Pacman -Syu fscked up my system

Question

I ran in a disk-full situation while running pacman -Syu. This totally and irreversably ruined my system . After downloading all packages (everything since the last full update of 20 august) it ran the usual pacman checks and then started installing the packages. After a few succesfull installs the / filesystem was full and installing failed from thereon. Yet pacman went on and on with the remaining packages, including a new kernel which also failed miserably and from there it went nasty. Messages from ldconfig about invalid ELF headers in libraries etc.. Yet pacman continued like nothing happened.
After it had finally finished, my system was unusable and also beyond repair. First i freed up some disk space (/bin/rm still worked). But pacman would not run anymore (segmentation error). Pacman --debug also crashed. Just about everything i tried to start, failed with /urs/lib/libetcetera errors about invalid ELF headers.
Finally i tried rebooting but that didn't work (it could not locate the root filesystem), which was no surprise having seen all the error messages during the installation of the kernel package.
I'm left with no alternative but to download a fresh iso image and continue from there.
With all the checks from pacman during its upgrades, apparently there is no check or warning for a safe marging of free diskspace. Wouldn't that be a nice feature? It also would be nice if pacman would just stop after the first failed package.

Answer 1

11639 is probably about the same issue. Although this person could still use pacman to repair his system. I can imagine more people could run into this situation.
I see pacman makes a estimate on required disk size before installation. Maybe just add some percentage extra as a safety margin?
And again, don't let pacman continue after the first failed package. A simple "Errors occured. Continue Y/n?" would be enough.