__open_relation

#!/bin/bash
#
# This script contains code that is common to all convenience scripts.
#
# Utility scripts mostly consist of some logic for exporting wxHexEditor-format
# offset cache entries to the OFFSETS environment variable, and/or logic for
# printing something to stdout that's useful to the user.  Everything else
# happens here.
#
# Most convenience scripts set the $OFFSETS env var to something useful for us.
# Utility scripts must have run "source ./hexedit.cfg" for us.

relname=$1

# Spoof home director, to avoid clobbering real /.wxHexEditor file
HOME=$(pwd)
wxconfig="$HOME/.wxHexEditor"

if ! psql --no-psqlrc -c "CHECKPOINT"
then
  echo "CHECKPOINT failed"
  exit 1
fi

if ! RFN=$(psql --no-psqlrc -tA -c "SELECT pg_relation_filepath('$relname')")
then
  echo "invoking pg_relation_filepath() failed"
  exit 1
fi

if [ "$RFN" = "" ]
then
  echo "relation $relname has no associated relfile"
  exit 1
fi

# Put minimal .wxHexEditor registry style config file in place, so old tags are
# forgotten.  This is also where we generate convenience "Go to Offset" dialog
# offsets in the registry/cache (this comes from OFFSETS env var).
echo "Replacing $wxconfig with pg_hexedit optimized settings..."
cat > "$wxconfig" <<- EOM
UpdateCheck=0
FakeBlockLines=1
FakeBlockSize=8k
ColourHexBackground=#FFFFFF
ColourHexBackgroundZebra=#FFFFFF
UseBytesPerLineLimit=1
BytesPerLineLimit=$BYTES_PER_LINE_LIMIT
FontSize=$FONTSIZE
CharacterEncodingFamily=Code for Information Interchange
CharacterEncoding=ASCII - American Standard Code for Information Interchange
ScreenFullScreen=1
AutoShowTagPanel=0
GoToOptions=7
$OFFSETS
EOM

PGDATA=$(psql --no-psqlrc -tA -c "SELECT setting FROM pg_settings WHERE name = 'data_directory'")
echo "Determined that data directory is $PGDATA"

# wxHexEditor XML encoding is always UTF-8.  Make sure that attname fields come
# back as UTF-8.
export PGCLIENTENCODING="UTF8"
if ! ATTRLIST=$(psql --no-psqlrc -tA -c "SELECT string_agg(attlen || ',\"' || attname  || '\",' || attalign::text, ',')
FROM
(SELECT * FROM pg_attribute WHERE attrelid = '$relname'::regclass AND attnum > 0 ORDER BY attnum ASC) t;")
then
  echo "failed to generate attrlist string for -D option"
  exit 1
fi

# Check if data file exists locally, download $MAX_BLOCK_TAGS to /tmp if it doesn't
FULLPATH="$PGDATA/$RFN"
if [ -f "$FULLPATH" ]; then
  echo "Running pg_hexedit against $FULLPATH, the first segment in relation $relname..."
  echo "Note: Only blocks $MIN_BLOCK_TAGS - $MAX_BLOCK_TAGS will be annotated, to keep overhead low."
else
  PAGEINSPECT_INSTALLED=$(psql -XAtc "select count(*) from pg_extension where extname='pageinspect'")
  if (( PAGEINSPECT_INSTALLED && MIN_BLOCK_TAGS == 0 )); then
    TMPDIR="/tmp/postgresql-relfiles/$PGHOST-$PGPORT-DB/$(dirname "$RFN")"
    mkdir -p "$TMPDIR"
    FULLPATH="$TMPDIR/$(basename "$RFN")"
    echo "Downloading blocks from $MIN_BLOCK_TAGS to $MAX_BLOCK_TAGS inclusive from relation $relname to $FULLPATH..."
    psql -XAtc "SELECT encode(get_raw_page('$relname', block::int4),'base64')
                FROM generate_series(0, least(pg_relation_size('$relname') / 8192 - 1, $MAX_BLOCK_TAGS))
                block" | base64 -d > "$FULLPATH"
    echo "Opening local temp file..."
  else
    echo "File $FULLPATH doesn't exist."
    if (( MIN_BLOCK_TAGS == 0 )); then
      echo "Tip: Install pageinspect to automatically download remote files."
    else
      echo "Note: Cannot automatically download remote files when MIN_BLOCK_TAGS is non-zero."
    fi
    exit 1
  fi
fi

# Deliberately put space before pg_hexedit frontend debug output here:
echo -e "pg_hexedit frontend utility debug/notice output:\n"

# Generate tags at a path that we know wxHexEditor will look for them:
# shellcheck disable=SC2086
if ! ./pg_hexedit $EXTRAFLAGS -D "$ATTRLIST" -z -R "$MIN_BLOCK_TAGS" "$MAX_BLOCK_TAGS" "$FULLPATH" > "$FULLPATH.tags"
then
  echo "Error encountered by pg_hexedit. Could not generate all tags."
  echo "You may still wish to run: $HEXEDITOR $FULLPATH"
  exit 1
fi

if [ ! -f "$HEXEDITOR" ]
then
  echo "\"$HEXEDITOR\" executable not found"
  echo "\"$FULLPATH.tags\" annotation file was still created"
  exit 1
fi

# Deliberately put space after pg_hexedit frontend debug output here:
echo

echo "Opening $FULLPATH with $HEXEDITOR..."
# Output from wxHexEditor is verbose, and not terribly useful, so we redirect:
$HEXEDITOR "$FULLPATH" &> /dev/null