On 2024-04-08 22:37:50, Jacob Bachmeyer <jcb62281@gmail.com> spake thus:
Richard Stallman wrote:
[...]
In principle it could be posible to output something different to
describe this stramge situation explicitly. For instance, output "via
stdin" as a comment, or output `stdin/../filename' as the file name.
(Programs that optimize the file name by deleting XXX/.../ are likely
not to check whether XXX is a real directory.)
With the small difference that I believe the special marker should be
'<stdin>' (with the angle brackets, as it is now), this could be another
good idea. Example output: "[working directory]/<stdin>///[specified
filename]" or "[specified filename]///<>/[working directory]/<stdin>".
GDB could be modified to recognize either form and read the specified
file (presumably some form of augmented C) but report that the sources
were transformed prior to compilation. The use of triple-slash ensures
that these combined strings cannot be confused with valid POSIX
filenames, although I suspect that uses of these strings would have to
be a GNU extension to the debugging info format.
I do not think that the use of triple-slash (or any-N-slash) would
entirely prevent potential confusion with valid POSIX filenames, as
POSIX treats multiple slashes as equivalent to a single slash
(except in at the beginning of a path, where two slash characters
may have a different, implementation-defined meaning).
Since a pathname component name can basically contains any bytes
except <NUL> and <slash>, any token value chosen will likely have
some non-zero potential for confusion with a valid POSIX pathname.
From SUSv4 2018[0] (update from 2020-04-30, which is what I happen
to have handy):
<quote>
3.271 Pathname
A string that is used to identify a file. In the context of
POSIX.1-2017, a pathname may be limited to {PATH_MAX} bytes,
including the terminating null byte. It has optional beginning
<slash> characters, followed by zero or more filenames separated
by <slash> characters. A pathname can optionally contain one or
more trailing <slash> characters. Multiple successive <slash>
characters are considered to be the same as one <slash>, except
for the case of exactly two leading <slash> characters.
</quote>