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#define _POSIX_C_SOURCE 200112L
#include <stdio.h>
#include <stdint.h>
#include <limits.h>
#include <error.h>
#include <assert.h>
#include <unistd.h>
#include <wait.h>
#define ARGV0 "unamem"
#define DONT_FORK 1
static void report_wait (const int status) {
if (WIFEXITED(status)) {
printf("exit %d\n", WEXITSTATUS(status));
}
else if (WIFSIGNALED(status)) {
printf("signal %d\n", WTERMSIG(status));
}
else {
printf("?\n");
}
}
int main (void) {
static char m[9]; // bss address is nicer than stack
char *c;
uintptr_t *p;
pid_t pid;
int status;
printf(
"CHAR_BIT: %d\n"
"word: %zd\n"
"uintptr_t: %zd\n"
"size_t: %zd\n"
"short: %zd\n"
"int: %zd\n"
"long: %zd\n"
"long long: %zd\n"
,
CHAR_BIT,
CHAR_BIT * sizeof(uintptr_t),
sizeof(uintptr_t),
sizeof(size_t),
sizeof(short),
sizeof(int),
sizeof(long),
sizeof(long long));
c = m;
p = (void*)(m + 1);
printf(
"malloc: %zx", (uintptr_t)m);
for (size_t i = sizeof(uintptr_t); i > 1; i /= 2) {
if ((uintptr_t)m % i == 0) {
printf(" {%zu}", i);
}
}
printf("\n");
printf(
"c: %zx\n"
"p: %zx\n"
,
(uintptr_t)c,
(uintptr_t)p);
pid = DONT_FORK ? 0 : fork();
if (pid > 0) {
printf(
"access: "
);
wait(&status);
report_wait(status);
}
else if (pid == 0) {
*p = UINTPTR_MAX;
*c = 0;
assert(*p == UINTPTR_MAX);
assert(*c == 0);
*c = 0;
*p = UINTPTR_MAX;
assert(*p == UINTPTR_MAX);
assert(*c == 0);
}
else {
perror(ARGV0": fork()");
return 1;
}
pid = DONT_FORK ? 0 : fork();
if (pid > 0) {
printf(
"float: "
);
wait(&status);
report_wait(status);
}
else if (pid == 0) {
volatile float a, b, c;
a = 0.1;
b = 1.0;
c = b / a;
assert(c > 1.0);
}
else {
perror(ARGV0": fork()");
return 1;
}
return 0;
}
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