[PATCH 2/2] fincore: Handle large files on 32 bit without LFS

[PATCH 2/2] fincore: Handle large files on 32 bit without LFS

[Tobias Stoeckmann]

If util-linux is installed on a system without large file support,
an out of memory issue can occur while processing a file which is
2 GB in size:

$ ./configure --disable-largefile && make

$ dd if=/dev/zero of=2gb-file seek=2147483646 count=1 bs=1
$ fincore 2gb-file
(endless loop)
fincore: failed to do mmap: 2gb-file: Cannot allocate memory

Even though iterating with "len" seems counter-intuitive, it fixes
this issue. The variable len is only in the last iteration not a
multiplication of pagesize -- which is the requirement for mmap.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
---
 misc-utils/fincore.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/misc-utils/fincore.c b/misc-utils/fincore.c
index ab11594cc..f9534e85b 100644
--- a/misc-utils/fincore.c
+++ b/misc-utils/fincore.c
@@ -194,12 +194,11 @@ static int fincore_fd (struct fincore_control *ctl,
 		       off_t *count_incore)
 {
 	size_t window_size = N_PAGES_IN_WINDOW * ctl->pagesize;
-	off_t file_offset;
+	off_t file_offset, len;
 	int rc = 0;
 	int warned_once = 0;
 
-	for (file_offset = 0; file_offset < file_size; file_offset += window_size) {
-		off_t len;
+	for (file_offset = 0; file_offset < file_size; file_offset += len) {
 		void  *window = NULL;
 
 		len = file_size - file_offset;
-- 
2.16.2

Re: [PATCH 2/2] fincore: Handle large files on 32 bit without LFS

[Karel Zak]

On Sun, Feb 25, 2018 at 08:27:59PM +0100, Tobias Stoeckmann wrote:
>  misc-utils/fincore.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)

Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com