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Adjust the behavior of the args passed to json_patch_apply to make it easier to do in place modifications, and add a struct json_patch_error to report more details on failures.

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This commit is contained in:
Eric Hawicz
2023-07-26 22:01:04 -04:00
parent a14a3a680c
commit 9dbf2880cc
4 changed files with 210 additions and 58 deletions
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162
json_patch.c
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@@ -1,9 +1,9 @@
/*
* Copyright (c) 2021 Alexandru Ardelean.
* Copyright (c) 2023 Eric Hawicz
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See COPYING for details.
*
*/
#include "config.h"
@@ -16,6 +16,33 @@
#include "json_object_private.h"
#include "json_pointer_private.h"
#include <limits.h>
#ifndef SIZE_T_MAX
#if SIZEOF_SIZE_T == SIZEOF_INT
#define SIZE_T_MAX UINT_MAX
#elif SIZEOF_SIZE_T == SIZEOF_LONG
#define SIZE_T_MAX ULONG_MAX
#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
#define SIZE_T_MAX ULLONG_MAX
#else
#error Unable to determine size of size_t
#endif
#endif
#define _set_err(_errval, _errmsg) do { \
patch_error->errno_code = (_errval); \
patch_error->errmsg = (_errmsg); \
errno = 0; /* To avoid confusion */ \
} while (0)
#define _set_err_from_ptrget(_errval, _fieldname) do { \
patch_error->errno_code = (_errval); \
patch_error->errmsg = (_errval) == ENOENT ? \
"Did not find element referenced by " _fieldname " field" : \
"Invalid " _fieldname " field"; \
errno = 0; /* To avoid confusion */ \
} while(0)
/**
* JavaScript Object Notation (JSON) Patch
* RFC 6902 - https://tools.ietf.org/html/rfc6902
@@ -23,23 +50,23 @@
static int json_patch_apply_test(struct json_object **res,
struct json_object *patch_elem,
const char *path)
const char *path, struct json_patch_error *patch_error)
{
struct json_object *value1, *value2;
if (!json_object_object_get_ex(patch_elem, "value", &value1)) {
errno = EINVAL;
_set_err(EINVAL, "Patch object does not contain a 'value' field");
return -1;
}
/* errno should be set by json_pointer_get() */
if (json_pointer_get(*res, path, &value2))
{
_set_err_from_ptrget(errno, "path");
return -1;
}
if (!json_object_equal(value1, value2)) {
json_object_put(*res);
*res = NULL;
errno = ENOENT;
_set_err(ENOENT, "Value of element referenced by 'path' field did not match 'value' field");
return -1;
}
@@ -58,61 +85,79 @@ static int __json_patch_apply_remove(struct json_pointer_get_result *jpres)
}
}
static int json_patch_apply_remove(struct json_object **res, const char *path)
static int json_patch_apply_remove(struct json_object **res, const char *path, struct json_patch_error *patch_error)
{
struct json_pointer_get_result jpres;
int rc;
if (json_pointer_get_internal(*res, path, &jpres))
{
_set_err_from_ptrget(errno, "path");
return -1;
}
return __json_patch_apply_remove(&jpres);
rc = __json_patch_apply_remove(&jpres);
if (rc < 0)
_set_err(EINVAL, "Unable to remove path referenced by 'path' field");
return rc;
}
// callback for json_pointer_set_with_array_cb()
static int json_object_array_insert_idx_cb(struct json_object *parent, size_t idx,
struct json_object *value, void *priv)
{
int rc;
int *add = priv;
if (idx > json_object_array_length(parent))
{
// Note: will propagate back out through json_pointer_set_with_array_cb()
errno = EINVAL;
return -1;
}
if (*add)
return json_object_array_insert_idx(parent, idx, value);
rc = json_object_array_insert_idx(parent, idx, value);
else
return json_object_array_put_idx(parent, idx, value);
rc = json_object_array_put_idx(parent, idx, value);
if (rc < 0)
errno = EINVAL;
return rc;
}
static int json_patch_apply_add_replace(struct json_object **res,
struct json_object *patch_elem,
const char *path, int add)
const char *path, int add, struct json_patch_error *patch_error)
{
struct json_object *value;
int rc;
if (!json_object_object_get_ex(patch_elem, "value", &value)) {
errno = EINVAL;
_set_err(EINVAL, "Patch object does not contain a 'value' field");
return -1;
}
/* if this is a replace op, then we need to make sure it exists before replacing */
if (!add && json_pointer_get(*res, path, NULL)) {
errno = ENOENT;
_set_err_from_ptrget(errno, "path");
return -1;
}
rc = json_pointer_set_with_array_cb(res, path, json_object_get(value),
json_object_array_insert_idx_cb, &add);
if (rc)
{
_set_err(errno, "Failed to set value at path referenced by 'path' field");
json_object_put(value);
}
return rc;
}
// callback for json_pointer_set_with_array_cb()
static int json_object_array_move_cb(struct json_object *parent, size_t idx,
struct json_object *value, void *priv)
{
int rc;
struct json_pointer_get_result *from = priv;
size_t len = json_object_array_length(parent);
@@ -127,16 +172,20 @@ static int json_object_array_move_cb(struct json_object *parent, size_t idx,
if (idx > len)
{
// Note: will propagate back out through json_pointer_set_with_array_cb()
errno = EINVAL;
return -1;
}
return json_object_array_insert_idx(parent, idx, value);
rc = json_object_array_insert_idx(parent, idx, value);
if (rc < 0)
errno = EINVAL;
return rc;
}
static int json_patch_apply_move_copy(struct json_object **res,
struct json_object *patch_elem,
const char *path, int move)
const char *path, int move, struct json_patch_error *patch_error)
{
json_pointer_array_set_cb array_set_cb;
struct json_pointer_get_result from;
@@ -146,7 +195,7 @@ static int json_patch_apply_move_copy(struct json_object **res,
int rc;
if (!json_object_object_get_ex(patch_elem, "from", &jfrom)) {
errno = EINVAL;
_set_err(EINVAL, "Patch does not contain a 'from' field");
return -1;
}
@@ -163,13 +212,16 @@ static int json_patch_apply_move_copy(struct json_object **res,
*/
if (from_s_len == strlen(path))
return 0;
errno = EINVAL;
_set_err(EINVAL, "Invalid attempt to move parent under a child");
return -1;
}
rc = json_pointer_get_internal(*res, from_s, &from);
if (rc)
{
_set_err_from_ptrget(errno, "from");
return rc;
}
json_object_get(from.obj);
@@ -186,65 +238,87 @@ static int json_patch_apply_move_copy(struct json_object **res,
rc = json_pointer_set_with_array_cb(res, path, from.obj, array_set_cb, &from);
if (rc)
{
_set_err(errno, "Failed to set value at path referenced by 'path' field");
json_object_put(from.obj);
}
return rc;
}
int json_patch_apply(struct json_object *base, struct json_object *patch,
struct json_object **res)
int json_patch_apply(struct json_object *copy_from, struct json_object *patch,
struct json_object **base, struct json_patch_error *patch_error)
{
size_t ii;
int rc = 0;
struct json_patch_error placeholder;
if (!base || !json_object_is_type(patch, json_type_array)) {
errno = EINVAL;
if (!patch_error)
patch_error = &placeholder;
patch_error->patch_failure_idx = SIZE_T_MAX;
patch_error->errno_code = 0;
if (base == NULL||
(*base == NULL && copy_from == NULL) ||
(*base != NULL && copy_from != NULL))
{
_set_err(EFAULT, "Exactly one of *base or copy_from must be non-NULL");
return -1;
}
if (!json_object_is_type(patch, json_type_array)) {
_set_err(EFAULT, "Patch object is not of type json_type_array");
return -1;
}
/* errno should be set inside json_object_deep_copy() */
if (json_object_deep_copy(base, res, NULL) < 0)
return -1;
if (copy_from != NULL)
{
if (json_object_deep_copy(copy_from, base, NULL) < 0)
{
_set_err(ENOMEM, "Unable to copy copy_from using json_object_deep_copy()");
return -1;
}
}
/* Go through all operations ; apply them on res */
for (ii = 0; ii < json_object_array_length(patch); ii++) {
struct json_object *jop, *jpath;
struct json_object *patch_elem = json_object_array_get_idx(patch, ii);
const char *op, *path;
patch_error->patch_failure_idx = ii;
if (!json_object_object_get_ex(patch_elem, "op", &jop)) {
errno = EINVAL;
rc = -1;
break;
_set_err(EINVAL, "Patch object does not contain 'op' field");
return -1;
}
op = json_object_get_string(jop);
json_object_object_get_ex(patch_elem, "path", &jpath);
path = json_object_get_string(jpath);
if (!json_object_object_get_ex(patch_elem, "path", &jpath)) {
_set_err(EINVAL, "Patch object does not contain 'path' field");
return -1;
}
path = json_object_get_string(jpath); // Note: empty string is ok!
if (!strcmp(op, "test"))
rc = json_patch_apply_test(res, patch_elem, path);
rc = json_patch_apply_test(base, patch_elem, path, patch_error);
else if (!strcmp(op, "remove"))
rc = json_patch_apply_remove(res, path);
rc = json_patch_apply_remove(base, path, patch_error);
else if (!strcmp(op, "add"))
rc = json_patch_apply_add_replace(res, patch_elem, path, 1);
rc = json_patch_apply_add_replace(base, patch_elem, path, 1, patch_error);
else if (!strcmp(op, "replace"))
rc = json_patch_apply_add_replace(res, patch_elem, path, 0);
rc = json_patch_apply_add_replace(base, patch_elem, path, 0, patch_error);
else if (!strcmp(op, "move"))
rc = json_patch_apply_move_copy(res, patch_elem, path, 1);
rc = json_patch_apply_move_copy(base, patch_elem, path, 1, patch_error);
else if (!strcmp(op, "copy"))
rc = json_patch_apply_move_copy(res, patch_elem, path, 0);
rc = json_patch_apply_move_copy(base, patch_elem, path, 0, patch_error);
else {
errno = EINVAL;
rc = -1;
break;
_set_err(EINVAL, "Patch object has invalid 'op' field");
return -1;
}
if (rc < 0)
break;
}
if (rc < 0) {
json_object_put(*res);
*res = NULL;
}
return rc;
}