Re: $HOME does not get abbreviated in prompt \w output when there is a trailing slash

[Libor Pechacek]

On Fri 23-05-14 06:13:13, Eric Blake wrote:
> On 05/23/2014 02:32 AM, Libor Pechacek wrote:
> 
> > +++ b/general.c
> > @@ -699,7 +699,10 @@ polite_directory_format (name)
> >    int l;
> >  
> >    home = get_string_value ("HOME");
> > -  l = home ? strlen (home) : 0;
> > +
> > +  /* remove trailing slashes from $HOME before comparisons */
> > +  for (l = home ? strlen (home) : 0; l > 1 && home[l-1] == '/'; l--);
> > +
> 
> Does this still work correctly on systems where / and // are distinct
> (as allowed by POSIX) and someone has set $HOME to //?

Good question.  The trimming should not be applied to paths shorter than two
characters.  As part of the testing, I've found another bug.  Updated patch
attached.

This is how Bash behaves without the patch:
bash-master-4.3$ cd
bash-master-4.3$ PS1='\w | \W \$ '
~ | ~ $ HOME=/home
/home.local/lpechacek | lpechacek $ cd
~ | ~ $ HOME=/home/
/home | home $ cd
/home | home $ HOME=//home
/home | home $ cd
~ | ~ $ HOME=//home/
//home | home $ cd
//home | home $ HOME=/
//home | home $ cd
/ | / $ HOME=//
/ | / $ cd
~ | ~ $ exit

and this is behavior with the patch:
bash-4.3$ cd
bash-4.3$ PS1='\w | \W \$ '
~ | ~ $ HOME=/home
/home.local/lpechacek | lpechacek $ cd
~ | ~ $ HOME=/home/
~ | ~ $ cd
~ | ~ $ HOME=//home
/home | home $ cd
~ | ~ $ HOME=//home/
~ | ~ $ cd
~ | ~ $ HOME=/
//home | home $ cd
/ | / $ HOME=//
/ | / $ cd
~ | ~ $ exit


>From ef9c5e823131098d90b3f2aabaf539df59a01cba Mon Sep 17 00:00:00 2001
From: Libor Pechacek <lpechacek@suse.cz>
Date: Fri, 23 May 2014 09:30:49 +0200
Subject: [PATCH] Make \w and \W tolerate trailing slash in $HOME

Currently \w and \W abbreviate $HOME into tilde only when it ends with a
character different from slash.  This patch makes them tolerate trailing
slashes.
---
 general.c |  5 ++++-
 parse.y   | 10 ++++++++--
 y.tab.c   | 10 ++++++++--
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/general.c b/general.c
index 087689eb74cc..02163d3079c3 100644
--- a/general.c
+++ b/general.c
@@ -699,7 +699,10 @@ polite_directory_format (name)
   int l;
 
   home = get_string_value ("HOME");
-  l = home ? strlen (home) : 0;
+
+  /* remove trailing slashes from $HOME before comparisons */
+  for (l = home ? strlen (home) : 0; l > 2 && home[l-1] == '/'; l--);
+
   if (l > 1 && strncmp (home, name, l) == 0 && (!name[l] || name[l] == '/'))
     {
       strncpy (tdir + 1, name + l, sizeof(tdir) - 2);
diff --git a/parse.y b/parse.y
index 91bf3bf649bd..91fbaaa924de 100644
--- a/parse.y
+++ b/parse.y
@@ -5384,7 +5384,7 @@ decode_prompt_string (string)
              {
                /* Use the value of PWD because it is much more efficient. */
                char t_string[PATH_MAX];
-               int tlen;
+               int tlen, l;
 
                temp = get_string_value ("PWD");
 
@@ -5415,7 +5415,13 @@ decode_prompt_string (string)
 #define ROOT_PATH(x)   ((x)[0] == '/' && (x)[1] == 0)
 #define DOUBLE_SLASH_ROOT(x)   ((x)[0] == '/' && (x)[1] == '/' && (x)[2] == 0)
                /* Abbreviate \W as ~ if $PWD == $HOME */
-               if (c == 'W' && (((t = get_string_value ("HOME")) == 0) || 
STREQ (t, t_string) == 0))
+               /* remove trailing slashes from $HOME before comparisons */
+               t = get_string_value ("HOME");
+               for (l = t ? strlen (t) : 0; l > 2 && t[l-1] == '/'; l--);
+               if (l)
+                 t[l] = 0;
+
+               if (c == 'W' && ((t == 0) || STREQ (t, t_string) == 0))
                  {
                    if (ROOT_PATH (t_string) == 0 && DOUBLE_SLASH_ROOT 
(t_string) == 0)
                      {
diff --git a/y.tab.c b/y.tab.c
index 80fe9308398e..d9bf6b1d056a 100644
--- a/y.tab.c
+++ b/y.tab.c
@@ -7696,7 +7696,7 @@ decode_prompt_string (string)
              {
                /* Use the value of PWD because it is much more efficient. */
                char t_string[PATH_MAX];
-               int tlen;
+               int tlen, l;
 
                temp = get_string_value ("PWD");
 
@@ -7727,7 +7727,13 @@ decode_prompt_string (string)
 #define ROOT_PATH(x)   ((x)[0] == '/' && (x)[1] == 0)
 #define DOUBLE_SLASH_ROOT(x)   ((x)[0] == '/' && (x)[1] == '/' && (x)[2] == 0)
                /* Abbreviate \W as ~ if $PWD == $HOME */
-               if (c == 'W' && (((t = get_string_value ("HOME")) == 0) || 
STREQ (t, t_string) == 0))
+               /* remove trailing slashes from $HOME before comparisons */
+               t = get_string_value ("HOME");
+               for (l = t ? strlen (t) : 0; l > 2 && t[l-1] == '/'; l--);
+               if (l)
+                 t[l] = 0;
+
+               if (c == 'W' && ((t == 0) || STREQ (t, t_string) == 0))
                  {
                    if (ROOT_PATH (t_string) == 0 && DOUBLE_SLASH_ROOT 
(t_string) == 0)
                      {
-- 
1.7.12.4