base: Make `open` calls interruptiblewip/T17912

As noted in #17912, `open` system calls were `safe` rather than
`interruptible`. Consequently, the program could not be interrupted with
SIGINT if stuck in a slow open operation. Fix this by marking
`c_safe_open` as interruptible.

2 files changed, 7 insertions, 2 deletions

diff --git a/libraries/base/System/Posix/Internals.hs b/libraries/base/System/Posix/Internals.hs
index 15a02ff1e1..ea8ddf2173 100644
--- a/libraries/base/System/Posix/Internals.hs
+++ b/libraries/base/System/Posix/Internals.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE InterruptibleFFI #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, CApiFFI #-}
 {-# OPTIONS_HADDOCK not-home #-}
 
@@ -355,7 +356,8 @@ type CFilePath = CWString
 foreign import ccall unsafe "HsBase.h __hscore_open"
    c_open :: CFilePath -> CInt -> CMode -> IO CInt
 
-foreign import ccall safe "HsBase.h __hscore_open"
+-- e.g. use `interruptible` rather than `safe` due to #17912.
+foreign import ccall interruptible "HsBase.h __hscore_open"
    c_safe_open :: CFilePath -> CInt -> CMode -> IO CInt
 
 foreign import ccall unsafe "HsBase.h __hscore_fstat"
diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md
index 026de1df82..e667b3fef9 100644
--- a/libraries/base/changelog.md
+++ b/libraries/base/changelog.md
@@ -1,7 +1,10 @@
 # Changelog for [`base` package](http://hackage.haskell.org/package/base)
 
 ## 4.15.0.0 *TBA*
-  * TODO
+
+  * `openFile` now calls the `open` system call with an `interruptible` FFI
+    call, ensuring that the call can be interrupted with `SIGINT` on POSIX
+    systems.
 
 ## 4.14.0.0 *TBA*
   * Bundled with GHC 8.10.1