Initial commit

Mostly functioning, but missing a few binaries and libraries
required to boot a system's kernel.

1 files changed, 103 insertions, 0 deletions

diff --git a/mkinitramfs b/mkinitramfs
new file mode 100755
index 0000000..e11adf7
--- /dev/null
+++ b/mkinitramfs
@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+
+function get_bin_deps {
+  [[ -z ${1} ]] && echo 'Binary path required.\n' & exit 1
+
+  ldd ${1}
+}
+
+
+#
+# Gets first path locatable in a string
+#
+function get_first_path {
+  local str=${1}
+
+  local out=''
+  local cursor=''
+
+  for ((i=0; i<${#str}; i++)); do
+    if [[ ${str:$i:1} == '/' ]]; then
+      cursor=${i}
+      break
+    fi
+  done
+
+  # Exit if no path found
+  [[ ${cursor} == '' ]] && return
+
+  while [[ ${str:$cursor:1} != ' ' ]] && [[ ${cursor} -lt ${#str} ]]; do
+    out="${out}${str:$cursor:1}"
+    cursor=$((${cursor} + 1))
+  done
+
+  echo "${out}"
+}
+
+
+function get_deps {
+  local bin=${1}
+
+  for dep in $(ldd ${bin}); do
+     get_first_path "${dep}"
+  done
+}
+
+
+function mkcpio {
+  [[ -z ${1} ]] && echo "Initramfs cache path required." && exit 1
+
+  cd ${1}
+  fsname="initramfs-$(uname -m)-$(uname -r).cpio.xz"
+  find . -print0 | cpio --null -ov --format=newc | xz -v -9 -c > ../${fsname}
+}
+
+
+function main {
+  local cache='initramfs'
+
+  # Clean the cache so we start fresh
+  rm -rf ${cache} && mkdir ${cache}
+
+  # List of binaries to exist in the new initramfs
+  local bins=(
+    /bin/bash
+    #/bin/sh
+    /sbin/cryptsetup
+    /bin/chmod
+    /bin/chown
+    /usr/bin/vi
+    /usr/bin/less
+    #/bin/ps
+    #/sbin/shutdown
+    /sbin/switch_root
+  )
+
+  # # Create the temporary directory structure
+  mkdir -p ./${cache}/{bin,dev,etc,lib,lib64,mnt/root,proc,root,sbin,sys,usr,usr/lib,usr/lib64,usr/lib32,usr/bin}
+
+  # # Copy in live system devices
+  # cp -a /dev/{null,console,tty,sda1} ./${cache}/dev/
+
+  # Copy binary and dependencies locally
+  for bin in ${bins[@]}; do
+    bindirname=$(dirname ${bin})
+    # Copy the binary of interest
+    cp -u ${bin} "${cache}/${bindirname}/"
+
+    deps=$(get_deps ${bin})
+    # Copy each of the binary's deps
+    for dep in ${deps[@]}; do
+      local depdirname=$(dirname ${dep})
+      cp -u ${dep} "${cache}/${depdirname}/"
+    done
+  done
+
+  cp init ${cache}/init && chmod +x ${cache}/init
+
+
+  mkcpio ${cache}
+}
+
+
+main ${@}