posix_fallocate() *returns* error codes but does not set errno

Also updates the fhandler_*::ftruncate implementations to adhere to the same
semantics.  The error handling semantics of those syscalls that use
fhandler_*::ftruncate are moved to the implementations of those syscalls (
in particular ftruncate() and friends still set errno and return -1 on error
but that logic is handled in the syscall implementation).

winsup/cygwin/fhandler.cc

@@ -1771,8 +1771,7 @@ fhandler_base::fadvise (off_t offset, off_t length, int advice)
 int
 fhandler_base::ftruncate (off_t length, bool allow_truncate)
 {
-  set_errno (EINVAL);
-  return -1;
+  return EINVAL;
 }
 
 int

winsup/cygwin/fhandler_disk_file.cc

@@ -1112,14 +1112,14 @@ fhandler_disk_file::fadvise (off_t offset, off_t length, int advice)
 int
 fhandler_disk_file::ftruncate (off_t length, bool allow_truncate)
 {
-  int res = -1;
+  int res = 0;
 
   if (length < 0 || !get_handle ())
-    set_errno (EINVAL);
+    res = EINVAL;
   else if (pc.isdir ())
-    set_errno (EISDIR);
+    res = EISDIR;
   else if (!(get_access () & GENERIC_WRITE))
-    set_errno (EBADF);
+    res = EBADF;
   else
     {
       NTSTATUS status;
@@ -1130,10 +1130,7 @@ fhandler_disk_file::ftruncate (off_t length, bool allow_truncate)
       status = NtQueryInformationFile (get_handle (), &io, &fsi, sizeof fsi,
 				       FileStandardInformation);
       if (!NT_SUCCESS (status))
-	{
-	  __seterrno_from_nt_status (status);
-	  return -1;
-	}
+	return geterrno_from_nt_status (status);
 
       /* If called through posix_fallocate, silently succeed if length
 	 is less than the file's actual length. */
@@ -1159,9 +1156,7 @@ fhandler_disk_file::ftruncate (off_t length, bool allow_truncate)
 				     &feofi, sizeof feofi,
 				     FileEndOfFileInformation);
       if (!NT_SUCCESS (status))
-	__seterrno_from_nt_status (status);
-      else
-	res = 0;
+	res = geterrno_from_nt_status (status);
     }
   return res;
 }

winsup/cygwin/pipe.cc

@@ -171,8 +171,7 @@ fhandler_pipe::fadvise (off_t offset, off_t length, int advice)
 int
 fhandler_pipe::ftruncate (off_t length, bool allow_truncate)
 {
-  set_errno (allow_truncate ? EINVAL : ESPIPE);
-  return -1;
+  return allow_truncate ? EINVAL : ESPIPE;
 }
 
 char *

winsup/cygwin/syscalls.cc

@@ -2946,16 +2946,16 @@ posix_fadvise (int fd, off_t offset, off_t len, int advice)
 extern "C" int
 posix_fallocate (int fd, off_t offset, off_t len)
 {
-  int res = -1;
+  int res = 0;
   if (offset < 0 || len == 0)
-    set_errno (EINVAL);
+    res = EINVAL;
   else
     {
       cygheap_fdget cfd (fd);
       if (cfd >= 0)
 	res = cfd->ftruncate (offset + len, false);
       else
-	set_errno (EBADF);
+	res = EBADF;
     }
   syscall_printf ("%R = posix_fallocate(%d, %D, %D)", res, fd, offset, len);
   return res;
@@ -2968,6 +2968,11 @@ ftruncate64 (int fd, off_t length)
   cygheap_fdget cfd (fd);
   if (cfd >= 0)
     res = cfd->ftruncate (length, true);
+    if (res)
+      {
+        set_errno (res);
+        res = -1;
+      }
   else
     set_errno (EBADF);
   syscall_printf ("%R = ftruncate(%d, %D)", res, fd, length);