win: Fix reading from stdin

* Reading from stdin on Windows is fixed in the same way as it was in
  #8267.
* The file_read function was returning without filling the
  destination buffer when it was called with a non-blocking file
  descriptor.

3 files changed, 16 insertions, 6 deletions

diff --git a/src/nvim/main.c b/src/nvim/main.c
index 067184c8c7..4f9a5a979f 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1096,6 +1096,17 @@ scripterror:
             int error;
             if (STRCMP(argv[0], "-") == 0) {
               const int stdin_dup_fd = os_dup(STDIN_FILENO);
+#ifdef WIN32
+              // On Windows, replace the original stdin with the
+              // console input handle.
+              close(STDIN_FILENO);
+              const HANDLE conin_handle =
+                CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
+                           FILE_SHARE_READ, (LPSECURITY_ATTRIBUTES)NULL,
+                           OPEN_EXISTING, 0, (HANDLE)NULL);
+              const int conin_fd = _open_osfhandle(conin_handle, _O_RDONLY);
+              assert(conin_fd == STDIN_FILENO);
+#endif
               FileDescriptor *const stdin_dup = file_open_fd_new(
                   &error, stdin_dup_fd, kFileReadOnly|kFileNonBlocking);
               assert(stdin_dup != NULL);
diff --git a/src/nvim/os/fileio.c b/src/nvim/os/fileio.c
index 0ef9307a5a..ccf35fd57c 100644
--- a/src/nvim/os/fileio.c
+++ b/src/nvim/os/fileio.c
@@ -282,6 +282,7 @@ ptrdiff_t file_read(FileDescriptor *const fp, char *const ret_buf,
   char *buf = ret_buf;
   size_t read_remaining = size;
   RBuffer *const rv = fp->rv;
+  bool called_read = false;
   while (read_remaining) {
     const size_t rv_size = rbuffer_size(rv);
     if (rv_size > 0) {
@@ -289,7 +290,9 @@ ptrdiff_t file_read(FileDescriptor *const fp, char *const ret_buf,
       buf += rsize;
       read_remaining -= rsize;
     }
-    if (fp->eof) {
+    if (fp->eof
+        // Allow only at most one os_read[v] call.
+        || (called_read && fp->non_blocking)) {
       break;
     }
     if (read_remaining) {
@@ -343,10 +346,7 @@ ptrdiff_t file_read(FileDescriptor *const fp, char *const ret_buf,
         }
       }
 #endif
-    }
-    if (fp->non_blocking) {
-      // Allow only at most one os_read[v] call.
-      break;
+      called_read = true;
     }
   }
   return (ptrdiff_t)(size - read_remaining);
diff --git a/test/functional/core/main_spec.lua b/test/functional/core/main_spec.lua
index 1641149c87..2c4d110f0f 100644
--- a/test/functional/core/main_spec.lua
+++ b/test/functional/core/main_spec.lua
@@ -36,7 +36,6 @@ describe('Command-line option', function()
       os.remove(dollar_fname)
     end)
     it('treats - as stdin', function()
-      if helpers.pending_win32(pending) then return end
       eq(nil, lfs.attributes(fname))
       funcs.system(
         {nvim_prog_abs(), '-u', 'NONE', '-i', 'NONE', '--headless',