/*
 * 632_w6l_manyflags — w6l -L/-l arrays must be sized by argc, not a
 * fixed 64-slot cap (drain F-C). The 65th -L used to write past the
 * allocation: `libdirs[nlibdirs] = ...` with no bound check, corrupting
 * the heap and dropping the flag.
 *
 * Behavioural discriminator: make a -L past slot 64 LOAD-BEARING. We
 * build libfoo.a in a real directory and reach it ONLY via the Nth -L,
 * preceded by N-1 junk dirs. w6l errors `cannot find -lfoo` unless it
 * can locate the archive, so a successful link (exit 0 + ET_EXEC) proves
 * the Nth -L was honoured. N is a table {1, 64, 65, 100, 128}; pre-fix,
 * N=65 (the slot exactly one past the 64-element array) reliably fails
 * to round-trip and the link errors — verified by rebuilding the pre-fix
 * w6l_ww. Both stages are driven for parity.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>

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

/* link `obj` with linker `lnk`, resolving -lfoo through `libdir` placed
 * as the Nth (last) -L after nflags-1 junk dirs. Returns the linker's
 * exit code; on success also fails (-1) if the output isn't an ET_EXEC
 * ELF — proving the archive was actually located and linked. */
static int
linkwith(const char *lnk, const char *obj, const char *libdir, int nflags)
{
	char exe[64];
	snprintf(exe, sizeof exe, "/tmp/wwfc_%d_x", getpid());

	char junk[8192];
	size_t off = 0;
	for (int i = 1; i < nflags; i++)
		off += snprintf(junk + off, sizeof junk - off,
		    " -L/nonexist/wwfc_d%d", i);

	char cmd[16384];
	snprintf(cmd, sizeof cmd,
	    "%s -o %s %s%s -L%s -lfoo 2>/dev/null",
	    lnk, exe, obj, junk, libdir);
	int rc = runwait(cmd);
	if (rc != 0) { unlink(exe); return rc; }

	FILE *f = fopen(exe, "rb");
	if (!f) return -1;
	unsigned char hdr[20];
	int ok = fread(hdr, 1, sizeof hdr, f) == sizeof hdr;
	fclose(f);
	unlink(exe);
	if (!ok || memcmp(hdr, "\x7f""ELF", 4) != 0) return -1;
	unsigned short etype = (unsigned short)hdr[16]
	    | ((unsigned short)hdr[17] << 8);
	if (etype != 2) return -1;	/* ET_EXEC */
	return 0;
}

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

	char src[64], asmf[64], obj[64];
	char fsrc[64], fasm[64], fobj[64];
	char libdir[64], lib[128], cmd[1024];
	int pid = getpid();
	snprintf(src,  sizeof src,  "/tmp/wwfc_%d_m.ww", pid);
	snprintf(asmf, sizeof asmf, "/tmp/wwfc_%d_m.s",  pid);
	snprintf(obj,  sizeof obj,  "/tmp/wwfc_%d_m.o",  pid);
	snprintf(fsrc, sizeof fsrc, "/tmp/wwfc_%d_f.ww", pid);
	snprintf(fasm, sizeof fasm, "/tmp/wwfc_%d_f.s",  pid);
	snprintf(fobj, sizeof fobj, "/tmp/wwfc_%d_f.o",  pid);
	snprintf(libdir, sizeof libdir, "/tmp/wwfc_%d_lib", pid);
	snprintf(lib, sizeof lib, "%s/libfoo.a", libdir);

	/* a standalone main.o (no undefs) + an unrelated archived foo.o. */
	FILE *f = fopen(src, "wb");
	fputs("fn main() i32 = { return 42; };", f);
	fclose(f);
	f = fopen(fsrc, "wb");
	fputs("export fn foo() i32 = { return 7; };", f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s", bin, asmf, src);
	if (runwait(cmd) != 0) { fprintf(stderr, "w6c main failed\n"); return 1; }
	snprintf(cmd, sizeof cmd, "%s/w6a -o %s %s", bin, obj, asmf);
	if (runwait(cmd) != 0) { fprintf(stderr, "w6a main failed\n"); return 1; }
	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s", bin, fasm, fsrc);
	if (runwait(cmd) != 0) { fprintf(stderr, "w6c foo failed\n"); return 1; }
	snprintf(cmd, sizeof cmd, "%s/w6a -o %s %s", bin, fobj, fasm);
	if (runwait(cmd) != 0) { fprintf(stderr, "w6a foo failed\n"); return 1; }
	snprintf(cmd, sizeof cmd, "mkdir -p %s && ar rcs %s %s", libdir, lib, fobj);
	if (runwait(cmd) != 0) { fprintf(stderr, "ar failed\n"); return 1; }

	int counts[] = { 1, 64, 65, 100, 128 };
	int fail = 0;
	for (int i = 0; i < (int)(sizeof counts / sizeof counts[0]); i++) {
		int n = counts[i];
		char wlnk[2048], clnk[2048];
		snprintf(wlnk, sizeof wlnk, "%s/w6l_ww", bin);
		snprintf(clnk, sizeof clnk, "%s/w6l", bin);
		int wrc = linkwith(wlnk, obj, libdir, n);
		int crc = linkwith(clnk, obj, libdir, n);
		if (wrc != 0) {
			fprintf(stderr, "FAIL: w6l_ww nflags=%d link rc=%d "
			    "(65th-style -L not honoured → heap overflow)\n",
			    n, wrc);
			fail++;
		}
		if (crc != 0) {
			fprintf(stderr, "FAIL: w6l (cstage) nflags=%d link rc=%d\n",
			    n, crc);
			fail++;
		}
	}

	snprintf(cmd, sizeof cmd, "rm -rf %s %s %s %s %s %s %s",
	    src, asmf, obj, fsrc, fasm, fobj, libdir);
	(void)runwait(cmd);

	if (fail) {
		fprintf(stderr, "w6l_manyflags: %d failure(s)\n", fail);
		return 1;
	}
	printf("w6l_manyflags: -L past slot 64 honoured by both stages "
	    "(1/64/65/100/128 flags)\n");
	return 0;
}