From 9ed69d70d9201817c7f36c7f210ce163e84eb54b Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Fri, 26 May 2017 00:39:02 +1200
Subject: Reimplement sd() without subshell

---
 sh/shrc.d/bd.sh |  6 ++---
 sh/shrc.d/sd.sh | 80 +++++++++++++++++++++++++++++----------------------------
 2 files changed, 44 insertions(+), 42 deletions(-)

(limited to 'sh')

diff --git a/sh/shrc.d/bd.sh b/sh/shrc.d/bd.sh
index 5b2c3d59..2dc21173 100644
--- a/sh/shrc.d/bd.sh
+++ b/sh/shrc.d/bd.sh
@@ -7,8 +7,8 @@ bd() {
         return 2
     fi
 
-    # Look at argument given
-    case $1 in
+    # Look at argument given; default to going up one level
+    case ${1:-..} in
 
         # If it has a leading slash or is . or .., don't touch the arguments
         /*|.|..) ;;
@@ -18,7 +18,7 @@ bd() {
         *)
 
             # Push the current directory onto the stack
-            set -- "$1" "$PWD"
+            set -- "${1%/}" "$PWD"
 
             # Keep chopping at the current directory until it's empty or it
             # matches the request
diff --git a/sh/shrc.d/sd.sh b/sh/shrc.d/sd.sh
index 4d63b7d6..561a77f4 100644
--- a/sh/shrc.d/sd.sh
+++ b/sh/shrc.d/sd.sh
@@ -40,48 +40,50 @@ sd() {
         return 2
     fi
 
-    # Change positional parameters to what will hopefully be a completed
-    # substitution
-    set -- "$(
+    # Read sole optional argument
+    case $1 in
 
-        # Set the positional parameters to either the requested directory, or
-        # all siblings of the current directory if no request
-        spec=$1
-        set --
-        if [ -n "$spec" ] ; then
-            set -- "$@" ../"$spec"
-        else
-            for sib in ../.* ../* ; do
-                case ${sib#../} in
-                    (.|..|"${PWD##*/}") continue ;;
-                esac
-                set -- "$@" "$sib"
-            done
-        fi
+        # If blank, get a full list of directories at this level; include
+        # dotfiles, but not the . and .. entries, using glob tricks to avoid
+        # Bash ruining things with `dotglob`
+        '')
+            set -- ../[!.]*/
+            [ -e "$1" ] || shift
+            set -- ../.[!.]*/ "$@"
+            [ -e "$1" ] || shift
+            set -- ../..?*/ "$@"
+            [ -e "$1" ] || shift
+            ;;
 
-        # We should have exactly one sibling
-        case $# in
-            (1) ;;
-            (0)
-                printf >&2 'sd(): No siblings\n'
-                exit 1
-                ;;
-            (*)
-                printf >&2 'sd(): More than one sibling\n'
-                exit 1
-                ;;
-        esac
+        # If not, get that directory, and the current one; shift it off if it
+        # doesn't exist
+        *)
+            set -- ../"${1%/}"/ ../"${PWD##*/}"/
+            [ -e "$1" ] || shift
+            ;;
+    esac
 
-        # Print the target with trailing slash to work around newline stripping
-        printf '%s/' "${1%/}"
-    )"
+    # We should now have two parameters: the current directory and the matched
+    # sibling
+    case $# in
+        2) ;;
+        0|1)
+            printf >&2 'sd(): No match\n'
+            return 1
+            ;;
+        *)
+            printf >&2 'sd(): Multiple matches\n'
+            return 1
+            ;;
+    esac
 
-    # Remove trailing slash
-    set -- "${1%/}"
+    # Find which of these two is not the current directory and set that as our
+    # sole parameter
+    case $1 in
+        ../"${PWD##*/}"/) set -- "$2" ;;
+        *) set -- "$1" ;;
+    esac
 
-    # If the subshell printed nothing, return with failure
-    [ -n "$1" ] || return
-
-    # Try to change into the determined directory
-    command cd -- "$@"
+    # Try and change into the first parameter
+    command cd -- "$1"
 }
-- 
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