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[PATCH 2/2] vvfat: Fix array_remove_slice()
From: |
Kevin Wolf |
Subject: |
[PATCH 2/2] vvfat: Fix array_remove_slice() |
Date: |
Tue, 23 Jun 2020 19:55:34 +0200 |
array_remove_slice() calls array_roll() with array->next - 1 as the
destination index. This is only correct for count == 1, otherwise we're
writing past the end of the array. array->next - count would be correct.
However, this is the only place ever calling array_roll(), so this
rather complicated operation isn't even necessary.
Fix the problem and simplify the code by replacing it with a single
memmove() call. array_roll() can now be removed.
Reported-by: Nathan Huckleberry <nhuck15@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/vvfat.c | 42 +++++-------------------------------------
1 file changed, 5 insertions(+), 37 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index 2fab371258..d6e464c595 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -140,48 +140,16 @@ static inline void* array_insert(array_t* array,unsigned
int index,unsigned int
return array->pointer+index*array->item_size;
}
-/* this performs a "roll", so that the element which was at index_from becomes
- * index_to, but the order of all other elements is preserved. */
-static inline int array_roll(array_t* array,int index_to,int index_from,int
count)
-{
- char* buf;
- char* from;
- char* to;
- int is;
-
- if(!array ||
- index_to<0 || index_to>=array->next ||
- index_from<0 || index_from>=array->next)
- return -1;
-
- if(index_to==index_from)
- return 0;
-
- is=array->item_size;
- from=array->pointer+index_from*is;
- to=array->pointer+index_to*is;
- buf=g_malloc(is*count);
- memcpy(buf,from,is*count);
-
- if(index_to<index_from)
- memmove(to+is*count,to,from-to);
- else
- memmove(from,from+is*count,to-from);
-
- memcpy(to,buf,is*count);
-
- g_free(buf);
-
- return 0;
-}
-
static inline int array_remove_slice(array_t* array,int index, int count)
{
assert(index >=0);
assert(count > 0);
assert(index + count <= array->next);
- if(array_roll(array,array->next-1,index,count))
- return -1;
+
+ memmove(array->pointer + index * array->item_size,
+ array->pointer + (index + count) * array->item_size,
+ (array->next - index - count) * array->item_size);
+
array->next -= count;
return 0;
}
--
2.25.4