Apache :: httpd on vista not as a service

samizdat

I built apache from source for vista (details of what that took below) and it runs when installed as a system service. But when run from the command line or under the debugger it fails at startup in code that's trying to open stdout (file handle 1) - the C runtime asserts (this is a debug version)

stack trace shows these calls:

main()
ap_run_pre_config()
winnt_pre_config()
apr_file_dup2()
_commit(1/*stdout*/)
(C runtime asserts invalid file handle)

anyone else encounter problems running apache on vista not as a service?

I'm going to try the binary release next and see if it has this problem.

In the debug version I built I changed apr.hw as follows:
#define _WIN32_WINNT 0x0600
#define APR_HAVE_IPV6 1
per this previous post:
http://www.apachelounge.com/viewtopic.php?t=2095
which got rid of compile errors for multicast.c.
Also I had to do the cvtdsp.pl fixup to work around the rc.exe errors.

Other than that it was clean InstallBin build under VS2008 (MSVC++ 9.0) using its default windows platform sdk (6.0A)
I used the IDE to build it (not the command line) after going thru the conversion of Apache.dsw to Apache.sln.
It built with no errors, and as I say, it runs as a service. It just can't open stdout.

tdonovan

That's been a known problem with debug builds for a long time. It was discussed on the Apache developers mailing list back in 2005.

re: "trying to open stdout" - actually it is trying to commit to stdout (i.e. flush unwritten data to disk). The same usually happens with stderr too.

The most common practice is to comment out these _commit calls for stdout and stderr when building with VS2005 or VS2008.

You should not see the assertion errors with a Release build, and you should be able to click [OK] and continue from them when they appear in a Debug build.

-tom-

samizdat

Thanks for your prompt reply! I guess I didn't search back far enough on the list, I thought it would be a recent Vista-related thing.

I did need to make debug builds run without asserts, so I can deploy them internally for testing, so I patched the source.

Commenting out the _commit() calls for stdout and stderr in filedup.c got me farther, but I was still getting one last assert, in the child process when it starts up. [Could not for the life of me figure out how to freeze it on start up in the vs2008 debugger to see what was happening - no process to attach to until after the CreateProcessW call, but after that is too late, it's off and running. Do you know a way to do that?]

Finally I commented out the _commit() for stdin as well, and that cured the last assert. Lucky guess.

So (for the record) to make debug builds assert-free at start-up when run not-as-a-service, patch this file:

httpd-2.2.8\srclib\apr\file_io\win32\filedup.c

to suppress these 3 calls in _DEBUG mode:

#ifndef _DEBUG
_commit(2 /* stderr */);
#endif

#ifndef _DEBUG
_commit(1 /* stdout */);
#endif

#ifndef _DEBUG
_commit(0 /* stdin */);
#endif

Thanks again for your hand-holding!

tdonovan

In practice the _commit calls are unnecessary for either debug or release builds.

Unlike Unix, Windows makes unwritten data visible to all other processes before the fflush call returns - and the _dup2 call a few lines down will trigger a physical disk write because it implies a _close call on the 2nd argument.

Simpler to just remove the _commit calls entirely.

-tom-