From f2fb351c391dca7c188a8623e71519619c2ce9a0 Mon Sep 17 00:00:00 2001
From: Mat M <matm@gmx.fr>
Date: Sun, 8 Dec 2019 00:25:53 +0100
Subject: Do not symlink a symlink in mkrc

We have a bug when calling mkrc(1) on a symlink:

```sh
mkrc ~/.vimrc # links ~/.vimrc to ~/.dotfiles/vimrc
mkrc ~/.vimrc # deletes ~/.dotfiles/vimrc
```

This catches that case ahead of time, preventing the user from running
mkrc(1) on a symlink.

Fix #144.
---
 Makefile.am             |  1 +
 NEWS.md.in              |  2 ++
 bin/mkrc.in             | 23 +++++++++++++++++++++++
 bin/rcup.in             |  4 ----
 share/rcm.sh.in         |  4 ++++
 test/mkrc-no-symlinks.t | 26 ++++++++++++++++++++++++++
 6 files changed, 56 insertions(+), 4 deletions(-)
 create mode 100644 test/mkrc-no-symlinks.t

diff --git a/Makefile.am b/Makefile.am
index 16164d9..4af524d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -24,6 +24,7 @@ TESTS = \
 	test/mkrc-copy-file.t \
 	test/mkrc-host-file.t \
 	test/mkrc-hostname.t \
+	test/mkrc-no-symlinks.t \
 	test/mkrc-simple-output.t \
 	test/mkrc-spaces.t \
 	test/mkrc-symlink-dirs.t \
diff --git a/NEWS.md.in b/NEWS.md.in
index 6af5d4e..4461a2f 100644
--- a/NEWS.md.in
+++ b/NEWS.md.in
@@ -1,5 +1,7 @@
 rcm (@PACKAGE_VERSION@) unstable; urgency=low
 
+  * Fix #144 and more: all symlinks in input are rejected (Mat M)
+  
  -- Mike Burns <mburns@thoughtbot.com>  Fri, 13 Jul 2018 14:12:00 -0500
 
 rcm (1.3.3) unstable; urgency=low
diff --git a/bin/mkrc.in b/bin/mkrc.in
index 5d6af7e..d246c33 100755
--- a/bin/mkrc.in
+++ b/bin/mkrc.in
@@ -20,6 +20,28 @@ destination() {
   fi
 }
 
+exit_if_dangerous() {
+  local file="$1"
+
+  if [ -L "$file" ]; then
+      $ERROR 1 "'$file' is a symlink. Cannot process file."
+  elif is_nested "$file"; then
+    # Remove DEST_DIR in case $HOME is under a symlink
+    saved_ifs="$IFS"
+    IFS=/
+    set -- $(dirname "$file" | sed "s|$DEST_DIR/||")
+    IFS="$saved_ifs"
+
+    built_dir="$DEST_DIR"
+    for dir in $@; do
+      built_dir="$built_dir/$dir"
+      if [ -L "$built_dir" ]; then
+        $ERROR 1 "'$file' path contains a symlink ($dir). Cannot process file."
+      fi
+    done
+  fi
+}
+
 show_help() {
   local exit_code=${1:-0}
 
@@ -84,6 +106,7 @@ fi
 
 files=""
 for i; do
+  exit_if_dangerous "$i" 
   files="$(printf "$files\n$i")"
 done
 
diff --git a/bin/rcup.in b/bin/rcup.in
index 910e534..78f5faa 100755
--- a/bin/rcup.in
+++ b/bin/rcup.in
@@ -121,10 +121,6 @@ replace_file() {
   link_file "$src" "$dest" "$sigil"
 }
 
-is_nested() {
-  echo "$1" | sed "s:$DEST_DIR/::" | grep '/' >/dev/null
-}
-
 is_identical() {
   diff -c "$1" "$2" > /dev/null 2>&1
 }
diff --git a/share/rcm.sh.in b/share/rcm.sh.in
index a2b4492..f7c6137 100644
--- a/share/rcm.sh.in
+++ b/share/rcm.sh.in
@@ -58,6 +58,10 @@ is_relative() {
   echo "$1" | grep -v '^/' >/dev/null
 }
 
+is_nested() {
+  echo "$1" | sed "s|$DEST_DIR/||" | grep '/' >/dev/null
+}
+
 version() {
   cat << EOV
 $1 (rcm) $VERSION
diff --git a/test/mkrc-no-symlinks.t b/test/mkrc-no-symlinks.t
new file mode 100644
index 0000000..e37d56a
--- /dev/null
+++ b/test/mkrc-no-symlinks.t
@@ -0,0 +1,26 @@
+  $ . "$TESTDIR/helper.sh"
+
+Passing a linked file is rejected.
+We need a second path not under what will be $HOME
+
+  $ EXTDIR="${CRAMTMP}2"
+  > mkdir -p "$EXTDIR"
+  > echo 'Content' > "$EXTDIR/example"
+  > ln -s "$EXTDIR/example" "$HOME/.example"
+
+  $ mkrc .example
+  '.example' is a symlink. Cannot process file.
+  [1]
+
+  $ refute "is a symlink" -h $HOME/.dotfiles/.example
+
+Passing a file in one linked dir is rejected
+
+  $ mkdir "$HOME/.config"
+  > ln -s "$EXTDIR/" "$HOME/.config/tmpdir"
+
+  $ mkrc -v .config/tmpdir/example
+  '.config/tmpdir/example' path contains a symlink (tmpdir). Cannot process file.
+  [1]
+
+  $ refute "is a symlink" -h "$HOME/.dotfiles/config/tmpdir/example"
-- 
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