Please add eazy-process

[guicho271828]

https://github.com/guicho271828/eazy-process

In run-program interface in the popular implementations, piping between subprocesses are hard. It requires either reading the entire output stream and packing the contents as a new string-input-stream, or using some other implementation-specific functions. Compatibility libraries e.g. trivial-shell or inferior-shell, often depend on run-program, but not implement "other impl-specific functions", therefore piping is again not clean. Iolib also has run-program that allows easy piping, but it is restricted to 3 fds: input,output,error.

Eazy-process provides a declarative and thin layer for manipulating processes. It is built on the concept of UNIX: "everything is a file" and do not provide interfaces to streams.

Currently, the only implementation verified to work as expected is SBCL on linux. CCL does not pass the test due to errors in opening /def/fd/[fd] to read/write the input/output/error directly. However, you can avoid this issue by writing the output to a temporary file and opening the file.

I suspect the same test might pass on the other OSes because it is a linux-specific problem (realpath(3) returns NULL and sets errno EACCES on those special files).

I used part of codes in SBCL and trivial-shell, so the current MIT licence might have to be changed.

[guicho271828]

if possible, please also "garbage collect" inner-conditional ...

[quicklisp]

Sorry, I do not like to add projects that work only on one implementation. Can you let me know when it supports more than one?

[guicho271828]

I do not mind if the addition is delayed. I use it in my private work anyways.

Ideally it should work on all implementations since it uses iolib.syscalls (and in turn CFFI) and quicklisp-available packages only. There is no dependency to the implementation-specific packages. Build passes on all impls except on ecl (which fails to load CFFI).

What has been shown here is that there is only 1 implementation that is able to (cl:open "/dev/fd/0") on Linux. It is not that eazy-process fails inside its functions because of this. Things happen outside eazy-process. See the test case below:

(test read
  (let ((p1 (shell `("hostname"))))       ; eazy-process:shell
    (let ((fdpath (fd-as-pathname p1 1))) ; eazy-process:fd-as-pathname returns #p"/dev/fd/16"
      (with-open-file (s fdpath)          ; abcl and ccl fail to open the file here
        (is (string= (machine-instance)
                     (read-line s)))))))

If you have a Mac, which I don't have, would you please try (cl:open "/dev/fd/0") in your CCL repl? It might be okay on darwin because it uses different file system for /dev/fd/. Darwin implements it with fdesc, while linux makes the symlinks to /proc/self/fd/, which is implemented with proc filesystem. Please also refer to http://trac.clozure.com/ccl/ticket/1261 . I wait for the time when the other impls are fixed, or I fix it.

[guicho271828]

I asked a Mac owner to test (cl:open "/dev/fd/[int]") and (with-open-file (s "/dev/fd/1" :direction :output :if-exists :overwrite) (write-char #\x s)), both worked well. I now think the test should pass on darwin on CCL and SBCL.