Merge branch 'jc/apply-binary-p0'

"git apply -p0" did not parse pathnames on "diff --git" line
correctly.  This caused patches that had pathnames in no other
places to be mistakenly rejected (most notably, binary patch that
does not rename nor change mode).  Textual patches, renames or
mode changes have preimage and postimage pathnames in different
places in a form that can be parsed unambiguously and did not suffer
from this problem.

* jc/apply-binary-p0:
  apply: compute patch->def_name correctly under -p0

builtin/apply.c

@@ -1095,15 +1095,23 @@ static int gitdiff_unrecognized(const char *line, struct patch *patch)
 	return -1;
 }
 
-static const char *stop_at_slash(const char *line, int llen)
+/*
+ * Skip p_value leading components from "line"; as we do not accept
+ * absolute paths, return NULL in that case.
+ */
+static const char *skip_tree_prefix(const char *line, int llen)
 {
-	int nslash = p_value;
+	int nslash;
 	int i;
 
+	if (!p_value)
+		return (llen && line[0] == '/') ? NULL : line;
+
+	nslash = p_value;
 	for (i = 0; i < llen; i++) {
 		int ch = line[i];
 		if (ch == '/' && --nslash <= 0)
-			return &line[i];
+			return (i == 0) ? NULL : &line[i + 1];
 	}
 	return NULL;
 }
@@ -1133,12 +1141,11 @@ static char *git_header_name(const char *line, int llen)
 		if (unquote_c_style(&first, line, &second))
 			goto free_and_fail1;
 
-		/* advance to the first slash */
-		cp = stop_at_slash(first.buf, first.len);
-		/* we do not accept absolute paths */
-		if (!cp || cp == first.buf)
+		/* strip the a/b prefix including trailing slash */
+		cp = skip_tree_prefix(first.buf, first.len);
+		if (!cp)
 			goto free_and_fail1;
-		strbuf_remove(&first, 0, cp + 1 - first.buf);
+		strbuf_remove(&first, 0, cp - first.buf);
 
 		/*
 		 * second points at one past closing dq of name.
@@ -1152,22 +1159,21 @@ static char *git_header_name(const char *line, int llen)
 		if (*second == '"') {
 			if (unquote_c_style(&sp, second, NULL))
 				goto free_and_fail1;
-			cp = stop_at_slash(sp.buf, sp.len);
-			if (!cp || cp == sp.buf)
+			cp = skip_tree_prefix(sp.buf, sp.len);
+			if (!cp)
 				goto free_and_fail1;
 			/* They must match, otherwise ignore */
-			if (strcmp(cp + 1, first.buf))
+			if (strcmp(cp, first.buf))
 				goto free_and_fail1;
 			strbuf_release(&sp);
 			return strbuf_detach(&first, NULL);
 		}
 
 		/* unquoted second */
-		cp = stop_at_slash(second, line + llen - second);
-		if (!cp || cp == second)
+		cp = skip_tree_prefix(second, line + llen - second);
+		if (!cp)
 			goto free_and_fail1;
-		cp++;
-		if (line + llen - cp != first.len + 1 ||
+		if (line + llen - cp != first.len ||
 		    memcmp(first.buf, cp, first.len))
 			goto free_and_fail1;
 		return strbuf_detach(&first, NULL);
@@ -1179,10 +1185,9 @@ static char *git_header_name(const char *line, int llen)
 	}
 
 	/* unquoted first name */
-	name = stop_at_slash(line, llen);
-	if (!name || name == line)
+	name = skip_tree_prefix(line, llen);
+	if (!name)
 		return NULL;
-	name++;
 
 	/*
 	 * since the first name is unquoted, a dq if exists must be
@@ -1196,10 +1201,9 @@ static char *git_header_name(const char *line, int llen)
 			if (unquote_c_style(&sp, second, NULL))
 				goto free_and_fail2;
 
-			np = stop_at_slash(sp.buf, sp.len);
-			if (!np || np == sp.buf)
+			np = skip_tree_prefix(sp.buf, sp.len);
+			if (!np)
 				goto free_and_fail2;
-			np++;
 
 			len = sp.buf + sp.len - np;
 			if (len < second - name &&
@@ -1231,13 +1235,27 @@ static char *git_header_name(const char *line, int llen)
 		case '\n':
 			return NULL;
 		case '\t': case ' ':
-			second = stop_at_slash(name + len, line_len - len);
+			/*
+			 * Is this the separator between the preimage
+			 * and the postimage pathname?  Again, we are
+			 * only interested in the case where there is
+			 * no rename, as this is only to set def_name
+			 * and a rename patch has the names elsewhere
+			 * in an unambiguous form.
+			 */
+			if (!name[len + 1])
+				return NULL; /* no postimage name */
+			second = skip_tree_prefix(name + len + 1,
+						  line_len - (len + 1));
 			if (!second)
 				return NULL;
-			second++;
-			if (second[len] == '\n' && !strncmp(name, second, len)) {
+			/*
+			 * Does len bytes starting at "name" and "second"
+			 * (that are separated by one HT or SP we just
+			 * found) exactly match?
+			 */
+			if (second[len] == '\n' && !strncmp(name, second, len))
 				return xmemdupz(name, len);
-			}
 		}
 	}
 }

t/t4103-apply-binary.sh

@@ -8,30 +8,28 @@ test_description='git apply handling binary patches
 '
 . ./test-lib.sh
 
-# setup
-
-cat >file1 <<EOF
-A quick brown fox jumps over the lazy dog.
-A tiny little penguin runs around in circles.
-There is a flag with Linux written on it.
-A slow black-and-white panda just sits there,
-munching on his bamboo.
-EOF
-cat file1 >file2
-cat file1 >file4
-
-test_expect_success 'setup' "
+test_expect_success 'setup' '
+	cat >file1 <<-\EOF &&
+	A quick brown fox jumps over the lazy dog.
+	A tiny little penguin runs around in circles.
+	There is a flag with Linux written on it.
+	A slow black-and-white panda just sits there,
+	munching on his bamboo.
+	EOF
+	cat file1 >file2 &&
+	cat file1 >file4 &&
+
 	git update-index --add --remove file1 file2 file4 &&
-	git commit -m 'Initial Version' 2>/dev/null &&
+	git commit -m "Initial Version" 2>/dev/null &&
 
 	git checkout -b binary &&
-	"$PERL_PATH" -pe 'y/x/\000/' <file1 >file3 &&
+	"$PERL_PATH" -pe "y/x/\000/" <file1 >file3 &&
 	cat file3 >file4 &&
 	git add file2 &&
-	"$PERL_PATH" -pe 'y/\000/v/' <file3 >file1 &&
+	"$PERL_PATH" -pe "y/\000/v/" <file3 >file1 &&
 	rm -f file2 &&
 	git update-index --add --remove file1 file2 file3 file4 &&
-	git commit -m 'Second Version' &&
+	git commit -m "Second Version" &&
 
 	git diff-tree -p master binary >B.diff &&
 	git diff-tree -p -C master binary >C.diff &&
@@ -42,17 +40,25 @@ test_expect_success 'setup' "
 	git diff-tree -p --full-index master binary >B-index.diff &&
 	git diff-tree -p -C --full-index master binary >C-index.diff &&
 
+	git diff-tree -p --binary --no-prefix master binary -- file3 >B0.diff &&
+
 	git init other-repo &&
-	(cd other-repo &&
-	 git fetch .. master &&
-	 git reset --hard FETCH_HEAD
+	(
+		cd other-repo &&
+		git fetch .. master &&
+		git reset --hard FETCH_HEAD
 	)
-"
+'
 
 test_expect_success 'stat binary diff -- should not fail.' \
 	'git checkout master &&
 	 git apply --stat --summary B.diff'
 
+test_expect_success 'stat binary -p0 diff -- should not fail.' '
+	 git checkout master &&
+	 git apply --stat -p0 B0.diff
+'
+
 test_expect_success 'stat binary diff (copy) -- should not fail.' \
 	'git checkout master &&
 	 git apply --stat --summary C.diff'
@@ -143,4 +149,10 @@ test_expect_success 'apply binary diff (copy).' \
 	 git apply --allow-binary-replacement --index CF.diff &&
 	 test -z "$(git diff --name-status binary)"'
 
+test_expect_success 'apply binary -p0 diff' '
+	do_reset &&
+	git apply -p0 --index B0.diff &&
+	test -z "$(git diff --name-status binary -- file3)"
+'
+
 test_done