Replacing value of static const char array

Question

I was writing unit tests and I needed to override the path in "static const char[] path = "/some/hardcoded/path" to something else. Whats the best way to do it. I think it can be done by LD_PRELOAD but it requires me to create another library. Is there any other easy way to do this?

It's const. Don't do this. If you have some functional requirement, then contact the author and make your case. Otherwise, deal with it. Sorry. — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Aug 18, 2011 at 23:50
I concur. Somebody putting a hard coded path should be shot! — Ed Heal
– Ed Heal, Commented Aug 19, 2011 at 0:07

OnlineCop · Accepted Answer · 2011-11-01 20:37:07Z

3

Comment it out and add in your own path.

You don't want to un-const something.

If you need, put it into a preprocessor block:

#ifndef __UNIT_TEST
   static const char[] path = "/some/hardcoded/path";
#else
   static const char[] path = "/some_other/hardcoded/path";
#endif

Then it won't fail on the original programmer's system either.

edited Nov 1, 2011 at 20:37

answered Aug 19, 2011 at 0:23

OnlineCop

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Comments

Chad · Accepted Answer · 2011-08-19 00:07:37Z

1

Is hiding it an option? Like this:

static const char* path = "...";

void f()
{
#if UNIT_TESTING
   static const char* path = "Ha!";
#endif
   cout << path;
}

answered Aug 19, 2011 at 0:07

Chad

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Comments

David Hammen · Accepted Answer · 2011-08-19 00:21:35Z

0

Changing the value of such a string at execution time is undefined behavior. On many systems, the implementation-defined response is to drop core (segmentation fault). That said, a formerly common paradigm in many UNIX applications was to have hard-coded but configurable pathnames. The name is set at compile time rather than execution time:

static const char * path = SOME_PREPROCESSOR_NAME;

answered Aug 19, 2011 at 0:21

David Hammen

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Maister · Accepted Answer · 2011-08-19 00:26:09Z

0

If you want to be hacky, and have no way to change the source directly, it is possible to use mprotect() on Unix and VirtualProtect() on Win32 to make the page of that array readable/writable/executable as a last resort.

answered Aug 19, 2011 at 0:26

Maister

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Duck · Accepted Answer · 2011-08-19 00:41:47Z

0

If your system supports it, make the hard coded file a symbolic link to what you want. Something like ln -T /where/i/want/file /some/hardcoded/path/file

answered Aug 19, 2011 at 0:41

Duck

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