cpio image generation silently fails if cpio cli tool not installed

[hnez]

I have recently tried building initramfs images with genimage inside a container. This seemingly just worked, but when I later tried using the initramfs it turned out to be empty.

After a bit of investigation I found out that I have missed this message on stderr while building the initramfs:

INFO: cpio(install.img): cmd: "(cd '/var/tmp/ptxdist.LwUO9c/genimage.2MOKvB/root' && find . | cpio -H 'newc'  -o | zstd -T0 -19) > '…/platform-x86_64/images/install.img'" (stderr):
/bin/sh: 1: cpio: not found
INFO: cmd: "rm -rf "/var/tmp/ptxdist.LwUO9c/genimage.2MOKvB"/*" (stderr):
finished target install.img

The generated install.img was just 13 bytes in size and if I had to guess just consisted of the zstd file header. Installing the cpio package in the container fixed the problem.

It would be preferable if the genimage call failed in this case.

---

I guess this piece of code should be modified to contain something like set -o pipefail:

genimage/image-cpio.c

Lines 32 to 36 in ff7da92

	ret = systemp(image, "(cd '%s' && find . | %s -H '%s' %s -o %s %s) > '%s'",
	mountpath(image),
	get_opt("cpio"),
	format, extraargs, comp[0] != '\0' ? "|" : "", comp,
	imageoutfile(image));

[michaelolbrich]

We should just add -o pipefail when calling the shell in systemp(). I'm not sure if it's posix but both bash and dash and even busybox ash support it and I don't think any other shell is relevant here.

[hnez]

Hi,

We should just add -o pipefail when calling the shell in systemp().

I have just opened a pull request that does that #322, but I am either doing something wrong or this does not work on at least Ubuntu 22.04. I think we should discuss this further in #322.

[Bastian-Krause]

We should just add -o pipefail when calling the shell in systemp(). I'm not sure if it's posix but both bash and dash and even busybox ash support it and I don't think any other shell is relevant here.

pipefail is posix: https://www.austingroupbugs.net/view.php?id=789