This mostly reverts 17af5d51de.
Suggested by Andy Wingo <wingo@igalia.com>.
* guix/ssh.scm (remote-daemon-channel)[redirect]: Remove 'read!' FFI
hack. Use buffered ports.
This fixes a regression in 'retrieve-files*' introduced in
896fec476f, whereby (guix scripts offload)
would not read the initial sexp now sent by the remote host via
'store-export-channel'. This would effectively prevent file retrieval
entirely when offloading.
* guix/ssh.scm (retrieve-files*): New procedure, like former
'retrieve-files' but with an extra #:import parameter.
(retrieve-files): Rewrite in terms of 'retrieve-files*'.
(file-retrieval-port): Make private.
* guix/scripts/offload.scm (transfer-and-offload): Pass #:import to
'retrieve-files*'.
(retrieve-files*): Remove.
Previously the redirect code could end up exiting prematurely because of
an uninteresting "exceptional condition" on the socket (info "(libc)
Waiting for I/O").
* guix/ssh.scm (remote-daemon-channel): Pass the empty list as the third
argument to 'select'. It was a mistake to pass a non-empty list there
in the first place.
This works around <https://bugs.gnu.org/30066> and noticeably improves
performance when using GUIX_DAEMON_SOCKET=ssh://HOST (the redirect code
was transferring data to guix-daemon one byte at a time!).
* guix/ssh.scm (remote-daemon-channel)[redirect]: Define 'read!' and use
it instead of 'get-bytevector-some'.
'guix copy --from' now reports messages much more useful than "failed to
retrieve files".
* guix/ssh.scm (store-export-channel)[export]: Wrap 'use-modules' in
'catch' and 'with-store' in 'guard'. Check for invalid items. Write a
status sexp on stdout.
(raise-error): New macro.
(retrieve-files): Read the initial status sexp and report errors
accordingly.
Fixes <http://bugs.gnu.org/26972>.
* guix/ssh.scm (store-import-channel)[import]: Add 'consume-input'
procedure. Wrap body in 'catch' and 'guard'. Use 'open-remote-pipe'
with OPEN_BOTH instead of 'open-remote-output-pipe'.
(send-files): After the 'channel-send-eof' call, do (read port).
Interpret the result sexp and raise an error condition if needed.
* guix/scripts/offload.scm (connect-to-remote-daemon)
(store-import-channel, store-export-channel, send-files)
(retrieve-files): Move to (guix ssh).
(nonce): Add optional 'name' parameter and use it.
(retrieve-files*): New procedure.
(transfer-and-offload): Use it instead of 'retrieve-files', and add
first parameter to 'send-files'.
(assert-node-can-import): Likewise.
(assert-node-can-export): Use 'retrieve-files' instead of
'store-export-channel'.
* guix/ssh.scm: New file.
* configure.ac: Use 'GUIX_CHECK_GUILE_SSH' and define 'HAVE_GUILE_SSH'
Automake conditional.
* Makefile.am (MODULES) [HAVE_GUILE_SSH]: Add guix/ssh.scm.
Ludovic Courtès