fix atf on MIPS64

[br]

Summary

on MIPS64 we have "ZZZZZZZZ" instead of "/bin/sh", for example:
https://people.freebsd.org/~br/kyua_mips/bin_cat_cat_test_align.html

Using strdup helps

[ngie]

Where's the "ZZZZZZZZ" coming from?

[br]

In D7952#164976, @ngie wrote:

Where's the "ZZZZZZZZ" coming from?

it comes from conversion from C++ std::string to C const char * using c_str()

This C++ function returns the correct value "/bin/sh":
std::string
impl::get(const std::string& name, const std::string& default_value)
{

const char *a;
a = atf_env_get_with_default(name.c_str(), default_value.c_str());
printf("a is %s\n", a);
return (a);

}

but then we converting it to C using c_str() here:
sh_argv[0] = atf::env::get("ATF_SHELL", ATF_SHELL).c_str();
and it gets to ZZZZZZZZZ

We use GCC 4.2.1 on MIPS, may be this is a reason ?
The only strdup() helps for me

[jmmv]

contrib/atf/atf-sh/atf-check.cpp

351 ↗

(On Diff #20486)

The original code is bogus because this statement is constructing a temporary std::string and getting a pointer to its contents. When the assignment is complete, the temporary std::string is destroyed so the pointer is invalid.

I guess that the STL in your platform (or something else, who knows) is being compiled with a debug option that is zeroing out (with Zs) the std::string's contents to spot this use-after-free issue.

If you do the following right after the assignment of "cmd":

const std::string shell = atf::env::get("ATF_SHELL", ATF_SHELL).c_str();

then you can do:

sh_argv[0] = shell.c_str();

I bet this will work, and is better than the strdup hack.

[br]

use different workaround

[br]

Yes, it works.
Thanks !

[jmmv]

Note that this is not a workaround: this is a proper fix for broken code.

contrib/atf/atf-sh/atf-check.cpp

351 ↗

(On Diff #20772)

For style reasons, please move this to right after line 348, as I previously said.

[br]

fix style

[jmmv]

contrib/atf/atf-sh/atf-check.cpp

349 ↗

(On Diff #20773)

Remove the c_str() from here, or else you are creating an extra string for no reason.

[br]

remove extra c_str()