PATCH: Allow tree-id to return the ID of a tree object

Index: commit-id
===================================================================
@@ -9,22 +9,30 @@
 SHA1ONLY="^$SHA1$"
 
 id=$1
+
 if [ ! "$id" ] || [ "$id" = "this" ] || [ "$id" = "HEAD" ]; then
 	id=$(cat .git/HEAD)
-fi
 
-if (echo $id | egrep -vq "$SHA1ONLY") && [ -r ".git/refs/tags/$id" ]; then
+elif [ -r ".git/refs/tags/$id" ]; then
 	id=$(cat ".git/refs/tags/$id")
-fi
 
-if (echo $id | egrep -vq "$SHA1ONLY") && [ -r ".git/refs/heads/$id" ]; then
+elif [ -r ".git/refs/heads/$id" ]; then
 	id=$(cat ".git/refs/heads/$id")
-fi
 
-idpref=$(echo "$id" | cut -c -2)
-idpost=$(echo "$id" | cut -c 3-)
-if [ $(find ".git/objects/$idpref" -name "$idpost*" 2>/dev/null | wc -l) -eq 1 ]; then
-	id=$idpref$(basename $(echo .git/objects/$idpref/$idpost*))
+# Short id's must be lower case and at least 4 digits.
+elif [[ "$id" == [0-9a-z][0-9a-z][0-9a-z][0-9a-z]* ]]; then
+	idpost=${id#??}
+	idpref=${id%$idpost}
+
+	# Assign array elements to matching names
+	idmatch=($(echo .git/objects/$idpref/$idpost*))
+
+	if [ ${#idmatch[*]} -eq 1 ] && [ -r "$idmatch" ]; then
+		id=$idpref${idmatch#.git/objects/$idpref/}
+	elif [ ${#idmatch[*]} -gt 1 ]; then
+		echo "Ambiguous id: $id" >&2
+		exit 1
+	fi
 fi
 
 if echo $id | egrep -vq "$SHA1ONLY"; then

Index: tree-id
===================================================================
@@ -7,8 +7,35 @@
 
 SHA1="[A-Za-z0-9]{40}"
 TREE="^tree $SHA1$"
+SHA1ONLY="^$SHA1$"
 
-id=$(cat-file commit $(commit-id "$1") | egrep "$TREE" | cut -d ' ' -f 2)
+id=$1
+
+# Is it a commit?
+commit=$(commit-id $id 2>/dev/null)
+if [ "$commit" ]; then
+	id=$(cat-file commit "$commit") | egrep "$TREE" | cut -d ' ' -f 2)
+
+# Short id's must be lower case and at least 4 digits.
+elif [[ "$id" == [0-9a-z][0-9a-z][0-9a-z][0-9a-z]* ]]; then
+	idpost=${id#??}
+	idpref=${id%$idpost}
+
+	# Assign array elements to matching names
+	idmatch=($(echo .git/objects/$idpref/$idpost*))
+
+	if [ ${#idmatch[*]} -eq 1 ] && [ -r "$idmatch" ]; then
+		id=$idpref${idmatch#.git/objects/$idpref/}
+	elif [ ${#idmatch[*]} -gt 1 ]; then
+		echo "Ambiguous id: $id" >&2
+		exit 1
+	fi
+fi
+
+if echo $id | egrep -vq "$SHA1ONLY"; then
+	echo "Invalid id: $id" >&2
+	exit 1
+fi
 
 if [ "$(cat-file -t "$id")" != "tree" ]; then
 	echo "Invalid id: $id" >&2

Index: parent-id
===================================================================
@@ -5,7 +5,8 @@
 #
 # Takes ID of the current commit, defaults to HEAD.
 
-PARENT="^parent [A-Za-z0-9]{40}$"
+SHA1="[A-Za-z0-9]{40}"
+PARENT="^parent $SHA1$"
 
 id=$(commit-id $1) || exit 1
 

Index: cg-Xnormid
===================================================================
@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+#
+# Normalize an ID to an SHA1 hash value
+#    Strings resolve in order:
+#       NULL, this, HEAD  => .git/HEAD
+#       <tags>
+#       <heads>
+#       short SHA1 (4 or more hex digits)
+#
+# Copyright (c) Philip Pokorny, 2005
+
+id="$1"
+
+if [ ! "$id" ] || [ "$id" = "this" ] || [ "$id" = "HEAD" ]; then
+	read id < .git/HEAD
+
+elif [ -r ".git/refs/tags/$id" ]; then
+	read id < ".git/refs/tags/$id"
+
+elif [ -r ".git/refs/heads/$id" ]; then
+	read id < ".git/refs/heads/$id"
+
+# Short id's must be lower case and at least 4 digits.
+elif [[ "$id" == [0-9a-z][0-9a-z][0-9a-z][0-9a-z]* ]]; then
+	idpost=${id#??}
+	idpref=${id%$idpost}
+
+	# Assign array elements to matching names
+	idmatch=(.git/objects/$idpref/$idpost*)
+
+	if [ ${#idmatch[*]} -eq 1 ] && [ -r "$idmatch" ]; then
+		id=$idpref${idmatch#.git/objects/$idpref/}
+	elif [ ${#idmatch[*]} -gt 1 ]; then
+		echo "Ambiguous id: $id" >&2
+		exit 1
+	fi
+fi
+
+# FIXME? Should we verify the existance of the ID in the object cache?
+
+# If we don't have a 40-char ID by now, it's an error
+if [ ${#id} -ne 40 ]; then
+	echo "Invalid id: $id" >&2
+	exit 1
+fi
+
+echo $id

Index: Makefile
===================================================================
@@ -44,7 +44,7 @@
 	cg-add cg-admin-lsobj cg-cancel cg-clone cg-commit cg-diff \
 	cg-export cg-help cg-init cg-log cg-ls cg-merge cg-mkpatch \
 	cg-patch cg-pull cg-branch-add cg-branch-ls cg-rm cg-seek cg-status \
-	cg-tag cg-update cg-Xlib
+	cg-tag cg-update cg-Xlib cg-Xnormid
 
 COMMON=	read-cache.o
 

Index: commit-id
===================================================================
@@ -1,39 +1,25 @@
 #!/usr/bin/env bash
 #
 # Get ID of commit associated with given id or HEAD.
+#
 # Copyright (c) Petr Baudis, 2005
 #
-# Takes the appropriate ID, defaults to HEAD.
-
-SHA1="[A-Za-z0-9]{40}"
-SHA1ONLY="^$SHA1$"
-
-id=$1
-if [ ! "$id" ] || [ "$id" = "this" ] || [ "$id" = "HEAD" ]; then
-	id=$(cat .git/HEAD)
-fi
 
-if (echo $id | egrep -vq "$SHA1ONLY") && [ -r ".git/refs/tags/$id" ]; then
-	id=$(cat ".git/refs/tags/$id")
-fi
-
-if (echo $id | egrep -vq "$SHA1ONLY") && [ -r ".git/refs/heads/$id" ]; then
-	id=$(cat ".git/refs/heads/$id")
-fi
+# Save for later error message
+orig="$1"
 
-idpref=$(echo "$id" | cut -c -2)
-idpost=$(echo "$id" | cut -c 3-)
-if [ $(find ".git/objects/$idpref" -name "$idpost*" 2>/dev/null | wc -l) -eq 1 ]; then
-	id=$idpref$(basename $(echo .git/objects/$idpref/$idpost*))
-fi
+# Normalize to SHA1 form
+id=$(cg-Xnormid "$orig")
 
-if echo $id | egrep -vq "$SHA1ONLY"; then
-	echo "Invalid id: $id" >&2
+if [ ! "$id" ]; then
+	# cg-Xnormid already reported the error
 	exit 1
 fi
 
-if [ "$(cat-file -t "$id")" != "commit" ]; then
-	echo "Invalid id: $id" >&2
+# cat-file will verify that $id is a valid SHA1 ID for us
+# If it isn't, we'll get '' back
+if [ "$(cat-file -t "$id" 2>/dev/null)" != "commit" ]; then
+	echo "Invalid commit id: $orig" >&2
 	exit 1
 fi
 

Index: tree-id
===================================================================
@@ -1,17 +1,31 @@
 #!/usr/bin/env bash
 #
 # Get ID of tree associated with given commit or HEAD.
+#
 # Copyright (c) Petr Baudis, 2005
 #
-# Takes ID of the appropriate commit, defaults to HEAD.
 
-SHA1="[A-Za-z0-9]{40}"
-TREE="^tree $SHA1$"
+# Save for later error message
+orig="$1"
 
-id=$(cat-file commit $(commit-id "$1") | egrep "$TREE" | cut -d ' ' -f 2)
+# Normalize to SHA1 form
+id=$(cg-Xnormid "$1")
+if [ ! "$id" ]; then
+	# cg-Xnormid already reported the error
+	exit 1
+fi
+
+# Is it a commit?
+idtype=$(cat-file -t $id 2>/dev/null)
+if [ "$idtype" = "commit" ]; then
+	# Get the tree
+	id=$(cat-file commit "$id" | sed -e 's/tree //;q')
+fi
 
-if [ "$(cat-file -t "$id")" != "tree" ]; then
-	echo "Invalid id: $id" >&2
+# cat-file will verify that $id is a valid SHA1 ID for us
+# If it isn't, we'll get '' back
+if [ "$(cat-file -t "$id" 2>/dev/null)" != "tree" ]; then
+	echo "Invalid tree id: $orig" >&2
 	exit 1
 fi
 

Index: parent-id
===================================================================
@@ -1,12 +1,19 @@
 #!/usr/bin/env bash
 #
 # Get ID of parent commit to a given revision or HEAD.
+# NOTE: will return multiple SHA1s if ID is a commit with multiple parents
+#
 # Copyright (c) Petr Baudis, 2005
 #
-# Takes ID of the current commit, defaults to HEAD.
 
-PARENT="^parent [A-Za-z0-9]{40}$"
+# Save for later error message
+orig="$1"
 
-id=$(commit-id $1) || exit 1
+# Normalize to SHA1 form and verify its a commit
+id=$(commit-id "$1")
+if [ ! "$id" ]; then
+	# commit-id already reported the error
+	exit 1
+fi
 
-cat-file commit $id | egrep "$PARENT" | cut -d ' ' -f 2
+cat-file commit $id | awk '/^parent/{print $2};/^$/{exit}'