Added compress and decompress variables

Install header now has a {{ DECOMPRESS }} variable that is interpolated
on run of pkgself with pkgself's value for ${DECOMPRESS}.

Also added DECOMPRESS, COMPRESS, and COMPRESSEXT variables to pkgself to
standardize compression tools and command calls across the script. This
will also make it easier to make compress tools selectable in the future
(eg: --gzip or --bzip2 will set the variables differently).

Moved install header size calculation after all interpolations with a
note that all interpolations need to occur before that line so the size
counts are accurate.

2 files changed, 29 insertions, 20 deletions

diff --git a/install-header.sh b/install-header.sh
index b54a0ec..1d36f2a 100755
--- a/install-header.sh
+++ b/install-header.sh
@@ -4,12 +4,11 @@
 # DO NOT CHANGE THIS without great care - it will break header length
 # calculations
 LENS=(                                       )
-export SELF       # Absolute path to the installer script (me!)
-export TMP        # Path to tmp install staging directory
-export PAYLOAD    # Path to the extracted payload directory
-export NOCLEANUP  # Do not clean up deploy resources. Useful for debugging
-export COMPRESS   # Command to compress data
-export DECOMPRESS # Command to decompress data
+export SELF             # Absolute path to the installer script (me!)
+export TMP              # Path to tmp install staging directory
+export PAYLOAD          # Path to the extracted payload directory
+export NOCLEANUP        # Do not clean up deploy resources. Useful for debugging
+export DECOMPRESS='{{ DECOMPRESS }}' # Command to decompress data
 
 # Header:    0
 # runscript: 1
@@ -36,15 +35,15 @@ extract_header() {
 }
 
 extract_libinstall() {
-  extract_chunk_index "${SELF}" '-' 1 | xz -d -c | tar -C "${TMP}" -x
+  extract_chunk_index "${SELF}" '-' 1 | ${DECOMPRESS} | tar -C "${TMP}" -x
 }
 
 extract_runscript() {
-  extract_chunk_index "${SELF}" '-' 2 | xz -d -c > "${TMP}/run.sh"
+  extract_chunk_index "${SELF}" '-' 2 | ${DECOMPRESS} > "${TMP}/run.sh"
 }
 
 extract_payload() {
-  extract_chunk_index "${SELF}" '-' 3 | xz -d -c | tar -C "${TMP}" -x
+  extract_chunk_index "${SELF}" '-' 3 | ${DECOMPRESS} | tar -C "${TMP}" -x
   export PAYLOAD="${TMP}/pkg"
 }
 
diff --git a/pkgself.sh b/pkgself.sh
index 6e75b33..6811dbf 100755
--- a/pkgself.sh
+++ b/pkgself.sh
@@ -17,6 +17,10 @@
 
 set -e
 
+export COMPRESS='xz -z -c -T 0'  # Command to compress data
+export DECOMPRESS='xz -d -c'     # Command to decompress data
+export COMPRESSEXT='xz'          # File extension for compressed data
+
 download_src() {
   local file
 
@@ -126,20 +130,26 @@ main() {
 
   printf "Reticulating splines...\n"
 
-  headsize=$(wc -c < ${output})
-
   # Package up the libinstall libraries
-  tar -C "${tmp}" -c libinstall | xz -c > ${tmp}/libinstall.tar.xz
-  libinstallsize=$(wc -c < ${tmp}/libinstall.tar.xz)
+  tar -C "${tmp}" -c libinstall \
+    | ${COMPRESS} > ${tmp}/libinstall.tar.${COMPRESSEXT}
+  libinstallsize=$(wc -c < ${tmp}/libinstall.tar.${COMPRESSEXT})
 
   # Compress and calculate byte size for run.sh
-  xz -c ${PKGSRC}/run.sh > ${tmp}/run.sh.xz
-  runsize="$(wc -c < ${tmp}/run.sh.xz)"
+  ${COMPRESS} ${PKGSRC}/run.sh > ${tmp}/run.sh.${COMPRESSEXT}
+  runsize="$(wc -c < ${tmp}/run.sh.${COMPRESSEXT})"
 
   # Compress and calculate byte size for payload
-  tar -c "$(basename ${PKG})" | xz -v > ${PKG}.tar.xz
-  payloadsize="$(wc -c < ${PKG}.tar.xz)"
+  tar -c "$(basename ${PKG})" \
+    | ${COMPRESS} -v > ${PKG}.tar.${COMPRESSEXT}
+  payloadsize="$(wc -c < ${PKG}.tar.${COMPRESSEXT})"
 
+  # Replace compress and decompress command variables
+  sed -i "s/{{ DECOMPRESS }}/${DECOMPRESS}/g" "${output}"
+
+  # NOTE: All variable interpolations in the header MUST occur before this line.
+  #       This solely exclides the 'lens' array interpolation
+  headsize=$(wc -c < ${output})
 
   # Print space padded values to meet expected character length.
   # Expected length: 8 + 8 + 12 + 2 == 30
@@ -154,9 +164,9 @@ main() {
   sed -i "s/LENS=(.*)/LENS=(${lens})/g" "${output}"
 
   # Append chunks to output file
-  cat "${tmp}/libinstall.tar.xz" >> "${output}"
-  cat "${tmp}/run.sh.xz"         >> "${output}"
-  cat "${PKG}.tar.xz"            >> "${output}"
+  cat "${tmp}/libinstall.tar.${COMPRESSEXT}" >> "${output}"
+  cat "${tmp}/run.sh.${COMPRESSEXT}"         >> "${output}"
+  cat "${PKG}.tar.${COMPRESSEXT}"            >> "${output}"
 
   # Cleanup
   rm -rf ${tmp}