RFR: 8338884: java/nio/file/attribute/BasicFileAttributeView/CreationTime.java#tmp fails on alinux3 [v2]

[Severin Gehwolf]

On Mon, 26 Aug 2024 09:53:57 GMT, SendaoYan <syan at openjdk.org> wrote:

>> test/jdk/java/nio/file/attribute/BasicFileAttributeView/CreationTime.java line 115:
>> 
>>> 113:             if (statxIsPresent && !Files.getFileStore(file).type().contentEquals("tmpfs")) {
>>> 114:                 supportsCreationTimeRead = true;
>>> 115:             }
>> 
>> Noting here that the test could still fail on some other filesystem which might not support birth time. For example `nfs` on Linux (IIRC).
>
> It is difficult to enumerate which file types in Linux do and do not support creation time.
> How about add a function that use `stat -c` linux command line to determise support or not.
> 
> 
> +    /**
> +     * read the output of linux command `stat -c "%w" file`, if the output is "-",
> +     * then the file system doesn't support birth time
> +     */
> +    public static boolean supportBirthTimeOnLinux(Path file) {
> +        try {
> +            String filePath = file.toAbsolutePath().toString();
> +            ProcessBuilder pb = new ProcessBuilder("stat", "-c", "%w", filePath);
> +            pb.redirectErrorStream(true);
> +            Process p = pb.start();
> +            BufferedReader b = new BufferedReader(new InputStreamReader(p.getInputStream()));
> +            String l = b.readLine();
> +            if (l != null && l.equals("-")) { return false; }
> +        } catch(Exception e) {
> +        }
> +        return true;
> +    }

It's a possibility. I'm fine with the current "tmpfs" special case in the test, but I guess what you proposed above would be more robust. So if others are OK with such an approach, that would be fine with me as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20687#discussion_r1731020143