Modify redefinition of strdup

[chses9440611]

There are two definitions of strdup in harness.h
and string2.h. This will cause a redefined error
when compile. Using macro #undef to undef the
strdup defined in string2.h:1291.

[jserv]

Since strdup-related work was contributed by @afcidk, I would defer to him.

[afcidk]

@chses9440611, may I ask your build environment and the string2.h source? Since I cannot reproduce the error on my machine

[chses9440611]

@afcidk,
kernel version: 4.15.0-76-generic, Ubuntu 16.04 GNU/linux
gcc version: 7.4.0
redefintion location is at /usr/include/x86_64-linux-gnu/bits/string2.h:1291

[chses9440611]

@afcidk, I think it's my own machine fault. For there exists a "string2.h" file under my /usr/include/x86_64-linux-gnu/bits/ , whcih will lead to redefinition error. I think most other machines won't have this problem. Should I close this pull request directly?

[afcidk]

The problem seems to lie in glibc version. string2.h is removed after glibc-2.26. The redefinition problem is caused by strdup inlines in string2.h. (It is removed in commit ae65d4f, so glibc version >= 2.26 should not see this problem)

I think we don't need the #ifdef strdup guard before #undef, maybe we could just leave

#undef strdup
#define strdup test_strdup

instead.

[afcidk]

@afcidk, I think it's my own machine fault. For there exists a "string2.h" file under my /usr/include/x86_64-linux-gnu/bits/ , whcih will lead to redefinition error. I think most other machines won't have this problem. Should I close this pull request directly?

Since we do not restrict glibc's version, I think this change is suitable.

[chses9440611]

So, just modify the pull request or submit another pull request ?

[afcidk]

Modify the pull request. You can force push the revised commit.

[jserv]

Use git commit --amend and/or git rebase -i to rework commits.

[jserv]

Thank @chses9440611 for contribution!

[chses9440611]

Thank @jserv @afcidk, I got a good experience.