storageutil: move metadata parsing and packing from revlog (API)
Parsing and writing of revision text metadata is likely identical
across storage backends. Let's move the code out of revlog so we
don't need to import the revlog module in order to use it.
Differential Revision: https://phab.mercurial-scm.org/D4754
Test encode/decode filters
$ hg init
$ cat > .hg/hgrc <<EOF
> [encode]
> not.gz = tr [:lower:] [:upper:]
> *.gz = gzip -d
> [decode]
> not.gz = tr [:upper:] [:lower:]
> *.gz = gzip
> EOF
$ echo "this is a test" | gzip > a.gz
$ echo "this is a test" > not.gz
$ hg add *
$ hg ci -m "test"
no changes
$ hg status
$ touch *
no changes
$ hg status
check contents in repo are encoded
$ hg debugdata a.gz 0
this is a test
$ hg debugdata not.gz 0
THIS IS A TEST
check committed content was decoded
$ gunzip < a.gz
this is a test
$ cat not.gz
this is a test
$ rm *
$ hg co -C
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
check decoding of our new working dir copy
$ gunzip < a.gz
this is a test
$ cat not.gz
this is a test
check hg cat operation
$ hg cat a.gz
this is a test
$ hg cat --decode a.gz | gunzip
this is a test
$ mkdir subdir
$ cd subdir
$ hg -R .. cat ../a.gz
this is a test
$ hg -R .. cat --decode ../a.gz | gunzip
this is a test
$ cd ..
check tempfile filter
$ hg cat a.gz --decode --config 'decode.*.gz=tempfile:gzip -c INFILE > OUTFILE' | gunzip
this is a test
$ hg cat a.gz --decode --config 'decode.*.gz=tempfile:sh -c "exit 1"'
abort: command '*' failed: exited with status 1 (glob)
[255]
$ cd ..