tests/pdiff

lfs: explicitly add the Content-Length header when uploading blobs, for py3

This was the reason for test-lfs-test-server.t#git-server complaining about an
"invalid byte in chunk length".  For some reason if this isn't explicitly added,
py3.7.1 is adding `transfer-encoding: chunked` as well as `Content-length: x`.
Wireshark flagged this as malformed.  However, if this is set, it doesn't bother
with `transfer-encoding`.

Before this patch with py3:

  PUT /objects/31cf46fbc4ecd458a0943c5b4881f1f5a6dd36c53d6167d5b69ac45149b38e5b HTTP/1.1
  Accept-Encoding: identity
  Content-length: 12
  accept: application/vnd.git-lfs
  content-type: application/octet-stream
  host: localhost:20062
  transfer-encoding: chunked
  user-agent: git-lfs/2.3.4 (Mercurial 4.9rc0+149-7eb7637e34bf)

Before this patch with py27:

  PUT /objects/31cf46fbc4ecd458a0943c5b4881f1f5a6dd36c53d6167d5b69ac45149b38e5b HTTP/1.1
  Accept-Encoding: identity
  accept: application/vnd.git-lfs
  content-type: application/octet-stream
  content-length: 12
  host: localhost:20062
  user-agent: git-lfs/2.3.4 (Mercurial 4.9rc0+149-7eb7637e34bf+20190128)

With this patch and py3, the content is the same as the py27 example.  RFC2616
says to ignore `Content-Length` if `Transfer-Encoding` is present, so maybe
there's nothing to do in the hg-server side (though I'm not sure which it is
using if presented both).

Maybe chunked encoding is better to do?  If someone knows how to suppress the
`Content-Length`, we can try that instead.

#!/bin/sh

# Script to get stable diff output on any platform.
#
# Output of this script is almost equivalent to GNU diff with "-Nru".
#
# Use this script as "hg pdiff" via extdiff extension with preparation
# below in test scripts:
#
#   $ cat >> $HGRCPATH <<EOF
#   > [extdiff]
#   > pdiff = sh "$RUNTESTDIR/pdiff"
#   > EOF

filediff(){
    # USAGE: filediff file1 file2 [header]

    # compare with /dev/null if file doesn't exist (as "-N" option)
    file1="$1"
    if test ! -f "$file1"; then
        file1=/dev/null
    fi
    file2="$2"
    if test ! -f "$file2"; then
        file2=/dev/null
    fi

    if cmp -s "$file1" "$file2" 2> /dev/null; then
        # Return immediately, because comparison isn't needed. This
        # also avoids redundant message of diff like "No differences
        # encountered" (on Solaris)
        return
    fi

    if test -n "$3"; then
        # show header only in recursive case
        echo "$3"
    fi

    # replace "/dev/null" by corresponded filename (as "-N" option)
    diff -u "$file1" "$file2" |
    sed "s@^--- /dev/null\(.*\)\$@--- $1\1@" |
    sed "s@^\+\+\+ /dev/null\(.*\)\$@+++ $2\1@"

    # in this case, files differ from each other
    return 1
}

if test -d "$1" -o -d "$2"; then
    # ensure comparison in dictionary order
    (
    if test -d "$1"; then (cd "$1" && find . -type f); fi
    if test -d "$2"; then (cd "$2" && find . -type f); fi
    ) |
    sed 's@^\./@@g' | sort | uniq |
    while read file; do
        filediff "$1/$file" "$2/$file" "diff -Nru $1/$file $2/$file"
    done

    # TODO: there is no portable way for current while-read based
    # implementation to return 1 at detecting changes.
    #
    # On bash and dash, assignment to variable inside while-block
    # doesn't affect outside, because inside while-block is executed
    # in sub-shell. BTW, it affects outside while-block on ksh (as sh
    # on Solaris).
else
    filediff "$1" "$2"
fi