configuration: Constify numerous pointers

Mark numerous function argument pointers as 'const' in the configuration
sub-system.

This also does the same with a few functions in
src/nxt_conf_validation.c that are required to accomplish the below,
attacking the rest is an exercise for another day...

While this is a worthwhile hardening exercise in its own right, the main
impetus for this is to 'constify' some local function variables which
are currently defined with 'static' storage class and turn them into
'static const', which will be done in a subsequent patch.

Reviewed-by: Zhidao HONG <z.hong@f5.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

3 files changed, 74 insertions, 68 deletions

diff --git a/src/nxt_conf.c b/src/nxt_conf.c
index 9ae25172..3e9f9f4a 100644
--- a/src/nxt_conf.c
+++ b/src/nxt_conf.c
@@ -123,12 +123,12 @@ static u_char *nxt_conf_json_parse_number(nxt_mp_t *mp, nxt_conf_value_t *value,
 static void nxt_conf_json_parse_error(nxt_conf_json_error_t *error, u_char *pos,
     const char *detail);
 
-static nxt_int_t nxt_conf_copy_value(nxt_mp_t *mp, nxt_conf_op_t *op,
-    nxt_conf_value_t *dst, nxt_conf_value_t *src);
-static nxt_int_t nxt_conf_copy_array(nxt_mp_t *mp, nxt_conf_op_t *op,
-    nxt_conf_value_t *dst, nxt_conf_value_t *src);
-static nxt_int_t nxt_conf_copy_object(nxt_mp_t *mp, nxt_conf_op_t *op,
-    nxt_conf_value_t *dst, nxt_conf_value_t *src);
+static nxt_int_t nxt_conf_copy_value(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src);
+static nxt_int_t nxt_conf_copy_array(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src);
+static nxt_int_t nxt_conf_copy_object(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src);
 
 static size_t nxt_conf_json_string_length(nxt_conf_value_t *value);
 static u_char *nxt_conf_json_print_string(u_char *p, nxt_conf_value_t *value);
@@ -186,7 +186,7 @@ nxt_conf_get_string_dup(nxt_conf_value_t *value, nxt_mp_t *mp, nxt_str_t *str)
 
 
 void
-nxt_conf_set_string(nxt_conf_value_t *value, nxt_str_t *str)
+nxt_conf_set_string(nxt_conf_value_t *value, const nxt_str_t *str)
 {
     if (str->length > NXT_CONF_MAX_SHORT_STRING) {
         value->type = NXT_CONF_VALUE_STRING;
@@ -245,7 +245,7 @@ nxt_conf_get_boolean(nxt_conf_value_t *value)
 
 
 nxt_uint_t
-nxt_conf_object_members_count(nxt_conf_value_t *value)
+nxt_conf_object_members_count(const nxt_conf_value_t *value)
 {
     return value->u.object->count;
 }
@@ -276,7 +276,7 @@ nxt_conf_create_object(nxt_mp_t *mp, nxt_uint_t count)
 
 
 void
-nxt_conf_set_member(nxt_conf_value_t *object, nxt_str_t *name,
+nxt_conf_set_member(nxt_conf_value_t *object, const nxt_str_t *name,
     const nxt_conf_value_t *value, uint32_t index)
 {
     nxt_conf_object_member_t  *member;
@@ -290,8 +290,8 @@ nxt_conf_set_member(nxt_conf_value_t *object, nxt_str_t *name,
 
 
 nxt_int_t
-nxt_conf_set_member_dup(nxt_conf_value_t *object, nxt_mp_t *mp, nxt_str_t *name,
-    nxt_conf_value_t *value, uint32_t index)
+nxt_conf_set_member_dup(nxt_conf_value_t *object, nxt_mp_t *mp,
+    const nxt_str_t *name, const nxt_conf_value_t *value, uint32_t index)
 {
     nxt_conf_object_member_t  *member;
 
@@ -304,8 +304,8 @@ nxt_conf_set_member_dup(nxt_conf_value_t *object, nxt_mp_t *mp, nxt_str_t *name,
 
 
 void
-nxt_conf_set_member_string(nxt_conf_value_t *object, nxt_str_t *name,
-    nxt_str_t *value, uint32_t index)
+nxt_conf_set_member_string(nxt_conf_value_t *object, const nxt_str_t *name,
+    const nxt_str_t *value, uint32_t index)
 {
     nxt_conf_object_member_t  *member;
 
@@ -319,7 +319,7 @@ nxt_conf_set_member_string(nxt_conf_value_t *object, nxt_str_t *name,
 
 nxt_int_t
 nxt_conf_set_member_string_dup(nxt_conf_value_t *object, nxt_mp_t *mp,
-    nxt_str_t *name, nxt_str_t *value, uint32_t index)
+    const nxt_str_t *name, const nxt_str_t *value, uint32_t index)
 {
     nxt_conf_object_member_t  *member;
 
@@ -332,7 +332,7 @@ nxt_conf_set_member_string_dup(nxt_conf_value_t *object, nxt_mp_t *mp,
 
 
 void
-nxt_conf_set_member_integer(nxt_conf_value_t *object, nxt_str_t *name,
+nxt_conf_set_member_integer(nxt_conf_value_t *object, const nxt_str_t *name,
     int64_t value, uint32_t index)
 {
     u_char                    *p, *end;
@@ -353,7 +353,7 @@ nxt_conf_set_member_integer(nxt_conf_value_t *object, nxt_str_t *name,
 
 
 void
-nxt_conf_set_member_null(nxt_conf_value_t *object, nxt_str_t *name,
+nxt_conf_set_member_null(nxt_conf_value_t *object, const nxt_str_t *name,
     uint32_t index)
 {
     nxt_conf_object_member_t  *member;
@@ -400,7 +400,7 @@ nxt_conf_set_element(nxt_conf_value_t *array, nxt_uint_t index,
 
 nxt_int_t
 nxt_conf_set_element_string_dup(nxt_conf_value_t *array, nxt_mp_t *mp,
-    nxt_uint_t index, nxt_str_t *value)
+    nxt_uint_t index, const nxt_str_t *value)
 {
     nxt_conf_value_t  *element;
 
@@ -411,21 +411,21 @@ nxt_conf_set_element_string_dup(nxt_conf_value_t *array, nxt_mp_t *mp,
 
 
 nxt_uint_t
-nxt_conf_array_elements_count(nxt_conf_value_t *value)
+nxt_conf_array_elements_count(const nxt_conf_value_t *value)
 {
     return value->u.array->count;
 }
 
 
 nxt_uint_t
-nxt_conf_array_elements_count_or_1(nxt_conf_value_t *value)
+nxt_conf_array_elements_count_or_1(const nxt_conf_value_t *value)
 {
     return (value->type == NXT_CONF_VALUE_ARRAY) ? value->u.array->count : 1;
 }
 
 
 nxt_uint_t
-nxt_conf_type(nxt_conf_value_t *value)
+nxt_conf_type(const nxt_conf_value_t *value)
 {
     switch (value->type) {
 
@@ -459,7 +459,7 @@ nxt_conf_type(nxt_conf_value_t *value)
 
 
 nxt_conf_value_t *
-nxt_conf_get_path(nxt_conf_value_t *value, nxt_str_t *path)
+nxt_conf_get_path(nxt_conf_value_t *value, const nxt_str_t *path)
 {
     nxt_str_t              token;
     nxt_int_t              ret, index;
@@ -550,7 +550,7 @@ nxt_conf_path_next_token(nxt_conf_path_parse_t *parse, nxt_str_t *token)
 
 
 nxt_conf_value_t *
-nxt_conf_get_object_member(nxt_conf_value_t *value, nxt_str_t *name,
+nxt_conf_get_object_member(const nxt_conf_value_t *value, const nxt_str_t *name,
     uint32_t *index)
 {
     nxt_str_t                 str;
@@ -584,8 +584,8 @@ nxt_conf_get_object_member(nxt_conf_value_t *value, nxt_str_t *name,
 
 
 nxt_int_t
-nxt_conf_map_object(nxt_mp_t *mp, nxt_conf_value_t *value, nxt_conf_map_t *map,
-    nxt_uint_t n, void *data)
+nxt_conf_map_object(nxt_mp_t *mp, const nxt_conf_value_t *value,
+    const nxt_conf_map_t *map, nxt_uint_t n, void *data)
 {
     double            num;
     nxt_str_t         str, *s;
@@ -736,7 +736,7 @@ nxt_conf_map_object(nxt_mp_t *mp, nxt_conf_value_t *value, nxt_conf_map_t *map,
 
 
 nxt_conf_value_t *
-nxt_conf_next_object_member(nxt_conf_value_t *value, nxt_str_t *name,
+nxt_conf_next_object_member(const nxt_conf_value_t *value, nxt_str_t *name,
     uint32_t *next)
 {
     uint32_t                  n;
@@ -764,7 +764,7 @@ nxt_conf_next_object_member(nxt_conf_value_t *value, nxt_str_t *name,
 
 
 nxt_conf_value_t *
-nxt_conf_get_array_element(nxt_conf_value_t *value, uint32_t index)
+nxt_conf_get_array_element(const nxt_conf_value_t *value, uint32_t index)
 {
     nxt_conf_array_t  *array;
 
@@ -802,7 +802,7 @@ nxt_conf_get_array_element_or_itself(nxt_conf_value_t *value, uint32_t index)
 
 
 void
-nxt_conf_array_qsort(nxt_conf_value_t *value,
+nxt_conf_array_qsort(const nxt_conf_value_t *value,
     int (*compare)(const void *, const void *))
 {
     nxt_conf_array_t  *array;
@@ -818,8 +818,9 @@ nxt_conf_array_qsort(nxt_conf_value_t *value,
 
 
 nxt_conf_op_ret_t
-nxt_conf_op_compile(nxt_mp_t *mp, nxt_conf_op_t **ops, nxt_conf_value_t *root,
-    nxt_str_t *path, nxt_conf_value_t *value, nxt_bool_t add)
+nxt_conf_op_compile(nxt_mp_t *mp, nxt_conf_op_t **ops,
+    const nxt_conf_value_t *root, const nxt_str_t *path,
+    nxt_conf_value_t *value, nxt_bool_t add)
 {
     nxt_str_t                 token;
     nxt_int_t                 ret, index;
@@ -956,7 +957,7 @@ nxt_conf_op_compile(nxt_mp_t *mp, nxt_conf_op_t **ops, nxt_conf_value_t *root,
 
 
 nxt_conf_value_t *
-nxt_conf_clone(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *value)
+nxt_conf_clone(nxt_mp_t *mp, nxt_conf_op_t *op, const nxt_conf_value_t *value)
 {
     nxt_int_t         rc;
     nxt_conf_value_t  *copy;
@@ -977,8 +978,8 @@ nxt_conf_clone(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *value)
 
 
 static nxt_int_t
-nxt_conf_copy_value(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *dst,
-    nxt_conf_value_t *src)
+nxt_conf_copy_value(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src)
 {
     if (op != NULL
         && src->type != NXT_CONF_VALUE_ARRAY
@@ -1020,8 +1021,8 @@ nxt_conf_copy_value(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *dst,
 
 
 static nxt_int_t
-nxt_conf_copy_array(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *dst,
-    nxt_conf_value_t *src)
+nxt_conf_copy_array(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src)
 {
     size_t            size;
     nxt_int_t         rc;
@@ -1120,8 +1121,8 @@ nxt_conf_copy_array(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *dst,
 
 
 static nxt_int_t
-nxt_conf_copy_object(nxt_mp_t *mp, nxt_conf_op_t *op, nxt_conf_value_t *dst,
-    nxt_conf_value_t *src)
+nxt_conf_copy_object(nxt_mp_t *mp, const nxt_conf_op_t *op,
+    nxt_conf_value_t *dst, const nxt_conf_value_t *src)
 {
     size_t                    size;
     nxt_int_t                 rc;
diff --git a/src/nxt_conf.h b/src/nxt_conf.h
index 626b6d4d..d1a475e5 100644
--- a/src/nxt_conf.h
+++ b/src/nxt_conf.h
@@ -79,27 +79,28 @@ typedef struct {
 } nxt_conf_validation_t;
 
 
-NXT_EXPORT nxt_uint_t nxt_conf_type(nxt_conf_value_t *value);
+NXT_EXPORT nxt_uint_t nxt_conf_type(const nxt_conf_value_t *value);
 
 NXT_EXPORT nxt_conf_value_t *nxt_conf_get_path(nxt_conf_value_t *value,
-    nxt_str_t *path);
-NXT_EXPORT nxt_conf_value_t *nxt_conf_get_object_member(nxt_conf_value_t *value,
-    nxt_str_t *name, uint32_t *index);
+    const nxt_str_t *path);
+NXT_EXPORT nxt_conf_value_t *nxt_conf_get_object_member(
+    const nxt_conf_value_t *value, const nxt_str_t *name, uint32_t *index);
 NXT_EXPORT nxt_conf_value_t *nxt_conf_next_object_member(
-    nxt_conf_value_t *value, nxt_str_t *name, uint32_t *next);
-NXT_EXPORT nxt_conf_value_t *nxt_conf_get_array_element(nxt_conf_value_t *value,
-    uint32_t index);
+    const nxt_conf_value_t *value, nxt_str_t *name, uint32_t *next);
+NXT_EXPORT nxt_conf_value_t *nxt_conf_get_array_element(
+    const nxt_conf_value_t *value, uint32_t index);
 NXT_EXPORT nxt_conf_value_t *nxt_conf_get_array_element_or_itself(
     nxt_conf_value_t *value, uint32_t index);
 
-NXT_EXPORT nxt_int_t nxt_conf_map_object(nxt_mp_t *mp, nxt_conf_value_t *value,
-    nxt_conf_map_t *map, nxt_uint_t n, void *data);
+NXT_EXPORT nxt_int_t nxt_conf_map_object(nxt_mp_t *mp,
+    const nxt_conf_value_t *value, const nxt_conf_map_t *map, nxt_uint_t n,
+    void *data);
 
 nxt_conf_op_ret_t nxt_conf_op_compile(nxt_mp_t *mp, nxt_conf_op_t **ops,
-    nxt_conf_value_t *root, nxt_str_t *path, nxt_conf_value_t *value,
+    const nxt_conf_value_t *root, const nxt_str_t *path, nxt_conf_value_t *value,
     nxt_bool_t add);
 nxt_conf_value_t *nxt_conf_clone(nxt_mp_t *mp, nxt_conf_op_t *op,
-    nxt_conf_value_t *value);
+    const nxt_conf_value_t *value);
 
 nxt_conf_value_t *nxt_conf_json_parse(nxt_mp_t *mp, u_char *start, u_char *end,
     nxt_conf_json_error_t *error);
@@ -119,37 +120,41 @@ nxt_int_t nxt_conf_validate(nxt_conf_validation_t *vldt);
 NXT_EXPORT void nxt_conf_get_string(nxt_conf_value_t *value, nxt_str_t *str);
 NXT_EXPORT nxt_str_t *nxt_conf_get_string_dup(nxt_conf_value_t *value,
     nxt_mp_t *mp, nxt_str_t *str);
-NXT_EXPORT void nxt_conf_set_string(nxt_conf_value_t *value, nxt_str_t *str);
+NXT_EXPORT void nxt_conf_set_string(nxt_conf_value_t *value,
+    const nxt_str_t *str);
 NXT_EXPORT nxt_int_t nxt_conf_set_string_dup(nxt_conf_value_t *value,
     nxt_mp_t *mp, const nxt_str_t *str);
 NXT_EXPORT double nxt_conf_get_number(nxt_conf_value_t *value);
 NXT_EXPORT uint8_t nxt_conf_get_boolean(nxt_conf_value_t *value);
 
 // FIXME reimplement and reorder functions below
-NXT_EXPORT nxt_uint_t nxt_conf_object_members_count(nxt_conf_value_t *value);
+NXT_EXPORT nxt_uint_t nxt_conf_object_members_count(
+    const nxt_conf_value_t *value);
 nxt_conf_value_t *nxt_conf_create_object(nxt_mp_t *mp, nxt_uint_t count);
-void nxt_conf_set_member(nxt_conf_value_t *object, nxt_str_t *name,
+void nxt_conf_set_member(nxt_conf_value_t *object, const nxt_str_t *name,
     const nxt_conf_value_t *value, uint32_t index);
 nxt_int_t nxt_conf_set_member_dup(nxt_conf_value_t *object, nxt_mp_t *mp,
-    nxt_str_t *name, nxt_conf_value_t *value, uint32_t index);
-void nxt_conf_set_member_string(nxt_conf_value_t *object, nxt_str_t *name,
-    nxt_str_t *value, uint32_t index);
-nxt_int_t nxt_conf_set_member_string_dup(nxt_conf_value_t *object, nxt_mp_t *mp,
-    nxt_str_t *name, nxt_str_t *value, uint32_t index);
-void nxt_conf_set_member_integer(nxt_conf_value_t *object, nxt_str_t *name,
-    int64_t value, uint32_t index);
-void nxt_conf_set_member_null(nxt_conf_value_t *object, nxt_str_t *name,
+    const nxt_str_t *name, const nxt_conf_value_t *value, uint32_t index);
+void nxt_conf_set_member_string(nxt_conf_value_t *object,
+    const nxt_str_t *name, const nxt_str_t *value, uint32_t index);
+nxt_int_t nxt_conf_set_member_string_dup(nxt_conf_value_t *object,
+    nxt_mp_t *mp, const nxt_str_t *name, const nxt_str_t *value,
+    uint32_t index);
+void nxt_conf_set_member_integer(nxt_conf_value_t *object,
+    const nxt_str_t *name, int64_t value, uint32_t index);
+void nxt_conf_set_member_null(nxt_conf_value_t *object, const nxt_str_t *name,
     uint32_t index);
 
 nxt_conf_value_t *nxt_conf_create_array(nxt_mp_t *mp, nxt_uint_t count);
 void nxt_conf_set_element(nxt_conf_value_t *array, nxt_uint_t index,
     const nxt_conf_value_t *value);
-nxt_int_t nxt_conf_set_element_string_dup(nxt_conf_value_t *array, nxt_mp_t *mp,
-    nxt_uint_t index, nxt_str_t *value);
-NXT_EXPORT nxt_uint_t nxt_conf_array_elements_count(nxt_conf_value_t *value);
+nxt_int_t nxt_conf_set_element_string_dup(nxt_conf_value_t *array,
+    nxt_mp_t *mp, nxt_uint_t index, const nxt_str_t *value);
+NXT_EXPORT nxt_uint_t nxt_conf_array_elements_count(
+    const nxt_conf_value_t *value);
 NXT_EXPORT nxt_uint_t nxt_conf_array_elements_count_or_1(
-    nxt_conf_value_t *value);
-void nxt_conf_array_qsort(nxt_conf_value_t *value,
+    const nxt_conf_value_t *value);
+void nxt_conf_array_qsort(const nxt_conf_value_t *value,
     int (*compare)(const void *, const void *));
 
 
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index 8f802fb7..38a918fb 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -73,11 +73,11 @@ struct nxt_conf_vldt_object_s {
 
 
 static nxt_int_t nxt_conf_vldt_type(nxt_conf_validation_t *vldt,
-    nxt_str_t *name, nxt_conf_value_t *value, nxt_conf_vldt_type_t type);
+    const nxt_str_t *name, nxt_conf_value_t *value, nxt_conf_vldt_type_t type);
 static nxt_int_t nxt_conf_vldt_error(nxt_conf_validation_t *vldt,
     const char *fmt, ...);
-static nxt_int_t nxt_conf_vldt_var(nxt_conf_validation_t *vldt, nxt_str_t *name,
-    nxt_str_t *value);
+static nxt_int_t nxt_conf_vldt_var(nxt_conf_validation_t *vldt,
+    const nxt_str_t *name, nxt_str_t *value);
 static nxt_int_t nxt_conf_vldt_if(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 nxt_inline nxt_int_t nxt_conf_vldt_unsupported(nxt_conf_validation_t *vldt,
@@ -1436,7 +1436,7 @@ nxt_conf_validate(nxt_conf_validation_t *vldt)
 
 
 static nxt_int_t
-nxt_conf_vldt_type(nxt_conf_validation_t *vldt, nxt_str_t *name,
+nxt_conf_vldt_type(nxt_conf_validation_t *vldt, const nxt_str_t *name,
     nxt_conf_value_t *value, nxt_conf_vldt_type_t type)
 {
     u_char      *p;
@@ -1548,7 +1548,7 @@ nxt_conf_vldt_unsupported(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
 
 
 static nxt_int_t
-nxt_conf_vldt_var(nxt_conf_validation_t *vldt, nxt_str_t *name,
+nxt_conf_vldt_var(nxt_conf_validation_t *vldt, const nxt_str_t *name,
     nxt_str_t *value)
 {
     u_char  error[NXT_MAX_ERROR_STR];