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fincore: Handle large files correctly on 32 bit 

If a file is larger than 4 GB on a 32 bit system with large file
support (default), it can happen that not all pages are properly
processed. This happens due to an int truncation (off_t vs size_t).

You can reproduce this on 32 bit with these commands:

$ dd if=/dev/zero of=4gb-file seek=4294967295 count=1 bs=1
$ fincore 4gb-file
fincore: failed to do mmap: 4gb-file: Invalid argument

If a file is larger than 4 GB, the first few pages of a file won't
be properly processed. "len" will be smaller than window_size,
but the for-loop iterates "window_size" bytes, skipping some pages.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
This commit is contained in:
Tobias Stoeckmann 2018-02-25 20:27:18 +01:00 committed by Karel Zak
parent 2e20500a44
commit ea62c15276
1 changed files with 2 additions and 2 deletions
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4
misc-utils/fincore.c
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@ -199,11 +199,11 @@ static int fincore_fd (struct fincore_control *ctl,
int warned_once = 0;
for (file_offset = 0; file_offset < file_size; file_offset += window_size) {
size_t len;
off_t len;
void *window = NULL;
len = file_size - file_offset;
if (len >= window_size)
if (len >= (off_t) window_size)
len = window_size;
window = mmap(window, len, PROT_NONE, MAP_PRIVATE, fd, file_offset);