chmod: incorrect error messages and missing errors during recursive chmod on read-only filesystem

Component

chmod

Description

When running chmod -R on a read-only filesystem, uutils produces incorrect output compared to GNU coreutils. There are two differences:

1. uutils shows a raw OS error instead of a formatted message
2. Only one error is reported instead of one per file/directory

Steps to reproduce

# Create a read-only filesystem
dd if=/dev/zero of=/tmp/testfs.img bs=1M count=10
mkfs.ext4 /tmp/testfs.img
mkdir /tmp/testmount
sudo mount /tmp/testfs.img /tmp/testmount
sudo mkdir /tmp/testmount/testdir
sudo touch /tmp/testmount/testdir/file1.txt
sudo touch /tmp/testmount/testdir/file2.txt
sudo touch /tmp/testmount/testdir/file3.txt
sudo chmod 500 /tmp/testmount/testdir
sudo chmod 400 /tmp/testmount/testdir/file1.txt
sudo chmod 400 /tmp/testmount/testdir/file2.txt
sudo chmod 400 /tmp/testmount/testdir/file3.txt
sudo mount -o remount,ro /tmp/testfs.img /tmp/testmount
# Attempt to change permissions on mountpoint
sudo ./target/debug/coreutils chmod -R ugo+w /tmp/testmount/testdir/

uutils output

chmod: Read-only file system (os error 30)
chmod: cannot access '/tmp/testmount/testdir/file2.txt': Permission denied

Expected (GNU) output

chmod: changing permissions of '/tmp/testmount/testdir/': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/file1.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/dir1': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/dir1/file1.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/dir1/file3.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/dir1/file4.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/dir1/file2.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/file3.txt': Read-only file system
chmod: changing permissions of '/tmp/testmount/testdir/file2.txt': Read-only file system

Additional Information

coreutils version

coreutils 0.8.0 (multi-call binary)

chmod version

chmod (GNU coreutils) 9.11

Platform

Linux archlinux 7.0.3-arch1-2

Start by running the provided read-only filesystem reproduction and inspect the chmod implementation, especially recursive traversal and error reporting. Compare the results with the expected GNU output; done means formatted errors are reported for each affected file and directory.