# e2fsprogs part 2 -- e2fsck checks a volume, debugfs reads and writes its
# contents, and e2fsck rebuilds the primary superblock after it is destroyed.
. "$BST_LIB"
require e2fsck e2fsprogs-fsck/present

T=${TMPDIR:-/tmp}/bst-e2fsck.$$
mkdir -p "$T" || exit 0
trap 'rm -rf "$T"' EXIT
IMG=$T/fs.img

sb()  { dumpe2fs -h "$IMG" 2>/dev/null | sed -n "s/^$1: *//p"; }
msg() { _i=$1; _n=$2; shift 2; _o=$("$@" 2>&1)
        case "$_o" in *"$_n"*) bst_ok "$_i" ;;
                      *) bst_notok "$_i" "want:'$_n' got:'$(_bst_1line "$_o")'" ;; esac; }

# 12288 blocks of 1024 is the smallest geometry that still puts a backup
# superblock on disk (blocks_per_group is 8192, so group 1 starts at 8192 and
# carries its copy at 8193) -- the recovery case at the end needs one to exist.
dd if=/dev/zero of="$IMG" bs=1024 count=12288 2>/dev/null
check    e2fsprogs-fsck/mke2fs   mke2fs -q -F -t ext4 -b 1024 "$IMG"
check_rc e2fsprogs-fsck/clean  0 e2fsck -f -n "$IMG"
msg      e2fsprogs-fsck/pass5    "Pass 5" e2fsck -f -n "$IMG"

# ------------------------------------------------------ debugfs reads + writes
# This is the ext2fs library doing structural work rather than reading a header:
# allocating an inode and a block, linking a directory entry, then finding it
# again on a second open.
printf 'brintos-e2fsprogs-payload\n' > "$T/payload.txt"
msg   e2fsprogs-fsck/debugfs-lost-found "lost+found" debugfs -R "ls /" "$IMG"
check e2fsprogs-fsck/debugfs-write      debugfs -w -R "write $T/payload.txt payload" "$IMG"
msg   e2fsprogs-fsck/debugfs-ls         "payload" debugfs -R "ls /" "$IMG"
msg   e2fsprogs-fsck/debugfs-cat        "brintos-e2fsprogs-payload" debugfs -R "cat payload" "$IMG"
msg   e2fsprogs-fsck/debugfs-stats      "Filesystem magic number:  0xEF53" debugfs -R "stats -h" "$IMG"
# a write debugfs made must leave the filesystem consistent, not merely readable
check_rc e2fsprogs-fsck/clean-after-write 0 e2fsck -f -n "$IMG"

# ------------------------------------------- destroy the superblock and rebuild
BS=$(sb 'Block size')
BACKUP=$(dumpe2fs "$IMG" 2>/dev/null | sed -n 's/.*Backup superblock at \([0-9][0-9]*\).*/\1/p' | head -1)
case "$BACKUP" in
  ''|*[!0-9]*) bst_notok e2fsprogs-fsck/backup-sb "dumpe2fs reported no backup superblock: '$BACKUP'" ;;
  *)           bst_ok    e2fsprogs-fsck/backup-sb ;;
esac
dd if=/dev/zero of="$IMG" bs=1024 seek=1 count=1 conv=notrunc 2>/dev/null
# e2fsck signals through its exit status, and the failure that matters here is the
# silent one -- calling a filesystem with no superblock clean. Assert non-zero
# rather than a particular code, which varies with what it manages to salvage.
e2fsck -f -n "$IMG" >/dev/null 2>&1; rc=$?
if [ "$rc" -ne 0 ]; then bst_ok e2fsprogs-fsck/detects-wiped-sb
else bst_notok e2fsprogs-fsck/detects-wiped-sb "e2fsck called a filesystem with a zeroed primary superblock clean"; fi
msg e2fsprogs-fsck/wiped-sb-message "Superblock invalid" e2fsck -f -n "$IMG"
e2fsck -f -y -b "$BACKUP" -B "$BS" "$IMG" >/dev/null 2>&1
check_rc e2fsprogs-fsck/repaired 0 e2fsck -f -n "$IMG"
# the repair has to have restored the CONTENT, not just a mountable header
msg e2fsprogs-fsck/repaired-payload "brintos-e2fsprogs-payload" debugfs -R "cat payload" "$IMG"