ref: cb1d10f3f49a9c1f8045a4896c2d9c4b235988e1
dir: /sys/src/ape/lib/ap/gen/_assert.c/
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
void
_assert(char *f, unsigned line)
{
char buf[20], *p, *s = &buf[20];
write(2, "assertion failed: file ", 23);
for(p = f; *p; p++) continue;
write(2, f, p-f);
*--s = '\n';
do *--s = line%10 + '0'; while (line /= 10);
*--s = ':';
write(2, s, &buf[20] - s);
abort();
}