dwww: cat and file (pipe race condition)

[ujr@physik.phy.tu-dresden.de (Ulf Jaenicke-Roessler)]

Hi,

 I'm reading my system documentation with dwww. However, with current
 potato/woody versions of dwww and file I have trouble for some files
 (i.e the web server hangs and reports a timeout)

 Examples for "bad" files are
 http://localhost/cgi-bin/dwww?type=file&location=/usr/doc/menu/html/ch3.html
 or
 http://localhost/cgi-bin/dwww?type=file&location=/usr/doc/menu/html/ch6.html

 while
 http://localhost/cgi-bin/dwww?type=file&location=/usr/doc/menu/html/ch2.html

 works fine.

 It seems, that the problem only occurs with longer (more than 10000 chars)
 files. Looking for the cause of this problem, I found that the line
 "$decompress $file | file -b - | magic2mime" in dwww-convert is responsible.

 Apparently the $decompress command (which is actually 'cat') is not
 finished when file has its job already done. I can find a 'dangling'
 cat process with 'ps'. So the pipe is not closed and the system would
 wait forever (actually just until the timeout is reached or cat is
 killed).

 I downloaded the source of the file package, but I don't know what
 I need to change. How are such pipe problems normally handled?


 Thanks,
  
  Ulf