As the title says, ltrace does not work properly on my system. It shows no output in most cases, like
$ltrace ls
[usual ls output]
+++ exited (status 0) +++
$gcc hello.c
$ltrace ./a.out
Hello world!
+++ exited (status 0) +++
I'm using the latest ltrace version (from package 0.7.3-5.1ubuntu4), I even tried recompiling from source with no difference.
I'm using Ubuntu 16.10, kernel 4.8.0-42-generic. gcc version is 6.2.0.
Weird thing is, binaries downloaded from the Internet seem to work, correctly displaying the library calls.
What am I missing? Is anyone able to reproduce the issue?
This may have to do with binaries being compiled with -z now. I created a quick test program (I'm using Ubuntu 16.04):
int main() {
write(0, "hello\n", 6);
return 0;
}
If I compile it with gcc -O2 test.c -o test then ltrace works:
$ ltrace ./test
__libc_start_main(0x400430, 1, 0x7ffc12326528, 0x400550 <unfinished ...>
write(0, "hello\n", 6hello
) = 6
+++ exited (status 0) +++
However when I compile with gcc -O2 test.c -Wl,-z,relro -Wl,-z,now -o test2 then it doesn't:
$ ltrace ./test2
hello
+++ exited (status 0) +++
You can check if a binary was compiled like so using scanelf from the pax-utils package on Ubuntu:
$ scanelf -a test*
TYPE PAX PERM ENDIAN STK/REL/PTL TEXTREL RPATH BIND FILE
ET_EXEC PeMRxS 0775 LE RW- R-- RW- - - LAZY test
ET_EXEC PeMRxS 0775 LE RW- R-- RW- - - NOW test2
Note the LAZY (ltrace works) versus NOW (ltrace doesn't).
There is a little bit more discussion (but no resolution) here: