First commitfirst-step

1 files changed, 204 insertions, 0 deletions

diff --git a/src/load.c b/src/load.c
new file mode 100644
index 0000000..3ae3bae
--- /dev/null
+++ b/src/load.c
@@ -0,0 +1,204 @@
+#include <wasmfs.h>
+#include <sections.h>
+#include <wasm_types.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int failed_read(FILE *const f)
+{
+    return fprintf(stderr, "%s: fread(3) failed, feof=%d, ferror=%d\n",
+            __func__, feof(f), ferror(f));
+}
+
+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))
+    {
+        failed_read(f);
+        return -1;
+    }
+    else if (memcmp(magic, m, sizeof magic))
+    {
+        fprintf(stderr, "%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))
+    {
+        failed_read(f);
+        return -1;
+    }
+    else if (memcmp(version, v, sizeof version))
+    {
+        fprintf(stderr, "%s: wrong version\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int load_section(struct wasmfs *const w, FILE *const f)
+{
+    enum
+    {
+        CUSTOM,
+        TYPE,
+        IMPORT,
+        FUNCTION,
+        TABLE,
+        MEMORY,
+        GLOBAL,
+        EXPORT,
+        START,
+        ELEMENT,
+        CODE,
+        DATA
+    };
+
+    static int (*const fn[])(struct wasmfs *, FILE *, unsigned long) =
+    {
+        [CUSTOM] = section_custom,
+        [TYPE] = section_type,
+        [IMPORT] = section_import,
+        [FUNCTION] = section_function,
+        [TABLE] = section_table,
+        [MEMORY] = section_memory,
+        [GLOBAL] = section_global,
+        [EXPORT] = section_export,
+        [START] = section_start,
+        [ELEMENT] = section_element,
+        [CODE] = section_code,
+        [DATA] = section_data
+    };
+
+    varuint7 section;
+    varuint32 len;
+    int ret;
+
+    if (varuint7_read(f, &section))
+    {
+        if (feof(f))
+            return 0;
+
+        fprintf(stderr, "%s: varuint7_read failed\n", __func__);
+        return 1;
+    }
+    else if (section >= sizeof fn / sizeof *fn)
+    {
+        fprintf(stderr, "%s: invalid section %u\n", __func__,
+            (unsigned)section);
+        return 1;
+    }
+    else if (varuint32_read(f, &len))
+    {
+        fprintf(stderr, "%s: varuint32_read failed\n", __func__);
+        return 1;
+    }
+    else if ((ret = fn[section](w, f, len)))
+        fprintf(stderr, "%s: failed to load section %u\n", __func__,
+            (unsigned)section);
+
+    return ret;
+}
+
+static int load_sections(struct wasmfs *const w, FILE *const f)
+{
+    while (!feof(f))
+        if (load_section(w, f))
+        {
+            fprintf(stderr, "%s: load_section failed\n", __func__);
+            return -1;
+        }
+
+    return 0;
+}
+
+static int load(struct wasmfs *const w, FILE *const f)
+{
+    if (check_magic(f))
+    {
+        fprintf(stderr, "%s: load_magic failed\n", __func__);
+        return -1;
+    }
+    else if (check_version(f))
+    {
+        fprintf(stderr, "%s: check_version failed\n", __func__);
+        return -1;
+    }
+    else if (load_sections(w, f))
+    {
+        fprintf(stderr, "%s: load_sections failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+struct wasmfs *wasmfs_load(const char *const path)
+{
+    struct wasmfs *ret = NULL, *w = NULL;
+    char *pathdup = NULL;
+    FILE *const f = fopen(path, "rb");
+    const size_t sz = strlen(path) + 1;
+
+    if (!f)
+    {
+        fprintf(stderr, "%s: fopen(3) %s: %s\n", __func__, path,
+            strerror(errno));
+        goto end;
+    }
+    else if (!(w = malloc(sizeof *w)))
+    {
+        fprintf(stderr, "%s: malloc(3) w: %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!(pathdup = malloc(sz)))
+    {
+        fprintf(stderr, "%s: malloc(3) pathdup: %s\n", __func__,
+            strerror(errno));
+        goto end;
+    }
+
+    memcpy(pathdup, path, sz);
+
+    *w = (const struct wasmfs)
+    {
+        .path = pathdup
+    };
+
+    if (load(w, f))
+    {
+        fprintf(stderr, "%s: load failed\n", __func__);
+        goto end;
+    }
+
+    ret = w;
+
+end:
+    if (f && fclose(f))
+    {
+        fprintf(stderr, "%s: fclose(3) %s: %s\n", __func__, path,
+            strerror(errno));
+        ret = NULL;
+    }
+
+    if (!ret)
+        wasmfs_unload(w);
+
+    return ret;
+}