| 1 | #!/bin/sh
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| 2 | #
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| 3 | # Update an single file (content via stdin) on the flash disk if the md5 does
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| 4 | # not match. This script tries to be on the safe side by checking md5 at
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| 5 | # various stages.
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| 6 | #
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| 7 | # TODO: Maybe rsync is also able to perform the mount and umount before and
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| 8 | # after, this will eliminate all the hacking with md5 checks.
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| 9 | #
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| 10 | # Rick van der Zwet <info@rickvanderzwet.nl>
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| 11 | #
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| 12 |
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| 13 | if [ -z "$1" ]; then
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| 14 | echo "Usage: $0 <filepath> [<md5sum> [<file mode bits> [<file ownership>]]]" 1>&2
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| 15 | exit 128
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| 16 | fi
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| 17 |
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| 18 | FILE=$1
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| 19 | NEW_MD5=${2:-""}
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| 20 | MODE_BITS=${3:-""}
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| 21 | OWNERSHIP=${4:-""}
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| 22 |
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| 23 | if [ ! -f "$FILE" ]; then
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| 24 | echo "# ERROR: File $FILE does not exists" 1>&2
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| 25 | exit 1
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| 26 | fi
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| 27 |
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| 28 | # First try to transfer file to local system
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| 29 | # this restricts the filesize to the maximum size of the /tmp system
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| 30 | TMPFILE=`mktemp -t $(basename $0)` || exit 1
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| 31 | cat > $TMPFILE || exit 1
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| 32 | TMP_MD5="`md5 -q $TMPFILE`" || exit 1
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| 33 |
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| 34 | # Check which md5 to use, the given one or the calculated one
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| 35 | if [ -n "$NEW_MD5" ]; then
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| 36 | TARGET_MD5="$NEW_MD5"
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| 37 | if [ "$TMP_MD5" != "$TARGET_MD5" ]; then
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| 38 | echo "# ERROR: File transfer failed" 1>&2
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| 39 | exit 2
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| 40 | fi
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| 41 | else
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| 42 | TARGET_MD5="$TMP_MD5"
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| 43 | fi
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| 44 |
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| 45 | # Actually check whether we need to copy the file
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| 46 | CURRENT_MD5=`md5 -q $FILE` || exit 1
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| 47 | if [ "$CURRENT_MD5" != "$TARGET_MD5" ]; then
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| 48 | echo "# INFO: Updating $FILE; old MD5 $CURRENT_MD5"
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| 49 | mount -uwo noatime / || exit 1
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| 50 | cp -f $TMPFILE $FILE
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| 51 | [ -n "$MODE_BITS" ] && chmod $MODE_BITS $FILE
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| 52 | [ -n "$OWNERSHIP" ] && chown $OWNERSHIP $FILE
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| 53 | mount -ur /
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| 54 |
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| 55 | # Make sure to recheck the md5 alter write to make sure all went ok
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| 56 | RECHECK_MD5=`md5 -q $FILE`
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| 57 | echo "# INFO: Updated $FILE; new MD5 $RECHECK_MD5"
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| 58 | else
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| 59 | echo "# INFO: File $FILE already has md5 $CURRENT_MD5"
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| 60 | fi
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