First commit

1 files changed, 274 insertions, 0 deletions

diff --git a/src/section/import.c b/src/section/import.c
new file mode 100644
index 0000000..5dd708e
--- /dev/null
+++ b/src/section/import.c
@@ -0,0 +1,274 @@
+/*
+ * 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/sections.h>
+#include <nw/fstring.h>
+#include <nw/log.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+static int dump_import_name(FILE *const f, const varuint32 len)
+{
+    for (varuint32 i = 0; i < len; i++)
+    {
+        uint8_t byte;
+
+        if (!fread(&byte, sizeof byte, 1, f))
+        {
+            LOG("%s: fread(3) failed, feof=%d, ferror=%d\n",
+                __func__, feof(f), ferror(f));
+            return -1;
+        }
+
+        LOG("%c", (char)byte);
+    }
+
+    return 0;
+}
+
+static int check_module_string(const struct nw_mod_cfg *const cfg,
+    FILE *const f)
+{
+    varuint32 len;
+
+    if (varuint32_read(f, &len))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    for (size_t i = 0; i < cfg->n_imports; i++)
+    {
+        const struct nw_import *const im = &cfg->imports[i];
+        const char *const mod = im->module;
+
+        if (strlen(mod) == len)
+        {
+            const long offset = ftell(f);
+
+            if (offset < 0)
+            {
+                LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+            else if (!fstrcmp(mod, f, true))
+                return 0;
+            else if (fseek(f, offset, SEEK_SET))
+            {
+                LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+        }
+    }
+
+    LOG("%s: required imported module ", __func__);
+    dump_import_name(f, len);
+    LOG(" not found\n");
+    return -1;
+}
+
+static int check_field_string(const struct nw_mod_cfg *const cfg,
+    FILE *const f)
+{
+    varuint32 len;
+
+    if (varuint32_read(f, &len))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    for (size_t i = 0; i < cfg->n_imports; i++)
+    {
+        const struct nw_import *const im = &cfg->imports[i];
+        const char *const field = im->field;
+
+        if (strlen(field) == len)
+        {
+            const long offset = ftell(f);
+
+            if (offset < 0)
+            {
+                LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+            else if (!fstrcmp(field, f, true))
+                return 0;
+            else if (fseek(f, offset, SEEK_SET))
+            {
+                LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+        }
+    }
+
+    LOG("%s: required imported field ", __func__);
+    dump_import_name(f, len);
+    LOG(" not found\n");
+    return -1;
+}
+
+static int check_function_kind(FILE *const f)
+{
+    varuint32 type;
+
+    if (varuint32_read(f, &type))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_table_kind(FILE *const f)
+{
+    varint7 type;
+
+    if (varint7_read(f, &type))
+    {
+        LOG("%s: varint7_read failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_memory_kind(FILE *const f)
+{
+    /* TODO. */
+    return -1;
+}
+
+static int check_global_kind(FILE *const f)
+{
+    /* TODO. */
+    return -1;
+}
+
+static int check_import_entry(const struct nw_mod_cfg *const cfg,
+    FILE *const f)
+{
+    if (check_module_string(cfg, f))
+    {
+        LOG("%s: check_module_string failed\n", __func__);
+        return -1;
+    }
+    else if (check_field_string(cfg, f))
+    {
+        LOG("%s: check_field_string failed\n", __func__);
+        return -1;
+    }
+
+    uint8_t kind;
+
+    if (!fread(&kind, sizeof kind, 1, f))
+    {
+        LOG("%s: fread(3) failed, feof=%d, ferror=%d\n",
+            __func__, feof(f), ferror(f));
+        return -1;
+    }
+
+    static int (*const fn[])(FILE *) =
+    {
+        [NW_KIND_FUNCTION] = check_function_kind,
+        [NW_KIND_TABLE] = check_table_kind,
+        [NW_KIND_MEMORY] = check_memory_kind,
+        [NW_KIND_GLOBAL] = check_global_kind
+    };
+
+    if (kind >= sizeof fn / sizeof *fn)
+    {
+        LOG("%s: unexpected kind %#" PRIx8 "\n", __func__, kind);
+        return -1;
+    }
+
+    return fn[kind](f);
+}
+
+static int check(const struct nw_mod_cfg *const cfg, 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_import_entry(cfg, f))
+        {
+            LOG("%s: check_import_entry 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_import_check(const struct section *const s, struct nw_mod *m,
+    const unsigned long len)
+{
+    const struct nw_mod_cfg *const cfg = s->cfg;
+    FILE *const f = s->f;
+
+    if (m->sections.import)
+    {
+        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(cfg, f, len))
+    {
+        LOG("%s: check failed\n", __func__);
+        return -1;
+    }
+
+    m->sections.import = offset;
+    return 0;
+}