Michael

#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <stdint.h>
#include <stdlib.h>

const uint8_t sp=' ';
const uint8_t ret='\n';
const uint8_t quo='\"';
const uint8_t scr='\\';
const uint8_t hxp='x';
const uint8_t blst='[';
const uint8_t elst=']';
const uint8_t bdct='(';
const uint8_t edct=')';
const uint8_t eqv='=';
const int stdout=1;

enum obj_type {OBJ_NUL, OBJ_INT, OBJ_STR, OBJ_LST, OBJ_DCT};

void Byte2Hex(uint8_t ch);
void PrintSpc(int num);
enum obj_type DetType(const uint8_t* d, size_t shift);
size_t FindSym(const uint8_t* d, uint8_t s, size_t shift, size_t len);
size_t PrintInt(const uint8_t* d, size_t shift, size_t len);
size_t PrintStr(const uint8_t* d, size_t shift, size_t len);
size_t PrintLst(const uint8_t* d, size_t shift, size_t len, int skip);
size_t PrintDct(const uint8_t* d, size_t shift, size_t len, int skip);
size_t PrintObj(const uint8_t* d, size_t shift, size_t len, int skip);

void Byte2Hex(uint8_t ch)
{
 static const uint8_t cnv[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
 write(stdout,cnv+((ch&(15<<4))>>4),1);
 write(stdout,cnv+(ch&15),1);
}

void PrintSpc(int num)
{
 int i;
 for(i=0;i<num;i++) write(stdout,&sp,1);
}

enum obj_type DetType(const uint8_t* d, size_t shift)
{
// write(2,d+shift,1);
 if(d[shift]=='i') return OBJ_INT;
 if(d[shift]=='l') return OBJ_LST;
 if(d[shift]=='d') return OBJ_DCT;
 if(d[shift]>=49 && d[shift]<=57) return OBJ_STR;
 return OBJ_NUL;
}

size_t FindSym(const uint8_t* d, uint8_t s, size_t shift, size_t len)
{
 size_t i;

 for(i=shift;i<len;i++) if(d[i]==s) return i;
 exit(2);
}

size_t PrintObj(const uint8_t* d, size_t shift, size_t len, int skip)
{
 switch(DetType(d,shift))
 {
  case(OBJ_NUL): exit(2);
  case(OBJ_INT): return PrintInt(d,shift,len);
  case(OBJ_STR): return PrintStr(d,shift,len);
  case(OBJ_LST): return PrintLst(d,shift,len,skip);
  case(OBJ_DCT): return PrintDct(d,shift,len,skip);
 }
 exit(2);
}

size_t PrintInt(const uint8_t* d, size_t shift, size_t len)
{
 size_t e=FindSym(d,'e',shift,len);
 write(stdout,d+shift+1,e-shift-1);
 return e+1;
}

size_t PrintStr(const uint8_t* d, size_t shift, size_t len)
{
 size_t e=FindSym(d,':',shift,len);
 int l=atoi(d+shift);
 if(e+l>=len) exit(2);
 size_t p;

 write(stdout,&quo,1);
 for(p=e+1;p<=e+l;p++)
 {
  if(d[p]==127 || d[p]<=32)
  {
   write(stdout,&scr,1);
   write(stdout,&hxp,1);
   Byte2Hex(d[p]);
  }
  else if(d[p]=='\\')
  {
   write(stdout,&scr,1);
   write(stdout,&scr,1);
  }
  else if(d[p]=='\"')
  {
   write(stdout,&scr,1);
   write(stdout,&quo,1);
  }
  else write(stdout,d+p,1);
 }

 write(stdout,&quo,1);
 return e+l+1;
}

size_t PrintLst(const uint8_t* d, size_t shift, size_t len, int skip)
{
 size_t ishift=shift+1;

 write(stdout,&blst,1);
 write(stdout,&ret,1);

 while(d[ishift]!='e')
 {
  PrintSpc(skip+1);
  ishift=PrintObj(d,ishift,len,skip+1);
  write(stdout,&ret,1);
  if(ishift>=len) exit(2);
 }
 PrintSpc(skip);
 write(stdout,&elst,1);
 return ishift+1;
}

size_t PrintDct(const uint8_t* d, size_t shift, size_t len, int skip)
{
 size_t ishift=shift+1;

 write(stdout,&bdct,1);
 write(stdout,&ret,1);

 while(d[ishift]!='e')
 {
  PrintSpc(skip+1);
  if(DetType(d,ishift)!=OBJ_STR) exit(2);
  ishift=PrintStr(d,ishift,len);
  write(stdout,&sp,1);
  write(stdout,&eqv,1);
  write(stdout,&sp,1);
  ishift=PrintObj(d,ishift,len,skip+1);
  write(stdout,&ret,1);
  if(ishift>=len) exit(2);
 }
 PrintSpc(skip);
 write(stdout,&edct,1);
 return ishift+1;
}

int main(int argc, char** argv)
{
 if(argc!=2) return 1;

 int fd;
 struct stat st;
 uint8_t *pdata;

 fd=open(argv[1],O_RDONLY); if(fd==-1) return 1;
 if(fstat(fd,&st)!=0) return 1;
 if(st.st_size==0) return 1;
 pdata=(uint8_t*) mmap(0,st.st_size,PROT_READ,MAP_SHARED,fd,0);
 PrintDct(pdata,0,st.st_size,0);
 write(stdout,&ret,1);
 munmap(pdata,st.st_size);
 close(fd);

 return 0;
}