| 1 | /* An interface to read and write that retries (if necessary) until complete. |
| 2 | |
| 3 | Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002, 2003, |
| 4 | 2004, 2005, 2006 Free Software Foundation, Inc. |
| 5 | |
| 6 | This program is free software: you can redistribute it and/or modify |
| 7 | it under the terms of the GNU Lesser General Public License as published by |
| 8 | the Free Software Foundation; either version 3 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU Lesser General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU Lesser General Public License |
| 17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <config.h> |
| 20 | |
| 21 | /* Specification. */ |
| 22 | #ifdef FULL_READ |
| 23 | # include "full-read.h" |
| 24 | #else |
| 25 | # include "full-write.h" |
| 26 | #endif |
| 27 | |
| 28 | #include <errno.h> |
| 29 | |
| 30 | #ifdef FULL_READ |
| 31 | # include "safe-read.h" |
| 32 | # define safe_rw safe_read |
| 33 | # define full_rw full_read |
| 34 | # undef const |
| 35 | # define const /* empty */ |
| 36 | #else |
| 37 | # include "safe-write.h" |
| 38 | # define safe_rw safe_write |
| 39 | # define full_rw full_write |
| 40 | #endif |
| 41 | |
| 42 | #ifdef FULL_READ |
| 43 | /* Set errno to zero upon EOF. */ |
| 44 | # define ZERO_BYTE_TRANSFER_ERRNO 0 |
| 45 | #else |
| 46 | /* Some buggy drivers return 0 when one tries to write beyond |
| 47 | a device's end. (Example: Linux 1.2.13 on /dev/fd0.) |
| 48 | Set errno to ENOSPC so they get a sensible diagnostic. */ |
| 49 | # define ZERO_BYTE_TRANSFER_ERRNO ENOSPC |
| 50 | #endif |
| 51 | |
| 52 | /* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if |
| 53 | interrupted or if a partial write(read) occurs. Return the number |
| 54 | of bytes transferred. |
| 55 | When writing, set errno if fewer than COUNT bytes are written. |
| 56 | When reading, if fewer than COUNT bytes are read, you must examine |
| 57 | errno to distinguish failure from EOF (errno == 0). */ |
| 58 | size_t |
| 59 | full_rw (int fd, const void *buf, size_t count) |
| 60 | { |
| 61 | size_t total = 0; |
| 62 | const char *ptr = (const char *) buf; |
| 63 | |
| 64 | while (count > 0) |
| 65 | { |
| 66 | size_t n_rw = safe_rw (fd, ptr, count); |
| 67 | if (n_rw == (size_t) -1) |
| 68 | break; |
| 69 | if (n_rw == 0) |
| 70 | { |
| 71 | errno = ZERO_BYTE_TRANSFER_ERRNO; |
| 72 | break; |
| 73 | } |
| 74 | total += n_rw; |
| 75 | ptr += n_rw; |
| 76 | count -= n_rw; |
| 77 | } |
| 78 | |
| 79 | return total; |
| 80 | } |