On Tue, Sep 07, 2021 at 12:23:38PM +0200, Axel Beckert wrote:
...
David wrote:
...
Sorry for the trouble. I (and the tests) admittedly only test the
non-static zsh. And except for some special lookups known to be not
possible with static compiled binaries, I also don't expect any
difference in functionality with zsh-static.
Thank you both so much for looking into it! And Vincent noticing that
/lib/x86_64-linux-gnu/libc.so.6 is being opened and mapped into memory
is very eye opening, for a static binary!
Please forgive my ignorange in the automated test suites, but perhaps
for a future test, would verifying the expected exit status of these
commands help intercept this (and any other) weird problem? :-)
zsh-static -f -c "exit 0"
zsh-static -f -c "exit 1"
Now for a more thorough test: Is it possible (or even desireable?) to
test the binary to verify it really is statically linked? Perhaps grep
strace output looking for potential evidence of .so files getting opened
in some lib directory?
strace zsh-static -f -c "exit 0" 2>&1 | grep
'^open[a-zA-Z0-9_]*(.*"[^"]*lib.*\.so\>[^"]*"'
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libnss_compat.so.2",
O_RDONLY|O_CLOEXEC) = 11
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 11
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2",
O_RDONLY|O_CLOEXEC) = 11
echo $?
0
For comparison, busybox is statically linked:
strace /bin/busybox -f -c "exit 0" 2>&1 | grep '^open[a-zA-Z0-9_]*(.*"[^"]*lib.*\.so\>[^"]*"'
echo $?
1
(And I also just tested a couple small C programs invoking printf and
compiled with and without "-static".)
There's gotta be a better test to detect run-time opening of shared
libraries. (My regex of looking for open...("... .so ...") feels
hackish.)
- David
