I've finally gotten 'cpio' into a shape where it could be useable. This version can archive and extract directories, sockets, FIFOs, devices, symlinks, and regular files. Supported options are -iot, -H FMT (which is a dummy right now). It only writes newc, and could read newc or newcrc. This does NOT implement -d, which essentially is equivalent to mkdir -p $(dirname $FILE) for every file that needs it. Hard links are not supported, though it would be easy to add them given a hash table or something like that. I also have not implemented the "<n> blocks" output on stderr. If desired, I can add it pretty simply. There is one assumption this makes: that the mode of a file, as mode_t, is bitwise equivalent to the mode as defined for the cpio format. This is true of Linux, but is not mandated by POSIX. If it is compiled for a system where that is false, the archives will not be portable.

# Toybox configuration file.

# This sets environment variables used by scripts/make.sh

# A synonym.
[ -z "$CROSS_COMPILE" ] && CROSS_COMPILE="$CROSS"
[ -z "$CFLAGS" ] && CFLAGS="-Wall -Wundef -Wno-char-subscripts"
# Required for our expected ABI. we're 8-bit clean thus "char" must be unsigned.
CFLAGS="$CFLAGS -funsigned-char"

[ -z "$OPTIMIZE" ] && OPTIMIZE="-Os -ffunction-sections -fdata-sections -Wl,--gc-sections -fno-asynchronous-unwind-tables"
[ -z "$CC" ] && CC=cc
[ -z "$STRIP" ] && STRIP=strip

# If HOSTCC needs CFLAGS, add them to the variable ala HOSTCC="blah-cc --static"
[ -z "$HOSTCC" ] && HOSTCC=gcc