wip: working on extern in VM

- Feat: add writer externs writing fns
- Feat: add VM reader functions

src/vm/fzl_vm_reader.c

@@ -0,0 +1,147 @@
+#include <common/fzl_extern.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <vm/fzl_vm_reader.h>
+#include <vm/internals/reader.h>
+
+char reader_err[256];
+
+fzl_vm_reader_t *fzl_vm_mkreader(char *filepath)
+{
+  if (!filepath)
+  {
+    snprintf(reader_err, sizeof(reader_err),
+             "init error - filepath is not defined");
+    return NULL;
+  }
+
+  fzl_vm_reader_t *reader = malloc(sizeof(fzl_vm_reader_t));
+  if (!reader)
+  {
+    snprintf(reader_err, sizeof(reader_err),
+             "init error - couldn't allocate memory for reader");
+    return NULL;
+  }
+
+  memset(reader, 0, sizeof(fzl_vm_reader_t));
+  reader->filepath = filepath;
+
+  return reader;
+}
+
+void wr_validation_err(char *section)
+{
+  snprintf(reader_err, sizeof(reader_err),
+           "init error - section '%s' is not valid", section);
+}
+
+bool fzl_vm_read(fzl_vm_reader_t *reader)
+{
+  if (!reader)
+  {
+    snprintf(reader_err, sizeof(reader_err),
+             "init error - reader is not provided");
+    return false;
+  }
+
+  FILE *fd = fopen(reader->filepath, "rb");
+  if (!fd)
+  {
+    snprintf(reader_err, sizeof(reader_err),
+             "init error - couldn't open file '%s'", reader->filepath);
+    return false;
+  }
+
+  bool result = vm_rd_header(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("header");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_sections_sz(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("sizes");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_consts(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("constants table");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_extern_libs(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("extern libs");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_extern_types(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("extern types");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_extern_fns(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("extern functions");
+    fclose(fd);
+    return false;
+  }
+
+  result = vm_rd_ops(reader, fd);
+  if (!result)
+  {
+    wr_validation_err("opcodes");
+    fclose(fd);
+    return false;
+  }
+
+  return true;
+}
+
+char *fzl_vm_getreadererror() { return reader_err; }
+
+void fzl_vm_freereader(fzl_vm_reader_t *reader)
+{
+  if (!reader)
+    return;
+
+  if (reader->consts)
+  {
+    for (uint16_t i = 0; i < reader->consts_count; i++)
+      if (reader->consts[i].as.s.value)
+        free((void *)reader->consts[i].as.s.value);
+
+    free(reader->consts);
+  }
+
+  if (reader->extern_libs)
+    free(reader->extern_libs);
+
+  if (reader->extern_types)
+    free(reader->extern_types);
+
+  if (reader->extern_fns)
+    free(reader->extern_fns);
+
+  if (reader->ops)
+    free(reader->ops);
+
+  free(reader);
+}