RFR: 8262491: AArch64: CPU description should contain compatible board list [v6]

[Andrew Haley]

On Wed, 10 Mar 2021 12:57:42 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>>> So I set `\0` to the tail of `buf` at L178.
>> 
>> Which you then overwrite on Line 183. You really do need to move Line 174 to the end.
>> I ran a test with the read fulling the whole buffer.
>
> Thanks for your comment! I pushed new commit.
> 
> I issue `read()` with `buflen - 1` bytes, then I set `\0' to tail of `buf` after `read()`. And also `\0` will be converted to blank will happen when `read()` return 1 or greater. How about it?

I think you need this to cope with errors, empty files, and so on:

void VM_Version::get_compatible_board(char *buf, int buflen) {
  assert(buf != NULL, "invalid argument");
  assert(buflen >= 1, "invalid argument");
  *buf = '\0';
  int fd = open("/proc/device-tree/compatible", O_RDONLY);
  ssize_t read_sz = read(fd, buf, buflen - 1);
  if (read_sz >= 0) {
    buf[read_sz] = '\0';
    // Replace '\0' to ' '                                                                                                                                                                                                                                                                   
    for (char *ch = buf; ch < buf + read_sz; ch++) {
      if (*ch == '\0') {
        *ch = ' ';
      }
    }
  } else { // read() retuned an error                                                                                                                                                                                                                                                        
    buf[0] = '\0';
  }
=>close(fd);
}

-------------

PR: https://git.openjdk.java.net/jdk/pull/2759