propagate errors from flush and close within ios_close (#35326)

Author: JeffBezanson

NEWS.md

@@ -116,6 +116,8 @@ Standard library changes
   order from `order` is used to compare the values of `by(element)`. In the latter case,
   any order different from `Forward` or `Reverse` will raise an error about the
   ambiguity.
+* `close` on a file (`IOStream`) can now throw an exception if an error occurs when trying
+  to flush buffered data to disk ([#35303]).
 
 #### LinearAlgebra
 * The BLAS submodule now supports the level-2 BLAS subroutine `hpmv!` ([#34211]).

base/iostream.jl

@@ -42,15 +42,23 @@ to synchronous `File`'s and `IOStream`'s not to any of the asynchronous streams.
 fd(s::IOStream) = Int(ccall(:jl_ios_fd, Clong, (Ptr{Cvoid},), s.ios))
 
 stat(s::IOStream) = stat(fd(s))
-close(s::IOStream) = @lock_nofail s.lock ccall(:ios_close, Cvoid, (Ptr{Cvoid},), s.ios)
+
 isopen(s::IOStream) = ccall(:ios_isopen, Cint, (Ptr{Cvoid},), s.ios) != 0
+
+function close(s::IOStream)
+    bad = @lock_nofail s.lock ccall(:ios_close, Cint, (Ptr{Cvoid},), s.ios) != 0
+    systemerror("close", bad)
+end
+
 function flush(s::IOStream)
     sigatomic_begin()
     bad = @lock_nofail s.lock ccall(:ios_flush, Cint, (Ptr{Cvoid},), s.ios) != 0
     sigatomic_end()
     systemerror("flush", bad)
 end
+
 iswritable(s::IOStream) = ccall(:ios_get_writable, Cint, (Ptr{Cvoid},), s.ios)!=0
+
 isreadable(s::IOStream) = ccall(:ios_get_readable, Cint, (Ptr{Cvoid},), s.ios)!=0
 
 """

src/support/ios.c

@@ -648,17 +648,21 @@ int ios_flush(ios_t *s)
     return 0;
 }
 
-void ios_close(ios_t *s)
+int ios_close(ios_t *s)
 {
-    ios_flush(s);
-    if (s->fd != -1 && s->ownfd)
-        close(s->fd);
+    int err = ios_flush(s);
+    if (s->fd != -1 && s->ownfd) {
+        int err2 = close(s->fd);
+        if (err2 != 0)
+            err = err2;
+    }
     s->fd = -1;
     if (s->buf!=NULL && s->ownbuf && s->buf!=&s->local[0]) {
         LLT_FREE(s->buf);
     }
     s->buf = NULL;
     s->size = s->maxsize = s->bpos = 0;
+    return err;
 }
 
 int ios_isopen(ios_t *s)

src/support/ios.h

@@ -93,7 +93,7 @@ JL_DLLEXPORT int ios_trunc(ios_t *s, size_t size) JL_NOTSAFEPOINT;
 JL_DLLEXPORT int ios_eof(ios_t *s);
 JL_DLLEXPORT int ios_eof_blocking(ios_t *s);
 JL_DLLEXPORT int ios_flush(ios_t *s);
-JL_DLLEXPORT void ios_close(ios_t *s);
+JL_DLLEXPORT int ios_close(ios_t *s);
 JL_DLLEXPORT int ios_isopen(ios_t *s);
 JL_DLLEXPORT char *ios_take_buffer(ios_t *s, size_t *psize);  // release buffer to caller
 // set buffer space to use