Basic Install Cygwin Windows 10 - IO Error opening <file>

0
votes

I am using Windows 10.

I downloaded setup-x86_64.exe from https://cygwin.com/install.html and am selecting the defaults (Install from Internet/Direct Connection/default locations).

I have tried several mirrors including cygwin.mirror.constant.com

I am accepting all the default packages plus some basic developer stuff (gdb, make) and check "Select required packages (RECOMMENDED)".

I get quite a way through the Cygwin Setup and then get the first of many pop-up messages "IO Error Opening file....._autorebase/binutils/cygwin/grep/mintty etc. Do you want to skip this package?"

If I skip the packages, I get a non-working Cygwin install (it can't find mintty). If I don't skip the packages, it hangs when the Cygwin installer hangs when it gets to the first of the problem packages.

Thanks in advance about what part of the setup process I am missing.

1
cygwin
I will bet on a Antivirus interfering - matzeri
I turned off my firewall, tried a ftp mirror instead of http, and tried using the command line and none of that helped. Ended up realizing that the missing files were being downloaded but still had the suffix *.tmp. I used a "forfiles" DOS command to remove the suffix and eventually got it to install but it took several hours over two days to figure it out. I'm still very interested in a better solution; I'd hate to have to do this again. - Excelsior1024

1 Answers

1
votes

A bit late, but anyway: I have stumbled across the same problems yesterday when I tried to install Cygwin on Windows 10 the first time.

I have followed all advice given at various sites (including this one): Disabled antivirus software, followed the Cygwin FAQ, and so on, but to no avail.

Then I studied the setup log and found a line which told something about an address mismatch (sorry that I don't have the exact wording - I surely won't repeat the experiment ...). That lead me to the idea that it might something have to do with ASLR (a technique for hardening the system against malware).

The next step was to turn off ASLR via the UI of Windows Defender. After I had done that, I could install Cygwin without any problems. I have not yet tested if I actually could use Cygwin when I turn on ASLR again; I don't feel very comfortable when having turned it off completely.

The alternative would be to turn off ASLR per executable. This is also possible in Windows Defender's UI. But it could mean adding dozens of exceptions, depending on how many Cygwin packages you have installed.

The technical reason for the problem is how POSIX's fork() works. Basically, it clones the parent process's image, using the same offset addresses. But when ASLR is active, those offsets will change when cloning the process, which will make fork() fail. Since fork() is extensively used by Cygwin, it can't operate as intended when ASLR is active.