Merge branch 'gb/apply-ignore-whitespace'

* gb/apply-ignore-whitespace:
  git apply: option to ignore whitespace differences

1 files changed, 166 insertions, 7 deletions

diff --git a/builtin-apply.c b/builtin-apply.c
index 39dc96ae02..ae11b41ef2 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -61,6 +61,13 @@ static enum ws_error_action {
 static int whitespace_error;
 static int squelch_whitespace_errors = 5;
 static int applied_after_fixing_ws;
+
+static enum ws_ignore {
+	ignore_ws_none,
+	ignore_ws_change,
+} ws_ignore_action = ignore_ws_none;
+
+
 static const char *patch_input_file;
 static const char *root;
 static int root_len;
@@ -97,6 +104,21 @@ static void parse_whitespace_option(const char *option)
 	die("unrecognized whitespace option '%s'", option);
 }
 
+static void parse_ignorewhitespace_option(const char *option)
+{
+	if (!option || !strcmp(option, "no") ||
+	    !strcmp(option, "false") || !strcmp(option, "never") ||
+	    !strcmp(option, "none")) {
+		ws_ignore_action = ignore_ws_none;
+		return;
+	}
+	if (!strcmp(option, "change")) {
+		ws_ignore_action = ignore_ws_change;
+		return;
+	}
+	die("unrecognized whitespace ignore option '%s'", option);
+}
+
 static void set_default_whitespace_mode(const char *whitespace_option)
 {
 	if (!whitespace_option && !apply_default_whitespace)
@@ -214,6 +236,62 @@ static uint32_t hash_line(const char *cp, size_t len)
 	return h;
 }
 
+/*
+ * Compare lines s1 of length n1 and s2 of length n2, ignoring
+ * whitespace difference. Returns 1 if they match, 0 otherwise
+ */
+static int fuzzy_matchlines(const char *s1, size_t n1,
+			    const char *s2, size_t n2)
+{
+	const char *last1 = s1 + n1 - 1;
+	const char *last2 = s2 + n2 - 1;
+	int result = 0;
+
+	if (n1 < 0 || n2 < 0)
+		return 0;
+
+	/* ignore line endings */
+	while ((*last1 == '\r') || (*last1 == '\n'))
+		last1--;
+	while ((*last2 == '\r') || (*last2 == '\n'))
+		last2--;
+
+	/* skip leading whitespace */
+	while (isspace(*s1) && (s1 <= last1))
+		s1++;
+	while (isspace(*s2) && (s2 <= last2))
+		s2++;
+	/* early return if both lines are empty */
+	if ((s1 > last1) && (s2 > last2))
+		return 1;
+	while (!result) {
+		result = *s1++ - *s2++;
+		/*
+		 * Skip whitespace inside. We check for whitespace on
+		 * both buffers because we don't want "a b" to match
+		 * "ab"
+		 */
+		if (isspace(*s1) && isspace(*s2)) {
+			while (isspace(*s1) && s1 <= last1)
+				s1++;
+			while (isspace(*s2) && s2 <= last2)
+				s2++;
+		}
+		/*
+		 * If we reached the end on one side only,
+		 * lines don't match
+		 */
+		if (
+		    ((s2 > last2) && (s1 <= last1)) ||
+		    ((s1 > last1) && (s2 <= last2)))
+			return 0;
+		if ((s1 > last1) && (s2 > last2))
+			break;
+	}
+
+	return !result;
+}
+
 static void add_line_info(struct image *img, const char *bol, size_t len, unsigned flag)
 {
 	ALLOC_GROW(img->line_allocated, img->nr + 1, img->alloc);
@@ -1672,10 +1750,17 @@ static int read_old_data(struct stat *st, const char *path, struct strbuf *buf)
 	}
 }
 
+/*
+ * Update the preimage, and the common lines in postimage,
+ * from buffer buf of length len. If postlen is 0 the postimage
+ * is updated in place, otherwise it's updated on a new buffer
+ * of length postlen
+ */
+
 static void update_pre_post_images(struct image *preimage,
 				   struct image *postimage,
 				   char *buf,
-				   size_t len)
+				   size_t len, size_t postlen)
 {
 	int i, ctx;
 	char *new, *old, *fixed;
@@ -1694,11 +1779,19 @@ static void update_pre_post_images(struct image *preimage,
 	*preimage = fixed_preimage;
 
 	/*
-	 * Adjust the common context lines in postimage, in place.
-	 * This is possible because whitespace fixing does not make
-	 * the string grow.
+	 * Adjust the common context lines in postimage. This can be
+	 * done in-place when we are just doing whitespace fixing,
+	 * which does not make the string grow, but needs a new buffer
+	 * when ignoring whitespace causes the update, since in this case
+	 * we could have e.g. tabs converted to multiple spaces.
+	 * We trust the caller to tell us if the update can be done
+	 * in place (postlen==0) or not.
 	 */
-	new = old = postimage->buf;
+	old = postimage->buf;
+	if (postlen)
+		new = postimage->buf = xmalloc(postlen);
+	else
+		new = old;
 	fixed = preimage->buf;
 	for (i = ctx = 0; i < postimage->nr; i++) {
 		size_t len = postimage->line[i].len;
@@ -1773,12 +1866,58 @@ static int match_fragment(struct image *img,
 	    !memcmp(img->buf + try, preimage->buf, preimage->len))
 		return 1;
 
+	/*
+	 * No exact match. If we are ignoring whitespace, run a line-by-line
+	 * fuzzy matching. We collect all the line length information because
+	 * we need it to adjust whitespace if we match.
+	 */
+	if (ws_ignore_action == ignore_ws_change) {
+		size_t imgoff = 0;
+		size_t preoff = 0;
+		size_t postlen = postimage->len;
+		size_t imglen[preimage->nr];
+		for (i = 0; i < preimage->nr; i++) {
+			size_t prelen = preimage->line[i].len;
+
+			imglen[i] = img->line[try_lno+i].len;
+			if (!fuzzy_matchlines(
+				img->buf + try + imgoff, imglen[i],
+				preimage->buf + preoff, prelen))
+				return 0;
+			if (preimage->line[i].flag & LINE_COMMON)
+				postlen += imglen[i] - prelen;
+			imgoff += imglen[i];
+			preoff += prelen;
+		}
+
+		/*
+		 * Ok, the preimage matches with whitespace fuzz. Update it and
+		 * the common postimage lines to use the same whitespace as the
+		 * target. imgoff now holds the true length of the target that
+		 * matches the preimage, and we need to update the line lengths
+		 * of the preimage to match the target ones.
+		 */
+		fixed_buf = xmalloc(imgoff);
+		memcpy(fixed_buf, img->buf + try, imgoff);
+		for (i = 0; i < preimage->nr; i++)
+			preimage->line[i].len = imglen[i];
+
+		/*
+		 * Update the preimage buffer and the postimage context lines.
+		 */
+		update_pre_post_images(preimage, postimage,
+				fixed_buf, imgoff, postlen);
+		return 1;
+	}
+
 	if (ws_error_action != correct_ws_error)
 		return 0;
 
 	/*
 	 * The hunk does not apply byte-by-byte, but the hash says
-	 * it might with whitespace fuzz.
+	 * it might with whitespace fuzz. We haven't been asked to
+	 * ignore whitespace, we were asked to correct whitespace
+	 * errors, so let's try matching after whitespace correction.
 	 */
 	fixed_buf = xmalloc(preimage->len + 1);
 	buf = fixed_buf;
@@ -1830,7 +1969,7 @@ static int match_fragment(struct image *img,
 	 * hunk match.  Update the context lines in the postimage.
 	 */
 	update_pre_post_images(preimage, postimage,
-			       fixed_buf, buf - fixed_buf);
+			       fixed_buf, buf - fixed_buf, 0);
 	return 1;
 
  unmatch_exit:
@@ -3272,6 +3411,8 @@ static int git_apply_config(const char *var, const char *value, void *cb)
 {
 	if (!strcmp(var, "apply.whitespace"))
 		return git_config_string(&apply_default_whitespace, var, value);
+	else if (!strcmp(var, "apply.ignorewhitespace"))
+		return git_config_string(&apply_default_ignorewhitespace, var, value);
 	return git_default_config(var, value, cb);
 }
 
@@ -3308,6 +3449,16 @@ static int option_parse_z(const struct option *opt,
 	return 0;
 }
 
+static int option_parse_space_change(const struct option *opt,
+			  const char *arg, int unset)
+{
+	if (unset)
+		ws_ignore_action = ignore_ws_none;
+	else
+		ws_ignore_action = ignore_ws_change;
+	return 0;
+}
+
 static int option_parse_whitespace(const struct option *opt,
 				   const char *arg, int unset)
 {
@@ -3384,6 +3535,12 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 		{ OPTION_CALLBACK, 0, "whitespace", &whitespace_option, "action",
 			"detect new or modified lines that have whitespace errors",
 			0, option_parse_whitespace },
+		{ OPTION_CALLBACK, 0, "ignore-space-change", NULL, NULL,
+			"ignore changes in whitespace when finding context",
+			PARSE_OPT_NOARG, option_parse_space_change },
+		{ OPTION_CALLBACK, 0, "ignore-whitespace", NULL, NULL,
+			"ignore changes in whitespace when finding context",
+			PARSE_OPT_NOARG, option_parse_space_change },
 		OPT_BOOLEAN('R', "reverse", &apply_in_reverse,
 			"apply the patch in reverse"),
 		OPT_BOOLEAN(0, "unidiff-zero", &unidiff_zero,
@@ -3408,6 +3565,8 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 	git_config(git_apply_config, NULL);
 	if (apply_default_whitespace)
 		parse_whitespace_option(apply_default_whitespace);
+	if (apply_default_ignorewhitespace)
+		parse_ignorewhitespace_option(apply_default_ignorewhitespace);
 
 	argc = parse_options(argc, argv, prefix, builtin_apply_options,
 			apply_usage, 0);