* grub-core/kern/efi/efi.c (grub_efi_get_filename): Avoid inefficient

[grub2.git] / grub-core / kern / efi / efi.c

diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index e8a62ec7b829611cd4a38e43075b571e31ed556e..8be9b01dbfdd87463dda591a630ef28f62c00a4d 100644 (file)
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -309,7 +309,34 @@ grub_efi_modules_addr (void)
 char *
 grub_efi_get_filename (grub_efi_device_path_t *dp)
 {
-  char *name = 0;
+  char *name = 0, *p;
+  grub_size_t filesize = 0;
+
+  while (1)
+    {
+      grub_efi_uint8_t type = GRUB_EFI_DEVICE_PATH_TYPE (dp);
+      grub_efi_uint8_t subtype = GRUB_EFI_DEVICE_PATH_SUBTYPE (dp);
+
+      if (type == GRUB_EFI_END_DEVICE_PATH_TYPE)
+       break;
+      if (type == GRUB_EFI_MEDIA_DEVICE_PATH_TYPE
+              && subtype == GRUB_EFI_FILE_PATH_DEVICE_PATH_SUBTYPE)
+       {
+         grub_efi_uint16_t len;
+         len = ((GRUB_EFI_DEVICE_PATH_LENGTH (dp) - 4)
+                / sizeof (grub_efi_char16_t));
+         filesize += GRUB_MAX_UTF8_PER_UTF16 * len + 1;
+       }
+
+      dp = GRUB_EFI_NEXT_DEVICE_PATH (dp);
+    }
+
+  if (!filesize)
+    return NULL;
+
+  p = name = grub_malloc (filesize);
+  if (!name)
+    return NULL;
 
   while (1)
     {
@@ -323,45 +350,25 @@ grub_efi_get_filename (grub_efi_device_path_t *dp)
        {
          grub_efi_file_path_device_path_t *fp;
          grub_efi_uint16_t len;
-         char *p;
-         grub_size_t size;
 
-         if (name)
-           {
-             size = grub_strlen (name);
-             name[size] = '/';
-             size++;
-           }
-         else
-           size = 0;
+         if (p != name)
+           *p++ = '/';
 
          len = ((GRUB_EFI_DEVICE_PATH_LENGTH (dp) - 4)
                 / sizeof (grub_efi_char16_t));
-         p = grub_realloc (name, size + len * 4 + 1);
-         if (! p)
-           {
-             grub_free (name);
-             return 0;
-           }
-
-         name = p;
          fp = (grub_efi_file_path_device_path_t *) dp;
-         *grub_utf16_to_utf8 ((grub_uint8_t *) name + size,
-                              fp->path_name, len) = '\0';
+         p = (char *) grub_utf16_to_utf8 ((unsigned char *) p, fp->path_name, len);
        }
 
       dp = GRUB_EFI_NEXT_DEVICE_PATH (dp);
     }
 
-  if (name)
-    {
-      /* EFI breaks paths with backslashes.  */
-      char *p;
+  *p = '\0';
 
-      for (p = name; *p; p++)
-       if (*p == '\\')
-         *p = '/';
-    }
+  /* EFI breaks paths with backslashes.  */
+  for (p = name; *p; p++)
+    if (*p == '\\')
+      *p = '/';
 
   return name;
 }