[Webkit-unassigned] [Bug 36938] Add basic FileSystem operations for FileReader/FileWriter support

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=36938


Jian Li <jianli at chromium.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #52673|review?                     |review-
               Flag|                            |




--- Comment #12 from Jian Li <jianli at chromium.org>  2010-04-06 15:36:37 PST ---
(From update of attachment 52673)
Noticed another problem in read file logic plus a couple minor comment
suggestions. Almost there.

> +// Returns seeked offset if successful, -1 otherwise.
Probably need to rephrase a little bit, like:
    // Returns the resulting offset from the beginning of the file if
successful, -1 otherwise.
> +long long seekFile(PlatformFileHandle, long long offset, FileSeekOrigin);

> +bool truncateFile(PlatformFileHandle handle, long long offset)
> +{
> +    // ftruncate return 0 to indicate the success.
r/return/returns
> +    return !ftruncate(handle, offset);
> +}
> +

> +int readFromFile(PlatformFileHandle handle, char* data, int length)
> +{
> +    int totalBytesRead = 0;
> +    while (totalBytesRead < length) {
> +        int bytesRead = read(handle, data + totalBytesRead, static_cast<size_t>(length - totalBytesRead));
> +        if (bytesRead <= 0 && errno != EINTR)
> +            break;
If we encounter non-EINTR error and break out of the loop, we will return
totalBytesRead that is not -1.
In addition, we should not continue the reading if bytesRead >= 0.
I think the block can be reorganized like the following:
           if (bytesRead >= 0) {
               totalBytesRead += bytesRead;
               break;
           }
           if (errno != EINTR)
               return -1;

writeToFile could also do the similar thing for better readerability.

> +        if (bytesRead > 0)
> +            totalBytesRead += bytesRead;
> +    }
> +
> +    return totalBytesRead;
> +}

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