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 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 General Public License for more details. 15 16 You should have received a copy of the GNU 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). */ 58size_t 59full_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} 81