/*
 * 996_dyn_ww — phase-8 marker for ET_DYN linking on the ww side.
 *
 * Drives w6l_ww with -L/-l flags over examples/snake/snake.o and diffs
 * the result against the C-built w6l on the same inputs. A green run
 * means the ww-side linker emits PT_INTERP/PT_DYNAMIC binaries byte-
 * for-byte identical to the C linker — i.e. the dynamic linking story
 * is fully ported and snake no longer depends on Cstage.
 */
#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;
}

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

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

	/* Ensure snake.o exists. The example's Makefile produces it via
	 * the C-side `ww build`. Re-run that so the test is self-contained. */
	char cmd[4096];
	snprintf(cmd, sizeof cmd,
	    "cd %s/examples/snake && %s/ww build snake.ww -L /usr/lib "
	    "-l ncurses -l c >/dev/null 2>&1",
	    cwd, bin);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "w6l_ww-dyn FAIL: cannot build snake.o via C driver\n");
		return 1;
	}

	char co[64], wo[64];
	snprintf(co, sizeof co, "/tmp/wwld_%d_c", getpid());
	snprintf(wo, sizeof wo, "/tmp/wwld_%d_w", getpid());

	/* C-side w6l with the dynamic flags. */
	snprintf(cmd, sizeof cmd,
	    "%s/w6l -o %s %s/examples/snake/snake.o -L /usr/lib "
	    "-l ncurses -l c %s/out/lib/libwwrt.a 2>/dev/null",
	    bin, co, cwd, cwd);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "w6l_ww-dyn FAIL: C w6l errored\n");
		unlink(co);
		return 1;
	}

	/* ww-side w6l with the same flags. */
	snprintf(cmd, sizeof cmd,
	    "%s/w6l_ww -o %s %s/examples/snake/snake.o -L /usr/lib "
	    "-l ncurses -l c %s/out/lib/libwwrt.a 2>/dev/null",
	    bin, wo, cwd, cwd);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "w6l_ww-dyn FAIL: ww w6l errored\n");
		unlink(co); unlink(wo);
		return 1;
	}

	char *bc = NULL, *bw = NULL;
	size_t nc = 0, nw = 0;
	int rc = 0;
	if (slurp(co, &bc, &nc) < 0 || slurp(wo, &bw, &nw) < 0) {
		fprintf(stderr, "w6l_ww-dyn FAIL: cannot read outputs\n");
		rc = 1;
	} else if (nc != nw || memcmp(bc, bw, nc) != 0) {
		fprintf(stderr, "w6l_ww-dyn FAIL: C %zu vs ww %zu bytes\n",
		    nc, nw);
		rc = 1;
	} else {
		printf("w6l_ww-dyn: byte-identical to C w6l on snake "
		    "(PT_INTERP + PT_DYNAMIC + .rela.plt + .gnu.version_r, "
		    "%zu bytes)\n", nc);
	}
	free(bc); free(bw);
	unlink(co); unlink(wo);
	return rc;
}