Avoid pipe2 in support/interactive

[thorehusfeldt]

pipe2 is linux-specific, so that make fails on BSD-based unixes such as OS X.

My (limited) understanding is that the flag in the 2nd argument pipe2(fd, O_CLOEXEC) in makepipe ensures that the pipes are closed upon exit, which can be achieved with fcntl in a platform-independent way.

https://github.com/Kattis/problemtools/blob/eb7b60722582b26d9a0ad75963f5d31616fba8f3/support/interactive/interactive.cc#L194

Linux man page: http://man7.org/linux/man-pages/man2/pipe.2.html

An easy fix is to revert that part of the code to the state before 0d38a8bc9a6f455e976aa9824f6329f6f7d1f790

[simonlindholm]

The changes in that commit should really be made conditional on Linux, yeah. Some previous discussion in #122.

[thorehusfeldt]

Like this:

#ifdef _GNU_SOURCE
const int PIPE_SIZE = 1<<20; // 1 MiB (the default max value for an unprivileged user)
#endif 
...
#ifdef _GNU_SOURCE
    if(pipe2(fd, O_CLOEXEC)) {
        perror("pipe failed");
        exit(EXIT_FAILURE);
    }
    if (fcntl(fd[0], F_SETPIPE_SZ, PIPE_SIZE) == -1) {
        perror("failed to set pipe size");
    }
 #else
    if(pipe(fd)) {
        perror("pipe failed");
        exit(EXIT_FAILURE);
    }
    for(int i = 0; i < 2; i++) {        
        set_cloexec(fd[i], 1);      
    }
 #endif

Not sure which variable to ifdef on. With the above changes, I can cleanly compile this part at least on OS X. (The other issue, apparently also known, is with libchecktestdata.)

[thorehusfeldt]

Re “the other issue”: the one-line patch at https://github.com/DOMjudge/checktestdata/commit/470b9e5d00d95748b7daba27ad38ff82076b8003 does indeed fix libchecktestdata, and with those two changes the whole problemtools suite seems to compile on OS X. (Well, there are some warnings about unused variables in libchecktestdata.)

[thorehusfeldt]

@simonlindholm : What’s the preferred way to test for “are we on Linux?”

[simonlindholm]

Not certain, I guess #ifdef __linux__?

[thorehusfeldt]

Closed in 9d85d66068950d990c25ef9f9e2c07f5eeb0f94c