CVS commit: src/bin/sh

["Robert Elz" <kre%netbsd.org@localhost>]

Module Name:    src
Committed By:   kre
Date:           Mon Mar  6 05:54:34 UTC 2023

Modified Files:
        src/bin/sh: expand.c

Log Message:
Adjust tilde expansion as will be documented in the forthcoming
version of the POSIX standard (Issue 8).   I believe we were already
compliant with what is to be required, but POSIX is now encouraging
(and will likely require in a later version) that if a tilde expansion
produces a string which ends in a '/' and the '~' that was expanded
is immediately followed by a '/' in the input word, that one of those
two slashes be omitted.   The worst (current) example of this is
when HOME=/ and we expand ~/foo - previously producing //foo which is
(in POSIX) a path with implementation defined semantics, and so not
what we should be generating by accident.   Change that, so now if
the ~ prefix expansion ends in a '/' and there is a '/' following
immediately after, the resulting word contains only one of those
chars (in the example just given, we will now produce /foo instead).

POSIX is also making it clear that the expansion that results from
the tilde expansion is treated as quoted (not subject to pathname
expansion, or field splitting, or any var/arith/command substitutions)
and that if HOME="" the expansion of ~ must generate "" (not nothing).
Our implementation did all of that already (though older versions
used to treat an empty expansion of HOME the same as if HOME was
unset - that was fixed some time ago).

The actual modification made here is probably smaller than this log entry,
and without added comments, certainly is!


To generate a diff of this commit:
cvs rdiff -u -r1.141 -r1.142 src/bin/sh/expand.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.