Re: Read all from stdin

On Feb 13, 4:36 pm, Wan-Teh Chang <[email protected]> wrote:
> soubok wrote:
> > Hello,
> > I need to read all remaining data from stdin (PR_StandardInput) but it
> > seems that PR_Available do not work with stdin file.
>
> PR_Available should work with stdin on Unix (including Linux
> and Mac OS X).  On Windows PR_Available does not work with
> stdin because the implementation of PR_Available uses a Winsock
> function.
>
> > Is there a way to PR_Read all datas from stdin at once ?
>
> This depends on exactly what you want to do.  Again, Windows
> presents a challenge.
>
> 1. You can put PR_StandardInput in non-blocking mode and
> keep reading from PR_StandardInput until PR_Read returns
> 0 or -1.
>
> This method only works on Unix (including Linux and Mac OS
> X).  This method doesn't work on Windows because the function
> to set a PRFileDesc in non-blocking mode calls Winsock functions.
>
> 2. If you know the maximum number of bytes that you may
> read from stdin, you can allocate a buffer of that size,
> and call PR_Read on stdin (in the default blocking mode).
> When PR_Read returns, you have read all the data.
>
> 3. If you control how the peer sends data to your stdin,
> you can arrange for the peer to send the byte count before
> the data.  After you have read the byte count, you know
> how many bytes of data will follow.
>
> Wan-Teh

Thanks for your response.

I am writing a CGI ( for Linux and win32 ) and I need to read data on
stdin.
The first solution I have is to read several times small amount of
data:

  var data='';
  for ( var tmp; tmp = File.stdin.Read(1000); tmp == 1000 )
    data += tmp;

But I do not like this solution because string concatenation causes a
slight overhead.

The other solution is to read a big amount of data, but I waste
memory.

This is why I wondering if there is a way to know in advance how many
data I can read.

Soubok.