syscalltest.c
jmg (John-Mark Gurney)
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	jmg
	Aug 29 2025, 5:27 PM

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syscalltest.c
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	#include <sys/mman.h>
	#include <sys/syscall.h>
	#include <signal.h>
	#include <stdlib.h>
	#include <unistd.h>

	sig_atomic_t gotsigsys;

	void
	sigsys_handler(int sig)
	{

	gotsigsys = 1;
	}

	int
	main()
	{
	int pipefds[2];
	int wfd, rfd;

	char p[] = "V";
	char readchar;
	int r;

	if (pipe(pipefds) == -1)
	exit(1);

	rfd = pipefds[0];
	wfd = pipefds[1];

	if (write(wfd, p, 1) != 1)
	exit(1);

	if (read(rfd, &readchar, 1) != 1)
	exit(1);

	if (readchar != p[0])
	exit(1);

	if (syscall(SYS_write, wfd, p, 1) != 1)
	exit(1);

	if (read(rfd, &readchar, 1) != 1)
	exit(1);

	if (readchar != p[0])
	exit(1);

	signal(SIGSYS, sigsys_handler);

	/* check for bug in arm64 32-bit compat code */
	gotsigsys = 0;
	r = __syscall((quad_t)SYS_write << 32, wfd, p, 1);

	if (!gotsigsys)
	exit(1);
	gotsigsys = 0;
	r = __syscall((quad_t)SYS_write, wfd, p, 1);

	if (gotsigsys)
	exit(1);

	if (r != 1)
	exit(1);

	if (read(rfd, &readchar, 1) != 1)
	exit(1);

	if (readchar != p[0])
	exit(1);

	void *addr;

	/* xxx would be better to map a real file with an offset to make sure off_t is endian clean */
	addr = mmap(NULL, 8192, PROT_READ\|PROT_WRITE, MAP_ANON, -1, 0);

	if (gotsigsys)
	exit(1);

	if (addr == NULL)
	exit(1);

	if (sizeof(void *) <= sizeof(int)) {
	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wint-to-void-pointer-cast"
	addr = (void *)syscall(SYS_mmap, NULL, 8192, PROT_READ\|PROT_WRITE, MAP_ANON, -1, 0);
	#pragma clang diagnostic pop

	if (addr == NULL)
	exit(1);
	}

	addr = (void *)__syscall(SYS_mmap, NULL, 8192, PROT_READ\|PROT_WRITE, MAP_ANON, -1, 0);

	if (gotsigsys)
	exit(1);

	if (addr == NULL)
	exit(1);

	return 0;
	}