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From: Maxim Suhanov <dfirblog@gmail.com>
Date: Mon, 28 Aug 2023 16:40:07 +0300
Subject: 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 ff5e374..de435aa 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);
@@ -805,7 +823,7 @@ 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;
@@ -834,7 +852,7 @@ 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);
@@ -855,14 +873,14 @@ 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
@@ -1226,12 +1244,12 @@ 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
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