ll-merge.c - pub/scm/git/git - Git at Google

 /*
  * Low level 3-way in-core file merge.
  *
  * Copyright (c) 2007 Junio C Hamano
  */

 #include "cache.h"
 #include "attr.h"
 #include "xdiff-interface.h"
 #include "run-command.h"
 #include "ll-merge.h"

 struct ll_merge_driver;

 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 			   mmbuffer_t *result,
 			   const char *path,
 			   mmfile_t *orig, const char *orig_name,
 			   mmfile_t *src1, const char *name1,
 			   mmfile_t *src2, const char *name2,
 			   int flag,
 			   int marker_size);

 struct ll_merge_driver {
 	const char *name;
 	const char *description;
 	ll_merge_fn fn;
 	const char *recursive;
 	struct ll_merge_driver *next;
 	char *cmdline;
 };

 /*
  * Built-in low-levels
  */
 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   mmbuffer_t *result,
 			   const char *path_unused,
 			   mmfile_t *orig, const char *orig_name,
 			   mmfile_t *src1, const char *name1,
 			   mmfile_t *src2, const char *name2,
 			   int flag, int marker_size)
 {
 	/*
 	 * The tentative merge result is "ours" for the final round,
 	 * or common ancestor for an internal merge.  Still return
 	 * "conflicted merge" status.
 	 */
 	mmfile_t *stolen = (flag & 01) ? orig : src1;

 	result->ptr = stolen->ptr;
 	result->size = stolen->size;
 	stolen->ptr = NULL;
 	return 1;
 }

 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 			mmbuffer_t *result,
 			const char *path,
 			mmfile_t *orig, const char *orig_name,
 			mmfile_t *src1, const char *name1,
 			mmfile_t *src2, const char *name2,
 			int flag, int marker_size)
 {
 	xmparam_t xmp;

 	if (buffer_is_binary(orig->ptr, orig->size) ||
 	    buffer_is_binary(src1->ptr, src1->size) ||
 	    buffer_is_binary(src2->ptr, src2->size)) {
 		warning("Cannot merge binary files: %s (%s vs. %s)\n",
 			path, name1, name2);
 		return ll_binary_merge(drv_unused, result,
 				       path,
 				       orig, orig_name,
 				       src1, name1,
 				       src2, name2,
 				       flag, marker_size);
 	}

 	memset(&xmp, 0, sizeof(xmp));
 	xmp.level = XDL_MERGE_ZEALOUS;
 	xmp.favor= (flag >> 1) & 03;
 	if (git_xmerge_style >= 0)
 		xmp.style = git_xmerge_style;
 	if (marker_size > 0)
 		xmp.marker_size = marker_size;
 	xmp.ancestor = orig_name;
 	xmp.file1 = name1;
 	xmp.file2 = name2;
 	return xdl_merge(orig, src1, src2, &xmp, result);
 }

 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 			  mmbuffer_t *result,
 			  const char *path_unused,
 			  mmfile_t *orig, const char *orig_name,
 			  mmfile_t *src1, const char *name1,
 			  mmfile_t *src2, const char *name2,
 			  int flag, int marker_size)
 {
 	/* Use union favor */
 	flag = (flag & 1) | (XDL_MERGE_FAVOR_UNION << 1);
 	return ll_xdl_merge(drv_unused, result, path_unused,
 			    orig, NULL, src1, NULL, src2, NULL,
 			    flag, marker_size);
 	return 0;
 }

 #define LL_BINARY_MERGE 0
 #define LL_TEXT_MERGE 1
 #define LL_UNION_MERGE 2
 static struct ll_merge_driver ll_merge_drv[] = {
 	{ "binary", "built-in binary merge", ll_binary_merge },
 	{ "text", "built-in 3-way text merge", ll_xdl_merge },
 	{ "union", "built-in union merge", ll_union_merge },
 };

 static void create_temp(mmfile_t *src, char *path)
 {
 	int fd;

 	strcpy(path, ".merge_file_XXXXXX");
 	fd = xmkstemp(path);
 	if (write_in_full(fd, src->ptr, src->size) != src->size)
 		die_errno("unable to write temp-file");
 	close(fd);
 }

 /*
  * User defined low-level merge driver support.
  */
 static int ll_ext_merge(const struct ll_merge_driver *fn,
 			mmbuffer_t *result,
 			const char *path,
 			mmfile_t *orig, const char *orig_name,
 			mmfile_t *src1, const char *name1,
 			mmfile_t *src2, const char *name2,
 			int flag, int marker_size)
 {
 	char temp[4][50];
 	struct strbuf cmd = STRBUF_INIT;
 	struct strbuf_expand_dict_entry dict[] = {
 		{ "O", temp[0] },
 		{ "A", temp[1] },
 		{ "B", temp[2] },
 		{ "L", temp[3] },
 		{ NULL }
 	};
 	const char *args[] = { NULL, NULL };
 	int status, fd, i;
 	struct stat st;

 	if (fn->cmdline == NULL)
 		die("custom merge driver %s lacks command line.", fn->name);

 	result->ptr = NULL;
 	result->size = 0;
 	create_temp(orig, temp[0]);
 	create_temp(src1, temp[1]);
 	create_temp(src2, temp[2]);
 	sprintf(temp[3], "%d", marker_size);

 	strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);

 	args[0] = cmd.buf;
 	status = run_command_v_opt(args, RUN_USING_SHELL);
 	fd = open(temp[1], O_RDONLY);
 	if (fd < 0)
 		goto bad;
 	if (fstat(fd, &st))
 		goto close_bad;
 	result->size = st.st_size;
 	result->ptr = xmalloc(result->size + 1);
 	if (read_in_full(fd, result->ptr, result->size) != result->size) {
 		free(result->ptr);
 		result->ptr = NULL;
 		result->size = 0;
 	}
  close_bad:
 	close(fd);
  bad:
 	for (i = 0; i < 3; i++)
 		unlink_or_warn(temp[i]);
 	strbuf_release(&cmd);
 	return status;
 }

 /*
  * merge.default and merge.driver configuration items
  */
 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 static const char *default_ll_merge;

 static int read_merge_config(const char *var, const char *value, void *cb)
 {
 	struct ll_merge_driver *fn;
 	const char *ep, *name;
 	int namelen;

 	if (!strcmp(var, "merge.default")) {
 		if (value)
 			default_ll_merge = xstrdup(value);
 		return 0;
 	}

 	/*
 	 * We are not interested in anything but "merge.<name>.variable";
 	 * especially, we do not want to look at variables such as
 	 * "merge.summary", "merge.tool", and "merge.verbosity".
 	 */
 	if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 		return 0;

 	/*
 	 * Find existing one as we might be processing merge.<name>.var2
 	 * after seeing merge.<name>.var1.
 	 */
 	name = var + 6;
 	namelen = ep - name;
 	for (fn = ll_user_merge; fn; fn = fn->next)
 		if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 			break;
 	if (!fn) {
 		fn = xcalloc(1, sizeof(struct ll_merge_driver));
 		fn->name = xmemdupz(name, namelen);
 		fn->fn = ll_ext_merge;
 		*ll_user_merge_tail = fn;
 		ll_user_merge_tail = &(fn->next);
 	}

 	ep++;

 	if (!strcmp("name", ep)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		fn->description = xstrdup(value);
 		return 0;
 	}

 	if (!strcmp("driver", ep)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		/*
 		 * merge.<name>.driver specifies the command line:
 		 *
 		 *	command-line
 		 *
 		 * The command-line will be interpolated with the following
 		 * tokens and is given to the shell:
 		 *
 		 *    %O - temporary file name for the merge base.
 		 *    %A - temporary file name for our version.
 		 *    %B - temporary file name for the other branches' version.
 		 *    %L - conflict marker length
 		 *
 		 * The external merge driver should write the results in the
 		 * file named by %A, and signal that it has done with zero exit
 		 * status.
 		 */
 		fn->cmdline = xstrdup(value);
 		return 0;
 	}

 	if (!strcmp("recursive", ep)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		fn->recursive = xstrdup(value);
 		return 0;
 	}

 	return 0;
 }

 static void initialize_ll_merge(void)
 {
 	if (ll_user_merge_tail)
 		return;
 	ll_user_merge_tail = &ll_user_merge;
 	git_config(read_merge_config, NULL);
 }

 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 {
 	struct ll_merge_driver *fn;
 	const char *name;
 	int i;

 	initialize_ll_merge();

 	if (ATTR_TRUE(merge_attr))
 		return &ll_merge_drv[LL_TEXT_MERGE];
 	else if (ATTR_FALSE(merge_attr))
 		return &ll_merge_drv[LL_BINARY_MERGE];
 	else if (ATTR_UNSET(merge_attr)) {
 		if (!default_ll_merge)
 			return &ll_merge_drv[LL_TEXT_MERGE];
 		else
 			name = default_ll_merge;
 	}
 	else
 		name = merge_attr;

 	for (fn = ll_user_merge; fn; fn = fn->next)
 		if (!strcmp(fn->name, name))
 			return fn;

 	for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 		if (!strcmp(ll_merge_drv[i].name, name))
 			return &ll_merge_drv[i];

 	/* default to the 3-way */
 	return &ll_merge_drv[LL_TEXT_MERGE];
 }

 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 {
 	if (!check[0].attr) {
 		check[0].attr = git_attr("merge");
 		check[1].attr = git_attr("conflict-marker-size");
 	}
 	return git_checkattr(path, 2, check);
 }

 int ll_merge(mmbuffer_t *result_buf,
 	     const char *path,
 	     mmfile_t *ancestor, const char *ancestor_label,
 	     mmfile_t *ours, const char *our_label,
 	     mmfile_t *theirs, const char *their_label,
 	     int flag)
 {
 	static struct git_attr_check check[2];
 	const char *ll_driver_name = NULL;
 	int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 	const struct ll_merge_driver *driver;
 	int virtual_ancestor = flag & 01;

 	if (!git_path_check_merge(path, check)) {
 		ll_driver_name = check[0].value;
 		if (check[1].value) {
 			marker_size = atoi(check[1].value);
 			if (marker_size <= 0)
 				marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 		}
 	}
 	driver = find_ll_merge_driver(ll_driver_name);
 	if (virtual_ancestor && driver->recursive)
 		driver = find_ll_merge_driver(driver->recursive);
 	return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 			  ours, our_label, theirs, their_label,
 			  flag, marker_size);
 }

 int ll_merge_marker_size(const char *path)
 {
 	static struct git_attr_check check;
 	int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;

 	if (!check.attr)
 		check.attr = git_attr("conflict-marker-size");
 	if (!git_checkattr(path, 1, &check) && check.value) {
 		marker_size = atoi(check.value);
 		if (marker_size <= 0)
 			marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 	}
 	return marker_size;
 }
	/*
	* Low level 3-way in-core file merge.
	*
	* Copyright (c) 2007 Junio C Hamano
	*/

	#include "cache.h"
	#include "attr.h"
	#include "xdiff-interface.h"
	#include "run-command.h"
	#include "ll-merge.h"

	struct ll_merge_driver;

	typedef int (ll_merge_fn)(const struct ll_merge_driver ,
	mmbuffer_t *result,
	const char *path,
	mmfile_t orig, const char orig_name,
	mmfile_t src1, const char name1,
	mmfile_t src2, const char name2,
	int flag,
	int marker_size);

	struct ll_merge_driver {
	const char *name;
	const char *description;
	ll_merge_fn fn;
	const char *recursive;
	struct ll_merge_driver *next;
	char *cmdline;
	};

	/*
	* Built-in low-levels
	*/
	static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
	mmbuffer_t *result,
	const char *path_unused,
	mmfile_t orig, const char orig_name,
	mmfile_t src1, const char name1,
	mmfile_t src2, const char name2,
	int flag, int marker_size)
	{
	/*
	* The tentative merge result is "ours" for the final round,
	* or common ancestor for an internal merge. Still return
	* "conflicted merge" status.
	*/
	mmfile_t *stolen = (flag & 01) ? orig : src1;

	result->ptr = stolen->ptr;
	result->size = stolen->size;
	stolen->ptr = NULL;
	return 1;
	}

	static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
	mmbuffer_t *result,
	const char *path,
	mmfile_t orig, const char orig_name,
	mmfile_t src1, const char name1,
	mmfile_t src2, const char name2,
	int flag, int marker_size)
	{
	xmparam_t xmp;

	if (buffer_is_binary(orig->ptr, orig->size) \|\|
	buffer_is_binary(src1->ptr, src1->size) \|\|
	buffer_is_binary(src2->ptr, src2->size)) {
	warning("Cannot merge binary files: %s (%s vs. %s)\n",
	path, name1, name2);
	return ll_binary_merge(drv_unused, result,
	path,
	orig, orig_name,
	src1, name1,
	src2, name2,
	flag, marker_size);
	}

	memset(&xmp, 0, sizeof(xmp));
	xmp.level = XDL_MERGE_ZEALOUS;
	xmp.favor= (flag >> 1) & 03;
	if (git_xmerge_style >= 0)
	xmp.style = git_xmerge_style;
	if (marker_size > 0)
	xmp.marker_size = marker_size;
	xmp.ancestor = orig_name;
	xmp.file1 = name1;
	xmp.file2 = name2;
	return xdl_merge(orig, src1, src2, &xmp, result);
	}

	static int ll_union_merge(const struct ll_merge_driver *drv_unused,
	mmbuffer_t *result,
	const char *path_unused,
	mmfile_t orig, const char orig_name,
	mmfile_t src1, const char name1,
	mmfile_t src2, const char name2,
	int flag, int marker_size)
	{
	/* Use union favor */
	flag = (flag & 1) \| (XDL_MERGE_FAVOR_UNION << 1);
	return ll_xdl_merge(drv_unused, result, path_unused,
	orig, NULL, src1, NULL, src2, NULL,
	flag, marker_size);
	return 0;
	}

	#define LL_BINARY_MERGE 0
	#define LL_TEXT_MERGE 1
	#define LL_UNION_MERGE 2
	static struct ll_merge_driver ll_merge_drv[] = {
	{ "binary", "built-in binary merge", ll_binary_merge },
	{ "text", "built-in 3-way text merge", ll_xdl_merge },
	{ "union", "built-in union merge", ll_union_merge },
	};

	static void create_temp(mmfile_t src, char path)
	{
	int fd;

	strcpy(path, ".merge_file_XXXXXX");
	fd = xmkstemp(path);
	if (write_in_full(fd, src->ptr, src->size) != src->size)
	die_errno("unable to write temp-file");
	close(fd);
	}

	/*
	* User defined low-level merge driver support.
	*/
	static int ll_ext_merge(const struct ll_merge_driver *fn,
	mmbuffer_t *result,
	const char *path,
	mmfile_t orig, const char orig_name,
	mmfile_t src1, const char name1,
	mmfile_t src2, const char name2,
	int flag, int marker_size)
	{
	char temp[4][50];
	struct strbuf cmd = STRBUF_INIT;
	struct strbuf_expand_dict_entry dict[] = {
	{ "O", temp[0] },
	{ "A", temp[1] },
	{ "B", temp[2] },
	{ "L", temp[3] },
	{ NULL }
	};
	const char *args[] = { NULL, NULL };
	int status, fd, i;
	struct stat st;

	if (fn->cmdline == NULL)
	die("custom merge driver %s lacks command line.", fn->name);

	result->ptr = NULL;
	result->size = 0;
	create_temp(orig, temp[0]);
	create_temp(src1, temp[1]);
	create_temp(src2, temp[2]);
	sprintf(temp[3], "%d", marker_size);

	strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);

	args[0] = cmd.buf;
	status = run_command_v_opt(args, RUN_USING_SHELL);
	fd = open(temp[1], O_RDONLY);
	if (fd < 0)
	goto bad;
	if (fstat(fd, &st))
	goto close_bad;
	result->size = st.st_size;
	result->ptr = xmalloc(result->size + 1);
	if (read_in_full(fd, result->ptr, result->size) != result->size) {
	free(result->ptr);
	result->ptr = NULL;
	result->size = 0;
	}
	close_bad:
	close(fd);
	bad:
	for (i = 0; i < 3; i++)
	unlink_or_warn(temp[i]);
	strbuf_release(&cmd);
	return status;
	}

	/*
	* merge.default and merge.driver configuration items
	*/
	static struct ll_merge_driver ll_user_merge, *ll_user_merge_tail;
	static const char *default_ll_merge;

	static int read_merge_config(const char var, const char value, void *cb)
	{
	struct ll_merge_driver *fn;
	const char ep, name;
	int namelen;

	if (!strcmp(var, "merge.default")) {
	if (value)
	default_ll_merge = xstrdup(value);
	return 0;
	}

	/*
	* We are not interested in anything but "merge.<name>.variable";
	* especially, we do not want to look at variables such as
	* "merge.summary", "merge.tool", and "merge.verbosity".
	*/
	if (prefixcmp(var, "merge.") \|\| (ep = strrchr(var, '.')) == var + 5)
	return 0;

	/*
	* Find existing one as we might be processing merge.<name>.var2
	* after seeing merge.<name>.var1.
	*/
	name = var + 6;
	namelen = ep - name;
	for (fn = ll_user_merge; fn; fn = fn->next)
	if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
	break;
	if (!fn) {
	fn = xcalloc(1, sizeof(struct ll_merge_driver));
	fn->name = xmemdupz(name, namelen);
	fn->fn = ll_ext_merge;
	*ll_user_merge_tail = fn;
	ll_user_merge_tail = &(fn->next);
	}

	ep++;

	if (!strcmp("name", ep)) {
	if (!value)
	return error("%s: lacks value", var);
	fn->description = xstrdup(value);
	return 0;
	}

	if (!strcmp("driver", ep)) {
	if (!value)
	return error("%s: lacks value", var);
	/*
	* merge.<name>.driver specifies the command line:
	*
	* command-line
	*
	* The command-line will be interpolated with the following
	* tokens and is given to the shell:
	*
	* %O - temporary file name for the merge base.
	* %A - temporary file name for our version.
	* %B - temporary file name for the other branches' version.
	* %L - conflict marker length
	*
	* The external merge driver should write the results in the
	* file named by %A, and signal that it has done with zero exit
	* status.
	*/
	fn->cmdline = xstrdup(value);
	return 0;
	}

	if (!strcmp("recursive", ep)) {
	if (!value)
	return error("%s: lacks value", var);
	fn->recursive = xstrdup(value);
	return 0;
	}

	return 0;
	}

	static void initialize_ll_merge(void)
	{
	if (ll_user_merge_tail)
	return;
	ll_user_merge_tail = &ll_user_merge;
	git_config(read_merge_config, NULL);
	}

	static const struct ll_merge_driver find_ll_merge_driver(const char merge_attr)
	{
	struct ll_merge_driver *fn;
	const char *name;
	int i;

	initialize_ll_merge();

	if (ATTR_TRUE(merge_attr))
	return &ll_merge_drv[LL_TEXT_MERGE];
	else if (ATTR_FALSE(merge_attr))
	return &ll_merge_drv[LL_BINARY_MERGE];
	else if (ATTR_UNSET(merge_attr)) {
	if (!default_ll_merge)
	return &ll_merge_drv[LL_TEXT_MERGE];
	else
	name = default_ll_merge;
	}
	else
	name = merge_attr;

	for (fn = ll_user_merge; fn; fn = fn->next)
	if (!strcmp(fn->name, name))
	return fn;

	for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
	if (!strcmp(ll_merge_drv[i].name, name))
	return &ll_merge_drv[i];

	/* default to the 3-way */
	return &ll_merge_drv[LL_TEXT_MERGE];
	}

	static int git_path_check_merge(const char *path, struct git_attr_check check[2])
	{
	if (!check[0].attr) {
	check[0].attr = git_attr("merge");
	check[1].attr = git_attr("conflict-marker-size");
	}
	return git_checkattr(path, 2, check);
	}

	int ll_merge(mmbuffer_t *result_buf,
	const char *path,
	mmfile_t ancestor, const char ancestor_label,
	mmfile_t ours, const char our_label,
	mmfile_t theirs, const char their_label,
	int flag)
	{
	static struct git_attr_check check[2];
	const char *ll_driver_name = NULL;
	int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
	const struct ll_merge_driver *driver;
	int virtual_ancestor = flag & 01;

	if (!git_path_check_merge(path, check)) {
	ll_driver_name = check[0].value;
	if (check[1].value) {
	marker_size = atoi(check[1].value);
	if (marker_size <= 0)
	marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
	}
	}
	driver = find_ll_merge_driver(ll_driver_name);
	if (virtual_ancestor && driver->recursive)
	driver = find_ll_merge_driver(driver->recursive);
	return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
	ours, our_label, theirs, their_label,
	flag, marker_size);
	}

	int ll_merge_marker_size(const char *path)
	{
	static struct git_attr_check check;
	int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;

	if (!check.attr)
	check.attr = git_attr("conflict-marker-size");
	if (!git_checkattr(path, 1, &check) && check.value) {
	marker_size = atoi(check.value);
	if (marker_size <= 0)
	marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
	}
	return marker_size;
	}