digitalmars.D - Return value of std.process.system
- H. S. Teoh (25/25) Feb 25 2012 What should the return value of std.process.system be?
What should the return value of std.process.system be? I'm looking at issue 6926, and upon investigation found that std.process.system always returns WEXITSTATUS(status) regardless of the value of WIFEXITED(status). This means that if the child process exits with a signal or dumps core, it may still return 0, whereas one would expect it should return some non-zero value. The comments in the code indicate that WEXITSTATUS(status) is used to provide maximum convenience (no need to use another macro/translation scheme to get at the return code, uniformity with Windows, etc.), but the current behaviour is obviously broken. There's currently a check for status==-1, in which case -1 is returned. I think we should extend this so that if WIFEXITED(status) is false, then -1 should be returned. What do y'all think? Furthermore, the version(Posix) block doesn't use any of the C macros at all, but has (status & 0xff00)>>>8, which equals WEXITSTATUS(status) on Linux systems. Do we know for sure that this is correct across *all* Unixen? AFAIK, the Posix spec leaves the details of WEXITSTATUS up to implementation. If so, the current implementation is technically broken. What's the best way to fix this? I'm inclined to move the implementation of this function into C, at least for version(Posix), so that we can get at the C macros and be sure that the result will be correct. Comments? T -- People tell me that I'm skeptical, but I don't believe it.
Feb 25 2012