[CD] support drive letters on Cygwin
The Cygwin platform supports DOS style drive-letter paths such
as "C:\\dir", even though the preferred form is a POSIX-style
"/cygdrive/c/dir". This can be seen by doing things such as
chdir("c:") (which succeeds) followed by getcwd(NULL, 0) (which
returns the normalized "/cygdrive/c"). However, dash was trying
to perform local manipulations on the argument to 'cd' prior to
calling into libc, in order to update the state of $PWD and
friends; these manipulations were assuming that the user meant
to change to a relative subdirectory of the current location,
as in './c:', instead of honoring the drive letter. None of
the other dash builtins take a filename and manipulate it to
affect shell state (some, like 'test', take a file name, but as
stat("c:") works just fine, there is no need to normalize).
This patch has no impact outside of cygwin; on cygwin, it takes
advantage of a native function call to canonicalize any
incoming name into preferred form before updating shell state.
Pre-patch:
$ dash -c 'cd c: && echo $PWD'
dash: 1: cd: can't cd to c:
Post-patch:
$ dash -c 'cd c: && echo $PWD'
/cygdrive/c
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2 files changed
