From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 17 Jan 2017 22:49:28 +0000 (-0800)
Subject: Merge branch 'jc/renormalize-merge-kill-safer-crlf' into maint
X-Git-Tag: v2.11.1~56
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/7479ca4b44193acee43c480ae37e0bec98316f7a?hp=-c

Merge branch 'jc/renormalize-merge-kill-safer-crlf' into maint

Fix a corner case in merge-recursive regression that crept in
during 2.10 development cycle.

* jc/renormalize-merge-kill-safer-crlf:
convert: git cherry-pick -Xrenormalize did not work
merge-recursive: handle NULL in add_cacheinfo() correctly
cherry-pick: demonstrate a segmentation fault
---

7479ca4b44193acee43c480ae37e0bec98316f7a
diff --combined convert.c
index be91358462,2f90f363c6..4e17e45ed2
--- a/convert.c
+++ b/convert.c
@@@ -3,7 -3,6 +3,7 @@@
  #include "run-command.h"
  #include "quote.h"
  #include "sigchain.h"
 +#include "pkt-line.h"
  
  /*
   * convert.c - convert a file when checking it out and checking it in.
@@@ -198,21 -197,17 +198,21 @@@ static void check_safe_crlf(const char 
  		 * CRLFs would not be restored by checkout
  		 */
  		if (checksafe == SAFE_CRLF_WARN)
 -			warning("CRLF will be replaced by LF in %s.\nThe file will have its original line endings in your working directory.", path);
 +			warning(_("CRLF will be replaced by LF in %s.\n"
 +				  "The file will have its original line"
 +				  " endings in your working directory."), path);
  		else /* i.e. SAFE_CRLF_FAIL */
 -			die("CRLF would be replaced by LF in %s.", path);
 +			die(_("CRLF would be replaced by LF in %s."), path);
  	} else if (old_stats->lonelf && !new_stats->lonelf ) {
  		/*
  		 * CRLFs would be added by checkout
  		 */
  		if (checksafe == SAFE_CRLF_WARN)
 -			warning("LF will be replaced by CRLF in %s.\nThe file will have its original line endings in your working directory.", path);
 +			warning(_("LF will be replaced by CRLF in %s.\n"
 +				  "The file will have its original line"
 +				  " endings in your working directory."), path);
  		else /* i.e. SAFE_CRLF_FAIL */
 -			die("LF would be replaced by CRLF in %s", path);
 +			die(_("LF would be replaced by CRLF in %s"), path);
  	}
  }
  
@@@ -279,15 -274,16 +279,16 @@@ static int crlf_to_git(const char *path
  		if (convert_is_binary(len, &stats))
  			return 0;
  		/*
- 		 * If the file in the index has any CR in it, do not convert.
- 		 * This is the new safer autocrlf handling.
+ 		 * If the file in the index has any CR in it, do not
+ 		 * convert.  This is the new safer autocrlf handling,
+ 		 * unless we want to renormalize in a merge or
+ 		 * cherry-pick.
  		 */
- 		if (checksafe == SAFE_CRLF_RENORMALIZE)
- 			checksafe = SAFE_CRLF_FALSE;
- 		else if (has_cr_in_index(path))
+ 		if ((checksafe != SAFE_CRLF_RENORMALIZE) && has_cr_in_index(path))
  			convert_crlf_into_lf = 0;
  	}
- 	if (checksafe && len) {
+ 	if ((checksafe == SAFE_CRLF_WARN ||
+ 	    (checksafe == SAFE_CRLF_FAIL)) && len) {
  		struct text_stat new_stats;
  		memcpy(&new_stats, &stats, sizeof(new_stats));
  		/* simulate "git add" */
@@@ -417,7 -413,7 +418,7 @@@ static int filter_buffer_or_fd(int in, 
  	child_process.out = out;
  
  	if (start_command(&child_process))
 -		return error("cannot fork to run external filter %s", params->cmd);
 +		return error("cannot fork to run external filter '%s'", params->cmd);
  
  	sigchain_push(SIGPIPE, SIG_IGN);
  
@@@ -435,19 -431,19 +436,19 @@@
  	if (close(child_process.in))
  		write_err = 1;
  	if (write_err)
 -		error("cannot feed the input to external filter %s", params->cmd);
 +		error("cannot feed the input to external filter '%s'", params->cmd);
  
  	sigchain_pop(SIGPIPE);
  
  	status = finish_command(&child_process);
  	if (status)
 -		error("external filter %s failed %d", params->cmd, status);
 +		error("external filter '%s' failed %d", params->cmd, status);
  
  	strbuf_release(&cmd);
  	return (write_err || status);
  }
  
 -static int apply_filter(const char *path, const char *src, size_t len, int fd,
 +static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
                          struct strbuf *dst, const char *cmd)
  {
  	/*
@@@ -456,11 -452,17 +457,11 @@@
  	 *
  	 * (child --> cmd) --> us
  	 */
 -	int ret = 1;
 +	int err = 0;
  	struct strbuf nbuf = STRBUF_INIT;
  	struct async async;
  	struct filter_params params;
  
 -	if (!cmd || !*cmd)
 -		return 0;
 -
 -	if (!dst)
 -		return 1;
 -
  	memset(&async, 0, sizeof(async));
  	async.proc = filter_buffer_or_fd;
  	async.data = &params;
@@@ -476,304 -478,23 +477,304 @@@
  		return 0;	/* error was already reported */
  
  	if (strbuf_read(&nbuf, async.out, len) < 0) {
 -		error("read from external filter %s failed", cmd);
 -		ret = 0;
 +		err = error("read from external filter '%s' failed", cmd);
  	}
  	if (close(async.out)) {
 -		error("read from external filter %s failed", cmd);
 -		ret = 0;
 +		err = error("read from external filter '%s' failed", cmd);
  	}
  	if (finish_async(&async)) {
 -		error("external filter %s failed", cmd);
 -		ret = 0;
 +		err = error("external filter '%s' failed", cmd);
  	}
  
 -	if (ret) {
 +	if (!err) {
  		strbuf_swap(dst, &nbuf);
  	}
  	strbuf_release(&nbuf);
 -	return ret;
 +	return !err;
 +}
 +
 +#define CAP_CLEAN    (1u<<0)
 +#define CAP_SMUDGE   (1u<<1)
 +
 +struct cmd2process {
 +	struct hashmap_entry ent; /* must be the first member! */
 +	unsigned int supported_capabilities;
 +	const char *cmd;
 +	struct child_process process;
 +};
 +
 +static int cmd_process_map_initialized;
 +static struct hashmap cmd_process_map;
 +
 +static int cmd2process_cmp(const struct cmd2process *e1,
 +			   const struct cmd2process *e2,
 +			   const void *unused)
 +{
 +	return strcmp(e1->cmd, e2->cmd);
 +}
 +
 +static struct cmd2process *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
 +{
 +	struct cmd2process key;
 +	hashmap_entry_init(&key, strhash(cmd));
 +	key.cmd = cmd;
 +	return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int packet_write_list(int fd, const char *line, ...)
 +{
 +	va_list args;
 +	int err;
 +	va_start(args, line);
 +	for (;;) {
 +		if (!line)
 +			break;
 +		if (strlen(line) > LARGE_PACKET_DATA_MAX)
 +			return -1;
 +		err = packet_write_fmt_gently(fd, "%s\n", line);
 +		if (err)
 +			return err;
 +		line = va_arg(args, const char*);
 +	}
 +	va_end(args);
 +	return packet_flush_gently(fd);
 +}
 +
 +static void read_multi_file_filter_status(int fd, struct strbuf *status)
 +{
 +	struct strbuf **pair;
 +	char *line;
 +	for (;;) {
 +		line = packet_read_line(fd, NULL);
 +		if (!line)
 +			break;
 +		pair = strbuf_split_str(line, '=', 2);
 +		if (pair[0] && pair[0]->len && pair[1]) {
 +			/* the last "status=<foo>" line wins */
 +			if (!strcmp(pair[0]->buf, "status=")) {
 +				strbuf_reset(status);
 +				strbuf_addbuf(status, pair[1]);
 +			}
 +		}
 +		strbuf_list_free(pair);
 +	}
 +}
 +
 +static void kill_multi_file_filter(struct hashmap *hashmap, struct cmd2process *entry)
 +{
 +	if (!entry)
 +		return;
 +
 +	entry->process.clean_on_exit = 0;
 +	kill(entry->process.pid, SIGTERM);
 +	finish_command(&entry->process);
 +
 +	hashmap_remove(hashmap, entry, NULL);
 +	free(entry);
 +}
 +
 +static void stop_multi_file_filter(struct child_process *process)
 +{
 +	sigchain_push(SIGPIPE, SIG_IGN);
 +	/* Closing the pipe signals the filter to initiate a shutdown. */
 +	close(process->in);
 +	close(process->out);
 +	sigchain_pop(SIGPIPE);
 +	/* Finish command will wait until the shutdown is complete. */
 +	finish_command(process);
 +}
 +
 +static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
 +{
 +	int err;
 +	struct cmd2process *entry;
 +	struct child_process *process;
 +	const char *argv[] = { cmd, NULL };
 +	struct string_list cap_list = STRING_LIST_INIT_NODUP;
 +	char *cap_buf;
 +	const char *cap_name;
 +
 +	entry = xmalloc(sizeof(*entry));
 +	entry->cmd = cmd;
 +	entry->supported_capabilities = 0;
 +	process = &entry->process;
 +
 +	child_process_init(process);
 +	process->argv = argv;
 +	process->use_shell = 1;
 +	process->in = -1;
 +	process->out = -1;
 +	process->clean_on_exit = 1;
 +	process->clean_on_exit_handler = stop_multi_file_filter;
 +
 +	if (start_command(process)) {
 +		error("cannot fork to run external filter '%s'", cmd);
 +		return NULL;
 +	}
 +
 +	hashmap_entry_init(entry, strhash(cmd));
 +
 +	sigchain_push(SIGPIPE, SIG_IGN);
 +
 +	err = packet_write_list(process->in, "git-filter-client", "version=2", NULL);
 +	if (err)
 +		goto done;
 +
 +	err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
 +	if (err) {
 +		error("external filter '%s' does not support filter protocol version 2", cmd);
 +		goto done;
 +	}
 +	err = strcmp(packet_read_line(process->out, NULL), "version=2");
 +	if (err)
 +		goto done;
 +	err = packet_read_line(process->out, NULL) != NULL;
 +	if (err)
 +		goto done;
 +
 +	err = packet_write_list(process->in, "capability=clean", "capability=smudge", NULL);
 +
 +	for (;;) {
 +		cap_buf = packet_read_line(process->out, NULL);
 +		if (!cap_buf)
 +			break;
 +		string_list_split_in_place(&cap_list, cap_buf, '=', 1);
 +
 +		if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
 +			continue;
 +
 +		cap_name = cap_list.items[1].string;
 +		if (!strcmp(cap_name, "clean")) {
 +			entry->supported_capabilities |= CAP_CLEAN;
 +		} else if (!strcmp(cap_name, "smudge")) {
 +			entry->supported_capabilities |= CAP_SMUDGE;
 +		} else {
 +			warning(
 +				"external filter '%s' requested unsupported filter capability '%s'",
 +				cmd, cap_name
 +			);
 +		}
 +
 +		string_list_clear(&cap_list, 0);
 +	}
 +
 +done:
 +	sigchain_pop(SIGPIPE);
 +
 +	if (err || errno == EPIPE) {
 +		error("initialization for external filter '%s' failed", cmd);
 +		kill_multi_file_filter(hashmap, entry);
 +		return NULL;
 +	}
 +
 +	hashmap_add(hashmap, entry);
 +	return entry;
 +}
 +
 +static int apply_multi_file_filter(const char *path, const char *src, size_t len,
 +				   int fd, struct strbuf *dst, const char *cmd,
 +				   const unsigned int wanted_capability)
 +{
 +	int err;
 +	struct cmd2process *entry;
 +	struct child_process *process;
 +	struct strbuf nbuf = STRBUF_INIT;
 +	struct strbuf filter_status = STRBUF_INIT;
 +	const char *filter_type;
 +
 +	if (!cmd_process_map_initialized) {
 +		cmd_process_map_initialized = 1;
 +		hashmap_init(&cmd_process_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 +		entry = NULL;
 +	} else {
 +		entry = find_multi_file_filter_entry(&cmd_process_map, cmd);
 +	}
 +
 +	fflush(NULL);
 +
 +	if (!entry) {
 +		entry = start_multi_file_filter(&cmd_process_map, cmd);
 +		if (!entry)
 +			return 0;
 +	}
 +	process = &entry->process;
 +
 +	if (!(wanted_capability & entry->supported_capabilities))
 +		return 0;
 +
 +	if (CAP_CLEAN & wanted_capability)
 +		filter_type = "clean";
 +	else if (CAP_SMUDGE & wanted_capability)
 +		filter_type = "smudge";
 +	else
 +		die("unexpected filter type");
 +
 +	sigchain_push(SIGPIPE, SIG_IGN);
 +
 +	assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
 +	err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
 +	if (err)
 +		goto done;
 +
 +	err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
 +	if (err) {
 +		error("path name too long for external filter");
 +		goto done;
 +	}
 +
 +	err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
 +	if (err)
 +		goto done;
 +
 +	err = packet_flush_gently(process->in);
 +	if (err)
 +		goto done;
 +
 +	if (fd >= 0)
 +		err = write_packetized_from_fd(fd, process->in);
 +	else
 +		err = write_packetized_from_buf(src, len, process->in);
 +	if (err)
 +		goto done;
 +
 +	read_multi_file_filter_status(process->out, &filter_status);
 +	err = strcmp(filter_status.buf, "success");
 +	if (err)
 +		goto done;
 +
 +	err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
 +	if (err)
 +		goto done;
 +
 +	read_multi_file_filter_status(process->out, &filter_status);
 +	err = strcmp(filter_status.buf, "success");
 +
 +done:
 +	sigchain_pop(SIGPIPE);
 +
 +	if (err || errno == EPIPE) {
 +		if (!strcmp(filter_status.buf, "error")) {
 +			/* The filter signaled a problem with the file. */
 +		} else if (!strcmp(filter_status.buf, "abort")) {
 +			/*
 +			 * The filter signaled a permanent problem. Don't try to filter
 +			 * files with the same command for the lifetime of the current
 +			 * Git process.
 +			 */
 +			 entry->supported_capabilities &= ~wanted_capability;
 +		} else {
 +			/*
 +			 * Something went wrong with the protocol filter.
 +			 * Force shutdown and restart if another blob requires filtering.
 +			 */
 +			error("external filter '%s' failed", cmd);
 +			kill_multi_file_filter(&cmd_process_map, entry);
 +		}
 +	} else {
 +		strbuf_swap(dst, &nbuf);
 +	}
 +	strbuf_release(&nbuf);
 +	return !err;
  }
  
  static struct convert_driver {
@@@ -781,35 -502,9 +782,35 @@@
  	struct convert_driver *next;
  	const char *smudge;
  	const char *clean;
 +	const char *process;
  	int required;
  } *user_convert, **user_convert_tail;
  
 +static int apply_filter(const char *path, const char *src, size_t len,
 +			int fd, struct strbuf *dst, struct convert_driver *drv,
 +			const unsigned int wanted_capability)
 +{
 +	const char *cmd = NULL;
 +
 +	if (!drv)
 +		return 0;
 +
 +	if (!dst)
 +		return 1;
 +
 +	if ((CAP_CLEAN & wanted_capability) && !drv->process && drv->clean)
 +		cmd = drv->clean;
 +	else if ((CAP_SMUDGE & wanted_capability) && !drv->process && drv->smudge)
 +		cmd = drv->smudge;
 +
 +	if (cmd && *cmd)
 +		return apply_single_file_filter(path, src, len, fd, dst, cmd);
 +	else if (drv->process && *drv->process)
 +		return apply_multi_file_filter(path, src, len, fd, dst, drv->process, wanted_capability);
 +
 +	return 0;
 +}
 +
  static int read_convert_config(const char *var, const char *value, void *cb)
  {
  	const char *key, *name;
@@@ -847,9 -542,6 +848,9 @@@
  	if (!strcmp("clean", key))
  		return git_config_string(&drv->clean, var, value);
  
 +	if (!strcmp("process", key))
 +		return git_config_string(&drv->process, var, value);
 +
  	if (!strcmp("required", key)) {
  		drv->required = git_config_bool(var, value);
  		return 0;
@@@ -1151,7 -843,7 +1152,7 @@@ int would_convert_to_git_filter_fd(cons
  	if (!ca.drv->required)
  		return 0;
  
 -	return apply_filter(path, NULL, 0, -1, NULL, ca.drv->clean);
 +	return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN);
  }
  
  const char *get_convert_attr_ascii(const char *path)
@@@ -1184,12 -876,18 +1185,12 @@@ int convert_to_git(const char *path, co
                     struct strbuf *dst, enum safe_crlf checksafe)
  {
  	int ret = 0;
 -	const char *filter = NULL;
 -	int required = 0;
  	struct conv_attrs ca;
  
  	convert_attrs(&ca, path);
 -	if (ca.drv) {
 -		filter = ca.drv->clean;
 -		required = ca.drv->required;
 -	}
  
 -	ret |= apply_filter(path, src, len, -1, dst, filter);
 -	if (!ret && required)
 +	ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN);
 +	if (!ret && ca.drv && ca.drv->required)
  		die("%s: clean filter '%s' failed", path, ca.drv->name);
  
  	if (ret && dst) {
@@@ -1211,9 -909,9 +1212,9 @@@ void convert_to_git_filter_fd(const cha
  	convert_attrs(&ca, path);
  
  	assert(ca.drv);
 -	assert(ca.drv->clean);
 +	assert(ca.drv->clean || ca.drv->process);
  
 -	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv->clean))
 +	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
  		die("%s: clean filter '%s' failed", path, ca.drv->name);
  
  	crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
@@@ -1225,9 -923,15 +1226,9 @@@ static int convert_to_working_tree_inte
  					    int normalizing)
  {
  	int ret = 0, ret_filter = 0;
 -	const char *filter = NULL;
 -	int required = 0;
  	struct conv_attrs ca;
  
  	convert_attrs(&ca, path);
 -	if (ca.drv) {
 -		filter = ca.drv->smudge;
 -		required = ca.drv->required;
 -	}
  
  	ret |= ident_to_worktree(path, src, len, dst, ca.ident);
  	if (ret) {
@@@ -1236,10 -940,9 +1237,10 @@@
  	}
  	/*
  	 * CRLF conversion can be skipped if normalizing, unless there
 -	 * is a smudge filter.  The filter might expect CRLFs.
 +	 * is a smudge or process filter (even if the process filter doesn't
 +	 * support smudge).  The filters might expect CRLFs.
  	 */
 -	if (filter || !normalizing) {
 +	if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
  		ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
  		if (ret) {
  			src = dst->buf;
@@@ -1247,8 -950,8 +1248,8 @@@
  		}
  	}
  
 -	ret_filter = apply_filter(path, src, len, -1, dst, filter);
 -	if (!ret_filter && required)
 +	ret_filter = apply_filter(path, src, len, -1, dst, ca.drv, CAP_SMUDGE);
 +	if (!ret_filter && ca.drv && ca.drv->required)
  		die("%s: smudge filter %s failed", path, ca.drv->name);
  
  	return ret | ret_filter;
@@@ -1700,7 -1403,7 +1701,7 @@@ struct stream_filter *get_stream_filter
  	struct stream_filter *filter = NULL;
  
  	convert_attrs(&ca, path);
 -	if (ca.drv && (ca.drv->smudge || ca.drv->clean))
 +	if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
  		return NULL;
  
  	if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
diff --combined merge-recursive.c
index e64b48b25d,56385d4c01..214f5a693b
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@@ -23,46 -23,15 +23,46 @@@
  #include "dir.h"
  #include "submodule.h"
  
 +static void flush_output(struct merge_options *o)
 +{
 +	if (o->buffer_output < 2 && o->obuf.len) {
 +		fputs(o->obuf.buf, stdout);
 +		strbuf_reset(&o->obuf);
 +	}
 +}
 +
 +static int err(struct merge_options *o, const char *err, ...)
 +{
 +	va_list params;
 +
 +	if (o->buffer_output < 2)
 +		flush_output(o);
 +	else {
 +		strbuf_complete(&o->obuf, '\n');
 +		strbuf_addstr(&o->obuf, "error: ");
 +	}
 +	va_start(params, err);
 +	strbuf_vaddf(&o->obuf, err, params);
 +	va_end(params);
 +	if (o->buffer_output > 1)
 +		strbuf_addch(&o->obuf, '\n');
 +	else {
 +		error("%s", o->obuf.buf);
 +		strbuf_reset(&o->obuf);
 +	}
 +
 +	return -1;
 +}
 +
  static struct tree *shift_tree_object(struct tree *one, struct tree *two,
  				      const char *subtree_shift)
  {
  	struct object_id shifted;
  
  	if (!*subtree_shift) {
 -		shift_tree(one->object.oid.hash, two->object.oid.hash, shifted.hash, 0);
 +		shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
  	} else {
 -		shift_tree_by(one->object.oid.hash, two->object.oid.hash, shifted.hash,
 +		shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
  			      subtree_shift);
  	}
  	if (!oidcmp(&two->object.oid, &shifted))
@@@ -73,9 -42,12 +73,9 @@@
  static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  {
  	struct commit *commit = alloc_commit_node();
 -	struct merge_remote_desc *desc = xmalloc(sizeof(*desc));
  
 -	desc->name = comment;
 -	desc->obj = (struct object *)commit;
 +	set_merge_remote_desc(commit, comment, (struct object *)commit);
  	commit->tree = tree;
 -	commit->util = desc;
  	commit->object.parsed = 1;
  	return commit;
  }
@@@ -84,11 -56,11 +84,11 @@@
   * Since we use get_tree_entry(), which does not put the read object into
   * the object pool, we cannot rely on a == b.
   */
 -static int sha_eq(const unsigned char *a, const unsigned char *b)
 +static int oid_eq(const struct object_id *a, const struct object_id *b)
  {
  	if (!a && !b)
  		return 2;
 -	return a && b && hashcmp(a, b) == 0;
 +	return a && b && oidcmp(a, b) == 0;
  }
  
  enum rename_type {
@@@ -118,7 -90,7 +118,7 @@@ struct rename_conflict_info 
  struct stage_data {
  	struct {
  		unsigned mode;
 -		unsigned char sha[20];
 +		struct object_id oid;
  	} stages[4];
  	struct rename_conflict_info *rename_conflict_info;
  	unsigned processed:1;
@@@ -162,11 -134,11 +162,11 @@@ static inline void setup_rename_conflic
  		int ostage2 = ostage1 ^ 1;
  
  		ci->ren1_other.path = pair1->one->path;
 -		hashcpy(ci->ren1_other.sha1, src_entry1->stages[ostage1].sha);
 +		oidcpy(&ci->ren1_other.oid, &src_entry1->stages[ostage1].oid);
  		ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
  
  		ci->ren2_other.path = pair2->one->path;
 -		hashcpy(ci->ren2_other.sha1, src_entry2->stages[ostage2].sha);
 +		oidcpy(&ci->ren2_other.oid, &src_entry2->stages[ostage2].oid);
  		ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
  	}
  }
@@@ -176,6 -148,14 +176,6 @@@ static int show(struct merge_options *o
  	return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
  }
  
 -static void flush_output(struct merge_options *o)
 -{
 -	if (o->obuf.len) {
 -		fputs(o->obuf.buf, stdout);
 -		strbuf_reset(&o->obuf);
 -	}
 -}
 -
  __attribute__((format (printf, 3, 4)))
  static void output(struct merge_options *o, int v, const char *fmt, ...)
  {
@@@ -197,44 -177,44 +197,46 @@@
  
  static void output_commit_title(struct merge_options *o, struct commit *commit)
  {
 -	int i;
 -	flush_output(o);
 -	for (i = o->call_depth; i--;)
 -		fputs("  ", stdout);
 +	strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
  	if (commit->util)
 -		printf("virtual %s\n", merge_remote_util(commit)->name);
 +		strbuf_addf(&o->obuf, "virtual %s\n",
 +			merge_remote_util(commit)->name);
  	else {
 -		printf("%s ", find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 +		strbuf_add_unique_abbrev(&o->obuf, commit->object.oid.hash,
 +					 DEFAULT_ABBREV);
 +		strbuf_addch(&o->obuf, ' ');
  		if (parse_commit(commit) != 0)
 -			printf(_("(bad commit)\n"));
 +			strbuf_addstr(&o->obuf, _("(bad commit)\n"));
  		else {
  			const char *title;
  			const char *msg = get_commit_buffer(commit, NULL);
  			int len = find_commit_subject(msg, &title);
  			if (len)
 -				printf("%.*s\n", len, title);
 +				strbuf_addf(&o->obuf, "%.*s\n", len, title);
  			unuse_commit_buffer(commit, msg);
  		}
  	}
 +	flush_output(o);
  }
  
 -static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 +static int add_cacheinfo(struct merge_options *o,
 +		unsigned int mode, const struct object_id *oid,
  		const char *path, int stage, int refresh, int options)
  {
  	struct cache_entry *ce;
  	int ret;
  
 -	ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, 0);
 +	ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
  	if (!ce)
 -		return error(_("addinfo_cache failed for path '%s'"), path);
 +		return err(o, _("addinfo_cache failed for path '%s'"), path);
  
  	ret = add_cache_entry(ce, options);
  	if (refresh) {
  		struct cache_entry *nce;
  
  		nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
+ 		if (!nce)
 -			return error(_("addinfo_cache failed for path '%s'"), path);
++			return err(o, _("addinfo_cache failed for path '%s'"), path);
  		if (nce != ce)
  			ret = add_cache_entry(nce, options);
  	}
@@@ -290,17 -270,15 +292,17 @@@ struct tree *write_tree_from_memory(str
  				fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
  					(int)ce_namelen(ce), ce->name);
  		}
 -		die("Bug in merge-recursive.c");
 +		die("BUG: unmerged index entries in merge-recursive.c");
  	}
  
  	if (!active_cache_tree)
  		active_cache_tree = cache_tree();
  
  	if (!cache_tree_fully_valid(active_cache_tree) &&
 -	    cache_tree_update(&the_index, 0) < 0)
 -		die(_("error building trees"));
 +	    cache_tree_update(&the_index, 0) < 0) {
 +		err(o, _("error building trees"));
 +		return NULL;
 +	}
  
  	result = lookup_tree(active_cache_tree->sha1);
  
@@@ -347,11 -325,11 +349,11 @@@ static struct stage_data *insert_stage_
  	struct string_list_item *item;
  	struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
  	get_tree_entry(o->object.oid.hash, path,
 -			e->stages[1].sha, &e->stages[1].mode);
 +			e->stages[1].oid.hash, &e->stages[1].mode);
  	get_tree_entry(a->object.oid.hash, path,
 -			e->stages[2].sha, &e->stages[2].mode);
 +			e->stages[2].oid.hash, &e->stages[2].mode);
  	get_tree_entry(b->object.oid.hash, path,
 -			e->stages[3].sha, &e->stages[3].mode);
 +			e->stages[3].oid.hash, &e->stages[3].mode);
  	item = string_list_insert(entries, path);
  	item->util = e;
  	return e;
@@@ -382,7 -360,7 +384,7 @@@ static struct string_list *get_unmerged
  		}
  		e = item->util;
  		e->stages[ce_stage(ce)].mode = ce->ce_mode;
 -		hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 +		oidcpy(&e->stages[ce_stage(ce)].oid, &ce->oid);
  	}
  
  	return unmerged;
@@@ -433,7 -411,7 +435,7 @@@ static void record_df_conflict_files(st
  	 * and the file need to be present, then the D/F file will be
  	 * reinstated with a new unique name at the time it is processed.
  	 */
 -	struct string_list df_sorted_entries;
 +	struct string_list df_sorted_entries = STRING_LIST_INIT_NODUP;
  	const char *last_file = NULL;
  	int last_len = 0;
  	int i;
@@@ -446,6 -424,7 +448,6 @@@
  		return;
  
  	/* Ensure D/F conflicts are adjacent in the entries list. */
 -	memset(&df_sorted_entries, 0, sizeof(struct string_list));
  	for (i = 0; i < entries->nr; i++) {
  		struct string_list_item *next = &entries->items[i];
  		string_list_append(&df_sorted_entries, next->string)->util =
@@@ -565,8 -544,7 +567,8 @@@ static struct string_list *get_renames(
  	return renames;
  }
  
 -static int update_stages(const char *path, const struct diff_filespec *o,
 +static int update_stages(struct merge_options *opt, const char *path,
 +			 const struct diff_filespec *o,
  			 const struct diff_filespec *a,
  			 const struct diff_filespec *b)
  {
@@@ -585,13 -563,13 +587,13 @@@
  		if (remove_file_from_cache(path))
  			return -1;
  	if (o)
 -		if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 +		if (add_cacheinfo(opt, o->mode, &o->oid, path, 1, 0, options))
  			return -1;
  	if (a)
 -		if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 +		if (add_cacheinfo(opt, a->mode, &a->oid, path, 2, 0, options))
  			return -1;
  	if (b)
 -		if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 +		if (add_cacheinfo(opt, b->mode, &b->oid, path, 3, 0, options))
  			return -1;
  	return 0;
  }
@@@ -605,9 -583,9 +607,9 @@@ static void update_entry(struct stage_d
  	entry->stages[1].mode = o->mode;
  	entry->stages[2].mode = a->mode;
  	entry->stages[3].mode = b->mode;
 -	hashcpy(entry->stages[1].sha, o->sha1);
 -	hashcpy(entry->stages[2].sha, a->sha1);
 -	hashcpy(entry->stages[3].sha, b->sha1);
 +	oidcpy(&entry->stages[1].oid, &o->oid);
 +	oidcpy(&entry->stages[2].oid, &a->oid);
 +	oidcpy(&entry->stages[3].oid, &b->oid);
  }
  
  static int remove_file(struct merge_options *o, int clean,
@@@ -655,7 -633,7 +657,7 @@@ static char *unique_path(struct merge_o
  	base_len = newpath.len;
  	while (string_list_has_string(&o->current_file_set, newpath.buf) ||
  	       string_list_has_string(&o->current_directory_set, newpath.buf) ||
 -	       file_exists(newpath.buf)) {
 +	       (!o->call_depth && file_exists(newpath.buf))) {
  		strbuf_setlen(&newpath, base_len);
  		strbuf_addf(&newpath, "_%d", suffix++);
  	}
@@@ -664,13 -642,7 +666,13 @@@
  	return strbuf_detach(&newpath, NULL);
  }
  
 -static int dir_in_way(const char *path, int check_working_copy)
 +/**
 + * Check whether a directory in the index is in the way of an incoming
 + * file.  Return 1 if so.  If check_working_copy is non-zero, also
 + * check the working directory.  If empty_ok is non-zero, also return
 + * 0 in the case where the working-tree dir exists but is empty.
 + */
 +static int dir_in_way(const char *path, int check_working_copy, int empty_ok)
  {
  	int pos;
  	struct strbuf dirpath = STRBUF_INIT;
@@@ -690,29 -662,30 +692,29 @@@
  	}
  
  	strbuf_release(&dirpath);
 -	return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 +	return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode) &&
 +		!(empty_ok && is_empty_dir(path));
  }
  
  static int was_tracked(const char *path)
  {
  	int pos = cache_name_pos(path, strlen(path));
  
 -	if (pos < 0)
 -		pos = -1 - pos;
 -	while (pos < active_nr &&
 -	       !strcmp(path, active_cache[pos]->name)) {
 -		/*
 -		 * If stage #0, it is definitely tracked.
 -		 * If it has stage #2 then it was tracked
 -		 * before this merge started.  All other
 -		 * cases the path was not tracked.
 -		 */
 -		switch (ce_stage(active_cache[pos])) {
 -		case 0:
 -		case 2:
 +	if (0 <= pos)
 +		/* we have been tracking this path */
 +		return 1;
 +
 +	/*
 +	 * Look for an unmerged entry for the path,
 +	 * specifically stage #2, which would indicate
 +	 * that "our" side before the merge started
 +	 * had the path tracked (and resulted in a conflict).
 +	 */
 +	for (pos = -1 - pos;
 +	     pos < active_nr && !strcmp(path, active_cache[pos]->name);
 +	     pos++)
 +		if (ce_stage(active_cache[pos]) == 2)
  			return 1;
 -		}
 -		pos++;
 -	}
  	return 0;
  }
  
@@@ -747,10 -720,12 +749,10 @@@ static int make_room_for_path(struct me
  	/* Make sure leading directories are created */
  	status = safe_create_leading_directories_const(path);
  	if (status) {
 -		if (status == SCLD_EXISTS) {
 +		if (status == SCLD_EXISTS)
  			/* something else exists */
 -			error(msg, path, _(": perhaps a D/F conflict?"));
 -			return -1;
 -		}
 -		die(msg, path, "");
 +			return err(o, msg, path, _(": perhaps a D/F conflict?"));
 +		return err(o, msg, path, "");
  	}
  
  	/*
@@@ -758,7 -733,7 +760,7 @@@
  	 * tracking it.
  	 */
  	if (would_lose_untracked(path))
 -		return error(_("refusing to lose untracked file at '%s'"),
 +		return err(o, _("refusing to lose untracked file at '%s'"),
  			     path);
  
  	/* Successful unlink is good.. */
@@@ -768,18 -743,16 +770,18 @@@
  	if (errno == ENOENT)
  		return 0;
  	/* .. but not some other error (who really cares what?) */
 -	return error(msg, path, _(": perhaps a D/F conflict?"));
 +	return err(o, msg, path, _(": perhaps a D/F conflict?"));
  }
  
 -static void update_file_flags(struct merge_options *o,
 -			      const unsigned char *sha,
 -			      unsigned mode,
 -			      const char *path,
 -			      int update_cache,
 -			      int update_wd)
 +static int update_file_flags(struct merge_options *o,
 +			     const struct object_id *oid,
 +			     unsigned mode,
 +			     const char *path,
 +			     int update_cache,
 +			     int update_wd)
  {
 +	int ret = 0;
 +
  	if (o->call_depth)
  		update_wd = 0;
  
@@@ -798,13 -771,11 +800,13 @@@
  			goto update_index;
  		}
  
 -		buf = read_sha1_file(sha, &type, &size);
 +		buf = read_sha1_file(oid->hash, &type, &size);
  		if (!buf)
 -			die(_("cannot read object %s '%s'"), sha1_to_hex(sha), path);
 -		if (type != OBJ_BLOB)
 -			die(_("blob expected for %s '%s'"), sha1_to_hex(sha), path);
 +			return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
 +		if (type != OBJ_BLOB) {
 +			ret = err(o, _("blob expected for %s '%s'"), oid_to_hex(oid), path);
 +			goto free_buf;
 +		}
  		if (S_ISREG(mode)) {
  			struct strbuf strbuf = STRBUF_INIT;
  			if (convert_to_working_tree(path, buf, size, &strbuf)) {
@@@ -816,7 -787,8 +818,7 @@@
  
  		if (make_room_for_path(o, path) < 0) {
  			update_wd = 0;
 -			free(buf);
 -			goto update_index;
 +			goto free_buf;
  		}
  		if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
  			int fd;
@@@ -825,11 -797,8 +827,11 @@@
  			else
  				mode = 0666;
  			fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 -			if (fd < 0)
 -				die_errno(_("failed to open '%s'"), path);
 +			if (fd < 0) {
 +				ret = err(o, _("failed to open '%s': %s"),
 +					  path, strerror(errno));
 +				goto free_buf;
 +			}
  			write_in_full(fd, buf, size);
  			close(fd);
  		} else if (S_ISLNK(mode)) {
@@@ -837,35 -806,31 +839,35 @@@
  			safe_create_leading_directories_const(path);
  			unlink(path);
  			if (symlink(lnk, path))
 -				die_errno(_("failed to symlink '%s'"), path);
 +				ret = err(o, _("failed to symlink '%s': %s"),
 +					path, strerror(errno));
  			free(lnk);
  		} else
 -			die(_("do not know what to do with %06o %s '%s'"),
 -			    mode, sha1_to_hex(sha), path);
 +			ret = err(o,
 +				  _("do not know what to do with %06o %s '%s'"),
 +				  mode, oid_to_hex(oid), path);
 + free_buf:
  		free(buf);
  	}
   update_index:
 -	if (update_cache)
 -		add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 +	if (!ret && update_cache)
 +		add_cacheinfo(o, mode, oid, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 +	return ret;
  }
  
 -static void update_file(struct merge_options *o,
 -			int clean,
 -			const unsigned char *sha,
 -			unsigned mode,
 -			const char *path)
 +static int update_file(struct merge_options *o,
 +		       int clean,
 +		       const struct object_id *oid,
 +		       unsigned mode,
 +		       const char *path)
  {
 -	update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 +	return update_file_flags(o, oid, mode, path, o->call_depth || clean, !o->call_depth);
  }
  
  /* Low level file merging, update and removal */
  
  struct merge_file_info {
 -	unsigned char sha[20];
 +	struct object_id oid;
  	unsigned mode;
  	unsigned clean:1,
  		 merge:1;
@@@ -917,9 -882,9 +919,9 @@@ static int merge_3way(struct merge_opti
  		name2 = mkpathdup("%s", branch2);
  	}
  
 -	read_mmblob(&orig, one->sha1);
 -	read_mmblob(&src1, a->sha1);
 -	read_mmblob(&src2, b->sha1);
 +	read_mmblob(&orig, &one->oid);
 +	read_mmblob(&src1, &a->oid);
 +	read_mmblob(&src2, &b->oid);
  
  	merge_status = ll_merge(result_buf, a->path, &orig, base_name,
  				&src1, name1, &src2, name2, &ll_opts);
@@@ -933,144 -898,138 +935,144 @@@
  	return merge_status;
  }
  
 -static struct merge_file_info merge_file_1(struct merge_options *o,
 +static int merge_file_1(struct merge_options *o,
  					   const struct diff_filespec *one,
  					   const struct diff_filespec *a,
  					   const struct diff_filespec *b,
  					   const char *branch1,
 -					   const char *branch2)
 +					   const char *branch2,
 +					   struct merge_file_info *result)
  {
 -	struct merge_file_info result;
 -	result.merge = 0;
 -	result.clean = 1;
 +	result->merge = 0;
 +	result->clean = 1;
  
  	if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 -		result.clean = 0;
 +		result->clean = 0;
  		if (S_ISREG(a->mode)) {
 -			result.mode = a->mode;
 -			hashcpy(result.sha, a->sha1);
 +			result->mode = a->mode;
 +			oidcpy(&result->oid, &a->oid);
  		} else {
 -			result.mode = b->mode;
 -			hashcpy(result.sha, b->sha1);
 +			result->mode = b->mode;
 +			oidcpy(&result->oid, &b->oid);
  		}
  	} else {
 -		if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 -			result.merge = 1;
 +		if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
 +			result->merge = 1;
  
  		/*
  		 * Merge modes
  		 */
  		if (a->mode == b->mode || a->mode == one->mode)
 -			result.mode = b->mode;
 +			result->mode = b->mode;
  		else {
 -			result.mode = a->mode;
 +			result->mode = a->mode;
  			if (b->mode != one->mode) {
 -				result.clean = 0;
 -				result.merge = 1;
 +				result->clean = 0;
 +				result->merge = 1;
  			}
  		}
  
 -		if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 -			hashcpy(result.sha, b->sha1);
 -		else if (sha_eq(b->sha1, one->sha1))
 -			hashcpy(result.sha, a->sha1);
 +		if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
 +			oidcpy(&result->oid, &b->oid);
 +		else if (oid_eq(&b->oid, &one->oid))
 +			oidcpy(&result->oid, &a->oid);
  		else if (S_ISREG(a->mode)) {
  			mmbuffer_t result_buf;
 -			int merge_status;
 +			int ret = 0, merge_status;
  
  			merge_status = merge_3way(o, &result_buf, one, a, b,
  						  branch1, branch2);
  
  			if ((merge_status < 0) || !result_buf.ptr)
 -				die(_("Failed to execute internal merge"));
 +				ret = err(o, _("Failed to execute internal merge"));
  
 -			if (write_sha1_file(result_buf.ptr, result_buf.size,
 -					    blob_type, result.sha))
 -				die(_("Unable to add %s to database"),
 -				    a->path);
 +			if (!ret && write_sha1_file(result_buf.ptr, result_buf.size,
 +						    blob_type, result->oid.hash))
 +				ret = err(o, _("Unable to add %s to database"),
 +					  a->path);
  
  			free(result_buf.ptr);
 -			result.clean = (merge_status == 0);
 +			if (ret)
 +				return ret;
 +			result->clean = (merge_status == 0);
  		} else if (S_ISGITLINK(a->mode)) {
 -			result.clean = merge_submodule(result.sha,
 -						       one->path, one->sha1,
 -						       a->sha1, b->sha1,
 +			result->clean = merge_submodule(result->oid.hash,
 +						       one->path,
 +						       one->oid.hash,
 +						       a->oid.hash,
 +						       b->oid.hash,
  						       !o->call_depth);
  		} else if (S_ISLNK(a->mode)) {
 -			hashcpy(result.sha, a->sha1);
 +			oidcpy(&result->oid, &a->oid);
  
 -			if (!sha_eq(a->sha1, b->sha1))
 -				result.clean = 0;
 -		} else {
 -			die(_("unsupported object type in the tree"));
 -		}
 +			if (!oid_eq(&a->oid, &b->oid))
 +				result->clean = 0;
 +		} else
 +			die("BUG: unsupported object type in the tree");
  	}
  
 -	return result;
 +	return 0;
  }
  
 -static struct merge_file_info
 -merge_file_special_markers(struct merge_options *o,
 +static int merge_file_special_markers(struct merge_options *o,
  			   const struct diff_filespec *one,
  			   const struct diff_filespec *a,
  			   const struct diff_filespec *b,
  			   const char *branch1,
  			   const char *filename1,
  			   const char *branch2,
 -			   const char *filename2)
 +			   const char *filename2,
 +			   struct merge_file_info *mfi)
  {
  	char *side1 = NULL;
  	char *side2 = NULL;
 -	struct merge_file_info mfi;
 +	int ret;
  
  	if (filename1)
  		side1 = xstrfmt("%s:%s", branch1, filename1);
  	if (filename2)
  		side2 = xstrfmt("%s:%s", branch2, filename2);
  
 -	mfi = merge_file_1(o, one, a, b,
 -			   side1 ? side1 : branch1, side2 ? side2 : branch2);
 +	ret = merge_file_1(o, one, a, b,
 +			   side1 ? side1 : branch1,
 +			   side2 ? side2 : branch2, mfi);
  	free(side1);
  	free(side2);
 -	return mfi;
 +	return ret;
  }
  
 -static struct merge_file_info merge_file_one(struct merge_options *o,
 +static int merge_file_one(struct merge_options *o,
  					 const char *path,
 -					 const unsigned char *o_sha, int o_mode,
 -					 const unsigned char *a_sha, int a_mode,
 -					 const unsigned char *b_sha, int b_mode,
 +					 const struct object_id *o_oid, int o_mode,
 +					 const struct object_id *a_oid, int a_mode,
 +					 const struct object_id *b_oid, int b_mode,
  					 const char *branch1,
 -					 const char *branch2)
 +					 const char *branch2,
 +					 struct merge_file_info *mfi)
  {
  	struct diff_filespec one, a, b;
  
  	one.path = a.path = b.path = (char *)path;
 -	hashcpy(one.sha1, o_sha);
 +	oidcpy(&one.oid, o_oid);
  	one.mode = o_mode;
 -	hashcpy(a.sha1, a_sha);
 +	oidcpy(&a.oid, a_oid);
  	a.mode = a_mode;
 -	hashcpy(b.sha1, b_sha);
 +	oidcpy(&b.oid, b_oid);
  	b.mode = b_mode;
 -	return merge_file_1(o, &one, &a, &b, branch1, branch2);
 +	return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
  }
  
 -static void handle_change_delete(struct merge_options *o,
 +static int handle_change_delete(struct merge_options *o,
  				 const char *path,
 -				 const unsigned char *o_sha, int o_mode,
 -				 const unsigned char *a_sha, int a_mode,
 -				 const unsigned char *b_sha, int b_mode,
 +				 const struct object_id *o_oid, int o_mode,
 +				 const struct object_id *a_oid, int a_mode,
 +				 const struct object_id *b_oid, int b_mode,
  				 const char *change, const char *change_past)
  {
  	char *renamed = NULL;
 -	if (dir_in_way(path, !o->call_depth)) {
 -		renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
 +	int ret = 0;
 +	if (dir_in_way(path, !o->call_depth, 0)) {
 +		renamed = unique_path(o, path, a_oid ? o->branch1 : o->branch2);
  	}
  
  	if (o->call_depth) {
@@@ -1079,23 -1038,21 +1081,23 @@@
  		 * correct; since there is no true "middle point" between
  		 * them, simply reuse the base version for virtual merge base.
  		 */
 -		remove_file_from_cache(path);
 -		update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
 -	} else if (!a_sha) {
 +		ret = remove_file_from_cache(path);
 +		if (!ret)
 +			ret = update_file(o, 0, o_oid, o_mode,
 +					  renamed ? renamed : path);
 +	} else if (!a_oid) {
  		if (!renamed) {
  			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
  			       "and %s in %s. Version %s of %s left in tree."),
  			       change, path, o->branch1, change_past,
  			       o->branch2, o->branch2, path);
 -			update_file(o, 0, b_sha, b_mode, path);
 +			ret = update_file(o, 0, b_oid, b_mode, path);
  		} else {
  			output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
  			       "and %s in %s. Version %s of %s left in tree at %s."),
  			       change, path, o->branch1, change_past,
  			       o->branch2, o->branch2, path, renamed);
 -			update_file(o, 0, b_sha, b_mode, renamed);
 +			ret = update_file(o, 0, b_oid, b_mode, renamed);
  		}
  	} else {
  		if (!renamed) {
@@@ -1108,7 -1065,7 +1110,7 @@@
  			       "and %s in %s. Version %s of %s left in tree at %s."),
  			       change, path, o->branch2, change_past,
  			       o->branch1, o->branch1, path, renamed);
 -			update_file(o, 0, a_sha, a_mode, renamed);
 +			ret = update_file(o, 0, a_oid, a_mode, renamed);
  		}
  		/*
  		 * No need to call update_file() on path when !renamed, since
@@@ -1118,60 -1075,59 +1120,60 @@@
  		 */
  	}
  	free(renamed);
 +
 +	return ret;
  }
  
 -static void conflict_rename_delete(struct merge_options *o,
 +static int conflict_rename_delete(struct merge_options *o,
  				   struct diff_filepair *pair,
  				   const char *rename_branch,
  				   const char *other_branch)
  {
  	const struct diff_filespec *orig = pair->one;
  	const struct diff_filespec *dest = pair->two;
 -	const unsigned char *a_sha = NULL;
 -	const unsigned char *b_sha = NULL;
 +	const struct object_id *a_oid = NULL;
 +	const struct object_id *b_oid = NULL;
  	int a_mode = 0;
  	int b_mode = 0;
  
  	if (rename_branch == o->branch1) {
 -		a_sha = dest->sha1;
 +		a_oid = &dest->oid;
  		a_mode = dest->mode;
  	} else {
 -		b_sha = dest->sha1;
 +		b_oid = &dest->oid;
  		b_mode = dest->mode;
  	}
  
 -	handle_change_delete(o,
 -			     o->call_depth ? orig->path : dest->path,
 -			     orig->sha1, orig->mode,
 -			     a_sha, a_mode,
 -			     b_sha, b_mode,
 -			     _("rename"), _("renamed"));
 -
 -	if (o->call_depth) {
 -		remove_file_from_cache(dest->path);
 -	} else {
 -		update_stages(dest->path, NULL,
 -			      rename_branch == o->branch1 ? dest : NULL,
 -			      rename_branch == o->branch1 ? NULL : dest);
 -	}
 +	if (handle_change_delete(o,
 +				 o->call_depth ? orig->path : dest->path,
 +				 &orig->oid, orig->mode,
 +				 a_oid, a_mode,
 +				 b_oid, b_mode,
 +				 _("rename"), _("renamed")))
 +		return -1;
  
 +	if (o->call_depth)
 +		return remove_file_from_cache(dest->path);
 +	else
 +		return update_stages(o, dest->path, NULL,
 +				     rename_branch == o->branch1 ? dest : NULL,
 +				     rename_branch == o->branch1 ? NULL : dest);
  }
  
  static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
  						 struct stage_data *entry,
  						 int stage)
  {
 -	unsigned char *sha = entry->stages[stage].sha;
 +	struct object_id *oid = &entry->stages[stage].oid;
  	unsigned mode = entry->stages[stage].mode;
 -	if (mode == 0 || is_null_sha1(sha))
 +	if (mode == 0 || is_null_oid(oid))
  		return NULL;
 -	hashcpy(target->sha1, sha);
 +	oidcpy(&target->oid, oid);
  	target->mode = mode;
  	return target;
  }
  
 -static void handle_file(struct merge_options *o,
 +static int handle_file(struct merge_options *o,
  			struct diff_filespec *rename,
  			int stage,
  			struct rename_conflict_info *ci)
@@@ -1181,7 -1137,6 +1183,7 @@@
  	const char *cur_branch, *other_branch;
  	struct diff_filespec other;
  	struct diff_filespec *add;
 +	int ret;
  
  	if (stage == 2) {
  		dst_entry = ci->dst_entry1;
@@@ -1196,32 -1151,28 +1198,32 @@@
  	add = filespec_from_entry(&other, dst_entry, stage ^ 1);
  	if (add) {
  		char *add_name = unique_path(o, rename->path, other_branch);
 -		update_file(o, 0, add->sha1, add->mode, add_name);
 +		if (update_file(o, 0, &add->oid, add->mode, add_name))
 +			return -1;
  
  		remove_file(o, 0, rename->path, 0);
  		dst_name = unique_path(o, rename->path, cur_branch);
  	} else {
 -		if (dir_in_way(rename->path, !o->call_depth)) {
 +		if (dir_in_way(rename->path, !o->call_depth, 0)) {
  			dst_name = unique_path(o, rename->path, cur_branch);
  			output(o, 1, _("%s is a directory in %s adding as %s instead"),
  			       rename->path, other_branch, dst_name);
  		}
  	}
 -	update_file(o, 0, rename->sha1, rename->mode, dst_name);
 -	if (stage == 2)
 -		update_stages(rename->path, NULL, rename, add);
 +	if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
 +		; /* fall through, do allow dst_name to be released */
 +	else if (stage == 2)
 +		ret = update_stages(o, rename->path, NULL, rename, add);
  	else
 -		update_stages(rename->path, NULL, add, rename);
 +		ret = update_stages(o, rename->path, NULL, add, rename);
  
  	if (dst_name != rename->path)
  		free(dst_name);
 +
 +	return ret;
  }
  
 -static void conflict_rename_rename_1to2(struct merge_options *o,
 +static int conflict_rename_rename_1to2(struct merge_options *o,
  					struct rename_conflict_info *ci)
  {
  	/* One file was renamed in both branches, but to different names. */
@@@ -1239,21 -1190,18 +1241,21 @@@
  		struct merge_file_info mfi;
  		struct diff_filespec other;
  		struct diff_filespec *add;
 -		mfi = merge_file_one(o, one->path,
 -				 one->sha1, one->mode,
 -				 a->sha1, a->mode,
 -				 b->sha1, b->mode,
 -				 ci->branch1, ci->branch2);
 +		if (merge_file_one(o, one->path,
 +				 &one->oid, one->mode,
 +				 &a->oid, a->mode,
 +				 &b->oid, b->mode,
 +				 ci->branch1, ci->branch2, &mfi))
 +			return -1;
 +
  		/*
  		 * FIXME: For rename/add-source conflicts (if we could detect
  		 * such), this is wrong.  We should instead find a unique
  		 * pathname and then either rename the add-source file to that
  		 * unique path, or use that unique path instead of src here.
  		 */
 -		update_file(o, 0, mfi.sha, mfi.mode, one->path);
 +		if (update_file(o, 0, &mfi.oid, mfi.mode, one->path))
 +			return -1;
  
  		/*
  		 * Above, we put the merged content at the merge-base's
@@@ -1264,26 -1212,22 +1266,26 @@@
  		 * resolving the conflict at that path in its favor.
  		 */
  		add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
 -		if (add)
 -			update_file(o, 0, add->sha1, add->mode, a->path);
 +		if (add) {
 +			if (update_file(o, 0, &add->oid, add->mode, a->path))
 +				return -1;
 +		}
  		else
  			remove_file_from_cache(a->path);
  		add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
 -		if (add)
 -			update_file(o, 0, add->sha1, add->mode, b->path);
 +		if (add) {
 +			if (update_file(o, 0, &add->oid, add->mode, b->path))
 +				return -1;
 +		}
  		else
  			remove_file_from_cache(b->path);
 -	} else {
 -		handle_file(o, a, 2, ci);
 -		handle_file(o, b, 3, ci);
 -	}
 +	} else if (handle_file(o, a, 2, ci) || handle_file(o, b, 3, ci))
 +		return -1;
 +
 +	return 0;
  }
  
 -static void conflict_rename_rename_2to1(struct merge_options *o,
 +static int conflict_rename_rename_2to1(struct merge_options *o,
  					struct rename_conflict_info *ci)
  {
  	/* Two files, a & b, were renamed to the same thing, c. */
@@@ -1294,7 -1238,6 +1296,7 @@@
  	char *path = c1->path; /* == c2->path */
  	struct merge_file_info mfi_c1;
  	struct merge_file_info mfi_c2;
 +	int ret;
  
  	output(o, 1, _("CONFLICT (rename/rename): "
  	       "Rename %s->%s in %s. "
@@@ -1302,16 -1245,15 +1304,16 @@@
  	       a->path, c1->path, ci->branch1,
  	       b->path, c2->path, ci->branch2);
  
 -	remove_file(o, 1, a->path, would_lose_untracked(a->path));
 -	remove_file(o, 1, b->path, would_lose_untracked(b->path));
 +	remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
 +	remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
  
 -	mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
 -					    o->branch1, c1->path,
 -					    o->branch2, ci->ren1_other.path);
 -	mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
 -					    o->branch1, ci->ren2_other.path,
 -					    o->branch2, c2->path);
 +	if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
 +				       o->branch1, c1->path,
 +				       o->branch2, ci->ren1_other.path, &mfi_c1) ||
 +	    merge_file_special_markers(o, b, &ci->ren2_other, c2,
 +				       o->branch1, ci->ren2_other.path,
 +				       o->branch2, c2->path, &mfi_c2))
 +		return -1;
  
  	if (o->call_depth) {
  		/*
@@@ -1322,25 -1264,19 +1324,25 @@@
  		 * again later for the non-recursive merge.
  		 */
  		remove_file(o, 0, path, 0);
 -		update_file(o, 0, mfi_c1.sha, mfi_c1.mode, a->path);
 -		update_file(o, 0, mfi_c2.sha, mfi_c2.mode, b->path);
 +		ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, a->path);
 +		if (!ret)
 +			ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
 +					  b->path);
  	} else {
  		char *new_path1 = unique_path(o, path, ci->branch1);
  		char *new_path2 = unique_path(o, path, ci->branch2);
  		output(o, 1, _("Renaming %s to %s and %s to %s instead"),
  		       a->path, new_path1, b->path, new_path2);
  		remove_file(o, 0, path, 0);
 -		update_file(o, 0, mfi_c1.sha, mfi_c1.mode, new_path1);
 -		update_file(o, 0, mfi_c2.sha, mfi_c2.mode, new_path2);
 +		ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
 +		if (!ret)
 +			ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
 +					  new_path2);
  		free(new_path2);
  		free(new_path1);
  	}
 +
 +	return ret;
  }
  
  static int process_renames(struct merge_options *o,
@@@ -1418,7 -1354,7 +1420,7 @@@
  			const char *ren2_dst = ren2->pair->two->path;
  			enum rename_type rename_type;
  			if (strcmp(ren1_src, ren2_src) != 0)
 -				die("ren1_src != ren2_src");
 +				die("BUG: ren1_src != ren2_src");
  			ren2->dst_entry->processed = 1;
  			ren2->processed = 1;
  			if (strcmp(ren1_dst, ren2_dst) != 0) {
@@@ -1452,7 -1388,7 +1454,7 @@@
  			ren2 = lookup->util;
  			ren2_dst = ren2->pair->two->path;
  			if (strcmp(ren1_dst, ren2_dst) != 0)
 -				die("ren1_dst != ren2_dst");
 +				die("BUG: ren1_dst != ren2_dst");
  
  			clean_merge = 0;
  			ren2->processed = 1;
@@@ -1496,15 -1432,13 +1498,15 @@@
  			remove_file(o, 1, ren1_src,
  				    renamed_stage == 2 || !was_tracked(ren1_src));
  
 -			hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
 +			oidcpy(&src_other.oid,
 +			       &ren1->src_entry->stages[other_stage].oid);
  			src_other.mode = ren1->src_entry->stages[other_stage].mode;
 -			hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
 +			oidcpy(&dst_other.oid,
 +			       &ren1->dst_entry->stages[other_stage].oid);
  			dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
  			try_merge = 0;
  
 -			if (sha_eq(src_other.sha1, null_sha1)) {
 +			if (oid_eq(&src_other.oid, &null_oid)) {
  				setup_rename_conflict_info(RENAME_DELETE,
  							   ren1->pair,
  							   NULL,
@@@ -1516,7 -1450,7 +1518,7 @@@
  							   NULL,
  							   NULL);
  			} else if ((dst_other.mode == ren1->pair->two->mode) &&
 -				   sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
 +				   oid_eq(&dst_other.oid, &ren1->pair->two->oid)) {
  				/*
  				 * Added file on the other side identical to
  				 * the file being renamed: clean merge.
@@@ -1525,14 -1459,13 +1527,14 @@@
  				 * update_file_flags() instead of
  				 * update_file().
  				 */
 -				update_file_flags(o,
 -						  ren1->pair->two->sha1,
 -						  ren1->pair->two->mode,
 -						  ren1_dst,
 -						  1, /* update_cache */
 -						  0  /* update_wd    */);
 -			} else if (!sha_eq(dst_other.sha1, null_sha1)) {
 +				if (update_file_flags(o,
 +						      &ren1->pair->two->oid,
 +						      ren1->pair->two->mode,
 +						      ren1_dst,
 +						      1, /* update_cache */
 +						      0  /* update_wd    */))
 +					clean_merge = -1;
 +			} else if (!oid_eq(&dst_other.oid, &null_oid)) {
  				clean_merge = 0;
  				try_merge = 1;
  				output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
@@@ -1541,33 -1474,22 +1543,33 @@@
  				       ren1_dst, branch2);
  				if (o->call_depth) {
  					struct merge_file_info mfi;
 -					mfi = merge_file_one(o, ren1_dst, null_sha1, 0,
 -							 ren1->pair->two->sha1, ren1->pair->two->mode,
 -							 dst_other.sha1, dst_other.mode,
 -							 branch1, branch2);
 +					if (merge_file_one(o, ren1_dst, &null_oid, 0,
 +							   &ren1->pair->two->oid,
 +							   ren1->pair->two->mode,
 +							   &dst_other.oid,
 +							   dst_other.mode,
 +							   branch1, branch2, &mfi)) {
 +						clean_merge = -1;
 +						goto cleanup_and_return;
 +					}
  					output(o, 1, _("Adding merged %s"), ren1_dst);
 -					update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
 +					if (update_file(o, 0, &mfi.oid,
 +							mfi.mode, ren1_dst))
 +						clean_merge = -1;
  					try_merge = 0;
  				} else {
  					char *new_path = unique_path(o, ren1_dst, branch2);
  					output(o, 1, _("Adding as %s instead"), new_path);
 -					update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 +					if (update_file(o, 0, &dst_other.oid,
 +							dst_other.mode, new_path))
 +						clean_merge = -1;
  					free(new_path);
  				}
  			} else
  				try_merge = 1;
  
 +			if (clean_merge < 0)
 +				goto cleanup_and_return;
  			if (try_merge) {
  				struct diff_filespec *one, *a, *b;
  				src_other.path = (char *)ren1_src;
@@@ -1594,39 -1516,36 +1596,39 @@@
  			}
  		}
  	}
 +cleanup_and_return:
  	string_list_clear(&a_by_dst, 0);
  	string_list_clear(&b_by_dst, 0);
  
  	return clean_merge;
  }
  
 -static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
 +static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
  {
 -	return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
 +	return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
  }
  
 -static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
 +static int read_oid_strbuf(struct merge_options *o,
 +	const struct object_id *oid, struct strbuf *dst)
  {
  	void *buf;
  	enum object_type type;
  	unsigned long size;
 -	buf = read_sha1_file(sha1, &type, &size);
 +	buf = read_sha1_file(oid->hash, &type, &size);
  	if (!buf)
 -		return error(_("cannot read object %s"), sha1_to_hex(sha1));
 +		return err(o, _("cannot read object %s"), oid_to_hex(oid));
  	if (type != OBJ_BLOB) {
  		free(buf);
 -		return error(_("object %s is not a blob"), sha1_to_hex(sha1));
 +		return err(o, _("object %s is not a blob"), oid_to_hex(oid));
  	}
  	strbuf_attach(dst, buf, size, size + 1);
  	return 0;
  }
  
 -static int blob_unchanged(const unsigned char *o_sha,
 +static int blob_unchanged(struct merge_options *opt,
 +			  const struct object_id *o_oid,
  			  unsigned o_mode,
 -			  const unsigned char *a_sha,
 +			  const struct object_id *a_oid,
  			  unsigned a_mode,
  			  int renormalize, const char *path)
  {
@@@ -1636,13 -1555,13 +1638,13 @@@
  
  	if (a_mode != o_mode)
  		return 0;
 -	if (sha_eq(o_sha, a_sha))
 +	if (oid_eq(o_oid, a_oid))
  		return 1;
  	if (!renormalize)
  		return 0;
  
 -	assert(o_sha && a_sha);
 -	if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
 +	assert(o_oid && a_oid);
 +	if (read_oid_strbuf(opt, o_oid, &o) || read_oid_strbuf(opt, a_oid, &a))
  		goto error_return;
  	/*
  	 * Note: binary | is used so that both renormalizations are
@@@ -1659,25 -1578,25 +1661,25 @@@ error_return
  	return ret;
  }
  
 -static void handle_modify_delete(struct merge_options *o,
 +static int handle_modify_delete(struct merge_options *o,
  				 const char *path,
 -				 unsigned char *o_sha, int o_mode,
 -				 unsigned char *a_sha, int a_mode,
 -				 unsigned char *b_sha, int b_mode)
 +				 struct object_id *o_oid, int o_mode,
 +				 struct object_id *a_oid, int a_mode,
 +				 struct object_id *b_oid, int b_mode)
  {
 -	handle_change_delete(o,
 -			     path,
 -			     o_sha, o_mode,
 -			     a_sha, a_mode,
 -			     b_sha, b_mode,
 -			     _("modify"), _("modified"));
 +	return handle_change_delete(o,
 +				    path,
 +				    o_oid, o_mode,
 +				    a_oid, a_mode,
 +				    b_oid, b_mode,
 +				    _("modify"), _("modified"));
  }
  
  static int merge_content(struct merge_options *o,
  			 const char *path,
 -			 unsigned char *o_sha, int o_mode,
 -			 unsigned char *a_sha, int a_mode,
 -			 unsigned char *b_sha, int b_mode,
 +			 struct object_id *o_oid, int o_mode,
 +			 struct object_id *a_oid, int a_mode,
 +			 struct object_id *b_oid, int b_mode,
  			 struct rename_conflict_info *rename_conflict_info)
  {
  	const char *reason = _("content");
@@@ -1686,16 -1605,16 +1688,16 @@@
  	struct diff_filespec one, a, b;
  	unsigned df_conflict_remains = 0;
  
 -	if (!o_sha) {
 +	if (!o_oid) {
  		reason = _("add/add");
 -		o_sha = (unsigned char *)null_sha1;
 +		o_oid = (struct object_id *)&null_oid;
  	}
  	one.path = a.path = b.path = (char *)path;
 -	hashcpy(one.sha1, o_sha);
 +	oidcpy(&one.oid, o_oid);
  	one.mode = o_mode;
 -	hashcpy(a.sha1, a_sha);
 +	oidcpy(&a.oid, a_oid);
  	a.mode = a_mode;
 -	hashcpy(b.sha1, b_sha);
 +	oidcpy(&b.oid, b_oid);
  	b.mode = b_mode;
  
  	if (rename_conflict_info) {
@@@ -1711,17 -1630,15 +1713,17 @@@
  			 o->branch2 == rename_conflict_info->branch1) ?
  			pair1->two->path : pair1->one->path;
  
 -		if (dir_in_way(path, !o->call_depth))
 +		if (dir_in_way(path, !o->call_depth,
 +			       S_ISGITLINK(pair1->two->mode)))
  			df_conflict_remains = 1;
  	}
 -	mfi = merge_file_special_markers(o, &one, &a, &b,
 -					 o->branch1, path1,
 -					 o->branch2, path2);
 +	if (merge_file_special_markers(o, &one, &a, &b,
 +				       o->branch1, path1,
 +				       o->branch2, path2, &mfi))
 +		return -1;
  
  	if (mfi.clean && !df_conflict_remains &&
 -	    sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
 +	    oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
  		int path_renamed_outside_HEAD;
  		output(o, 3, _("Skipped %s (merged same as existing)"), path);
  		/*
@@@ -1732,7 -1649,7 +1734,7 @@@
  		 */
  		path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
  		if (!path_renamed_outside_HEAD) {
 -			add_cacheinfo(mfi.mode, mfi.sha, path,
 +			add_cacheinfo(o, mfi.mode, &mfi.oid, path,
  				      0, (!o->call_depth), 0);
  			return mfi.clean;
  		}
@@@ -1745,8 -1662,7 +1747,8 @@@
  		output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
  				reason, path);
  		if (rename_conflict_info && !df_conflict_remains)
 -			update_stages(path, &one, &a, &b);
 +			if (update_stages(o, path, &one, &a, &b))
 +				return -1;
  	}
  
  	if (df_conflict_remains) {
@@@ -1754,33 -1670,30 +1756,33 @@@
  		if (o->call_depth) {
  			remove_file_from_cache(path);
  		} else {
 -			if (!mfi.clean)
 -				update_stages(path, &one, &a, &b);
 -			else {
 +			if (!mfi.clean) {
 +				if (update_stages(o, path, &one, &a, &b))
 +					return -1;
 +			} else {
  				int file_from_stage2 = was_tracked(path);
  				struct diff_filespec merged;
 -				hashcpy(merged.sha1, mfi.sha);
 +				oidcpy(&merged.oid, &mfi.oid);
  				merged.mode = mfi.mode;
  
 -				update_stages(path, NULL,
 -					      file_from_stage2 ? &merged : NULL,
 -					      file_from_stage2 ? NULL : &merged);
 +				if (update_stages(o, path, NULL,
 +						  file_from_stage2 ? &merged : NULL,
 +						  file_from_stage2 ? NULL : &merged))
 +					return -1;
  			}
  
  		}
  		new_path = unique_path(o, path, rename_conflict_info->branch1);
  		output(o, 1, _("Adding as %s instead"), new_path);
 -		update_file(o, 0, mfi.sha, mfi.mode, new_path);
 +		if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
 +			free(new_path);
 +			return -1;
 +		}
  		free(new_path);
  		mfi.clean = 0;
 -	} else {
 -		update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
 -	}
 +	} else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
 +		return -1;
  	return mfi.clean;
 -
  }
  
  /* Per entry merge function */
@@@ -1792,9 -1705,9 +1794,9 @@@ static int process_entry(struct merge_o
  	unsigned o_mode = entry->stages[1].mode;
  	unsigned a_mode = entry->stages[2].mode;
  	unsigned b_mode = entry->stages[3].mode;
 -	unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
 -	unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
 -	unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
 +	struct object_id *o_oid = stage_oid(&entry->stages[1].oid, o_mode);
 +	struct object_id *a_oid = stage_oid(&entry->stages[2].oid, a_mode);
 +	struct object_id *b_oid = stage_oid(&entry->stages[3].oid, b_mode);
  
  	entry->processed = 1;
  	if (entry->rename_conflict_info) {
@@@ -1803,105 -1716,99 +1805,105 @@@
  		case RENAME_NORMAL:
  		case RENAME_ONE_FILE_TO_ONE:
  			clean_merge = merge_content(o, path,
 -						    o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
 +						    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
  						    conflict_info);
  			break;
  		case RENAME_DELETE:
  			clean_merge = 0;
 -			conflict_rename_delete(o, conflict_info->pair1,
 -					       conflict_info->branch1,
 -					       conflict_info->branch2);
 +			if (conflict_rename_delete(o,
 +						   conflict_info->pair1,
 +						   conflict_info->branch1,
 +						   conflict_info->branch2))
 +				clean_merge = -1;
  			break;
  		case RENAME_ONE_FILE_TO_TWO:
  			clean_merge = 0;
 -			conflict_rename_rename_1to2(o, conflict_info);
 +			if (conflict_rename_rename_1to2(o, conflict_info))
 +				clean_merge = -1;
  			break;
  		case RENAME_TWO_FILES_TO_ONE:
  			clean_merge = 0;
 -			conflict_rename_rename_2to1(o, conflict_info);
 +			if (conflict_rename_rename_2to1(o, conflict_info))
 +				clean_merge = -1;
  			break;
  		default:
  			entry->processed = 0;
  			break;
  		}
 -	} else if (o_sha && (!a_sha || !b_sha)) {
 +	} else if (o_oid && (!a_oid || !b_oid)) {
  		/* Case A: Deleted in one */
 -		if ((!a_sha && !b_sha) ||
 -		    (!b_sha && blob_unchanged(o_sha, o_mode, a_sha, a_mode, normalize, path)) ||
 -		    (!a_sha && blob_unchanged(o_sha, o_mode, b_sha, b_mode, normalize, path))) {
 +		if ((!a_oid && !b_oid) ||
 +		    (!b_oid && blob_unchanged(o, o_oid, o_mode, a_oid, a_mode, normalize, path)) ||
 +		    (!a_oid && blob_unchanged(o, o_oid, o_mode, b_oid, b_mode, normalize, path))) {
  			/* Deleted in both or deleted in one and
  			 * unchanged in the other */
 -			if (a_sha)
 +			if (a_oid)
  				output(o, 2, _("Removing %s"), path);
  			/* do not touch working file if it did not exist */
 -			remove_file(o, 1, path, !a_sha);
 +			remove_file(o, 1, path, !a_oid);
  		} else {
  			/* Modify/delete; deleted side may have put a directory in the way */
  			clean_merge = 0;
 -			handle_modify_delete(o, path, o_sha, o_mode,
 -					     a_sha, a_mode, b_sha, b_mode);
 +			if (handle_modify_delete(o, path, o_oid, o_mode,
 +						 a_oid, a_mode, b_oid, b_mode))
 +				clean_merge = -1;
  		}
 -	} else if ((!o_sha && a_sha && !b_sha) ||
 -		   (!o_sha && !a_sha && b_sha)) {
 +	} else if ((!o_oid && a_oid && !b_oid) ||
 +		   (!o_oid && !a_oid && b_oid)) {
  		/* Case B: Added in one. */
  		/* [nothing|directory] -> ([nothing|directory], file) */
  
  		const char *add_branch;
  		const char *other_branch;
  		unsigned mode;
 -		const unsigned char *sha;
 +		const struct object_id *oid;
  		const char *conf;
  
 -		if (a_sha) {
 +		if (a_oid) {
  			add_branch = o->branch1;
  			other_branch = o->branch2;
  			mode = a_mode;
 -			sha = a_sha;
 +			oid = a_oid;
  			conf = _("file/directory");
  		} else {
  			add_branch = o->branch2;
  			other_branch = o->branch1;
  			mode = b_mode;
 -			sha = b_sha;
 +			oid = b_oid;
  			conf = _("directory/file");
  		}
 -		if (dir_in_way(path, !o->call_depth)) {
 +		if (dir_in_way(path, !o->call_depth,
 +			       S_ISGITLINK(a_mode))) {
  			char *new_path = unique_path(o, path, add_branch);
  			clean_merge = 0;
  			output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
  			       "Adding %s as %s"),
  			       conf, path, other_branch, path, new_path);
 -			if (o->call_depth)
 -				remove_file_from_cache(path);
 -			update_file(o, 0, sha, mode, new_path);
 -			if (o->call_depth)
 +			if (update_file(o, 0, oid, mode, new_path))
 +				clean_merge = -1;
 +			else if (o->call_depth)
  				remove_file_from_cache(path);
  			free(new_path);
  		} else {
  			output(o, 2, _("Adding %s"), path);
  			/* do not overwrite file if already present */
 -			update_file_flags(o, sha, mode, path, 1, !a_sha);
 +			if (update_file_flags(o, oid, mode, path, 1, !a_oid))
 +				clean_merge = -1;
  		}
 -	} else if (a_sha && b_sha) {
 +	} else if (a_oid && b_oid) {
  		/* Case C: Added in both (check for same permissions) and */
  		/* case D: Modified in both, but differently. */
  		clean_merge = merge_content(o, path,
 -					    o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
 +					    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
  					    NULL);
 -	} else if (!o_sha && !a_sha && !b_sha) {
 +	} else if (!o_oid && !a_oid && !b_oid) {
  		/*
  		 * this entry was deleted altogether. a_mode == 0 means
  		 * we had that path and want to actively remove it.
  		 */
  		remove_file(o, 1, path, !a_mode);
  	} else
 -		die(_("Fatal merge failure, shouldn't happen."));
 +		die("BUG: fatal merge failure, shouldn't happen.");
  
  	return clean_merge;
  }
@@@ -1919,7 -1826,7 +1921,7 @@@ int merge_trees(struct merge_options *o
  		common = shift_tree_object(head, common, o->subtree_shift);
  	}
  
 -	if (sha_eq(common->object.oid.hash, merge->object.oid.hash)) {
 +	if (oid_eq(&common->object.oid, &merge->object.oid)) {
  		output(o, 0, _("Already up-to-date!"));
  		*result = head;
  		return 1;
@@@ -1929,10 -1836,11 +1931,10 @@@
  
  	if (code != 0) {
  		if (show(o, 4) || o->call_depth)
 -			die(_("merging of trees %s and %s failed"),
 +			err(o, _("merging of trees %s and %s failed"),
  			    oid_to_hex(&head->object.oid),
  			    oid_to_hex(&merge->object.oid));
 -		else
 -			exit(128);
 +		return -1;
  	}
  
  	if (unmerged_cache()) {
@@@ -1948,23 -1856,17 +1950,23 @@@
  		re_head  = get_renames(o, head, common, head, merge, entries);
  		re_merge = get_renames(o, merge, common, head, merge, entries);
  		clean = process_renames(o, re_head, re_merge);
 +		if (clean < 0)
 +			return clean;
  		for (i = entries->nr-1; 0 <= i; i--) {
  			const char *path = entries->items[i].string;
  			struct stage_data *e = entries->items[i].util;
 -			if (!e->processed
 -				&& !process_entry(o, path, e))
 -				clean = 0;
 +			if (!e->processed) {
 +				int ret = process_entry(o, path, e);
 +				if (!ret)
 +					clean = 0;
 +				else if (ret < 0)
 +					return ret;
 +			}
  		}
  		for (i = 0; i < entries->nr; i++) {
  			struct stage_data *e = entries->items[i].util;
  			if (!e->processed)
 -				die(_("Unprocessed path??? %s"),
 +				die("BUG: unprocessed path??? %s",
  				    entries->items[i].string);
  		}
  
@@@ -1979,8 -1881,8 +1981,8 @@@
  	else
  		clean = 1;
  
 -	if (o->call_depth)
 -		*result = write_tree_from_memory(o);
 +	if (o->call_depth && !(*result = write_tree_from_memory(o)))
 +		return -1;
  
  	return clean;
  }
@@@ -2046,25 -1948,23 +2048,25 @@@ int merge_recursive(struct merge_option
  		/*
  		 * When the merge fails, the result contains files
  		 * with conflict markers. The cleanness flag is
 -		 * ignored, it was never actually used, as result of
 -		 * merge_trees has always overwritten it: the committed
 -		 * "conflicts" were already resolved.
 +		 * ignored (unless indicating an error), it was never
 +		 * actually used, as result of merge_trees has always
 +		 * overwritten it: the committed "conflicts" were
 +		 * already resolved.
  		 */
  		discard_cache();
  		saved_b1 = o->branch1;
  		saved_b2 = o->branch2;
  		o->branch1 = "Temporary merge branch 1";
  		o->branch2 = "Temporary merge branch 2";
 -		merge_recursive(o, merged_common_ancestors, iter->item,
 -				NULL, &merged_common_ancestors);
 +		if (merge_recursive(o, merged_common_ancestors, iter->item,
 +				    NULL, &merged_common_ancestors) < 0)
 +			return -1;
  		o->branch1 = saved_b1;
  		o->branch2 = saved_b2;
  		o->call_depth--;
  
  		if (!merged_common_ancestors)
 -			die(_("merge returned no commit"));
 +			return err(o, _("merge returned no commit"));
  	}
  
  	discard_cache();
@@@ -2074,10 -1974,6 +2076,10 @@@
  	o->ancestor = "merged common ancestors";
  	clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
  			    &mrtree);
 +	if (clean < 0) {
 +		flush_output(o);
 +		return clean;
 +	}
  
  	if (o->call_depth) {
  		*result = make_virtual_commit(mrtree, "merged tree");
@@@ -2085,19 -1981,17 +2087,19 @@@
  		commit_list_insert(h2, &(*result)->parents->next);
  	}
  	flush_output(o);
 +	if (!o->call_depth && o->buffer_output < 2)
 +		strbuf_release(&o->obuf);
  	if (show(o, 2))
  		diff_warn_rename_limit("merge.renamelimit",
  				       o->needed_rename_limit, 0);
  	return clean;
  }
  
 -static struct commit *get_ref(const unsigned char *sha1, const char *name)
 +static struct commit *get_ref(const struct object_id *oid, const char *name)
  {
  	struct object *object;
  
 -	object = deref_tag(parse_object(sha1), name, strlen(name));
 +	object = deref_tag(parse_object(oid->hash), name, strlen(name));
  	if (!object)
  		return NULL;
  	if (object->type == OBJ_TREE)
@@@ -2110,10 -2004,10 +2112,10 @@@
  }
  
  int merge_recursive_generic(struct merge_options *o,
 -			    const unsigned char *head,
 -			    const unsigned char *merge,
 +			    const struct object_id *head,
 +			    const struct object_id *merge,
  			    int num_base_list,
 -			    const unsigned char **base_list,
 +			    const struct object_id **base_list,
  			    struct commit **result)
  {
  	int clean;
@@@ -2126,9 -2020,9 +2128,9 @@@
  		int i;
  		for (i = 0; i < num_base_list; ++i) {
  			struct commit *base;
 -			if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
 -				return error(_("Could not parse object '%s'"),
 -					sha1_to_hex(base_list[i]));
 +			if (!(base = get_ref(base_list[i], oid_to_hex(base_list[i]))))
 +				return err(o, _("Could not parse object '%s'"),
 +					oid_to_hex(base_list[i]));
  			commit_list_insert(base, &ca);
  		}
  	}
@@@ -2136,12 -2030,9 +2138,12 @@@
  	hold_locked_index(lock, 1);
  	clean = merge_recursive(o, head_commit, next_commit, ca,
  			result);
 +	if (clean < 0)
 +		return clean;
 +
  	if (active_cache_changed &&
  	    write_locked_index(&the_index, lock, COMMIT_LOCK))
 -		return error(_("Unable to write index."));
 +		return err(o, _("Unable to write index."));
  
  	return clean ? 0 : 1;
  }
diff --combined t/t3501-revert-cherry-pick.sh
index 394f0005a1,22970d2223..4f2a263b63
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@@ -96,7 -96,7 +96,7 @@@ test_expect_success 'revert forbidden o
  	echo content >extra_file &&
  	git add extra_file &&
  	test_must_fail git revert HEAD 2>errors &&
 -	test_i18ngrep "Your local changes would be overwritten by " errors
 +	test_i18ngrep "your local changes would be overwritten by " errors
  
  '
  
@@@ -141,4 -141,16 +141,16 @@@ test_expect_success 'cherry-pick "-" wo
  	test_cmp expect actual
  '
  
+ test_expect_success 'cherry-pick works with dirty renamed file' '
+ 	test_commit to-rename &&
+ 	git checkout -b unrelated &&
+ 	test_commit unrelated &&
+ 	git checkout @{-1} &&
+ 	git mv to-rename.t renamed &&
+ 	test_tick &&
+ 	git commit -m renamed &&
+ 	echo modified >renamed &&
+ 	git cherry-pick refs/heads/unrelated
+ '
+ 
  test_done