parse_config_key(): return subsection len as size_t

We return the length to a subset of a string using an "int *"
out-parameter. This is fine most of the time, as we'd expect config keys
to be relatively short, but it could behave oddly if we had a gigantic
config key. A more appropriate type is size_t.

Let's switch over, which lets our callers use size_t as appropriate
(they are bound by our type because they must pass the out-parameter as
a pointer). This is mostly just a cleanup to make it clear this code
handles long strings correctly. In practice, our config parser already
chokes on long key names (because of a similar int/size_t mixup!).

When doing an int/size_t conversion, we have to be careful that nobody
was trying to assign a negative value to the variable. I manually
confirmed that for each case here. They tend to just feed the result to
xmemdupz() or similar; in a few cases I adjusted the parameter types for
helper functions to make sure the size_t is preserved.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

archive-tar.c

@@ -364,7 +364,7 @@ static struct archiver **tar_filters;
 static int nr_tar_filters;
 static int alloc_tar_filters;
 
-static struct archiver *find_tar_filter(const char *name, int len)
+static struct archiver *find_tar_filter(const char *name, size_t len)
 {
 	int i;
 	for (i = 0; i < nr_tar_filters; i++) {
@@ -380,7 +380,7 @@ static int tar_filter_config(const char *var, const char *value, void *data)
 	struct archiver *ar;
 	const char *name;
 	const char *type;
-	int namelen;
+	size_t namelen;
 
 	if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 		return 0;

builtin/help.c

@@ -242,7 +242,7 @@ static int add_man_viewer_cmd(const char *name,
 static int add_man_viewer_info(const char *var, const char *value)
 {
 	const char *name, *subkey;
-	int namelen;
+	size_t namelen;
 
 	if (parse_config_key(var, "man", &name, &namelen, &subkey) < 0 || !name)
 		return 0;

builtin/reflog.c

@@ -459,7 +459,7 @@ static struct reflog_expire_cfg *find_cfg_ent(const char *pattern, size_t len)
 static int reflog_expire_config(const char *var, const char *value, void *cb)
 {
 	const char *pattern, *key;
-	int pattern_len;
+	size_t pattern_len;
 	timestamp_t expire;
 	int slot;
 	struct reflog_expire_cfg *ent;

config.c

@@ -309,7 +309,7 @@ int git_config_include(const char *var, const char *value, void *data)
 {
 	struct config_include_data *inc = data;
 	const char *cond, *key;
-	int cond_len;
+	size_t cond_len;
 	int ret;
 
 	/*
@@ -3238,7 +3238,7 @@ int config_error_nonbool(const char *var)
 
 int parse_config_key(const char *var,
 		     const char *section,
-		     const char **subsection, int *subsection_len,
+		     const char **subsection, size_t *subsection_len,
 		     const char **key)
 {
 	const char *dot;

config.h

@@ -359,7 +359,7 @@ int git_config_include(const char *name, const char *value, void *data);
  */
 int parse_config_key(const char *var,
 		     const char *section,
-		     const char **subsection, int *subsection_len,
+		     const char **subsection, size_t *subsection_len,
 		     const char **key);
 
 /**

convert.c

@@ -1018,7 +1018,7 @@ static int apply_filter(const char *path, const char *src, size_t len,
 static int read_convert_config(const char *var, const char *value, void *cb)
 {
 	const char *key, *name;
-	int namelen;
+	size_t namelen;
 	struct convert_driver *drv;
 
 	/*

fsck.c

@@ -920,7 +920,7 @@ static int fsck_gitmodules_fn(const char *var, const char *value, void *vdata)
 {
 	struct fsck_gitmodules_data *data = vdata;
 	const char *subsection, *key;
-	int subsection_len;
+	size_t subsection_len;
 	char *name;
 
 	if (parse_config_key(var, "submodule", &subsection, &subsection_len, &key) < 0 ||

ll-merge.c

@@ -247,7 +247,7 @@ static int read_merge_config(const char *var, const char *value, void *cb)
 {
 	struct ll_merge_driver *fn;
 	const char *key, *name;
-	int namelen;
+	size_t namelen;
 
 	if (!strcmp(var, "merge.default"))
 		return git_config_string(&default_ll_merge, var, value);

promisor-remote.c

@@ -101,7 +101,7 @@ static void promisor_remote_move_to_tail(struct promisor_remote *r,
 static int promisor_remote_config(const char *var, const char *value, void *data)
 {
 	const char *name;
-	int namelen;
+	size_t namelen;
 	const char *subkey;
 
 	if (!strcmp(var, "core.partialclonefilter"))

remote.c

@@ -305,7 +305,7 @@ static void read_branches_file(struct remote *remote)
 static int handle_config(const char *key, const char *value, void *cb)
 {
 	const char *name;
-	int namelen;
+	size_t namelen;
 	const char *subkey;
 	struct remote *remote;
 	struct branch *branch;

submodule-config.c

@@ -225,7 +225,8 @@ static int name_and_item_from_var(const char *var, struct strbuf *name,
 				  struct strbuf *item)
 {
 	const char *subsection, *key;
-	int subsection_len, parse;
+	size_t subsection_len;
+	int parse;
 	parse = parse_config_key(var, "submodule", &subsection,
 			&subsection_len, &key);
 	if (parse < 0 || !subsection)

userdiff.c

@@ -222,7 +222,7 @@ static struct userdiff_driver driver_false = {
 	{ NULL, 0 }
 };
 
-static struct userdiff_driver *userdiff_find_by_namelen(const char *k, int len)
+static struct userdiff_driver *userdiff_find_by_namelen(const char *k, size_t len)
 {
 	int i;
 	for (i = 0; i < ndrivers; i++) {
@@ -266,7 +266,7 @@ int userdiff_config(const char *k, const char *v)
 {
 	struct userdiff_driver *drv;
 	const char *name, *type;
-	int namelen;
+	size_t namelen;
 
 	if (parse_config_key(k, "diff", &name, &namelen, &type) || !name)
 		return 0;