1 /* An interface to read and write that retries after interrupts. 2 3 Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2020 Free Software 4 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 <https://www.gnu.org/licenses/>. */ 18 19 #include <config.h> 20 21 /* Specification. */ 22 #ifdef SAFE_WRITE 23 # include "safe-write.h" 24 #else 25 # include "safe-read.h" 26 #endif 27 28 /* Get ssize_t. */ 29 #include <sys/types.h> 30 #include <unistd.h> 31 32 #include <errno.h> 33 34 #ifdef EINTR 35 # define IS_EINTR(x) ((x) == EINTR) 36 #else 37 # define IS_EINTR(x) 0 38 #endif 39 40 #include "sys-limits.h" 41 42 #ifdef SAFE_WRITE 43 # define safe_rw safe_write 44 # define rw write 45 #else 46 # define safe_rw safe_read 47 # define rw read 48 # undef const 49 # define const /* empty */ 50 #endif 51 52 /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if 53 interrupted. Return the actual number of bytes read(written), zero for EOF, 54 or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */ 55 size_t 56 safe_rw (int fd, void const *buf, size_t count) 57 { 58 for (;;) 59 { 60 ssize_t result = rw (fd, buf, count); 61 62 if (0 <= result) 63 return result; 64 else if (IS_EINTR (errno)) 65 continue; 66 else if (errno == EINVAL && SYS_BUFSIZE_MAX < count) 67 count = SYS_BUFSIZE_MAX; 68 else 69 return result; 70 } 71 } 72