Allow the Esperanto support for lwt
#945
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From this PR, this simple code works for Ubuntu: open Lwt.Infix
let rec full_write fd buf off len =
Lwt_unix.write fd buf off len >>= fun len' ->
if len - len' > 0
then full_write fd buf (off + len') (len - len')
else Lwt.return_unit
let tmp = Bytes.create 0x1000
let rec cat () =
Lwt.catch begin fun () ->
Lwt_unix.read Lwt_unix.stdin tmp 0 (Bytes.length tmp) >>= fun len ->
match len with
| 0 -> Lwt.return_unit
| len -> full_write Lwt_unix.stdout tmp 0 len >>= cat
end @@ function
| End_of_file -> Lwt.return_unit
| exn -> raise exn
let () = Lwt_main.run (cat ())If you want to try, you need to create a $ cat >dune <<EOF
(executable
(enabled_if
(= %{context_name} esperanto))
(libraries lwt.unix)
(modules cat_lwt_unix)
(name cat_lwt_unix))
(rule
(target cat_lwt_unix.com)
(enabled_if
(= %{context_name} esperanto))
(mode promote)
(deps cat_lwt_unix.exe)
(action (run objcopy -S -O binary %{deps} %{target})))
EOF
$ cat >dune-workspace <<EOF
(lang dune 2.0)
(context (default))
(context
(default
(name esperanto)
(toolchain esperanto)
(merlin)
(host default)))
EOF
$ cat >cat_lwt_unix.opam <<EOF
opam-version: "2.0"
name: "cat-lwt-unix"
maintainer: [ "Romain Calascibetta <[email protected]>" ]
authors: [ "Romain Calascibetta <[email protected]>" ]
homepage: "https://github.com/dinosaure/esperanto"
bug-reports: "https://github.com/dinosaure/esperanto/issues"
dev-repo: "git+https://github.com/dinosaure/esperanto"
doc: "https://dinosaure.github.io/esperanto/"
license: "MIT"
synopsis: "cat tool with lwt and compiled with esperanto"
description: "cat tool with lwt and compiled with esperanto"
build: [
[ "dune" "build" "-p" name "-j" jobs ]
]
install: [
[ "dune" "install" "-p" name ] {with-test}
]
depends: [
"ocaml" {>= "4.08.0"}
"dune" {>= "2.6.0"}
"lwt"
]
pin-depends: [
[ "lwt.dev" "git+https://github.com/dinosaure/lwt.git#69419f4352d1ae0e60039275ec9da893c505e2c6" ]
]
EOFThen, to be able to cross-compile this little project, you must use $ opam pin add -y https://github.com/dinosaure/esperanto.git
$ opam monorepo lock
$ opam monorepo pull
$ dune build
$ bash -c "echo 'Hello World!' | ./cat_lwt_unix.com"
Hello World! |
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This PR is definitely ready:
If you have any question, don't hesitate but I hope that I clearly described everything! |
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Thanks for this PR! I like the idea behind esperanto/cosmopolitan very nice! Some comments about the MR specifically:
Re: |
Currently, Esperanto support 4.12, 4.13 and 4.14 (MirageOS support) but I can not go further when it requires more time that I don't really have. |
Nice! I got the 4.14 support from the Esperanto README:
This might need updating. Otherwise I had a longer look and I don't think the two changesets will conflict. So we should be good on that front. |
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I added a CI which compile and run a simple LWT program with Regardless the Windows support, this PR is ready - however, you should get some conflict with #953. |
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@dinosaure Cosmopolitan Libc has pthreads support now. https://github.com/jart/cosmopolitan/releases/tag/2.1 If there's an issue with setcontext() and getcontext() that are causing issues for fibers, then let me know and I'll fix it. |
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Currently, this PR can compile a simple program. However, the example (a simple |
In some contexts, the C compiler can integrate few -I and -L and pthread becomes standalone from the user's point-of-view. However, in the context of a C cross-compiler, standalone pthread's definitions can be different than the host system (available into [default_search_paths]) and they can clash. This patch allow us to compile a C code without any flags and let the C (cross?)-compiler to solve by itself where is pthread. This behavior is added from what src/unix/config/discover.exe did before.
This patch use if/else if/else instead of a switch ... case which expects constants. These values are not constants from the Cosmopolitan libc which set these variables at the "boot" of the application and set them with the right value according to the running system.
Instead of a static & global array, we moved the array of MADV_* values into the function which uses it.
Instead of a static & global array, we moved the array of TC* values into the function which uses it.
Instead of a static & global array, we moved the array of WNOHANG & WUNTRACED values into the function which uses it.
This patch create 2 C functions to initialize an array with speed values or termios values. If we pass NULL to these functions, they returns the length of the array. By this way, we initiate required arrays which contains speeds & termios value at the runtime - instead of the compile time. This patch is needed because these values are not constants for the Cosmopolitan libc and we must set/initialize arrays at runtime.
This patch is probably the more invasive about Esperanto/Cosmopolitan. It adds a new compilation path when [__ESPERANTO__] is defined. A note was added to explain where it comes from: the cross-compiler [arch-esperanto-none-static-cc] systematically defines [-D__ESPERANTO__] in order to let third-party libraries (such as lwt) to choose different compilation paths. And here we are! Cosmopolitan does not defines required [_SC*] constants and [unix_get_pw_gr_nam_id_job] can not be compiled. We discard this piece of code when we want to compile with Cosmopolitan as it's the case for Android too.
The default case of [C_library_flags.detect] puts systematically [-I/usr/include] and [-L/usr/lib] even in a cross-compilation context which is wrong because [/usr/include/pthread.h] can clash [cross-env/pthread.h] for instance. The default case about underlying libraries (libev or pthread) should be available only from a restrictive set of flags instead of a pervasive one. This patch restricts this set to what we really need instead to pervasively picks some random flags. A clarification about the recognition of [pthread] was made too to really understand the behavior of [discover.exe] and give a chance to be more reproducible afterwards
If we consider pthread as the default implementation needed by lwt, we
should prioritize the recognition of [pthread] before [libev] but more
concretely, due to the undeterministic behavior of [discover.exe] and
our usage of [C_library_flags.set_{c,link}_flags] to reset any flags
when we can link [pthread] from a cross-compiler, it seems that we reset
aggregate flags needed for [libev] (specially [-lev]) in the same time.
This patch aggregate flags needed for [pthread] first and let the
recognition of [libev] then. However, that mostly means that in the
context of the cross-compilation, the user must NOT install
[conf-libev] (otherwise, we will try to link with the host's [libev]
which is obviously incompatible with our cross-compiler). This patch
wants to keep, as much as we can, the same behavior - but it highlights
limits of [discover.exe].
The last release of esperanto does not define speed_t constants. We must protect the definition of our speed_t table when the toolchain is esperanto.
Currently, the Cosmopolitan/Esperanto toolchain protects the usage of pthread and we are not able to pass to it 0. This patch allows us to compile (and recognize the support of pthread) the code with the esperanto toolchain.
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This PR is actually ready, the CI works on my side and we are able to compile & run a Cosmopolitan binary with |
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| static struct { | ||
| struct speed_t { |
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I don't think you should be re-defining speed_t here. It's in the libc.
Data Type: speed_t
The speed_t type is an unsigned integer data type used to represent line speeds.
https://www.gnu.org/software/libc/manual/html_node/Line-Speed.html
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I need to look on it but keep in your mind that we currently cross-compile lwt with the Cosmopolitan C library. The GNU C library is not involve anymore in the case of the esperanto toolchain. A #define will be appropriate to drive the compilation according to the target.
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Ah, my bad, I got confused! You're defining struct speed_t, but posix defines speed_t as a typedef to an unsigned integer type. They're two different namespaces, all is fine. Reusing speed_t is not great IMO, but works (although names ending in _t are reserved).
| {B150, 150}, | ||
| }; | ||
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| long _speedtable(struct speed_t dst[]) { |
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Strictly speaking names beginning with an underscore (_) are reserved by the C implementation.
| default: | ||
| return 0; | ||
| } | ||
| long _terminal_io_descr(long dst[]) { |
| void encode_terminal_status(struct termios *terminal_status, volatile value *dst) | ||
| { | ||
| long *pc; | ||
| int i; | ||
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| long _NSPEEDS = _speedtable(NULL); |
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Might be interesting to checkout this patch to GCC, allowing compilation of unmodified code with Cosmo, by compiler rewriting uses of preprocessor constants. |
This PR wants to fix the support with the Esperanto & Cosmopolitan. Esperanto is an OCaml toolchain which allows us to compile an OCaml application. The resulted application (an executable) should run anywhere (Linux, Mac, Windows and BSD family).
Currently, a simple project in OCaml can be compiled with Esperanto but a larger project which probably uses
lwtcan not be compiled because few details. This PR wants to fix these details and allow us to take an OCaml application which depends onlwtand be able to build-once an application which should run-anywhere.This PR is a draft because a special commit (the second to last) is probably the most invasive and dependant to Esperanto but I can probably find an other situation than what I proposed. Feel free to comment the rest of commits which are valid for us for the Esperanto toolchain. I tried to be less invasive as I can.