HOME=/dest cd does not honour the HOME environment

[McDutchie]

In ksh-community/ksh#19 (comment), @Earnestly wrote:

The builtin cd does not appear to check its environment for HOME when determining where to change the working directory when given no arguments.

# HOME=/bin cd; pwd
/root # Should be /bin

This otherwise works in every shell-including bourne-and is specified by POSIX:

2. If no directory operand is given and the HOME environment variable is set to a non-empty value, the cd utility shall behave as if the directory named in the HOME environment variable was specified as the directory operand.

I agree this should work, and it's a bug that it doesn't. cd is a regular built-in command, so the preceding assignment to HOME should be in effect while cd is executed.

Confirmed in ksh 93u+ 2012-08-01 and in current ksh 93u+m.

[McDutchie]

The fix is simple: there was a missing sh_scoped() call.

diff --git a/src/cmd/ksh93/bltins/cd_pwd.c b/src/cmd/ksh93/bltins/cd_pwd.c
index 977be2bcf..9a7d25fb8 100644
--- a/src/cmd/ksh93/bltins/cd_pwd.c
+++ b/src/cmd/ksh93/bltins/cd_pwd.c
@@ -107,7 +107,7 @@ int	b_cd(int argc, char *argv[],Shbltin_t *context)
 	if(argc==2)
 		dir = sh_substitute(oldpwd,dir,argv[1]);
 	else if(!dir)
-		dir = nv_getval(HOME);
+		dir = nv_getval(sh_scoped(HOME));
 	else if(*dir == '-' && dir[1]==0)
 		dir = nv_getval(opwdnod);
 	if(!dir || *dir==0)

[McDutchie]

This didn't work either, and is also fixed by the patch above:

$ ksh -c 'function f { typeset HOME=/bin; cd; }; f; pwd' 
/Users/martijn
$ arch/darwin.arm64-64/bin/ksh -c 'function f { typeset HOME=/bin; cd; }; f; pwd' 
/bin