf_clear(&stepbuffer);
  				if (retcode < 0) {
  					next_state = REVPARSE_STATE_DONE;
  				}
  			} else if (*spec_cur == ':') {
  				retcode = handle_caret_syntax(&next_obj, repo, cur_obj, git_buf_cstr(&stepbuffer));
  				git_buf_clear(&stepbuffer);
  				next_state = !retcode ? REVPARSE_STATE_COLON : REVPARSE_STATE_DONE;
  			} else {
  				git_buf_putc(&stepbuffer, *spec_cur);
  			}
  			spec_cur++;
  			break;
  
  		case REVPARSE_STATE_LINEAR:
  			if (!*spec_cur) {
  				retcode = handle_linear_syntax(out, cur_obj, git_buf_cstr(&stepbuffer));
  				next_state = REVPARSE_STATE_DONE;
  			} else if (*spec_cur == '~') {
  				retcode = handle_linear_syntax(&next_obj, cur_obj, git_buf_cstr(&stepbuffer));
  				git_buf_clear(&stepbuffer);
  				if (retcode < 0) {
  					next_state = REVPARSE_STATE_DONE;
  				}
  			} else if (*spec_cur == '^') {
  				retcode = handle_linear_syntax(&next_obj, cur_obj, git_buf_cstr(&stepbuffer));
  				git_buf_clear(&stepbuffer);
  				next_state = !retcode ? REVPARSE_STATE_CARET : REVPARSE_STATE_DONE;
  			} else {
  				git_buf_putc(&stepbuffer, *spec_cur);
  			}
  			spec_cur++;
  			break;
  
  		case REVPARSE_STATE_COLON:
  			if (*spec_cur) {
  				git_buf_putc(&stepbuffer, *spec_cur);
  			} else {
  				retcode = handle_colon_syntax(out, repo, cur_obj, git_buf_cstr(&stepbuffer));
  				next_state = REVPARSE_STATE_DONE;
  			}
  			spec_cur++;
  			break;
  
  		case REVPARSE_STATE_DONE:
  			if (cur_obj && *out != cur_obj) git_object_free(cur_obj);
  			if (next_obj && *out != next_obj) git_object_free(next_obj);
  			break;
  		}
  
  		current_state = next_state;
  		if (cur_obj != next_obj) {
  			if (cur_obj) git_object_free(cur_obj);
  			cur_obj = next_obj;
  		}
  	}
  
  	if (*out != cur_obj) git_object_free(cur_obj);
  	if (*out != next_obj && next_obj != cur_obj) git_object_free(next_obj);
  
  	git_buf_free(&specbuffer);
  	git_buf_free(&stepbuffer);
  	return retcode;
  }
  

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