Question

I wrote a function below to read the content of a file to memory.
It works well on my local machine(Ubuntu 32bit), but it produces wrong result on server(CentOS 64bit).

Wrong case:
With a 40 byte file, the content is below, on the 64bit os, it gave me wrong result.

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

The code:

char* file_get_contents(const char *filename) {
  FILE *stream = NULL;
  char *content = NULL;
  size_t ret;
  struct stat st;

  if ((stream = fopen(filename,"r")) == NULL) {
    fprintf(stderr, "Failed to open file %s\n", filename);
    exit(1002);
  }

  if(stat(filename, &st) < 0) {
    fprintf(stderr, "Failed to stat file %s\n", filename);
    exit(1002);
  }

  content = malloc(st.st_size);
  ret = fread(content, 1, st.st_size, stream);

  if (ret != st.st_size) {
    fprintf(stderr, "Failed to read file %s\n", filename);
    exit(1002);
  }

  fclose(stream);
  return content;
}

Answer 1

Your file_get_contents cannot be correctly used by its caller. It returns a char * but not its lenght, nor does it return a string (i.e. it isn’t null terminated.).

As long as you’re reading text, do e.g.

  content = malloc(st.st_size + 1); // + 1 here for the nul terminator
  ret = fread(content, 1, st.st_size, stream);

  if (ret != st.st_size) {
    fprintf(stderr, "Failed to read file %s\n", filename);
    exit(1002);
  }
  content[st.st_size] = 0; //nul terminate