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json_pointer: add json_pointer_getf/setf() function variants

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These include support for printf() style args for path.

Adds support for calling with 'json_pointer_getf(obj, &res, "/foo/%d/%s", 0, bar)'
style args.

Makes it easier for doing more dynamic stuff/magic, without
needing to use vasprintf() externally.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>
This commit is contained in:
Alexandru Ardelean
2016-11-16 11:55:41 +02:00
parent 97dd7d5103
commit 742e059da1
2 changed files with 131 additions and 0 deletions
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85
json_pointer.c
View File

@@ -8,6 +8,7 @@
#include "config.h"
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
@@ -192,6 +193,37 @@ int json_pointer_get(struct json_object *obj, const char *path, struct json_obje
return rc;
}
int json_pointer_getf(struct json_object *obj, struct json_object **res, const char *path_fmt, ...)
{
char *path_copy = NULL;
int rc = 0;
va_list args;
if (!obj || !path_fmt) {
errno = EINVAL;
return -1;
}
va_start(args, path_fmt);
rc = vasprintf(&path_copy, path_fmt, args);
va_end(args);
if (rc < 0)
return rc;
if (path_copy[0] == '\0') {
if (res)
*res = obj;
goto out;
}
rc = json_pointer_get_recursive(obj, path_copy, res);
out:
free(path_copy);
return rc;
}
int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value)
{
const char *endp;
@@ -237,3 +269,56 @@ int json_pointer_set(struct json_object **obj, const char *path, struct json_obj
return json_pointer_set_single_path(set, endp, value);
}
int json_pointer_setf(struct json_object **obj, struct json_object *value, const char *path_fmt, ...)
{
char *endp;
char *path_copy = NULL;
struct json_object *set = NULL;
va_list args;
int rc = 0;
if (!obj || !path_fmt) {
errno = EINVAL;
return -1;
}
/* pass a working copy to the recursive call */
va_start(args, path_fmt);
rc = vasprintf(&path_copy, path_fmt, args);
va_end(args);
if (rc < 0)
return rc;
if (path_copy[0] == '\0') {
json_object_put(*obj);
*obj = value;
goto out;
}
if (path_copy[0] != '/') {
errno = EINVAL;
rc = -1;
goto out;
}
/* If there's only 1 level to set, stop here */
if ((endp = strrchr(path_copy, '/')) == path_copy) {
set = *obj;
goto set_single_path;
}
*endp = '\0';
rc = json_pointer_get_recursive(*obj, path_copy, &set);
if (rc)
goto out;
set_single_path:
endp++;
rc = json_pointer_set_single_path(set, endp, value);
out:
free(path_copy);
return rc;
}

46
json_pointer.h
View File

@@ -27,6 +27,11 @@ extern "C" {
* Internally, this is equivalent to doing a series of 'json_object_object_get()'
* and 'json_object_array_get_idx()' along the given 'path'.
*
* Note that the 'path' string supports 'printf()' type arguments, so, whatever
* is added after the 'res' param will be treated as an argument for 'path'
* Example: json_pointer_get(obj, "/foo/%d/%s", &res, 0, bar)
* This means, that you need to escape '%' with '%%' (just like in printf())
*
* @param obj the json_object instance/tree from where to retrieve sub-objects
* @param path a (RFC6901) string notation for the sub-object to retrieve
* @param res a pointer where to store a reference to the json_object
@@ -36,6 +41,24 @@ extern "C" {
*/
int json_pointer_get(struct json_object *obj, const char *path, struct json_object **res);
/**
* This is a variant of 'json_pointer_get()' that supports printf() style arguments.
*
* Example: json_pointer_getf(obj, res, "/foo/%d/%s", 0, bak)
* This also means that you need to escape '%' with '%%' (just like in printf())
*
* Please take into consideration all recommended 'printf()' format security
* aspects when using this function.
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param res a pointer where to store a reference to the json_object
* associated with the given path
* @param path_fmt a printf() style format for the path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_getf(struct json_object *obj, struct json_object **res, const char *path_fmt, ...);
/**
* Sets JSON object 'value' in the 'obj' tree at the location specified
* by the 'path'. 'path' is JSON pointer notation as defined in RFC 6901
@@ -54,6 +77,11 @@ int json_pointer_get(struct json_object *obj, const char *path, struct json_obje
* That also implies that 'json_pointer_set()' does not do any refcount incrementing.
* (Just that single decrement that was mentioned above).
*
* Note that the 'path' string supports 'printf()' type arguments, so, whatever
* is added after the 'value' param will be treated as an argument for 'path'
* Example: json_pointer_set(obj, "/foo/%d/%s", value, 0, bak)
* This means, that you need to escape '%' with '%%' (just like in printf())
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param path a (RFC6901) string notation for the sub-object to set in the tree
* @param value object to set at path
@@ -62,6 +90,24 @@ int json_pointer_get(struct json_object *obj, const char *path, struct json_obje
*/
int json_pointer_set(struct json_object **obj, const char *path, struct json_object *value);
/**
* This is a variant of 'json_pointer_set()' that supports printf() style arguments.
*
* Example: json_pointer_setf(obj, value, "/foo/%d/%s", 0, bak)
* This also means that you need to escape '%' with '%%' (just like in printf())
*
* Please take into consideration all recommended 'printf()' format security
* aspects when using this function.
*
* @param obj the json_object instance/tree to which to add a sub-object
* @param value object to set at path
* @param path_fmt a printf() style format for the path
*
* @return negative if an error (or not found), or 0 if succeeded
*/
int json_pointer_setf(struct json_object **obj, struct json_object *value, const char *path_fmt, ...);
#ifdef __cplusplus
}
#endif