re_mprot.c

#include <errno.h>
#include <malloc.h>
#include <stdio.h>
#include <sys/mman.h>
//#define PAGE_SIZE 4096
//#include "dlog.h"
#include "re_mprot.h"
#include "stdlib.h"

struct buffer {
  int pos;
  int size;
  char *mem;
};

char *_buf_reset(struct buffer *b) {
  b->mem[b->pos] = 0;
  b->pos = 0;
  return b->mem;
}

struct buffer *_new_buffer(int length) {
  struct buffer *res = malloc(sizeof(struct buffer) + length + 4);
  res->pos = 0;
  res->size = length;
  res->mem = (void *)(res + 1);
  return res;
}

int _buf_putchar(struct buffer *b, int c) {
  b->mem[b->pos++] = c;
  return b->pos >= b->size;
}

void show_mappings(void) {
  int a;
  FILE *f = fopen("/proc/self/maps", "r");
  struct buffer *b = _new_buffer(1024);
  while ((a = fgetc(f)) >= 0) {
    if (_buf_putchar(b, a) || a == '\n') {
      // DLOG("/proc/self/maps: %s",_buf_reset(b));
    }
  }
  if (b->pos) {
    // DLOG("/proc/self/maps: %s",_buf_reset(b));
  }
  free(b);
  fclose(f);
}

unsigned int read_mprotection(const void *addr) {
  int a;
  unsigned int res = MPROT_0;
  FILE *f = fopen("/proc/self/maps", "r");
  struct buffer *b = _new_buffer(1024);
  while ((a = fgetc(f)) >= 0) {
    if (_buf_putchar(b, a) || a == '\n') {
      char *end0 = (void *)0;
      unsigned long addr0 = strtoul(b->mem, &end0, 0x10);
      char *end1 = (void *)0;
      unsigned long addr1 = strtoul(end0 + 1, &end1, 0x10);
      if ((void *)addr0 < addr && addr < (void *)addr1) {
        res |= (end1 + 1)[0] == 'r' ? MPROT_R : 0;
        res |= (end1 + 1)[1] == 'w' ? MPROT_W : 0;
        res |= (end1 + 1)[2] == 'x' ? MPROT_X : 0;
        res |= (end1 + 1)[3] == 'p'   ? MPROT_P
               : (end1 + 1)[3] == 's' ? MPROT_S
                                      : 0;
        break;
      }
      _buf_reset(b);
    }
  }
  free(b);
  fclose(f);
  return res;
}

int has_mprotection(const void *addr, unsigned int prot,
                    unsigned int prot_mask) {
  unsigned prot1 = read_mprotection(addr);
  return (prot1 & prot_mask) == prot;
}

char *_mprot_tostring_(char *buf, unsigned int prot) {
  buf[0] = prot & MPROT_R ? 'r' : '-';
  buf[1] = prot & MPROT_W ? 'w' : '-';
  buf[2] = prot & MPROT_X ? 'x' : '-';
  buf[3] = prot & MPROT_S ? 's' : prot & MPROT_P ? 'p' : '-';
  buf[4] = 0;
  return buf;
}