fincore: Handle large files on 32 bit without LFS

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>

diff --git a/misc-utils/fincore.c b/misc-utils/fincore.c
index ab11594cc77644025b05dc9c06c46386fcb7d85d..f9534e85be282b960a4b8b617a3ccf4870310cb6 100644 (file)
--- 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;