/*
 * 989_datargate_run (#59, F15 c5) — w6a must loud-reject a DATAR relocation
 * whose slot was never defined by a prior DATAW, not silently drop the reloc.
 *
 * THE BUG (wwstage w6a only, cat-A silent wrong output under rc=0): asm.ww's
 * A_DATAR arm, when holder.defined==0 or holder.isdata==0, did `p = p.link;
 * continue;` with no diagnostic and no errs++ — so the R_X86_64_64 .data
 * relocation was silently dropped and a rc=0 .o was emitted with a zero-filled
 * pointer slot (a null pointer at link/runtime). The cstage twin (cmd/w6a/
 * asm.c:363) printed a diagnostic + a->errs++, and main returns 1 before
 * opening the output, so no .o is written. THE FIX: emit a diagnostic and bump
 * a.errs (encode returns a.errs → main returns 1 before writing the .o).
 *
 *   row | shape                         | result (cs & ww agree)
 *   ----+-------------------------------+--------------------------------
 *   bad | DATAR on a slot with no DATAW | rc != 0, no .o written
 *   ok  | DATAW then DATAR on that slot | rc == 0, .o byte-identical (cs==ww)
 *
 * bad was RED pre-c5 on wwstage (rc=0, .o with the reloc silently dropped).
 * ok pins the defined-slot path: both stages rc=0 and a byte-identical .o.
 */
#include <stdio.h>
#include <stdlib.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 *BAD =
	"TEXT f,$0\n\tRET\n\tDATAR x+0(SB), f(SB)\n";
static const char *OK =
	"TEXT f,$0\n\tRET\n"
	"DATAW x(SB),\"\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\"\n"
	"\tDATAR x+0(SB), f(SB)\n";

static int
write_file(const char *path, const char *body)
{
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	fputs(body, f);
	fclose(f);
	return 0;
}

/* Assemble `src` with `tool` into `obj` (removed first). Returns rc; sets
 * *exists to whether the .o was created. */
static int
assemble(const char *tool, const char *src, const char *obj, int *exists)
{
	char cmd[1024];
	unlink(obj);
	snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", tool, obj, src);
	int rc = runwait(cmd);
	if (exists) *exists = (access(obj, F_OK) == 0);
	return rc;
}

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 ctool[1024], wtool[1024];
	snprintf(ctool, sizeof ctool, "%s/w6a", bin);
	snprintf(wtool, sizeof wtool, "%s/w6a_ww", bin);
	int have_ww = (access(wtool, X_OK) == 0);
	if (!have_ww)
		fprintf(stderr, "datargate: skip wwstage (no %s)\n", wtool);

	char bads[64], oks[64], co[64], wo[64];
	snprintf(bads, sizeof bads, "/tmp/datarg_bad_%d.s", getpid());
	snprintf(oks, sizeof oks, "/tmp/datarg_ok_%d.s", getpid());
	snprintf(co, sizeof co, "/tmp/datarg_c_%d.o", getpid());
	snprintf(wo, sizeof wo, "/tmp/datarg_w_%d.o", getpid());
	if (write_file(bads, BAD) || write_file(oks, OK)) return 1;

	int fail = 0, total = 0, ex;

	/* bad: both stages loud, no .o */
	total++;
	if (assemble(ctool, bads, co, &ex) == 0 || ex) {
		fprintf(stderr, "datargate[cstage][bad]: rc=0/.o written on "
		    "undefined DATAR slot\n");
		fail++;
	}
	if (have_ww) {
		if (assemble(wtool, bads, wo, &ex) == 0 || ex) {
			fprintf(stderr, "datargate[wwstage][bad]: rc=0/.o written on "
			    "undefined DATAR slot — reloc silently dropped (#59)\n");
			fail++;
		}
	}

	/* ok: both stages rc=0, byte-identical .o */
	total++;
	int crc = assemble(ctool, oks, co, &ex);
	if (crc != 0 || !ex) {
		fprintf(stderr, "datargate[cstage][ok]: rc=%d .o=%d\n", crc, ex);
		fail++;
	}
	if (have_ww) {
		int wrc = assemble(wtool, oks, wo, &ex);
		if (wrc != 0 || !ex) {
			fprintf(stderr, "datargate[wwstage][ok]: rc=%d .o=%d\n", wrc, ex);
			fail++;
		}
		char cmp[1024];
		snprintf(cmp, sizeof cmp, "cmp -s %s %s", co, wo);
		if (runwait(cmp) != 0) {
			fprintf(stderr, "datargate[ok]: cs/ww .o differ (#59)\n");
			fail++;
		}
	}

	unlink(bads); unlink(oks); unlink(co); unlink(wo);

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