global: improve const correctness when assigning string constants

We're about to enable `-Wwrite-strings`, which changes the type of
string constants to `const char[]`. Fix various sites where we assign
such constants to non-const variables.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 23 insertions, 24 deletions

diff --git a/reftable/basics.c b/reftable/basics.c
index fea711db7e..0058619ca6 100644
--- a/reftable/basics.c
+++ b/reftable/basics.c
@@ -67,9 +67,9 @@ void free_names(char **a)
 	reftable_free(a);
 }
 
-size_t names_length(char **names)
+size_t names_length(const char **names)
 {
-	char **p = names;
+	const char **p = names;
 	while (*p)
 		p++;
 	return p - names;
@@ -102,15 +102,12 @@ void parse_names(char *buf, int size, char ***namesp)
 	*namesp = names;
 }
 
-int names_equal(char **a, char **b)
+int names_equal(const char **a, const char **b)
 {
-	int i = 0;
-	for (; a[i] && b[i]; i++) {
-		if (strcmp(a[i], b[i])) {
+	size_t i = 0;
+	for (; a[i] && b[i]; i++)
+		if (strcmp(a[i], b[i]))
 			return 0;
-		}
-	}
-
 	return a[i] == b[i];
 }
 
diff --git a/reftable/basics.h b/reftable/basics.h
index 523ecd5307..c8fec68d4e 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -42,10 +42,10 @@ void free_names(char **a);
 void parse_names(char *buf, int size, char ***namesp);
 
 /* compares two NULL-terminated arrays of strings. */
-int names_equal(char **a, char **b);
+int names_equal(const char **a, const char **b);
 
 /* returns the array size of a NULL-terminated array of strings. */
-size_t names_length(char **names);
+size_t names_length(const char **names);
 
 /* Allocation routines; they invoke the functions set through
  * reftable_set_alloc() */
diff --git a/reftable/basics_test.c b/reftable/basics_test.c
index 997c4d9e01..13bc761817 100644
--- a/reftable/basics_test.c
+++ b/reftable/basics_test.c
@@ -58,8 +58,8 @@ static void test_binsearch(void)
 
 static void test_names_length(void)
 {
-	char *a[] = { "a", "b", NULL };
-	EXPECT(names_length(a) == 2);
+	const char *names[] = { "a", "b", NULL };
+	EXPECT(names_length(names) == 2);
 }
 
 static void test_parse_names_normal(void)
diff --git a/reftable/record.c b/reftable/record.c
index 5506f3e913..a2cba5ef74 100644
--- a/reftable/record.c
+++ b/reftable/record.c
@@ -116,7 +116,7 @@ static int decode_string(struct strbuf *dest, struct string_view in)
 	return start_len - in.len;
 }
 
-static int encode_string(char *str, struct string_view s)
+static int encode_string(const char *str, struct string_view s)
 {
 	struct string_view start = s;
 	int l = strlen(str);
@@ -969,9 +969,9 @@ done:
 	return REFTABLE_FORMAT_ERROR;
 }
 
-static int null_streq(char *a, char *b)
+static int null_streq(const char *a, const char *b)
 {
-	char *empty = "";
+	const char *empty = "";
 	if (!a)
 		a = empty;
 
diff --git a/reftable/stack.c b/reftable/stack.c
index a59ebe038d..09549c51c9 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -204,7 +204,8 @@ static struct reftable_reader **stack_copy_readers(struct reftable_stack *st,
 	return cur;
 }
 
-static int reftable_stack_reload_once(struct reftable_stack *st, char **names,
+static int reftable_stack_reload_once(struct reftable_stack *st,
+				      const char **names,
 				      int reuse_open)
 {
 	size_t cur_len = !st->merged ? 0 : st->merged->stack_len;
@@ -222,7 +223,7 @@ static int reftable_stack_reload_once(struct reftable_stack *st, char **names,
 
 	while (*names) {
 		struct reftable_reader *rd = NULL;
-		char *name = *names++;
+		const char *name = *names++;
 
 		/* this is linear; we assume compaction keeps the number of
 		   tables under control so this is not quadratic. */
@@ -354,7 +355,7 @@ static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
 				goto out;
 		}
 
-		err = reftable_stack_reload_once(st, names, reuse_open);
+		err = reftable_stack_reload_once(st, (const char **) names, reuse_open);
 		if (!err)
 			break;
 		if (err != REFTABLE_NOT_EXIST_ERROR)
@@ -368,7 +369,8 @@ static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
 		err = read_lines(st->list_file, &names_after);
 		if (err < 0)
 			goto out;
-		if (names_equal(names_after, names)) {
+		if (names_equal((const char **) names_after,
+				(const char **) names)) {
 			err = REFTABLE_NOT_EXIST_ERROR;
 			goto out;
 		}
diff --git a/reftable/stack_test.c b/reftable/stack_test.c
index 7889f818d1..07d89b45da 100644
--- a/reftable/stack_test.c
+++ b/reftable/stack_test.c
@@ -83,7 +83,7 @@ static void test_read_file(void)
 	char out[1024] = "line1\n\nline2\nline3";
 	int n, err;
 	char **names = NULL;
-	char *want[] = { "line1", "line2", "line3" };
+	const char *want[] = { "line1", "line2", "line3" };
 	int i = 0;
 
 	EXPECT(fd > 0);
@@ -116,9 +116,9 @@ static void test_parse_names(void)
 
 static void test_names_equal(void)
 {
-	char *a[] = { "a", "b", "c", NULL };
-	char *b[] = { "a", "b", "d", NULL };
-	char *c[] = { "a", "b", NULL };
+	const char *a[] = { "a", "b", "c", NULL };
+	const char *b[] = { "a", "b", "d", NULL };
+	const char *c[] = { "a", "b", NULL };
 
 	EXPECT(names_equal(a, a));
 	EXPECT(!names_equal(a, b));