First commitfirst-step

1 files changed, 235 insertions, 0 deletions

diff --git a/src/section/code.c b/src/section/code.c
new file mode 100644
index 0000000..6e131e7
--- /dev/null
+++ b/src/section/code.c
@@ -0,0 +1,235 @@
+#include <opcodes.h>
+#include <interp.h>
+#include <sections.h>
+#include <wasm_types.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <string.h>
+
+static int check_body(FILE *const f, const unsigned long n)
+{
+    unsigned long rem = n;
+
+    while (rem)
+    {
+        const long before = ftell(f);
+        uint8_t byte;
+
+        if (before < 0)
+        {
+            fprintf(stderr, "%s: ftell(3) before: %s\n", __func__,
+                strerror(errno));
+            return -1;
+        }
+        else if (!fread(&byte, sizeof byte, 1, f))
+        {
+            fprintf(stderr, "%s: fread(3) failed, feof=%d, ferror=%d\n",
+                __func__, feof(f), ferror(f));
+            return -1;
+        }
+        else if (rem == 1 && byte != OP_END)
+        {
+            fprintf(stderr, "%s: unexpected opcode %#" PRIx8 " at body end\n",
+                __func__, byte);
+            return -1;
+        }
+        else if (interp_check_opcode(byte, f))
+        {
+            fprintf(stderr, "%s: interp_check_opcode failed\n", __func__);
+            return -1;
+        }
+
+        const long after = ftell(f);
+
+        if (after < 0)
+        {
+            fprintf(stderr, "%s: ftell(3) after: %s\n", __func__,
+                strerror(errno));
+            return -1;
+        }
+
+        rem -= after - before;
+    }
+
+    return 0;
+}
+
+static int check_type(FILE *const f)
+{
+    varint7 type;
+
+    if (varint7_read(f, &type))
+    {
+        fprintf(stderr, "%s: varint7_read failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_local(FILE *const f)
+{
+    varuint32 count;
+
+    if (varuint32_read(f, &count))
+    {
+        fprintf(stderr, "%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+    else if (check_type(f))
+    {
+        fprintf(stderr, "%s: check_type failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_locals(FILE *const f)
+{
+    varuint32 local_count;
+
+    if (varuint32_read(f, &local_count))
+    {
+        fprintf(stderr, "%s: varuint32_read local_count failed\n", __func__);
+        return -1;
+    }
+
+    for (varuint32 i = 0; i < local_count; i++)
+        if (check_local(f))
+        {
+            fprintf(stderr, "%s: check_local failed\n", __func__);
+            return -1;
+        }
+
+    return 0;
+}
+
+static int check_function_body(FILE *const f)
+{
+    varuint32 body_size;
+
+    if (varuint32_read(f, &body_size))
+    {
+        fprintf(stderr, "%s: varuint32_read body_size failed\n", __func__);
+        return -1;
+    }
+
+    const long start = ftell(f);
+
+    if (start < 0)
+    {
+        fprintf(stderr, "%s: ftell(3) start: %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (check_locals(f))
+    {
+        fprintf(stderr, "%s: check_locals failed\n", __func__);
+        return -1;
+    }
+
+    const long end = ftell(f);
+
+    if (end < 0)
+    {
+        fprintf(stderr, "%s: ftell(3) end: %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    const unsigned long consumed = end - start;
+
+    if (consumed > body_size)
+    {
+        fprintf(stderr, "%s: exceeded function body size\n", __func__);
+        return -1;
+    }
+    else if (check_body(f, body_size - consumed))
+    {
+        fprintf(stderr, "%s: check_body failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_function_bodies(FILE *const f)
+{
+    varuint32 count;
+
+    if (varuint32_read(f, &count))
+    {
+        fprintf(stderr, "%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    for (varuint32 i = 0; i < count; i++)
+        if (check_function_body(f))
+        {
+            fprintf(stderr, "%s: check_function_body failed\n", __func__);
+            return -1;
+        }
+
+    return 0;
+}
+
+static int check(FILE *const f, const unsigned long len)
+{
+    const long start = ftell(f);
+
+    if (start < 0)
+    {
+        fprintf(stderr, "%s: ftell(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (check_function_bodies(f))
+    {
+        fprintf(stderr, "%s: check_function_bodies failed\n", __func__);
+        return -1;
+    }
+
+    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;
+    }
+
+    return 0;
+}
+
+int section_code(struct wasmfs *const w, FILE *const f,
+    const unsigned long len)
+{
+    if (w->sections.code)
+    {
+        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.code = offset;
+    return 0;
+}