From d1483150ab985ab368f16315a6dbe4f936ab7344 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Tue, 5 Jan 2021 04:55:07 +0000
Subject: [PATCH] 'cd': properly ignore $CDPATH if initial component is '.' or
 '..'

@stephane-chazelas writes:
> Per POSIX[*], cd should skip the $CDPATH processing if the first
> component of the directory given to cd is . or ...
>
> Yet, with ksh93u+m 2021-01-03 at least, while that's OK with ..,
> it's not with . with or without the posix option:
>
> $ CDPATH=/ ./ksh -o posix -c 'cd -P ./etc && pwd'
> /etc
> /etc
>
> It seems to be a regression introduced with ksh93u+ as I can't
> reproduce it with ksh93u or any version prior to that. I can also
> reproduce in u+, v- and the ksh2020 from the Ubuntu 20.04
> package.

src/cmd/ksh93/bltins/cd_pwd.c: b_cd():
- Skip $CDPATH processing not only if the path is absolute, but
  also if the initial path component is '.' or '..' (in the latter
  case the $CDPATH processing was done but appeared to be a no-op).

src/cmd/ksh93/tests/builtins.sh:
- Add regression test.

[*] https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/utilities/cd.html

Fixes: https://github.com/ksh93/ksh/issues/151
---
 NEWS                            |  4 ++++
 src/cmd/ksh93/bltins/cd_pwd.c   | 10 +++++++---
 src/cmd/ksh93/include/version.h |  2 +-
 src/cmd/ksh93/tests/builtins.sh |  6 ++++++
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/NEWS b/NEWS
index e7c70848c..3d8720350 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,10 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-01-05:
+
+- Fixed a bug in 'cd' that caused 'cd ./foo' to search for 'foo' in $CDPATH.
+
 2021-01-03:
 
 - The invocation
diff --git a/src/cmd/ksh93/bltins/cd_pwd.c b/src/cmd/ksh93/bltins/cd_pwd.c
index aae651fce..fcffc398b 100644
--- a/src/cmd/ksh93/bltins/cd_pwd.c
+++ b/src/cmd/ksh93/bltins/cd_pwd.c
@@ -100,11 +100,15 @@ int	b_cd(int argc, char *argv[],Shbltin_t *context)
 	if(shp->subshell && !shp->subshare)
 		sh_subfork();
 #endif /* !lib_fchdir */
+	/*
+	 * Do $CDPATH processing, except if the path is absolute or the first component is '.' or '..'
+	 */
+	if(dir[0] != '/'
 #if _WINIX
-	if(*dir != '/' && (dir[1]!=':'))
-#else
-	if(*dir != '/')
+	&& dir[1] != ':'  /* on Windows, an initial drive letter plus ':' denotes an absolute path */
 #endif /* _WINIX */
+	&& !(dir[0]=='.' && (dir[1]=='/' || dir[1]==0))
+	&& !(dir[0]=='.' && dir[1]=='.' && (dir[2]=='/' || dir[2]==0)))
 	{
 		if(!(cdpath = (Pathcomp_t*)shp->cdpathlist) && (dp=sh_scoped(shp,CDPNOD)->nvalue.cp))
 		{
diff --git a/src/cmd/ksh93/include/version.h b/src/cmd/ksh93/include/version.h
index c6db0fbef..c8c295671 100644
--- a/src/cmd/ksh93/include/version.h
+++ b/src/cmd/ksh93/include/version.h
@@ -20,7 +20,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-01-03"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-01-05"	/* must be in this format for $((.sh.version)) */
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */
 /* Arithmetic $((.sh.version)) uses the last 10 chars, so the date must be at the end. */
diff --git a/src/cmd/ksh93/tests/builtins.sh b/src/cmd/ksh93/tests/builtins.sh
index a482789b6..88f3c6e01 100755
--- a/src/cmd/ksh93/tests/builtins.sh
+++ b/src/cmd/ksh93/tests/builtins.sh
@@ -832,6 +832,12 @@ actual=$({ a=$(cd; pwd); } >&-; print -r -- "$a")
 [[ $actual == "$expect" ]] || err_exit "'cd' broke new-form command substitution with outer stdout closed" \
 	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
 
+# CDPATH was not ignored by 'cd ./dir': https://github.com/ksh93/ksh/issues/151
+expect=': cd: ./dev: [No such file or directory]'
+actual=$( (CDPATH=/ cd -P ./dev && pwd) 2>&1 )
+let "(e=$?)==1" && [[ $actual == *"$expect" ]] || err_exit "CDPATH not ignored by cd ./dir" \
+	"(expected *$(printf %q "$expect") with status 1, got $(printf %q "$actual") with status $e)"
+
 # ======
 # 'readonly' should set the correct scope when creating variables in functions
 unset foo