id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
4993	getDirectoryContents goes into an infinite loop	bos		"This is a really peculiar bug. Prepare for some fun!

I'm using a tool called boxgrinder to create a virtual machine image for running in Amazon's EC2 compute environment. The virtual machine is intended to contain GHC and a few libraries. I'm running boxgrinder itself in an EC2 virtual machine.

boxgrinder works fine on a 64-bit virtual machine, when creating a 64-bit virtual machine, but gets stuck forever when I try to run it in a 32-bit VM to create a 32-bit image.

The reason for boxgrinder hanging is that when installing {{{GHC}}}, {{{ghc-pkg}}} is going into an infinite loop. I've got a super simple reproduction:

{{{
import System.Directory

main = getDirectoryContents ""."" >>= print
}}}

If compiled, the above command runs fine in the regular 32-bit system image, but not in the {{{chroot}}} filesystem created by boxgrinder. In there, it goes into an infinite loop right after reading some of the directory contents:

{{{
... everything looks normal ...
open(""."", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = 3
getdents64(3, /* 25 entries */, 32768)  = 640
getdents64(3, /* 0 entries */, 32768)   = 0
--- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
sigreturn()                             = ? (mask now [])
--- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
sigreturn()                             = ? (mask now [])
--- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
sigreturn()                             = ? (mask now [])
... and no more life! ...
}}}

I have verified that this infinite loop occurs both with 6.12.3 and 7.0.2 RC2. Investigating further at the moment."	bug	closed	normal		libraries/directory	7.0.1	invalid			Linux	x86	Runtime crash