[PATCH e2fsprogs 2/5] fsck: fix -C fd option parsing when fd is a separate argument

[Baokun Li <libaokun@linux.alibaba.com>]

The e2fsprogs fsck wrapper (misc/fsck.c, installed via make install)
supports the -C option for progress reporting. The fd can be passed
either attached (-C6) or separated (-C 6).

Currently the wrapper handles "-C6" correctly, but fails to handle
"-C 6" properly:

  # fsck -h | head -n1
  fsck 1.47.4 (6-Mar-2025)
  # fsck -C6 -N /dev/sda
  [/sbin/fsck.ext4 (1) -- /dev/sda] fsck.ext4 -C6 /dev/sda
  # fsck -C 6 -N /dev/sda
  [/sbin/fsck.ext4 (1) -- /dev/sda] fsck.ext4 6 -C0 /dev/sda

When "-C 6" is passed, it is parsed as "-C0" with "6" leaked as a
stray argument. This is because in PRS(), the separate-argument branch
uses argv[i] (which is "-C") instead of argv[i+1] (which is "6")
to parse the fd value. string_to_int("-C") returns -1, so progress_fd
stays at 0 and the "6" is never consumed. Later the wrapper generates
"-C0" from progress_fd=0 and the stray "6" is passed before the device.

Fix by using argv[i+1] to correctly parse the separate fd argument.

Note: this is the e2fsprogs fsck wrapper (misc/fsck.c), not the
util-linux fsck wrapper (disk-utils/fsck.c) which handles this
correctly.

Signed-off-by: Baokun Li <libaokun@linux.alibaba.com>
---
 misc/fsck.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/fsck.c b/misc/fsck.c
index cb935e1b4b71..318ecfcb4102 100644
--- a/misc/fsck.c
+++ b/misc/fsck.c
@@ -1188,7 +1188,7 @@ static void PRS(int argc, char *argv[])
 						goto next_arg;
 				} else if (argc > i + 1 &&
 					   argv[i + 1][0] != '-') {
-					progress_fd = string_to_int(argv[i]);
+					progress_fd = string_to_int(argv[i+1]);
 					if (progress_fd < 0)
 						progress_fd = 0;
 					else {
-- 
2.43.7