From 2d17c12ac6b947e6ebf64f45bae6c2479a5d40fe Mon Sep 17 00:00:00 2001
From: Eli Barzilay <eli@barzilay.org>
Date: Wed, 18 Jul 2012 22:25:02 -0400
Subject: [PATCH] Make it possible to use "~" or "~user" in the installer.

I've looked for a while, and it seems that there is no easy way to do
this, not even in bash, and worse with /bin/sh.  So this is kind of
resorting to a simple parsing of the input, and using `eval' if it
starts with a tilde.  Note the hack of not doing that when there is a
space, otherwise the `eval' thing will silently ignore it.

This hack means that it's easy to get into a mess if quotes are used
after a tilde, but that was already the case with the use of `eval' to
handle environment variables.  It's not a real security issue, however,
since we're talking about a user who can just run any command anyway.

Also including a test file for the expansion functionality.  If anyone
wants to improve this code, making the tests pass would reveal the
tricky issues.

[FWIW, I've asked on the #bash channel, and the only serious suggestion
was getting the paths as command-line arguments.  This will, however,
defeat the point of being newbie friendly...]

Closes PR 12893.

original commit: 0814fd5fb5f660bc9698f21445976902317291d1
---
 .../build/unix-installer/installer-header     | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/collects/meta/build/unix-installer/installer-header b/collects/meta/build/unix-installer/installer-header
index 3edd4f7..6213215 100644
--- a/collects/meta/build/unix-installer/installer-header
+++ b/collects/meta/build/unix-installer/installer-header
@@ -54,6 +54,22 @@ lookfor mkdir
 lookfor basename
 lookfor dirname
 
+# substitute env vars and tildes
+expand_path_var() {
+  eval "expanded_val=\"\$$1\""
+  first_part="${expanded_val%%/*}"
+  if [ "x$first_part" = "x$expanded_val" ]; then
+    rest_parts=""
+  else
+    rest_parts="/${expanded_val#*/}"
+  fi
+  case "x$first_part" in
+    x*" "* ) ;;
+    x~* ) expanded_val="`eval \"echo $first_part\"`$rest_parts" ;;
+  esac
+  eval "$1=\"$expanded_val\""
+}
+
 # Need this to make new `tail' respect old-style command-line arguments.  Can't
 # use `tail -n #' because some old tails won't know what to do with that.
 _POSIX2_VERSION=199209
@@ -133,11 +149,9 @@ case "x$where" in
   x2     ) where="/usr/local${TARGET1}" ;;
   x3     ) where="${HOME}${TARGET1}" ;;
   x4 | x. | x./ ) where="`pwd`${TARGET1}" ;;
+  * ) expand_path_var where ;;
 esac
 
-# substitute env vars and tildes
-where="`eval \"echo \\\"$where\\\"\"`"
-
 ###############################################################################
 ## Default system directories prefixed by $1, mimic configure behavior
 ## used for unixstyle targets and for wholedir links
@@ -332,6 +346,7 @@ unixstyle_install() {
     echon "> "; read change_what
     read_dir() {
       echon "New directory (absolute or relative to $where): "; read new_dir
+      expand_path_var new_dir
       case "$new_dir" in
         "/"* ) eval "$1=\"$new_dir\"" ;;
         *    ) eval "$1=\"$where/$new_dir\"" ;;