| /* An interface to read and write that retries after interrupts. |
| |
| Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2011 Free Software |
| Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include <config.h> |
| |
| /* Specification. */ |
| #ifdef SAFE_WRITE |
| # include "safe-write.h" |
| #else |
| # include "safe-read.h" |
| #endif |
| |
| /* Get ssize_t. */ |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include <errno.h> |
| |
| #ifdef EINTR |
| # define IS_EINTR(x) ((x) == EINTR) |
| #else |
| # define IS_EINTR(x) 0 |
| #endif |
| |
| #include <limits.h> |
| |
| #ifdef SAFE_WRITE |
| # define safe_rw safe_write |
| # define rw write |
| #else |
| # define safe_rw safe_read |
| # define rw read |
| # undef const |
| # define const /* empty */ |
| #endif |
| |
| /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if |
| interrupted. Return the actual number of bytes read(written), zero for EOF, |
| or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */ |
| size_t |
| safe_rw (int fd, void const *buf, size_t count) |
| { |
| /* Work around a bug in Tru64 5.1. Attempting to read more than |
| INT_MAX bytes fails with errno == EINVAL. See |
| <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>. |
| When decreasing COUNT, keep it block-aligned. */ |
| enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 }; |
| |
| for (;;) |
| { |
| ssize_t result = rw (fd, buf, count); |
| |
| if (0 <= result) |
| return result; |
| else if (IS_EINTR (errno)) |
| continue; |
| else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count) |
| count = BUGGY_READ_MAXIMUM; |
| else |
| return result; |
| } |
| } |