zc0: a store into a local embed array is an error (its elements are in the code); test in tests/test.sh

3 files changed, 27 insertions, 8 deletions

diff --git a/src/tools/zc0.c b/src/tools/zc0.c
index d484016..6c62abf 100644
--- a/src/tools/zc0.c
+++ b/src/tools/zc0.c
@@ -48,6 +48,9 @@ static void tsroom(size_t n)
 	ts = nb; tscap = c;
 }
 static int xf, xs, lvi;	/* float, byte string; the plain local it came from, or -1 */
+/* xro: the value is a local embed array (Loc.ro); lro: the lvalue is one of its elements, which zc0 refuses to write */
+static int xro, lro;
+static void rocheck(void);
 
 static int64_t *img; static int imgcap, here = GORG;
 static void emit(int64_t w) {
@@ -296,7 +299,7 @@ static void fnref(const char *n)	/* push a function address, fixing it up later
 }
 
 /* ---- locals ---- */
-typedef struct { char name[64]; int slot, arr, flt, str, dstr; } Loc;	/* dstr: declared bstr, so always a byte string */
+typedef struct { char name[64]; int slot, arr, flt, str, dstr, ro; } Loc;	/* dstr: declared bstr, so always a byte string; ro: a local embed array, whose elements are in the code */
 static Loc lo[1024]; static int nlo, nslot, infn;
 static Loc *findl(const char *n) { int i; for (i = nlo; i--;) if (!strcmp(lo[i].name, n)) return &lo[i]; return 0; }
 static int isrecast(void)
@@ -597,10 +600,11 @@ static int returns_bstr(const char *n)
 }
 static int args(void) { int n = 0; expect("("); if (!accept(")")) { do { expr(); rval(); n++; } while (accept(",")); expect(")"); } return n; }
 static void asmblock(void);
+static void rocheck(void) { if (lro) die("a local embed array is part of the code; zc0 does not let a program write it (embed it at the top level)"); }
 static void primary(void)
 {
 	char n[64]; Loc *l; Sym *s;
-	lv = 0; lvi = -1; xf = 0; xs = 0;
+	lv = 0; lvi = -1; xf = 0; xs = 0; xro = 0; lro = 0;
 	if (tk == T_FLT) { emit(1200); emit(tv); xf = 1; next(); return; }
 	if (tk == T_NUM) { lit(tv); next(); return; }
 	if (tk == T_BSTR) { bstrlit(); xs = 1; return; }
@@ -608,7 +612,7 @@ static void primary(void)
 	if (accept("(")) { expr(); expect(")"); return; }
 	if (is("asm")) { next(); asmblock(); return; }
 	strcpy(n, ident());
-	if ((l = findl(n))) { laddr(l->slot); lv = !l->arr; if (!l->arr) { xf = l->flt; xs = l->str; lvi = (int)(l - lo); } return; }
+	if ((l = findl(n))) { laddr(l->slot); lv = !l->arr; if (!l->arr) { xf = l->flt; xs = l->str; lvi = (int)(l - lo); } xro = l->ro; return; }
 	s = find(n);
 	if (s && s->kind == K_CONST) { lit(s->val); return; }
 	if (s && s->kind == K_GVAR) { lit(s->val); lv = 1; xs = s->str; return; }
@@ -634,6 +638,7 @@ static void primary(void)
 static void incdec(int post, int d)
 {
 	if (!lv) die("++/-- needs an lvalue");
+	rocheck();
 	lv = 0;
 	if (lvi >= 0) lo[lvi].str = lo[lvi].dstr;
 	xs = 0;
@@ -646,6 +651,7 @@ static void postfix(void)
 	primary();
 	for (;;) {
 		if (accept("[")) {
+			int ro = xro;
 			was = xs; rval(); expr(); rval();
 			if (was && accept(":")) {
 				expr(); rval(); expect("]"); fnref("slice_s"); op(O_CALL);
@@ -654,8 +660,9 @@ static void postfix(void)
 				expect("]"); fnref("at_s"); op(O_CALL);
 				lv = 0; xs = 0; xf = 0; lvi = -1;
 			} else { expect("]"); op(O_ADD); lv = 1; xs = 0; xf = 0; lvi = -1; }
+			xro = 0; lro = ro;
 		}
-		else if (is("(")) { rval(); n = args(); lit(n); op(O_PICK); op(O_CALL); op(O_SWAP); op(O_DROP); xf = 0; xs = 0; lvi = -1; }
+		else if (is("(")) { rval(); n = args(); lit(n); op(O_PICK); op(O_CALL); op(O_SWAP); op(O_DROP); xf = 0; xs = 0; lvi = -1; xro = 0; lro = 0; }
 		else if (accept("++")) incdec(1, 1);
 		else if (accept("--")) incdec(1, -1);
 		else if (accept("as")) ptype0();	/* the whole type, as the compiler reads it: x as int*, x as char** */
@@ -671,7 +678,7 @@ static void unary(void)
 	}
 	else if (accept("!")) { unary(); rval(); ftest(); seq_isz(); xf = 0; xs = 0; }
 	else if (accept("~")) { unary(); rval(); lit(-1); op(O_XOR); xf = 0; xs = 0; }
-	else if (accept("*")) { unary(); rval(); lv = 1; xs = 0; }
+	else if (accept("*")) { unary(); rval(); lv = 1; xs = 0; xro = 0; lro = 0; }
 	else if (accept("&")) { unary(); if (!lv) die("& needs an lvalue"); lv = 0; xs = 0; }
 	else if (accept("++")) { unary(); incdec(0, 1); }
 	else if (accept("--")) { unary(); incdec(0, -1); }
@@ -698,7 +705,7 @@ static void bin(int minp)
 			} else if ((lf || rf) && fis(o)) { fbinop(o, lf, rf); xs = 0; }
 			else { binop(o); xf = 0; xs = 0; }
 		}
-		lv = 0; lvi = -1;
+		lv = 0; lvi = -1; xro = 0; lro = 0;
 	}
 }
 static void expr(void)
@@ -707,11 +714,13 @@ static void expr(void)
 	bin(1); dst = lvi;
 	if (is("=")) {
 		if (!lv) die("assignment needs an lvalue");
+		rocheck();
 		next(); expr(); rval();
 		op(O_SWAP); lit(1); op(O_PICK); op(O_SWAP); op(O_ST); lv = 0;
 		if (dst >= 0) { lo[dst].flt = xf; lo[dst].str = xs || lo[dst].dstr; }
 	} else if (tk == T_OP && strlen(ts) >= 2 && ts[strlen(ts) - 1] == '=' && strcmp(ts, "==") && strcmp(ts, "!=") && strcmp(ts, "<=") && strcmp(ts, ">=")) {
 		if (!lv) die("assignment needs an lvalue");
+		rocheck();
 		lf = xf; strcpy(o, ts); o[strlen(o) - 1] = 0; next();
 		lit(0); op(O_PICK); op(O_LD); lv = 0; expr(); rval();
 		if ((lf || xf) && fis(o)) fbinop(o, lf, xf);
@@ -956,7 +965,7 @@ static int embed_width(const char *t, int star)
 }
 static Loc *newloc(const char *n)
 {
-	Loc *l = &lo[nlo++]; strcpy(l->name, n); l->slot = nslot++; l->arr = l->flt = l->str = l->dstr = 0;
+	Loc *l = &lo[nlo++]; strcpy(l->name, n); l->slot = nslot++; l->arr = l->flt = l->str = l->dstr = l->ro = 0;
 	return l;
 }
 static void embeddecl(int local)
@@ -1031,7 +1040,7 @@ static void embeddecl(int local)
 			emit((int64_t)u);
 		}
 		if (!count) emit(0);
-		if (local) { setlit(j, here); l = newloc(n); lit(a); laddr(l->slot); op(O_ST); }
+		if (local) { setlit(j, here); l = newloc(n); l->ro = 1; lit(a); laddr(l->slot); op(O_ST); }
 		else add(n, K_GARR, a);
 	}
 	free(buf);
diff --git a/tests/programs/zc0embed_write.zc b/tests/programs/zc0embed_write.zc
new file mode 100644
index 0000000..09686b5
--- /dev/null
+++ b/tests/programs/zc0embed_write.zc
@@ -0,0 +1,9 @@
+include rt;
+// zc0 keeps a local embed array in the code, so it refuses a store into one; the
+// resident compiler accepts it (prints 9). tests/test.sh checks zc0's message.
+fn main() {
+	embed "tests/data/embed/bytes.bin" as u8[] b;
+	b[1] = 9;
+	rt.put_n(b[1]); rt.put_c(10);
+	return 0;
+}
diff --git a/tests/test.sh b/tests/test.sh
index 7a80c3c..5b62262 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -82,6 +82,7 @@ GI="-Isrc/core -I$MAP --embed-dir=$T/s1"
 # it, and the run-only and bare-metal sections read it as the reference.
 $CC -pthread -O2 -w -fwrapv -DJTYPE=int src/core/core.c src/core/io_linux.c $GI -o $T/zy || exit 1
 chk "$($T/zc0 < tests/programs/zc0typed.zc | md5sum)" "$($T/zc0 < tests/programs/zc0plain.zc | md5sum)" "zc0 reads types and throws them away: typed and plain sources give one image"
+case "$($T/zc0 < tests/programs/zc0embed_write.zc 2>&1 >/dev/null)" in *"line 6: a local embed array is part of the code"*) chk 1 1 "zc0 refuses a store into a local embed array";; *) chk 0 1 "zc0 refuses a store into a local embed array";; esac
 
 for n in $SECS; do
 	mkdir -p $ROOT/$n