lib: windows: _read: Call NtReadFile, rather than read

kaem.windows.run

@@ -84,6 +84,7 @@ M2-Planet                                               \
     -f ${srcdest}lib/linux/malloc.c                    \
     -f ${srcdest}lib/windows/ntdll.c                   \
     -f ${srcdest}lib/string/memset.c                   \
+    -f ${srcdest}lib/windows/_read.c                   \
     -f ${srcdest}lib/windows/read.c                    \
     -f ${srcdest}lib/mes/fdgetc.c                      \
     -f ${srcdest}lib/stdio/getchar.c                   \

lib/windows/_read.c

@@ -16,16 +16,34 @@
  * You should have received a copy of the GNU General Public License
  * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
  */
-
-/* Stands in for lib/linux/_read.c.  On Linux _read is the bare SYS_read and
- * read is the same call; here read (lib/windows/read.c) is already the bare
- * NtReadFile with nothing between, so this is that. */
-
+#include <windows/ntcall.h>
+#include <windows/ntdll.h>
 #include <mes/lib.h>
-#include <unistd.h>
+#include <fcntl.h>
+
+/* Stands in for lib/linux/_read.c: the bare read, with nothing above it.
+ * configure-lib.sh's lists build read from lib/posix/buffered-read.c, whose
+ * __buffered_read fills its buffer with this, so this must not call read.
+ * NtReadFile is NtWriteFile's twin, and an NTSTATUS below zero is how the end
+ * of the file arrives as much as how a failure does -- both mean nothing more
+ * was read, which is what a caller of read wants to hear as 0. */
 
 ssize_t
 _read (int filedes, void *buffer, size_t size)
 {
-  return read (filedes, buffer, size);
+  int NtReadFile;
+  int *iosb;
+  int handle;
+  int rc;
+
+  NtReadFile = __ntdll_resolve ("NtReadFile");
+  iosb = __iosb ();
+  iosb[0] = 0;
+  iosb[1] = 0;
+  handle = __handle (filedes);
+
+  rc = __ntcall9 (NtReadFile, handle, 0, 0, 0, iosb, buffer, size, 0, 0);
+  if (rc < 0)
+    return 0;
+  return iosb[1];
 }

lib/windows/read.c

@@ -16,32 +16,16 @@
  * You should have received a copy of the GNU General Public License
  * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include <windows/ntcall.h>
-#include <windows/ntdll.h>
 #include <mes/lib.h>
 #include <fcntl.h>
 
-/* Stands in for lib/linux/read.c.  NtReadFile is NtWriteFile's twin, and an
- * NTSTATUS below zero is how the end of the file arrives as much as how a
- * failure does -- both mean nothing more was read, which is what a caller of
- * read wants to hear as 0. */
+/* Stands in for lib/linux/read.c, for a build that buffers nothing, as
+ * kaem.windows.run's does: there read is lib/windows/_read.c's bare
+ * NtReadFile.  configure-lib.sh's lists take read from
+ * lib/posix/buffered-read.c instead, and do not build this file. */
 
 ssize_t
 read (int filedes, void *buffer, size_t size)
 {
-  int NtReadFile;
-  int *iosb;
-  int handle;
-  int rc;
-
-  NtReadFile = __ntdll_resolve ("NtReadFile");
-  iosb = __iosb ();
-  iosb[0] = 0;
-  iosb[1] = 0;
-  handle = __handle (filedes);
-
-  rc = __ntcall9 (NtReadFile, handle, 0, 0, 0, iosb, buffer, size, 0, 0);
-  if (rc < 0)
-    return 0;
-  return iosb[1];
+  return _read (filedes, buffer, size);
 }