Mirror of :pserver:cvs@cvs.fefe.de:/cvs libowfat https://www.fefe.de/libowfat/
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#include "fmt.h"
#include "textcode.h"
#include "scan.h"
size_t scan_jsonescape(const char *src,char *dest,size_t *destlen) {
register const unsigned char* s=(const unsigned char*) src;
size_t written=0,i;
char c;
unsigned int prev,cur,todo;
prev=cur=(unsigned int)-1;
for (i=0; s[i]; ++i) {
if ((c=s[i])=='\\') {
switch (s[i+1]) {
case '\\':
if (prev!=(unsigned int)-1) return 0; // lead surrogate not followed by tail surrogate
// c='\\'; // c already is backslash
break;
case 'u':
{
size_t j;
for (cur=j=0; j<4; ++j) {
char x=scan_fromhex(s[i+2+j]);
if (x<0) return 0; // not hex -> invalid input
cur=(cur<<4) | x;
}
if (cur>=0xd800 && cur<=0xdbff) {
// utf-16 surrogate pair; needs to be followed by another
// surrogate. We need to read both and convert to UTF-8
if (prev!=(unsigned int)-1) return 0; // two lead surrogates
prev=cur;
i+=5; // we want i to go up by 6, 1 is done by the for loop
continue; // write nothing!
} else if (cur>=0xdc00 && cur<=0xdfff) {
todo=(cur&0x3ff) | ((prev&0x3ff) << 10) | 0x100000;
} else
todo=cur;
written+=fmt_utf8(dest?dest+written:dest,todo);
i+=5;
prev=-1;
continue;
}
default:
if (prev!=(unsigned int)-1) return 0; // lead surrogate not followed by tail surrogate
c=s[i+1];
break;
}
++i;
}
if (dest) dest[written]=c;
++written;
}
*destlen=written;
return i;
}