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Fix the behavior of Unix.read on Windows + Makefile changes#797

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Fix the behavior of Unix.read on Windows + Makefile changes#797
msprotz wants to merge 7 commits intoocaml:trunkfrom
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@msprotz msprotz commented Sep 7, 2016

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gasche commented Sep 7, 2016

Could we have a test in the testsuite that would fail (on Windows, I guess) with present-day code and works after your patch?

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gasche commented Sep 7, 2016

Is 725b80c meant to be part of the PR?

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msprotz commented Sep 7, 2016

Yes I've fixed the runtop target because I needed it to test my fix, so I've submitted these changes along with the pull request.

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msprotz commented Sep 7, 2016

I meant: I added the runtop target to Makefile.nt (it wasn't there)

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msprotz commented Sep 7, 2016

Your request for a test is legitimate. I shall point out, however, that:

  • there is no testsuite/tests/lib-unix (no comment);
  • I just tried writing a test, and of course, the tests are not capable of adding the right PATH (not LD_LIBRARY_PATH) like I did for runtop on Windows.

This is definitely not fun.

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msprotz commented Sep 7, 2016

So the tests are run in bytecode and native; the bytecode version needs an extra -I ../../../otherlibs/win32unix after path/to/ocamlrun.exe, but the Makefile doesn't have a way of differentiating the native and bytecode targets...

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msprotz commented Sep 7, 2016

I couldn't find out how to add a new directory to the test suite, but looking at the Appveyor logs it was correctly picked up (and the test was successful it seems).

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fdopen commented Sep 7, 2016

This change will break third party code that re-use Unix.file_descr for named pipes (e.g. https://github.com/djs55/ocaml-named-pipe/ ). So it should be documented properly.
(In the case of named pipes you have to distinguish between 0 and EPIPE. 0 means that WriteFile was called with 0, EPIPE that the pipe was closed. Your change conflates both, so Unix.read can't be used any longer for named pipes)

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msprotz commented Sep 7, 2016

Any suggestion on how to fix this cleanly?

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msprotz commented Sep 8, 2016

Also, are you saying that WriteFile with 0 is ok on a named piped but not on an anonymous pipe?

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msprotz commented Sep 8, 2016

I am told that there's no way to distinguish a named pipe from an anonymous pipe using the Windows API.

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msprotz commented Sep 20, 2016

Had a quick chat with Damien.

  • Rename the existing function read_raw (or something similar)
  • Write a read wrapper that catches the EPIPE exception and turns it into a zero-read
  • Document in the description of Unix.read that advanced users who wish to tell apart EPIPE and 0 because they're on Windows should bind read_raw using an external declaration.

Thoughts?

@samoht samoht mentioned this pull request Nov 9, 2016
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xavierleroy commented Dec 4, 2016

The proposed code is an improvement over what we have today and which makes pipes completely nonportable between Unix and Windows. So, I'm in favor of merging this PR as is.

The problem with named pipes and zero-length writes is weird. I'm positive that under Unix a write of length 0 has no effect. I'm not sure we want to go out of our way to preserve this strange Win32 idiom.

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protz commented Dec 16, 2016

Apparently ocaml-named-pipes is aware of the issue and certainly will adapt their code if needed... Who should I see to actually perform the merge? (My personal account, i.e. this one, doesn't have commit rights on GitHub.)

gasche added a commit that referenced this pull request Dec 16, 2016
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epipe: Changelog entry for #797
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gasche commented Dec 16, 2016

I merged manually to squash as appropriate.

@gasche gasche closed this Dec 16, 2016
camlspotter pushed a commit to camlspotter/ocaml that referenced this pull request Oct 17, 2017
@gasche
epipe: Changelog entry for ocaml#797
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@vicuna vicuna mentioned this pull request Mar 14, 2019
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stedolan pushed a commit to stedolan/ocaml that referenced this pull request Oct 25, 2022
@gretay-js
Long frames in frametable (ocaml#797)
5b0dba7
sadiqj pushed a commit to sadiqj/ocaml that referenced this pull request Feb 21, 2023
@gretay-js
flambda-backend: Long frames in frametable (ocaml#797)
3d38d13
stedolan pushed a commit to stedolan/ocaml that referenced this pull request Mar 21, 2023
@mshinwell
Squashed 'ocaml/' changes from 5bf2820..b11eea1
f97a773 
b11eea1 flambda-backend: Introduce Import_info (ocaml#1036)
bc5b135 flambda-backend: Fix `ocamlobjinfo` on flambda2 .cmx files (ocaml#1029)
c8babbd flambda-backend: Compilation_unit optimisations (ocaml#1035)
e8d3e22 flambda-backend: Use 4.14.0 opam switch for building (includes upgrading ocamlformat to 0.24.1) (ocaml#1030)
eb14a86 flambda-backend: Port PR81 from ocaml-jst (ocaml#1024)
131bc12 flambda-backend: Merge ocaml-jst 2022-12-13 (ocaml#1022)
06c189a flambda-backend: Make stack allocation the default (ocaml#1013)
98debd5 flambda-backend: Initial support for value slots not of value kind (ocaml#946)
deb1714 flambda-backend: Add is_last flag to closinfo words (ocaml#938)
d07fce1 flambda-backend: Disable poll insertion in Configure (ocaml#967)
0f1ce0e flambda-backend: Regenerate ocaml/configure autoconf 2.69 (instead of 2.71) (ocaml#1012)
27132d8 flambda-backend: Fix for spurious typing error related to expanding through functor arguments (ocaml#997)
724fb68 flambda-backend: Use `Compilation_unit.t` instead of `Ident.t` for globals (ocaml#871)
396d5b8 flambda-backend: Add a test for frametable setup in natdynlinked libraries (ocaml#983)
b73ab12 flambda-backend: Fix invocation of `caml_shared_startup` in native dynlink (ocaml#980)
7c7d75a flambda-backend: Fix split_default_wrapper which did not trigger anymore with flambda2 (ocaml#970)
8fb75bd flambda-backend: Port ocaml#11727 and ocaml#11732 (ocaml#965)
fdb7987 flambda-backend: Fix include functor issue after 4.14 merge. (ocaml#948)
9745cdb flambda-backend: Print -dprofile/-dtimings output to stdout like 4.12 (ocaml#943)
5f51f21 flambda-backend: Merge pull request ocaml#932 from mshinwell/4.14-upgrade
841687d flambda-backend: Run make alldepend in ocaml/ (ocaml#936)
72a7658 flambda-backend: Remove reformatting changes only in dynlink/dune (preserving PR889 and adjusting to minimise diff)
6d758cd flambda-backend: Revert whitespace changes in dune files, to match upstream
c86bf6e flambda-backend: Remove duplicate tests for polling
971dbeb flambda-backend: Testsuite fixes
32f8356 flambda-backend: Topeval fix for symbols patch
befea01 flambda-backend: Compilation fixes / rectify merge faults
a84543f flambda-backend: Merge ocaml-jst
8e65056 flambda-backend: Merge ocaml-jst
4d70045 flambda-backend: Remove filename from system frametable (amd64) (ocaml#920)
5e57b7d flambda-backend: Bugfix for runtime frame_descr logic for C frames (ocaml#918)
6423d5e flambda-backend: Merge pull request ocaml#914 from mshinwell/merge-ocaml-jst-2022-10-24
ead605c flambda-backend: Add a missing Extract_exception (ocaml#916)
c8f1481 flambda-backend: Resolve conflicts and add specialise/specialised attributes to Builtin_attributes
cf4d0d3 flambda-backend: Merge fixes (ocaml#21)
c2f742f flambda-backend: Re-enable some tests for Flambda2 (ocaml#881)
3d38d13 flambda-backend: Long frames in frametable (ocaml#797)
85aec7b flambda-backend: Add loop attribute to Builtin_attributes
c0f16e3 flambda-backend: Compilation fixes
90dea23 flambda-backend: Merge flambda-backend/main
5acc6ea flambda-backend: Fixes after merge
e501946 flambda-backend: Merge ocaml-jst
115083b flambda-backend: Merge ocaml-jst
9943b2e flambda-backend: Revert "Revert "Transform tail-recursive functions into recursive continuations (ocaml#893)"" (ocaml#909)
ce339f1 flambda-backend: Fix alloc modes and call kinds for overapplications (ocaml#902)
e6a317c flambda-backend: Revert "Transform tail-recursive functions into recursive continuations (ocaml#893)"
853c488 flambda-backend: Transform tail-recursive functions into recursive continuations (ocaml#893)
5a977e4 flambda-backend: Fix missing End_region primitives on switch arms (ocaml#898)
7fa7f9d flambda-backend: Add missing dependencies to Dune files (ocaml#889)
3cd36f0 flambda-backend: Have Lambda `Pgetglobal` and `Psetglobal` take `Compilation_unit.t` (ocaml#896)
7565915 flambda-backend: [@poll error] attribute (ocaml#745)
9eb9448 flambda-backend: Backport the main safepoints PRs (ocaml#740)
689bdda flambda-backend: Add strict mode for ocamldep (ocaml#892)

git-subtree-dir: ocaml
git-subtree-split: b11eea1
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5 participants

@msprotz @gasche @fdopen @xavierleroy @protz