Re: [Speedycgi-users] Logical error in file_lock() [v. 2.21]

[Sam H. <sa...@da...>]

Thanks for the bug reports and the patch.  The new code is on the cvs server.

For Issue 2, I changed the code to set the file_removed flag only after
a successful unlink(), which should fix the problem.

 > Issue 1 (patch at the end of the message):
 > 
 > I've found a logical error in file_lock() (from speedy_file.c).  Note how
 > the test inside the for loop decrements the variable after the check is
 > performed.  Right after the loop, there's if (!tries).  If file could not
 > be locked, 'tries' is -1 at that point, not zero.  The easiest fix is of
 > course to change when decrement takes place.
 > 
 > 
 > Issue 2:
 > 
 > I found this bug because I found a box after power failure that segfaulted
 > apache each time a CGI handled by SpeedyCGI was requested.  Turns out, a
 > stale state file (/tmp/speedy.6.f.F), had file_removed byte = 1.
 > Apparently, the power went right after the flag was set but before unlink
 > could do its evil thing.
 > 
 > Now comes the question: is there a way to modify SpeedyCGI's algorithm so
 > that it could recover from these conditions itself, without having to
 > manually delete the offending file?  Right now, if this flag is set
 > (manually or after a power failure, as it was in my case), SpeedyCGI is
 > taken out of commission.  Maybe, besides being a boolean  flag,
 > file_removed could specify a PID of the process that removed it (but that
 > raises several more questions)?
 > 
 > 
 > My setup:
 >   Linux 2.4.21
 >   Apache 2.0.46
 >   SpeedyCGI 2.21
 > 
 > Thanks,
 > 
 >   - Dmitri.
 > 
 > *** speedy_file.c.orig  Mon Sep  8 18:54:37 2003
 > --- speedy_file.c.fixed Mon Sep  8 18:54:33 2003
 > ***************
 > *** 183,189 ****
 >         file_close2();
 >       }
 > 
 > !     for (tries = 5; tries--;) {
 >         /* If file is not open, open it */
 >         if (file_fd == -1) {
 >             str_replace(&saved_tmpbase,
 > speedy_util_strdup(OPTVAL_TMPBASE));
 > --- 183,189 ----
 >         file_close2();
 >       }
 > 
 > !     for (tries = 5; tries; --tries) {
 >         /* If file is not open, open it */
 >         if (file_fd == -1) {
 >             str_replace(&saved_tmpbase,
 > speedy_util_strdup(OPTVAL_TMPBASE));
 > 
 > 
 > 
 > 
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