1 files changed, 97 insertions, 0 deletions
diff --git a/src/coreutils/cat.sh b/src/coreutils/cat.sh
new file mode 100644
index 0000000..52c3a93
--- /dev/null
+++ b/src/coreutils/cat.sh
@@ -0,0 +1,97 @@
+#!/bin/bash
+# Bash alternative to external cat call
+#
+#  Copyright (C) 2014 Mike Gerwitz
+#
+#  This file is part of pkgsh.
+#
+#  pkgsh is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# N.B. While this shell implementation may be faster for most use cases, the
+# external binary will likely be much faster for large streams.
+#
+# This also contains some convenience functions that are not part of
+# GNU coreutils.
+##
+
+[ -z $__PKGSH_INC_COREUTILS_CAT ] || return
+__PKGSH_INC_COREUTILS_CAT=1
+
+
+##
+# Echo characters from stdin up to (but not including) the provided
+# delimiter
+cat-until()
+{
+  local -r delim="${1?Missing terminating delimiter}"
+  local -r file="${2:-/dev/stdin}"
+
+  read -rd "$delim" < "$file"
+  local -ri result=$?
+
+  echo -n "$REPLY"
+  return $result
+}
+
+
+##
+# Echo characters from stdin up to and including the provided delimiter
+cat-until-incl()
+{
+  # `cat-until` will validate
+  local -r delim="$1"
+  cat-until "$@" \
+    && echo -n "$delim"
+}
+
+
+##
+# Proxies to either the shell implementation of cat or the system binary,
+# depending on support
+cat()
+{
+  [[ "$1" =~ ^-[^-\ ] ]] \
+    && command cat "$@" \
+    || quickcat "$@"
+}
+
+
+##
+# Limited implementation of `cat` for performance
+#
+# TODO: The proper research has not yet gone into optimizing this; this is
+# just an initial implementation to get things going. I will be addressing
+# this shortly.
+#
+# TODO: Exit status.
+quickcat()
+{
+  local in="${1:-/dev/stdin}"
+  [ "$in" == - ] && in=/dev/stdin
+  readonly in
+
+  while true; do
+    IFS= read -r || {
+      echo -n "$REPLY"
+      break
+    }
+
+    echo "$REPLY"
+  done < "$in"
+
+  if shift && [ $# -ne 0 ]; then
+    quickcat "$@"
+  fi
+}
+