config: arbitrary number of matches for --unset and --replace-all

git-config used a static match array to hold the matches we want to
unset/replace when using --unset or --replace-all.  Use a
variable-sized array instead.

This in particular fixes the symptoms git-svn had when storing large
numbers of svn-remote.*.added-placeholder entries in the config file.

While the tests are rather more paranoid than just --unset and
--replace-all, the other operations already worked.  Indeed git-svn's
usage only breaks the first time *after* creating so many entries,
when it wants to unset and re-add them all.
Reported-by: NJess Hottenstein <jess.hottenstein@gmail.com>
Signed-off-by: NThomas Rast <tr@thomasrast.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

config.c

@@ -1160,15 +1160,14 @@ int git_config(config_fn_t fn, void *data)
  * Find all the stuff for git_config_set() below.
  */
 
-#define MAX_MATCHES 512
-
 static struct {
 	int baselen;
 	char *key;
 	int do_not_match;
 	regex_t *value_regex;
 	int multi_replace;
-	size_t offset[MAX_MATCHES];
+	size_t *offset;
+	unsigned int offset_alloc;
 	enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 	int seen;
 } store;
@@ -1191,11 +1190,11 @@ static int store_aux(const char *key, const char *value, void *cb)
 		if (matches(key, value)) {
 			if (store.seen == 1 && store.multi_replace == 0) {
 				warning("%s has multiple values", key);
-			} else if (store.seen >= MAX_MATCHES) {
-				error("too many matches for %s", key);
-				return 1;
 			}
 
+			ALLOC_GROW(store.offset, store.seen + 1,
+				   store.offset_alloc);
+
 			store.offset[store.seen] = cf->do_ftell(cf);
 			store.seen++;
 		}
@@ -1223,11 +1222,15 @@ static int store_aux(const char *key, const char *value, void *cb)
 		 * Do not increment matches: this is no match, but we
 		 * just made sure we are in the desired section.
 		 */
+		ALLOC_GROW(store.offset, store.seen + 1,
+			   store.offset_alloc);
 		store.offset[store.seen] = cf->do_ftell(cf);
 		/* fallthru */
 	case SECTION_END_SEEN:
 	case START:
 		if (matches(key, value)) {
+			ALLOC_GROW(store.offset, store.seen + 1,
+				   store.offset_alloc);
 			store.offset[store.seen] = cf->do_ftell(cf);
 			store.state = KEY_SEEN;
 			store.seen++;
@@ -1235,6 +1238,9 @@ static int store_aux(const char *key, const char *value, void *cb)
 			if (strrchr(key, '.') - key == store.baselen &&
 			      !strncmp(key, store.key, store.baselen)) {
 					store.state = SECTION_SEEN;
+					ALLOC_GROW(store.offset,
+						   store.seen + 1,
+						   store.offset_alloc);
 					store.offset[store.seen] = cf->do_ftell(cf);
 			}
 		}
@@ -1533,6 +1539,7 @@ int git_config_set_multivar_in_file(const char *config_filename,
 			}
 		}
 
+		ALLOC_GROW(store.offset, 1, store.offset_alloc);
 		store.offset[0] = 0;
 		store.state = START;
 		store.seen = 0;

t/t1303-wacky-config.sh

@@ -3,17 +3,28 @@
 test_description='Test wacky input to git config'
 . ./test-lib.sh
 
+# Leaving off the newline is intentional!
 setup() {
 	(printf "[section]\n" &&
 	printf "  key = foo") >.git/config
 }
 
+# 'check section.key value' verifies that the entry for section.key is
+# 'value'
 check() {
 	echo "$2" >expected
 	git config --get "$1" >actual 2>&1
 	test_cmp actual expected
 }
 
+# 'check section.key regex value' verifies that the entry for
+# section.key *that matches 'regex'* is 'value'
+check_regex() {
+	echo "$3" >expected
+	git config --get "$1" "$2" >actual 2>&1
+	test_cmp actual expected
+}
+
 test_expect_success 'modify same key' '
 	setup &&
 	git config section.key bar &&
@@ -47,4 +58,57 @@ test_expect_success 'do not crash on special long config line' '
 	check section.key "$LONG_VALUE"
 '
 
+setup_many() {
+	setup &&
+	# This time we want the newline so that we can tack on more
+	# entries.
+	echo >>.git/config &&
+	# Semi-efficient way of concatenating 5^5 = 3125 lines. Note
+	# that because 'setup' already put one line, this means 3126
+	# entries for section.key in the config file.
+	cat >5to1 <<-\EOF &&
+	  key = foo
+	  key = foo
+	  key = foo
+	  key = foo
+	  key = foo
+	EOF
+	cat 5to1 5to1 5to1 5to1 5to1 >5to2 &&	   # 25
+	cat 5to2 5to2 5to2 5to2 5to2 >5to3 &&	   # 125
+	cat 5to3 5to3 5to3 5to3 5to3 >5to4 &&	   # 635
+	cat 5to4 5to4 5to4 5to4 5to4 >>.git/config # 3125
+}
+
+test_expect_success 'get many entries' '
+	setup_many &&
+	git config --get-all section.key >actual &&
+	test_line_count = 3126 actual
+'
+
+test_expect_success 'get many entries by regex' '
+	setup_many &&
+	git config --get-regexp "sec.*ke." >actual &&
+	test_line_count = 3126 actual
+'
+
+test_expect_success 'add and replace one of many entries' '
+	setup_many &&
+	git config --add section.key bar &&
+	check_regex section.key "b.*r" bar &&
+	git config section.key beer "b.*r" &&
+	check_regex section.key "b.*r" beer
+'
+
+test_expect_success 'replace many entries' '
+	setup_many &&
+	git config --replace-all section.key bar &&
+	check section.key bar
+'
+
+test_expect_success 'unset many entries' '
+	setup_many &&
+	git config --unset-all section.key &&
+	test_must_fail git config section.key
+'
+
 test_done