ww/test/wcc/810_dyn.c

/*
 * Covers the claims the exit status alone can't show: dyn.c reading
 * ET_DYN and extracting exports, PLT/GOT generation with JUMP_SLOT
 * relocations, and PT_INTERP/PT_DYNAMIC emission.
 *
 * Symbol versioning (.gnu.version + .gnu.version_r): clock_gettime has
 * both GLIBC_2.2.5 (compat) and GLIBC_2.17 (default) on glibc; the
 * loader requires the right .gnu.version_r entry to bind the default
 * vDSO-aware impl.
 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "wwtestpkg.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 *src;
	int want_exit;
};

static const struct row rows[] = {
	/* 1. _exit via dynamically-linked libc. Exit code is the plumbing
	 * of choice — proves the PLT entry calls into libc.so.6. */
	{ "@symbol(\"_exit\") fn libc_exit(c: i32) void;\n"
	  "export fn main() i32 = { libc_exit(42); return 0; };", 42 },

	/* 2. Multiple dyn syms in one binary: write + _exit. */
	{ "@symbol(\"write\") fn libc_write(fd: i32, b: *u8, n: u64) i64;\n"
	  "@symbol(\"_exit\") fn libc_exit(c: i32) void;\n"
	  "export fn main() i32 = {\n"
	  "  libc_write(1, \"x\".ptr, 1u64);\n"
	  "  libc_exit(7);\n"
	  "  return 0;\n"
	  "};", 7 },

	/* 3. Symbol versioning: clock_gettime. Without DT_VERSYM/VERNEED
	 * pointing at a Vernaux entry for GLIBC_2.17, the loader either
	 * picks the wrong impl or fails outright on modern glibc. */
	{ "@symbol(\"clock_gettime\") fn clock_gettime(c: i32, ts: *u8) i32;\n"
	  "@symbol(\"_exit\")         fn libc_exit(c: i32) void;\n"
	  "export fn main() i32 = {\n"
	  "  let ts: [16]u8;\n"
	  "  let r: i32 = clock_gettime(1, ts.ptr);\n"  /* CLOCK_MONOTONIC */
	  "  libc_exit(r);\n"
	  "  return 0;\n"
	  "};", 0 },

	/* 4. Take the address of an FFI binding and call it indirectly.
	 * Codegen must apply @symbol resolution at the LEAQ site (so the
	 * stub address is `write`, not the ww-side ident `libc_write`),
	 * and the local-variable call must be CALL *AX, not CALL fp(SB). */
	{ "@symbol(\"write\") fn libc_write(fd: i32, b: *u8, n: u64) i64;\n"
	  "@symbol(\"_exit\") fn libc_exit(c: i32) void;\n"
	  "export fn main() i32 = {\n"
	  "  let fp: fn(fd: i32, b: *u8, n: u64) i64 = libc_write;\n"
	  "  fp(1, \"X\".ptr, 1u64);\n"
	  "  libc_exit(5);\n"
	  "  return 0;\n"
	  "};", 5 },

	/* 5. Writable global on the dyn-link path. .data now lives in the
	 * shared R+W segment with .got.plt and .dynamic; read and write
	 * exercise the new layout's data_va. */
	{ "@symbol(\"_exit\") fn libc_exit(c: i32) void;\n"
	  "let counter: i32 = 0;\n"
	  "export fn main() i32 = {\n"
	  "  counter = 11;\n"
	  "  libc_exit(counter);\n"
	  "  return 0;\n"
	  "};", 11 },

	/* 6. Zero-init slot under dyn-link: the BSS trailing-zero scan
	 * should still produce a valid p_filesz<p_memsz layout when the
	 * R+W segment is the shared gotplt+dynamic+.data one. */
	{ "@symbol(\"_exit\") fn libc_exit(c: i32) void;\n"
	  "let z: i64;\n"
	  "export fn main() i32 = {\n"
	  "  z = 9i64;\n"
	  "  libc_exit(z: i32);\n"
	  "  return 0;\n"
	  "};", 9 },

	{ NULL, 0 }
};

int
main(void)
{
	if (access("/usr/lib/libc.so.6", 0) != 0
	    && access("/lib/x86_64-linux-gnu/libc.so.6", 0) != 0
	    && access("/lib64/libc.so.6", 0) != 0) {
		puts("dyn: no libc.so.6 on this system — skipping");
		return 77;
	}

	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;
	}

	const char *libdir = NULL;
	if (access("/usr/lib/libc.so.6", 0) == 0) libdir = "/usr/lib";
	else if (access("/lib/x86_64-linux-gnu/libc.so.6", 0) == 0) libdir = "/lib/x86_64-linux-gnu";
	else if (access("/lib64/libc.so.6", 0) == 0) libdir = "/lib64";

	int n = 0, fail = 0;
	for (int i = 0; rows[i].src; i++, n++) {
		char tmpdir[] = "/tmp/wwdyn_XXXXXX";
		char src[128], outbin[128], scratch[160], rmcmd[192];
		int rowfail = 0;
		if (mkdtemp(tmpdir) == NULL) {
			fprintf(stderr, "dyn row %d: mkdtemp failed\n", i);
			fail++;
			continue;
		}
		snprintf(src, sizeof src, "%s/wwdyn_%d_%d.ww", tmpdir, getpid(), i);
		snprintf(outbin, sizeof outbin, "%s/wwdyn_%d_%d", tmpdir, getpid(), i);
		snprintf(scratch, sizeof scratch, "%s.sepwork", outbin);
		snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", scratch);

		FILE *f = fopen(src, "wb");
		if (f == NULL) {
			fprintf(stderr, "dyn row %d: source create failed\n", i);
			rowfail = 1;
			goto row_done;
		}
		wwtest_fputs(rows[i].src, f);
		int werr = ferror(f);
		if (fclose(f) != 0) werr = 1;
		if (werr) {
			fprintf(stderr, "dyn row %d: source write failed\n", i);
			rowfail = 1;
			goto row_done;
		}

		char cmd[1024];
		snprintf(cmd, sizeof cmd,
		    "%s/ww build -o %s -L %s -l c %s",
		    bin, outbin, libdir, src);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "dyn row %d: build failed\n", i);
			rowfail = 1;
			goto row_done;
		}

		int got = runwait(outbin);
		if (got != rows[i].want_exit) {
			fprintf(stderr, "dyn row %d: exit %d, want %d\n",
			    i, got, rows[i].want_exit);
			rowfail = 1;
		}

	row_done:
		if (runwait(rmcmd) != 0) {
			fprintf(stderr, "dyn row %d: scratch cleanup failed\n", i);
			rowfail = 1;
		}
		if (unlink(outbin) != 0 && errno != ENOENT) {
			fprintf(stderr, "dyn row %d: output cleanup failed\n", i);
			rowfail = 1;
		}
		if (unlink(src) != 0 && errno != ENOENT) {
			fprintf(stderr, "dyn row %d: source cleanup failed\n", i);
			rowfail = 1;
		}
		if (rmdir(tmpdir) != 0) {
			fprintf(stderr, "dyn row %d: workspace cleanup failed\n", i);
			rowfail = 1;
		}
		if (rowfail) fail++;
	}
	if (fail) {
		fprintf(stderr, "%d/%d dyn tests failed\n", fail, n);
		return 1;
	}
	printf("dyn: %d/%d ok\n", n, n);
	return 0;
}