diff --git a/build-src.sh b/build-src.sh
index b0124d0..2433b05 100755
--- a/build-src.sh
+++ b/build-src.sh
@@ -1,66 +1,14 @@
 #!/bin/bash
 # Recommended command-line:
 #
-# commit-db.rb list-valid nightly|GIT_DIR=/your/rust/dir/.git sync.sh
-
-git_file_exists() {
-	[ "$(git ls-tree --name-only $IO_COMMIT -- $1)" = "$1" ]
-}
-
-git_extract() {
-	slashes=${1//[^\/]/}
-	git archive $IO_COMMIT $1|tar xf - -C src/$IO_COMMIT --strip-components=${#slashes}
-}
-
-git_commits_ordered() {
-	format=$1
-	shift
-	if [ $# -ge 1 ]; then
-		git log --topo-order --no-walk=sorted --date=iso-local --pretty=format:$format "$@"
-	fi
-}
-
-echo_lines() {
-	for i in "$@"; do
-		echo $i
-	done
-}
-
-get_io_commits() {
-	for COMPILER_COMMIT in $COMPILER_COMMITS; do
-		IO_COMMIT=$(git log -n1 --pretty=format:%H $COMPILER_COMMIT -- src/libstd/io)
-		if ! grep -q $COMPILER_COMMIT mapping.rs; then
-			echo "-Mapping(\"$COMPILER_COMMIT\",\"$IO_COMMIT\")" >> mapping.rs
-		fi
-		echo $IO_COMMIT
-	done
-}
-
-get_patch_commits() {
-	find $PATCH_DIR -type f -printf %f\\n|cut -d. -f1
-}
-
-prepare_version() {
-	mkdir src/$IO_COMMIT
-	git_extract src/libstd/io/
-	if git_file_exists src/libstd/sys/common/memchr.rs; then
-		git_extract src/libstd/sys/common/memchr.rs
-	else
-		git_extract src/libstd/memchr.rs
-	fi
-	rm -f src/$IO_COMMIT/stdio.rs src/$IO_COMMIT/lazy.rs
-}
-
-bold_arrow() {
-	echo -ne '\e[1;36m==> \e[0m'
-}
+# commit-db.rb list-valid nightly|GIT_DIR=/your/rust/dir/.git ./build-src.sh
 
 prompt_changes() {
 	local MAIN_GIT_DIR="$GIT_DIR"
 	local GIT_DIR=./.git CORE_IO_COMMIT=$IO_COMMIT
 	git init > /dev/null
 	git add .
-	git commit -a -m "rust src import" > /dev/null
+	git commit -m "rust src import" > /dev/null
 	export CORE_IO_COMMIT
 	
 	bold_arrow; echo 'No patch found for' $IO_COMMIT
@@ -72,24 +20,7 @@ prompt_changes() {
 	bold_arrow; echo -e "Try applying one of those using: \e[1;36mpatch -p1 < ../../patches/COMMIT.patch\e[0m"
 	bold_arrow; echo -e "Remember to test your changes with: \e[1;36mcargo build\e[0m"
 	bold_arrow; echo -e "Make your changes now (\e[1;36mctrl-D\e[0m when finished)"
-	bash <> /dev/stderr
-	while git diff --exit-code > /dev/null; do
-		bold_arrow; echo "No changes were made"
-		while true; do
-			bold_arrow; echo -n "(T)ry again or (A)bort? "
-			read answer <> /dev/stderr
-			case "$answer" in
-				[tT])
-					break
-					;;
-				[aA])
-					bold_arrow; echo "Aborting..."
-					exit 1
-					;;
-			esac
-		done
-		bash <> /dev/stderr
-	done
+	bash_diff_loop "No changes were made"
 	bold_arrow; echo "Saving changes as $IO_COMMIT.patch"
 	git clean -f -x
 	git diff > ../../patches/$IO_COMMIT.patch
@@ -103,6 +34,9 @@ if [ ! -t 1 ] || [ ! -t 2 ]; then
 fi
 
 cd "$(dirname "$0")"
+
+. ./functions.sh
+
 PATCH_DIR="$PWD/patches"
 COMPILER_COMMITS=$(cat)
 IO_COMMITS=$(get_io_commits|sort -u)
@@ -110,6 +44,9 @@ PATCH_COMMITS=$(get_patch_commits|sort -u)
 NEW_COMMITS=$(comm -2 -3 <(echo_lines $IO_COMMITS) <(echo_lines $PATCH_COMMITS))
 OLD_COMMITS=$(comm -1 -2 <(echo_lines $IO_COMMITS) <(echo_lines $PATCH_COMMITS))
 
+set -e
+set -o pipefail
+
 find src -mindepth 1 -type d -prune -exec rm -rf {} \;
 
 for IO_COMMIT in $OLD_COMMITS $(git_commits_ordered %H $NEW_COMMITS|tac); do
@@ -117,6 +54,7 @@ for IO_COMMIT in $OLD_COMMITS $(git_commits_ordered %H $NEW_COMMITS|tac); do
 		prepare_version
 		
 		if [ -f patches/$IO_COMMIT.patch ]; then
+			bold_arrow; echo "Patching $IO_COMMIT"
 			patch -s -p1 -d src/$IO_COMMIT < patches/$IO_COMMIT.patch
 		else
 			cd src/$IO_COMMIT
@@ -126,6 +64,8 @@ for IO_COMMIT in $OLD_COMMITS $(git_commits_ordered %H $NEW_COMMITS|tac); do
 	fi
 done
 
+OLD_GIT_PERM=$(stat --printf=%a .git)
+trap "chmod $OLD_GIT_PERM .git; exit 1" SIGINT
 chmod 000 .git
 cargo package
-chmod 755 .git
+chmod $OLD_GIT_PERM .git
diff --git a/edit-patches.sh b/edit-patches.sh
new file mode 100755
index 0000000..0ce0a99
--- /dev/null
+++ b/edit-patches.sh
@@ -0,0 +1,61 @@
+#!/bin/bash
+# Recommended command-line:
+#
+# GIT_DIR=/your/rust/dir/.git ./edit-patches.sh
+
+prompt_changes() {
+	bold_arrow; echo "Editing $IO_COMMIT"
+	bold_arrow; echo -e "Remember to test your changes with: \e[1;36mcargo build\e[0m"
+
+	local MAIN_GIT_DIR="$GIT_DIR"
+	local GIT_DIR=./.git CORE_IO_COMMIT=$IO_COMMIT
+	export CORE_IO_COMMIT
+
+	git init > /dev/null
+	git add .
+	git commit -m "rust src import" > /dev/null
+	IMPORT_COMMIT=$(git log -n1 --pretty=format:%H)
+	patch -s -p1 < $PATCH_DIR/$IO_COMMIT.patch
+	git commit -a -m "existing patch for $IO_COMMIT" > /dev/null
+
+	bold_arrow; echo -e "Applying patch from \e[1;36m$TMP_PATCH\e[0m"
+	patch -p1 < $TMP_PATCH || true
+	bold_arrow; echo -e "Make your changes now (\e[1;36mctrl-D\e[0m when finished)"
+	bash_diff_loop "No changes were made"
+	bold_arrow; echo "Replacing $IO_COMMIT.patch with updated version"
+	git diff > $TMP_PATCH
+	git clean -f -x
+	git diff > $PATCH_DIR/$IO_COMMIT.patch
+	rm -rf .git
+}
+
+if [ ! -t 1 ] || [ ! -t 2 ]; then
+	echo "==> /dev/stdout or /dev/stderr is not attached to a terminal!"
+	echo "==> This script must be run interactively."
+	exit 1
+fi
+
+cd "$(dirname "$0")"
+
+. ./functions.sh
+
+PATCH_DIR="$PWD/patches"
+PATCH_COMMITS=$(get_patch_commits|sort -u)
+
+TMP_PATCH=$(mktemp)
+
+set -e
+set -o pipefail
+
+find src -mindepth 1 -type d -prune -exec rm -rf {} \;
+
+for IO_COMMIT in $(git_commits_ordered %H $PATCH_COMMITS|tac); do
+	prepare_version
+	cd src/$IO_COMMIT
+	prompt_changes
+	cd ../..
+done
+
+rm -rf $TMP_PATCH
+
+bold_arrow; echo "Done"
diff --git a/functions.sh b/functions.sh
new file mode 100644
index 0000000..1f291d0
--- /dev/null
+++ b/functions.sh
@@ -0,0 +1,75 @@
+#!/bin/bash
+
+git_file_exists() {
+	[ "$(git ls-tree --name-only $IO_COMMIT -- $1)" = "$1" ]
+}
+
+git_extract() {
+	slashes=${1//[^\/]/}
+	git archive $IO_COMMIT $1|tar xf - -C src/$IO_COMMIT --strip-components=${#slashes}
+}
+
+git_commits_ordered() {
+	format=$1
+	shift
+	if [ $# -ge 1 ]; then
+		git log --topo-order --no-walk=sorted --date=iso-local --pretty=format:$format "$@"
+	fi
+	echo
+}
+
+echo_lines() {
+	for i in "$@"; do
+		echo $i
+	done
+}
+
+get_io_commits() {
+	for COMPILER_COMMIT in $COMPILER_COMMITS; do
+		IO_COMMIT=$(git log -n1 --pretty=format:%H $COMPILER_COMMIT -- src/libstd/io)
+		if ! grep -q $COMPILER_COMMIT mapping.rs; then
+			echo "-Mapping(\"$COMPILER_COMMIT\",\"$IO_COMMIT\")" >> mapping.rs
+		fi
+		echo $IO_COMMIT
+	done
+}
+
+get_patch_commits() {
+	find $PATCH_DIR -type f -printf %f\\n|cut -d. -f1
+}
+
+prepare_version() {
+	mkdir src/$IO_COMMIT
+	git_extract src/libstd/io/
+	if git_file_exists src/libstd/sys/common/memchr.rs; then
+		git_extract src/libstd/sys/common/memchr.rs
+	else
+		git_extract src/libstd/memchr.rs
+	fi
+	rm -f src/$IO_COMMIT/stdio.rs src/$IO_COMMIT/lazy.rs
+}
+
+bold_arrow() {
+	echo -ne '\e[1;36m==> \e[0m'
+}
+
+bash_diff_loop() {
+	bash <> /dev/stderr
+	while git diff --exit-code > /dev/null; do
+		bold_arrow; echo "$1"
+		while true; do
+			bold_arrow; echo -n "(T)ry again or (A)bort? "
+			read answer <> /dev/stderr
+			case "$answer" in
+				[tT])
+					break
+					;;
+				[aA])
+					bold_arrow; echo "Aborting..."
+					exit 1
+					;;
+			esac
+		done
+		bash <> /dev/stderr
+	done
+}