From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Maxim Suhanov <dfirblog@gmail.com>

Date: Tue, 3 Oct 2023 19:12:28 +0200

Subject: [PATCH] fs/ntfs: Make code more readable

Move some calls used to access NTFS attribute header fields into

functions with human-readable names.

Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>

Signed-off-by: Maxim Suhanov <dfirblog@gmail.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

 grub-core/fs/ntfs.c | 48 +++++++++++++++++++++++++++++++++---------------

 1 file changed, 33 insertions(+), 15 deletions(-)

diff --git a/grub-core/fs/ntfs.c b/grub-core/fs/ntfs.c

index 32ba8276dd8d..991b1c2094f5 100644

--- a/grub-core/fs/ntfs.c

+++ b/grub-core/fs/ntfs.c

@@ -52,6 +52,24 @@ u64at (void *ptr, grub_size_t ofs)

   return grub_le_to_cpu64 (grub_get_unaligned64 ((char *) ptr + ofs));

 }

+static grub_uint16_t

+first_attr_off (void *mft_buf_ptr)

+{

+  return u16at (mft_buf_ptr, 0x14);

+}

+

+static grub_uint16_t

+res_attr_data_off (void *res_attr_ptr)

+{

+  return u16at (res_attr_ptr, 0x14);

+}

+

+static grub_uint32_t

+res_attr_data_len (void *res_attr_ptr)

+{

+  return u32at (res_attr_ptr, 0x10);

+}

+

 grub_ntfscomp_func_t grub_ntfscomp_func;

 static grub_err_t

@@ -106,7 +124,7 @@ init_attr (struct grub_ntfs_attr *at, struct grub_ntfs_file *mft)

 {

   at->mft = mft;

   at->flags = (mft == &mft->data->mmft) ? GRUB_NTFS_AF_MMFT : 0;

-  at->attr_nxt = mft->buf + u16at (mft->buf, 0x14);

+  at->attr_nxt = mft->buf + first_attr_off (mft->buf);

   at->attr_end = at->emft_buf = at->edat_buf = at->sbuf = NULL;

 }

@@ -154,7 +172,7 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)

 		    return NULL;

 		}

-	      new_pos = &at->emft_buf[u16at (at->emft_buf, 0x14)];

+	      new_pos = &at->emft_buf[first_attr_off (at->emft_buf)];

 	      while (*new_pos != 0xFF)

 		{

 		  if ((*new_pos == *at->attr_cur)

@@ -213,7 +231,7 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)

 	}

       else

 	{

-	  at->attr_nxt = at->attr_end + u16at (pa, 0x14);

+	  at->attr_nxt = at->attr_end + res_attr_data_off (pa);

 	  at->attr_end = at->attr_end + u32at (pa, 4);

 	  pa_end = at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR);

 	}

@@ -399,20 +417,20 @@ read_data (struct grub_ntfs_attr *at, grub_uint8_t *pa, grub_uint8_t *dest,

   if (pa[8] == 0)

     {

-      if (ofs + len > u32at (pa, 0x10))

+      if (ofs + len > res_attr_data_len (pa))

 	return grub_error (GRUB_ERR_BAD_FS, "read out of range");

-      if (u32at (pa, 0x10) > (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR))

+      if (res_attr_data_len (pa) > (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR))

 	return grub_error (GRUB_ERR_BAD_FS, "resident attribute too large");

       if (pa >= at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR))

 	return grub_error (GRUB_ERR_BAD_FS, "resident attribute out of range");

-      if (u16at (pa, 0x14) + u32at (pa, 0x10) >

+      if (res_attr_data_off (pa) + res_attr_data_len (pa) >

 	  (grub_addr_t) at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR) - (grub_addr_t) pa)

 	return grub_error (GRUB_ERR_BAD_FS, "resident attribute out of range");

-      grub_memcpy (dest, pa + u16at (pa, 0x14) + ofs, len);

+      grub_memcpy (dest, pa + res_attr_data_off (pa) + ofs, len);

       return 0;

     }

@@ -556,7 +574,7 @@ init_file (struct grub_ntfs_file *mft, grub_uint64_t mftno)

 			   (unsigned long long) mftno);

       if (!pa[8])

-	mft->size = u32at (pa, 0x10);

+	mft->size = res_attr_data_len (pa);

       else

 	mft->size = u64at (pa, 0x30);

@@ -801,7 +819,7 @@ grub_ntfs_iterate_dir (grub_fshelp_node_t dir,

 	  (u32at (cur_pos, 0x18) != 0x490024) ||

 	  (u32at (cur_pos, 0x1C) != 0x300033))

 	continue;

-      cur_pos += u16at (cur_pos, 0x14);

+      cur_pos += res_attr_data_off (cur_pos);

       if (*cur_pos != 0x30)	/* Not filename index */

 	continue;

       break;

@@ -830,7 +848,7 @@ grub_ntfs_iterate_dir (grub_fshelp_node_t dir,

 	{

           int is_resident = (cur_pos[8] == 0);

-          bitmap_len = ((is_resident) ? u32at (cur_pos, 0x10) :

+          bitmap_len = ((is_resident) ? res_attr_data_len (cur_pos) :

                         u32at (cur_pos, 0x28));

           bmp = grub_malloc (bitmap_len);

@@ -851,14 +869,14 @@ grub_ntfs_iterate_dir (grub_fshelp_node_t dir,

 		  goto done;

 		}

-              if (u16at (cur_pos, 0x14) + u32at (cur_pos, 0x10) >

+              if (res_attr_data_off (cur_pos) + res_attr_data_len (cur_pos) >

 		  (grub_addr_t) at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR) - (grub_addr_t) cur_pos)

 		{

 		  grub_error (GRUB_ERR_BAD_FS, "resident bitmap out of range");

 		  goto done;

 		}

-              grub_memcpy (bmp, cur_pos + u16at (cur_pos, 0x14),

+              grub_memcpy (bmp, cur_pos + res_attr_data_off (cur_pos),

                            bitmap_len);

 	    }

           else

@@ -1222,12 +1240,12 @@ grub_ntfs_label (grub_device_t device, char **label)

       goto fail;

     }

-  if ((pa) && (pa[8] == 0) && (u32at (pa, 0x10)))

+  if ((pa) && (pa[8] == 0) && (res_attr_data_len (pa)))

     {

       int len;

-      len = u32at (pa, 0x10) / 2;

-      pa += u16at (pa, 0x14);

+      len = res_attr_data_len (pa) / 2;

+      pa += res_attr_data_off (pa);

       if (mft->buf + (mft->data->mft_size << GRUB_NTFS_BLK_SHR) - pa >= 2 * len)

         *label = get_utf8 (pa, len);

       else