Kernel symbol parser

parse.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "parse.h"

#define BUFSIZE 256

FILE* open_map() {
  FILE* ver = fopen("/proc/version", "r");
  char buffer[BUFSIZE];

  if(!fgets(buffer, BUFSIZE, ver))
   return NULL;

  char* version = buffer + strcspn(buffer, "5");
  version[strcspn(version, " ")] = 0;

  char filename[BUFSIZE] = "/boot/System.map-";
  strcat(filename, version);

  return fopen(filename, "r");

}

symbol_list parse_symbols(char* names[], int num) {
   FILE* fp = open_map();
   char buffer[BUFSIZE];
   int len = 0;

   parsed_symbol* parsed_symbols = malloc(num * sizeof(parsed_symbol));
   parsed_symbol* curr_symbol = parsed_symbols;

   while(fgets(buffer, BUFSIZE, fp)) {
     buffer[strcspn(buffer, "\n")] = 0;

     char* symbol_name = buffer + 19;
     int symbol_name_length = strlen(symbol_name);

     for(int i = 0; i < num; i++) {
        if(strcmp(symbol_name, names[i]) == 0) {
          len++;

          curr_symbol->address = strtoul(buffer, NULL, 16) & ~0xffffffff81000000ull;

          curr_symbol->name = malloc(symbol_name_length + 1);
          strcpy(curr_symbol->name, symbol_name);

          curr_symbol++;
          break;
        }
     }
   }

   fclose(fp);

   symbol_list result = { len, parsed_symbols };
   return result;
}

int main() {
   char* names[] = {"commit_creds"};
   int num = 1;
   symbol_list s = parse_symbols(names, num);
   parsed_symbol* t = s.symbols;

   for(int i = 0; i < num; i++, t++) {
     printf("%s %p\n", t->name, t->address);
   }
   free_symbol_list(s);
}

parse.h

#ifndef _PARSE_H
#define _PARSE_H
#include <stdlib.h>

typedef struct parsed_symbol {
  unsigned long address;
  char* name;
} parsed_symbol;

typedef struct symbol_list {
  int length;
  parsed_symbol* symbols;
} symbol_list;

void free_symbol_list(symbol_list list) {
  parsed_symbol* sym = list.symbols;
  for(int i = 0; i < list.length; i++, sym++) {
     free(sym->name);
  }

  free(list.symbols);
}

symbol_list parse_symbols(char* names[], int num);
#endif