First commit

1 files changed, 112 insertions, 0 deletions

diff --git a/src/section/table.c b/src/section/table.c
new file mode 100644
index 0000000..15fc619
--- /dev/null
+++ b/src/section/table.c
@@ -0,0 +1,112 @@
+/*
+ * nanowasm, a tiny WebAssembly/Wasm interpreter
+ * Copyright (C) 2023-2024  Xavier Del Campo Romero
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include <nw/log.h>
+#include <nw/sections.h>
+#include <nanowasm/nw.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+static int check_table_type(FILE *const f)
+{
+    enum {ANYFUNC = 0x70};
+    varint7 elem_type;
+
+    if (varint7_read(f, &elem_type))
+    {
+        LOG("%s: varint7_read failed\n", __func__);
+        return -1;
+    }
+    else if (elem_type != ANYFUNC)
+    {
+        LOG("%s: expected %x, got %x", __func__, ANYFUNC,
+            (int)elem_type);
+        return -1;
+    }
+
+    /* TODO: what to do with this? */
+    struct resizable_limits r;
+
+    return check_resizable_limits(f, &r);
+}
+
+static int check(FILE *const f, const unsigned long len)
+{
+    const long start = ftell(f);
+
+    if (start < 0)
+    {
+        LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    varuint32 count;
+
+    if (varuint32_read(f, &count))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    for (varuint32 i = 0; i < count; i++)
+        if (check_table_type(f))
+        {
+            LOG("%s: check_table_type failed\n", __func__);
+            return -1;
+        }
+
+    const long end = ftell(f);
+
+    if (end < 0)
+    {
+        LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    const unsigned long size = end - start;
+
+    if (size != len)
+    {
+        LOG("%s: size exceeded (%lu expected, got %lu)\n",
+                __func__, len, size);
+        return -1;
+    }
+
+    return 0;
+}
+
+int section_table_check(const struct section *const s, struct nw_mod *const m,
+    const unsigned long len)
+{
+    FILE *const f = s->f;
+
+    if (m->sections.table)
+    {
+        LOG("%s: ignoring duplicate section\n", __func__);
+        return fseek(f, len, SEEK_CUR);
+    }
+
+    const long offset = ftell(f);
+
+    if (offset < 0)
+    {
+        LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (check(f, len))
+    {
+        LOG("%s: check failed\n", __func__);
+        return -1;
+    }
+
+    m->sections.table = offset;
+    return 0;
+}