ww/test/wcc/989_loopcap_run.c

/*
 * 989_loopcap_run (#42, F13 c2) — the loop-label stack must fail loud at its
 * cap in BOTH stages, not silently corrupt the heap / emit a wrong target.
 *
 * THE BUG (cat-A): wwstage cgfor / cgforrange pushed end+continue labels into
 * loopendbuf/loopcontbuf (sized exactly LOOP_MAX=16) with NO bounds check, so
 * nesting depth 17 wrote one past the heap allocation — silent compiler-heap
 * corruption. The cstage twins DID guard (`if (nloops < LOOP_MAX)`) but then
 * silently emitted the 16th loop's break/continue label for the 17th loop — a
 * wrong jump target, also silent. Both stages were wrong at the boundary and
 * diverged. The runtime-correct target (CAP-SEMANTICS rule): a hard compile
 * error at the shared cap (LOOP_MAX) in BOTH stages — ww adds the bounds
 * check, cstage turns its silent skip into a fatal.
 *
 *   row         | depth | shape                       | result (cs==ww)
 *   ------------+-------+-----------------------------+-----------------
 *   at_cap_16   | 16    | exactly LOOP_MAX nested for | exit 0 (byte-id)
 *   over_cap_17 | 17    | one past the cap            | build FAILS loud
 *
 * over_cap_17 was RED pre-c2 on BOTH stages (ww OOB write, cs wrong JMP
 * target, divergent and silent under rc=0). at_cap_16 pins the boundary stays
 * accepted byte-identically.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>

static int
runwait(const char *cmd)
{
	int rc = system(cmd);
	if (rc == -1) return -1;
	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
	return -1;
}

struct row { const char *label; int depth; int want_build_fail; int want_exit; };

static const struct row rows[] = {
	{ "at_cap_16",   16, 0, 0 },
	{ "over_cap_17", 17, 1, 0 },
};

/* Emit `depth` nested `for (n < 1) { ... }` over one shared counter that the
 * innermost body sets to 1, so every level terminates. */
static int
write_src(const char *path, int depth)
{
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	fputs("package main;\n"
	      "export fn main() i32 = {\n"
	      "\tlet n: i32 = 0;\n\t", f);
	for (int i = 0; i < depth; i++) fputs("for (n < 1) { ", f);
	fputs("n = 1;", f);
	for (int i = 0; i < depth; i++) fputs(" };", f);
	fputs("\n\treturn 0;\n};\n", f);
	fclose(f);
	return 0;
}

static int
build_run(const char *driver, const struct row *r, int i, int *brc)
{
	char tmpdir[64], src[128], outbin[128], cmd[1024], rmcmd[160];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/lcap_%d_d_%d", getpid(), i);
	snprintf(src, sizeof src, "%s/lcap_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/lcap_%d_%d", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);

	mkdir(tmpdir, 0755);
	if (write_src(src, r->depth) != 0) { runwait(rmcmd); *brc = -1; return -1; }

	snprintf(cmd, sizeof cmd, "%s build -o %s %s 2>/dev/null",
	    driver, outbin, src);
	*brc = runwait(cmd);

	int got = -1;
	if (*brc == 0) got = runwait(outbin);

	runwait(rmcmd);
	return got;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[1024];
	if (bin[0] != '/') {
		char cwd[1024];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[1024], wdrv[1024];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
	int have_ww = (access(wdrv, X_OK) == 0);

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;

	for (int i = 0; i < n; i++) {
		total++;
		int cbrc, gc = build_run(cdrv, &rows[i], i, &cbrc);

		if (rows[i].want_build_fail) {
			if (cbrc == 0) {
				fprintf(stderr, "loopcap[cstage][%s]: built rc=0, "
				    "expected loud build failure (#42)\n", rows[i].label);
				fail++;
			}
		} else {
			if (cbrc != 0 || gc != rows[i].want_exit) {
				fprintf(stderr, "loopcap[cstage][%s]: brc=%d exit=%d "
				    "want_exit=%d\n", rows[i].label, cbrc, gc,
				    rows[i].want_exit);
				fail++;
			}
		}

		if (!have_ww) {
			fprintf(stderr, "loopcap: skip wwstage (no %s)\n", wdrv);
			continue;
		}
		int wbrc, gw = build_run(wdrv, &rows[i], i, &wbrc);

		if (rows[i].want_build_fail) {
			if (wbrc == 0) {
				fprintf(stderr, "loopcap[wwstage][%s]: built rc=0, "
				    "expected loud build failure (#42)\n", rows[i].label);
				fail++;
			}
			if ((cbrc == 0) != (wbrc == 0)) {
				fprintf(stderr, "loopcap[%s]: build-fail divergence "
				    "cs_rc=%d ww_rc=%d (#42)\n", rows[i].label, cbrc, wbrc);
				fail++;
			}
		} else {
			if (wbrc != 0 || gw != rows[i].want_exit) {
				fprintf(stderr, "loopcap[wwstage][%s]: brc=%d exit=%d "
				    "want_exit=%d\n", rows[i].label, wbrc, gw,
				    rows[i].want_exit);
				fail++;
			}
			if (gw != gc) {
				fprintf(stderr, "loopcap[%s]: cs=%d != ww=%d "
				    "(loop-cap divergence — #42)\n", rows[i].label, gc, gw);
				fail++;
			}
		}
	}

	if (fail) {
		fprintf(stderr, "loopcap_run: %d/%d checks failed\n", fail, total);
		return 1;
	}
	printf("loopcap_run: %d/%d ok\n", total, total);
	return 0;
}