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POHow to use strsignal and WCOREDUMP in ANSI C?
 

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  1. POHow to use strsignal and WCOREDUMP in ANSI C?
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    <p>I've been trying to learn C the hard way - issuing basic calls, watching them fail, and trying to figure out what's going on. At the moment I'm working with fork() and the interoperation between parent and child processes. Everything has worked as expected, except tonight when I introduced <code>-ansi</code> into my CFLAGS. At that point, I got these messages from make:</p> <pre><code>waitpid.c: In function ‘wait_for_child’: waitpid.c:63:3: warning: implicit declaration of function ‘strsignal’ [-Wimplicit-function-declaration] printf("child exited with signal %s\n", strsignal(WTERMSIG(child_status))); ^ waitpid.c:63:3: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘int’ [-Wformat=] waitpid.c:64:3: warning: implicit declaration of function ‘WCOREDUMP’ [-Wimplicit-function-declaration] if ( WCOREDUMP(child_status) ) { ^ </code></pre> <p>The output of <code>gcc -C -E</code> is radically different depending on whether I specify -ansi as well. Both show expansions of WIFEXITED, WEXITSTATUS, WIFSIGNALED, and WTERMSIG, but only the non-ANSI version expands WCOREDUMP. It's also the one that gets a declaration of strsignal from sys/wait.h.</p> <p>I infer that strsignal and WCOREDUMP aren't supported in ANSI C, though I can't find anything explicit yet that says so. Is there some other way to perform their functions? Or am I missing something basic?</p> <p>Full code is at <a href="http://pastebin.com/hQ2pR7fF" rel="nofollow">http://pastebin.com/hQ2pR7fF</a>. Thanks.</p>
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    1. COTry `#define _GNU_SOURCE` before `#include <string.h>`.
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      1. POHow to use strsignal and WCOREDUMP in ANSI C?
      1. USElliott Frisch
    2. COSure enough, that works. `#define _POSIX_C_SOURCE 200809L` and `#define _XOPEN_SOURCE 700` both allowed strsignal, but continued to profess no knowledge of WCOREDUMP. Is there some more portable or compliant way to test whether core was dumped by a child process?
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