/*
 * 992_w6l_ww — phase-10 marker for the ww-side w6l port.
 *
 * Diffs the C-built `w6l` against the ww-built `w6l_ww` on a corpus of
 * link inputs. Both must produce byte-identical static ELF binaries.
 * The corpus mixes:
 *   - a single .o input (no archive resolution)
 *   - a .o + libwwrt.a link, exercising the SysV `ar` two-pass loader
 *
 * Any divergence is a port bug in selfhost/cmd/w6l/.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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;
}

static const char *
absbin(void)
{
	const char *b = getenv("BIN");
	if (!b) b = "out/bin";
	if (b[0] == '/') return b;
	static char buf[2048];
	char cwd[1024];
	if (getcwd(cwd, sizeof cwd) == NULL) return NULL;
	snprintf(buf, sizeof buf, "%s/%s", cwd, b);
	return buf;
}

static int
slurp(const char *path, char **outbuf, size_t *outlen)
{
	FILE *f = fopen(path, "rb");
	if (!f) return -1;
	fseek(f, 0, SEEK_END);
	long n = ftell(f);
	fseek(f, 0, SEEK_SET);
	if (n < 0) { fclose(f); return -1; }
	char *b = malloc((size_t)n + 1);
	if (!b) { fclose(f); return -1; }
	if (fread(b, 1, (size_t)n, f) != (size_t)n) { free(b); fclose(f); return -1; }
	b[n] = '\0';
	fclose(f);
	*outbuf = b;
	*outlen = (size_t)n;
	return 0;
}

/* #93 sep layout: the flip stops emitting a monolithic <tool>/main.o;
 * the linkable unit is now the per-package .o + reverse-topo .a set the
 * sep driver assembles (a raw `w6l <root>.o *.a libwwrt.a` from the test
 * side fails — `undefined reference` — because it can't reproduce the
 * driver's topo order). So isolate the LINKER by driving the sep build's
 * own link step twice over identical .o inputs (a shared pkgcache makes
 * the second build's package objects a cache hit → only the final link
 * re-runs): once with the default C w6l, once with WW_W6L=w6l_ww. Diff
 * the two real tool binaries. Exercises the full archive two-pass loader
 * + reverse-topo .a resolution — a stronger link than the old single
 * main.o. Flip-invariant: --sep is live on trunk, default post-flip. */
static int
build_and_diff(const char *bin, const char *cwd, const char *tool,
    const char *cache)
{
	char cstem[256], wstem[256], cmd[4096];
	snprintf(cstem, sizeof cstem, "/tmp/wwl_%d_c", getpid());
	snprintf(wstem, sizeof wstem, "/tmp/wwl_%d_w", getpid());

	snprintf(cmd, sizeof cmd,
	    "WW_PKGCACHE=%s timeout 300 %s/ww build --sep -o %s "
	    "%s/selfhost/cmd/%s >/dev/null 2>&1", cache, bin, cstem, cwd, tool);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "w6l_ww FAIL: C-link sep-build of %s\n", tool);
		return -1;
	}
	snprintf(cmd, sizeof cmd,
	    "WW_W6L=%s/w6l_ww WW_PKGCACHE=%s timeout 300 %s/ww build --sep "
	    "-o %s %s/selfhost/cmd/%s >/dev/null 2>&1",
	    bin, cache, bin, wstem, cwd, tool);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "w6l_ww FAIL: ww-link sep-build of %s\n", tool);
		snprintf(cmd, sizeof cmd, "rm -rf %s %s.sepwork", cstem, cstem);
		if (system(cmd)) {}
		return -1;
	}
	char *bc = NULL, *bw = NULL;
	size_t nc = 0, nw = 0;
	int rc = 0;
	if (slurp(cstem, &bc, &nc) < 0 || slurp(wstem, &bw, &nw) < 0) {
		fprintf(stderr, "w6l_ww FAIL: cannot read output for %s\n", tool);
		rc = -1;
	} else if (nc != nw || memcmp(bc, bw, nc) != 0) {
		fprintf(stderr, "w6l_ww FAIL: %s — C %zu vs ww %zu bytes\n",
		    tool, nc, nw);
		rc = -1;
	}
	free(bc); free(bw);
	snprintf(cmd, sizeof cmd, "rm -rf %s %s %s.sepwork %s.sepwork",
	    cstem, wstem, cstem, wstem);
	if (system(cmd)) {}
	return rc;
}

int
main(void)
{
	const char *bin = absbin();
	if (!bin) return 1;

	char cwd[1024];
	if (getcwd(cwd, sizeof cwd) == NULL) return 1;

	/* Real bootstrap-style links: each selfhost tool's full sep build
	 * (root .o + reverse-topo dep .a set + libwwrt.a). One shared
	 * pkgcache across all builds so each tool's second (w6l_ww) build
	 * re-links only. (wwdump is excluded — it imports the compiler-
	 * internal cmd packages syntax/check/cgen, which don't resolve
	 * under the lib-path sep dep scan; w6a/w6l are self-contained
	 * lib-only tools.) */
	const char *tools[] = { "w6a", "w6l", NULL };
	char cache[256];
	snprintf(cache, sizeof cache, "/tmp/wwl_%d_pkgc", getpid());

	int fail = 0;
	int n = 0;
	for (int i = 0; tools[i]; i++) {
		if (build_and_diff(bin, cwd, tools[i], cache) != 0) fail++;
		n++;
	}
	char rmc[320];
	snprintf(rmc, sizeof rmc, "rm -rf %s", cache);
	if (system(rmc)) {}
	if (fail) {
		fprintf(stderr, "w6l_ww: %d/%d diff(s) failed\n", fail, n);
		return 1;
	}
	printf("w6l_ww: byte-identical to C w6l on %d selfhost tool links "
	    "(sep root .o + reverse-topo .a set + libwwrt.a)\n", n);
	return 0;
}