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

[Andrew Haley]

On Fri, 12 Mar 2021 05:16:36 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> I think my latest commit includes your suggestion:
>> 
>> * returns empty string ( `\0` ) when `open()` failed.
>> * returns empty string when `read()` failed or read nothing (returns `0` )
>> * add `\0` to `buf[read_sz]` just after `read()` call, and skip it at the loop - it can be assumed `\0` is set to tail of `buf`
>> 
>> Or should I change as following for readability?
>> 
>> int fd = open("/proc/device-tree/compatible", O_RDONLY);
>> if (fd == -1) {
>>   *buf = '\0';
>>   return;
>> }
>> 
>> ssize_t read_sz = read(fd, buf, buflen - 1);
>> close(fd);
>> if (read_sz <= 0) {
>>   *buf = '\0';
>>   return;
>> }
>> 
>> // Add '\0' to the tail
>> buf[read_sz] = '\0';
>> // Replace '\0' to ' '
>> for (char *ch = buf; ch < buf + read_sz; ch++) {
>>   if (*ch == '\0') {
>>     *ch = ' ';
>>   }
>> }
>
> I tested current PR manually with this Gist code, it works fine without buffer overrun.
> https://gist.github.com/YaSuenag/bdc73c3540335a096fa289ead36ca8b5

That looks right.

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