1 files changed, 110 insertions, 0 deletions
diff --git a/src/section/global.c b/src/section/global.c
new file mode 100644
index 0000000..5616e21
--- /dev/null
+++ b/src/section/global.c
@@ -0,0 +1,110 @@
+#include <sections.h>
+#include <interp.h>
+#include <wasm_types.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+struct global_type
+{
+    varint7 value_type;
+    varuint1 mutability;
+};
+
+static int check_global_type(FILE *const f, struct global_type *const g)
+{
+    if (varint7_read(f, &g->value_type))
+    {
+        fprintf(stderr, "%s: varint7_read failed\n", __func__);
+        return -1;
+    }
+    else if (varuint1_read(f, &g->mutability))
+    {
+        fprintf(stderr, "%s: varuint1_read failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check(FILE *const f, const unsigned long len)
+{
+    int ret = -1;
+    struct global_type g;
+    struct interp *i = NULL;
+    const long start = ftell(f);
+    const struct interp_cfg cfg =
+    {
+        .f = f
+    };
+
+    if (start < 0)
+    {
+        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (check_global_type(f, &g))
+    {
+        fprintf(stderr, "%s: check_global_type\n", __func__);
+        goto end;
+    }
+    else if (!(i = interp_alloc(&cfg)))
+    {
+        fprintf(stderr, "%s: interp_alloc failed\n", __func__);
+        goto end;
+    }
+    else if (interp_run_limited(i, &interp_initexpr_set))
+    {
+        fprintf(stderr, "%s: interp_run failed\n", __func__);
+        goto end;
+    }
+
+    const long end = ftell(f);
+
+    if (end < 0)
+    {
+        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    const unsigned long size = end - start;
+
+    if (size != len)
+    {
+        fprintf(stderr, "%s: size exceeded (%lu expected, got %lu)\n",
+                __func__, len, size);
+        return -1;
+    }
+
+    ret = 0;
+
+end:
+    interp_free(i);
+    return ret;
+}
+
+int section_global(struct wasmfs *const w, FILE *const f,
+    const unsigned long len)
+{
+    if (w->sections.global)
+    {
+        fprintf(stderr, "%s: ignoring duplicate section\n", __func__);
+        return 0;
+    }
+
+    const long offset = ftell(f);
+
+    if (offset < 0)
+    {
+        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (check(f, len))
+    {
+        fprintf(stderr, "%s: check failed\n", __func__);
+        return -1;
+    }
+
+    w->sections.global = offset;
+    return 0;
+}