Update git-apply-patch-script for symbolic links.

This patch updates the git-apply-patch-script for the symbolic links
in the cache, recently added by Kay Sievers.

It currently is very anal about symbolic link changes.  It refuses to
change between a regular file and a symbolic link, and only allows
symbolic link changes if the patch is based on the same original.

Signed-off-by: Junio C Hamano <junkio@cox.net>

git-apply-patch-script

@@ -8,71 +8,134 @@
 #
 
 case "$#" in
-2)    exit 1 ;; # do not feed unmerged diff to me!
+2)
+    echo >&2 "cannot handle unmerged diff on path $1."
+    exit 1 ;;
 esac
 name="$1" tmp1="$2" hex1="$3" mode1="$4" tmp2="$5" hex2="$6" mode2="$7"
-case "$mode1" in *7??) mode1=+x ;; *6??) mode1=-x ;; esac
-case "$mode2" in *7??) mode2=+x ;; *6??) mode2=-x ;; esac
 
-if test -f "$name.orig" || test -f "$name.rej"
-then
-    echo >&2 "Unresolved patch conflicts in the previous run found."
-    exit 1
-fi
+type1=f
+case "$mode1" in
+*120???) type1=l  ;;
+*1007??) mode1=+x ;;
+*1006??) mode1=-x ;;
+.)       type1=-  ;; 
+esac
+
+type2=f
+case "$mode2" in
+*120???) type2=l  ;;
+*1007??) mode2=+x ;;
+*1006??) mode2=-x ;;
+.)       type2=-  ;; 
+esac
+
+case "$type1,$type2" in
 
-case "$mode1,$mode2" in
-.,?x)
-    # newly created
+-,?)
     dir=$(dirname "$name")
-    case "$dir" in '' | .) ;; *) mkdir -p "$dir" esac || {
+    case "$dir" in '' | .) ;; *) mkdir -p "$dir" ;; esac || {
 	echo >&2 "cannot create leading path for $name."
 	exit 1
     }
-    if test -f "$name"
+    if test -e "$name"
     then
-	echo >&2 "file $name to be created already exists."
+	echo >&2 "path $name to be created already exists."
 	exit 1
     fi
-    cat "$tmp2" >"$name" || {
-	echo >&2 "cannot create $name."
-	exit 1
-    } 
-    case "$mode2" in
-    +x)
-	echo >&2 "created $name with mode +x."
-	chmod "$mode2" "$name"
-	;;
-    -x)
-	echo >&2 "created $name."
+    case "$type2" in
+    f)
+        # creating a regular file
+	cat "$tmp2" >"$name" || {
+	    echo >&2 "cannot create a regular file $name."
+	    exit 1
+	} 
+	case "$mode2" in
+	+x)
+	    echo >&2 "created a regular file $name with mode +x."
+	    chmod "$mode2" "$name"
+	    ;;
+	-x)
+	    echo >&2 "created a regular file $name."
+            ;;
+        esac
 	;;
+    l)
+        # creating a symlink
+        ln -s "$(cat "$tmp2")" "$name" || {
+	    echo >&2 "cannot create a symbolic link $name."
+	    exit 1
+	}
+	echo >&2 "created a symbolic link $name."
+        ;;
+    *)
+        echo >&2 "do not know how to create $name of type $type2."
+	exit 1
     esac
-    git-update-cache --add -- "$name"
-    ;;
-?x,.)
-    # deleted
-    echo >&2 "deleted $name."
+    git-update-cache --add -- "$name" ;;
+
+?,-)
     rm -f "$name" || {
-	echo >&2 "cannot remove $name";
+	echo >&2 "cannot remove $name"
+	exit 1
+    }
+    echo >&2 "deleted $name."
+    git-update-cache --remove -- "$name" ;;
+
+l,f|f,l)
+    echo >&2 "cannot change a regular file $name and a symbolic link $name."
+    exit 1 ;;
+
+l,l)
+    # symlink to symlink
+    current=$(readlink "$name") || {
+	echo >&2 "cannot read the target of the symbolic link $name."
 	exit 1
     }
-    git-update-cache --remove -- "$name"
-    ;;
-*)
+    original=$(cat "$tmp1")
+    next=$(cat "$tmp2")
+    test "$original" != "$current" || {
+	echo >&2 "cannot apply symbolic link target change ($original->$next) to $name which points to $current."
+	exit 1
+    }
+    if test "$next" != "$current"
+    then
+	rm -f "$name" && ln -s "$next" "$name" || {
+	    echo >&2 "cannot create symbolic link $name."
+	    exit 1
+	}
+	echo >&2 "changed symbolic target of $name."
+        git-update-cache -- "$name"
+    fi ;;
+
+f,f)
     # changed
+    test -e "$name" || {
+	echo >&2 "regular file $name to be patched does not exist."
+	exit 1
+    }
     dir=$(dirname "$name")
-    case "$dir" in '' | .) ;; *) mkdir -p "$dir" esac || {
+    case "$dir" in '' | .) ;; *) mkdir -p "$dir";; esac || {
 	echo >&2 "cannot create leading path for $name."
 	exit 1
     }
-    # This will say "patching ..." so we do not say anything outselves.
-    diff -u -L "a/$name" -L "b/$name" "$tmp1" "$tmp2" | patch -p1 || exit
+    tmp=.git-apply-patch-$$
+    trap "rm -f $tmp-*" 0 1 2 3 15
 
+    # Be careful, in case "$tmp2" is borrowed path from the work tree
+    # we are looking at...
+    diff -u -L "a/$name" -L "b/$name" "$tmp1" "$tmp2" >$tmp-patch
+
+    # This will say "patching ..." so we do not say anything outselves.
+    patch -p1 <$tmp-patch || exit
+    rm -f $tmp-patch
     case "$mode1,$mode2" in
     "$mode2,$mode1") ;;
     *)
-	echo >&2 "changing mode from $mode1 to $mode2."
 	chmod "$mode2" "$name"
+	echo >&2 "changed mode from $mode1 to $mode2."
 	;;
     esac
     git-update-cache -- "$name"
+
 esac