First commit

1 files changed, 178 insertions, 0 deletions

diff --git a/src/load.c b/src/load.c
new file mode 100644
index 0000000..2ba0fcc
--- /dev/null
+++ b/src/load.c
@@ -0,0 +1,178 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/sections.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int check_magic(FILE *const f)
+{
+    static const uint8_t m[] = {'\0', 'a', 's', 'm'};
+    uint8_t magic[sizeof m];
+
+    if (!fread(magic, sizeof magic, 1, f))
+    {
+        LOG("%s: fread(3) failed, feof=%d, ferror=%d\n",
+            __func__, feof(f), ferror(f));
+        return -1;
+    }
+    else if (memcmp(magic, m, sizeof magic))
+    {
+        LOG("%s: wrong magic bytes\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int check_version(FILE *const f)
+{
+    static const uint8_t v[] = {1, 0, 0, 0};
+    uint8_t version[sizeof v];
+
+    if (!fread(version, sizeof version, 1, f))
+    {
+        LOG("%s: fread(3) failed, feof=%d, ferror=%d\n", __func__, feof(f),
+            ferror(f));
+        return -1;
+    }
+    else if (memcmp(version, v, sizeof version))
+    {
+        LOG("%s: wrong version\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int load_section(const struct nw_mod_cfg *const cfg,
+    struct nw_mod *const m, FILE *const f)
+{
+    static int (*const fn[])(const struct section *, struct nw_mod *,
+        unsigned long) =
+    {
+        section_custom_check,
+        section_type_check,
+        section_import_check,
+        section_function_check,
+        section_table_check,
+        section_memory_check,
+        section_global_check,
+        section_export_check,
+        section_start_check,
+        section_element_check,
+        section_code_check,
+        section_data_check
+    };
+
+    const struct section s =
+    {
+        .cfg = cfg,
+        .f = f
+    };
+
+    varuint7 section;
+    varuint32 len;
+    int ret;
+
+    if (varuint7_read(f, &section))
+    {
+        if (feof(f))
+            return 0;
+
+        LOG("%s: varuint7_read failed\n", __func__);
+        return 1;
+    }
+    else if (section >= sizeof fn / sizeof *fn)
+    {
+        LOG("%s: invalid section %u\n", __func__, (unsigned)section);
+        return 1;
+    }
+    else if (varuint32_read(f, &len))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return 1;
+    }
+    else if ((ret = fn[section](&s, m, len)))
+        LOG("%s: failed to load section %u\n", __func__, (unsigned)section);
+
+    return ret;
+}
+
+static int load_sections(const struct nw_mod_cfg *const cfg,
+    struct nw_mod *const m, FILE *const f)
+{
+    while (!feof(f))
+        if (load_section(cfg, m, f))
+        {
+            LOG("%s: load_section failed\n", __func__);
+            return -1;
+        }
+
+    return 0;
+}
+
+static int load(const struct nw_mod_cfg *const cfg, struct nw_mod *const m,
+    FILE *const f)
+{
+    if (check_magic(f))
+    {
+        LOG("%s: load_magic failed\n", __func__);
+        return -1;
+    }
+    else if (check_version(f))
+    {
+        LOG("%s: check_version failed\n", __func__);
+        return -1;
+    }
+    else if (load_sections(cfg, m, f))
+    {
+        LOG("%s: load_sections failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int nw_load(const struct nw_mod_cfg *const cfg, struct nw_mod *const m)
+{
+    int ret = -1;
+    FILE *const f = fopen(cfg->path, "rb");
+
+    *m = (const struct nw_mod){.cfg = *cfg};
+
+    if (!f)
+    {
+        LOG("%s: fopen(3) %s: %s\n", __func__, cfg->path, strerror(errno));
+        goto end;
+    }
+    else if (load(cfg, m, f))
+    {
+        LOG("%s: load failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    if (f && fclose(f))
+    {
+        LOG("%s: fclose(3) %s: %s\n", __func__, cfg->path, strerror(errno));
+        ret = -1;
+    }
+
+    return ret;
+}