110 lines
4.1 KiB
C
110 lines
4.1 KiB
C
/*
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* mkbootimg/jsonc.c
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*
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* Copyright (C) 2018 bzt (bztsrc@gitlab)
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*
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* This file is part of the BOOTBOOT Protocol package.
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* @brief Memory allocation-free, extremely fast JSON parser in pure ANSI C
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*
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*/
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#include <stdlib.h>
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#include <string.h>
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#define JSON_MAXPATHLEVEL 32
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/**
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* jsonstr: zero terminated UTF-8 string
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* key: path to a value, like "0.6.0.1" or "result.items.0.name"
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* returns the value in a malloc'd string or NULL
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*/
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char *json_get(const char *jsonstr, char *key)
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{
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char *m=key, *ret=NULL;
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unsigned char *c=(unsigned char*)jsonstr,*k[JSON_MAXPATHLEVEL+1];
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unsigned char *v,*s=NULL,*e=NULL;
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int l=0, j=1, i, n, x[JSON_MAXPATHLEVEL+1]={0};
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if(!jsonstr || !jsonstr[0] || !key) return NULL;
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while(1) {
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/* skip white spaces */
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while(*c && *c<=' ') c++;
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if(j) { j=0; k[l]=v=c; }
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switch(*c) {
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/* string literals */
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case '\"': c++; while(*c && *c!='\"'){if(*c=='\\'){c++;} c++;} break;
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/* field names */
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case ':': c++; while(*c && *c<=' ') { c++; } v=c--; break;
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/* control blocks */
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case 0: case ',': case '{': case '[': case '}': case ']':
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if(*v!=','&&*v!='{'&&*v!='['&&*v!=']'&&*v!='}') {
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/* skip index for topmost object */
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n=k[0][0]=='{'?1:0;
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/* match the path */
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m=key;
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for(i=n;i<=l && *m;i++) {
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if(i!=n) { if(*m=='.') m++; else break; }
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if(k[i][0]=='\"' && k[i]!=v && (*m<'0'||*m>'9')) {
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s=e=k[i]+1;
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while(*e&&*e!='\"') { if(*e=='\\') { e++; } e++; }
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if(memcmp(m,s,e-s)) break;
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m+=e-s;
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} else {
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if(atoi(m)!=x[i]) break;
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while(*m && *m!='.') m++;
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}
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}
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/* find start and end of the return value */
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if(!*m) {
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switch(*v) {
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case '\"':
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s=e=v+1;
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while(*e&&*e!='\"') { if(*e=='\\') { e++; } e++; }
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break;
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case 'n': return NULL;
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default:
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s=e=v;
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while(*e&&*e>' '&&*e!=','&&*e!=']'&&*e!='}') e++;
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break;
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}
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/* we can't break the loop inside a switch in ANSI C */
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goto end;
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}
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}
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switch(*c) {
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case 0: return NULL;
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case '{': case '[': x[++l]=0; if(l>=(int)sizeof(x)-1) return NULL; break;
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case '}': case ']': l--; break;
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case ',': x[l]++; break;
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}
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j++;
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break;
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}
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c++;
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}
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/* copy a zero terminated string of the value if any */
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end:if(!*m && e>s) {
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ret=malloc(e-s+1 < 256 ? 256 : e-s+1);
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if(ret) { memset(ret,0,256); memcpy(ret,s,e-s); ret[e-s]=0; }
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}
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return ret;
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}
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