| /* read for MMIXware. |
| |
| Copyright (C) 2001 Hans-Peter Nilsson |
| |
| Permission to use, copy, modify, and distribute this software is |
| freely granted, provided that the above copyright notice, this notice |
| and the following disclaimer are preserved with no changes. |
| |
| THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
| IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
| WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| PURPOSE. */ |
| |
| #include <_ansi.h> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include "sys/syscall.h" |
| #include <errno.h> |
| |
| int |
| _read (int file, |
| char *ptr, |
| size_t len) |
| { |
| long ret; |
| |
| if ((unsigned int) file >= 32 || _MMIX_allocated_filehandle[file] == 0) |
| { |
| errno = EBADF; |
| return -1; |
| } |
| |
| if (isatty(file)) |
| { |
| ret = TRAP3f (SYS_Fgets, file, ptr, len); |
| |
| if (ret == -1) |
| return 0; |
| |
| return ret; |
| } |
| |
| ret = TRAP3f (SYS_Fread, file, ptr, len); |
| |
| /* Map the return codes: |
| -1-len: an error. We return -1. |
| 0: success. We return len. |
| n-len: end-of-file after n chars read. We return n. */ |
| if (ret == 0) |
| return len; |
| |
| if (ret == -1 - (long) len) |
| { |
| /* We don't know the nature of the failure, so this is an |
| approximation. */ |
| errno = EIO; |
| return -1; |
| } |
| |
| return ret + len; |
| } |