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/* -*- c-file-style: "java"; indent-tabs-mode: nil; tab-width: 4; fill-column: 78 -*-
*
* distcc -- A simple distributed compiler system
*
* Copyright (C) 2002, 2003, 2004 by Martin Pool
* Copyright 2008 Google 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 2
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
/* "I've always wanted to use sendfile(), but
* never had a reason until now"
* -- mbp */
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#ifdef HAVE_SYS_SENDFILE_H
# include <sys/sendfile.h>
#endif /* !HAVE_SYS_SENDFILE_H */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include "distcc.h"
#include "trace.h"
#include "util.h"
#include "exitcode.h"
/*
* Could also use sendfilev() on Solaris >= 8:
*
* http://docs.sun.com/db/doc/816-0217/6m6nhtaps?a=view
*/
#ifdef HAVE_SENDFILE
/* If you don't have it, just use dcc_pump_readwrite */
/**
* sys_sendfile maps all the different implementations of sendfile() into
* something like the Linux interface.
*
* Our sockets are never non-blocking, so that seems to me to say that
* the kernel will never return EAGAIN -- we will always either send
* the whole thing or get an error. Is that really true?
*
* How nice to have the function parameters reversed between platforms
* in a way that will not give a compiler warning.
*
* @param offset offset in input to start writing; updated on return
* to reflect the number of bytes sent.
*
* sys_sendfile returns the number of bytes sent, if transmission succeeded.
* If there was an error, it returns -1 with errno set. It should never
* return 0.
**/
#if defined(__FreeBSD__)
static ssize_t sys_sendfile(int ofd, int ifd, off_t *offset, size_t size)
{
off_t sent_bytes;
int ret;
/* According to the manual, this can never partially complete on a
* socket open for blocking IO. */
ret = sendfile(ifd, ofd, *offset, size, 0, &sent_bytes, 0);
if (ret == -1) {
/* http://cvs.apache.org/viewcvs.cgi/apr/network_io/unix/sendrecv.c?rev=1.95&content-type=text/vnd.viewcvs-markup */
if (errno == EAGAIN) {
if (sent_bytes == 0) {
/* Didn't send anything. Return error with errno == EAGAIN. */
return -1;
} else {
/* We sent some bytes, but they we would block. Treat this as
* success for now. */
*offset += sent_bytes;
return sent_bytes;
}
} else {
/* some other error */
return -1;
}
} else if (ret == 0) {
*offset += size;
return size;
} else {
rs_log_error("don't know how to handle return %d from BSD sendfile",
ret);
return -1;
}
}
#elif defined(linux) || defined(__GNU__)
static ssize_t sys_sendfile(int ofd, int ifd, off_t *offset, size_t size)
{
return sendfile(ofd, ifd, offset, size);
}
#elif defined(__hpux) || defined(__hpux__)
/* HP cc in ANSI mode defines __hpux; gcc defines __hpux__ */
static ssize_t sys_sendfile(int ofd, int ifd, off_t *offset, size_t size)
{
ssize_t ret;
ret = sendfile(ofd, ifd, *offset, size, NULL, 0);
if (ret == -1) {
return -1;
} else if (ret > 0) {
*offset += ret;
return ret;
} else {
rs_log_error("don't know how to handle return %ld from HP-UX sendfile",
(long) ret);
return -1;
}
}
#elif defined(__MACH__) && defined(__APPLE__)
static ssize_t sys_sendfile(int ofd, int ifd, off_t *offset, size_t size)
{
off_t sent_bytes = size;
int ret;
ret = sendfile(ofd, ifd, *offset, &sent_bytes, NULL, 0);
if (ret == -1) {
if (errno == EAGAIN) {
if (sent_bytes == 0) {
/* Didn't send anything. Return error with errno == EAGAIN. */
return -1;
} else {
/* We sent some bytes, but they we would block. Treat this as
* success for now. */
*offset += sent_bytes;
return sent_bytes;
}
} else {
/* some other error */
return -1;
}
} else if (ret == 0) {
*offset += size;
return size;
} else {
rs_log_error("don't know how to handle return %d from OS X sendfile",
ret);
return -1;
}
}
#else
/* Please write a sendfile implementation for your system! */
static ssize_t sys_sendfile(int UNUSED(ofd), int UNUSED(ifd),
off_t *UNUSED(offset), size_t UNUSED(size))
{
rs_log_warning("no sendfile implementation on this platform");
errno = ENOSYS;
return -1;
}
#endif /* !(__FreeBSD__) && !def(linux) && ... */
/*
* Transmit the body of a file using sendfile().
*
* Linux at the moment requires the input be page-based -- ie a disk file, and
* only on particular filesystems. If the sendfile() call fails in a way that
* makes us think that regular IO might work, then we try that instead. For
* example, the /tmp filesystem may not support sendfile().
*/
int
dcc_pump_sendfile(int ofd, int ifd, size_t size)
{
ssize_t sent;
off_t offset = 0;
int ret;
while (size) {
/* Handle possibility of partial transmission, e.g. if
* sendfile() is interrupted by a signal. size is decremented
* as we go. */
sent = sys_sendfile(ofd, ifd, &offset, size);
if (sent == -1) {
if (errno == EAGAIN) {
/* Sleep until we're able to write out more data. */
if ((ret = dcc_select_for_write(ofd,
dcc_get_io_timeout())) != 0) {
return ret;
}
rs_trace("select() returned, continuing to write");
} else if (errno == EINTR) {
rs_trace("sendfile() interrupted, continuing");
} else if (offset == 0) {
/* The offset==0 tests is because we may be part way through
* the file. We can't just naively go back to read/write
* because sendfile() does not update the file pointer: we
* would need to lseek() first. That case is not handled at
* the moment because it's unlikely that sendfile() would
* suddenly be unsupported while we're using it. A failure
* halfway through probably indicates a genuine error.
*/
rs_log_info("decided to use read/write rather than sendfile");
return dcc_pump_readwrite(ofd, ifd, size);
} else {
rs_log_error("sendfile failed: %s", strerror(errno));
return EXIT_IO_ERROR;
}
} else if (sent == 0) {
rs_log_error("sendfile returned 0? can't cope");
return EXIT_IO_ERROR;
} else if (sent != (ssize_t) size) {
/* offset is automatically updated by sendfile. */
size -= sent;
rs_log_notice("sendfile: partial transmission of %ld bytes; retrying %ld @%ld",
(long) sent, (long) size, (long) offset);
} else {
/* normal case, everything was sent. */
break;
}
}
return 0;
}
#endif /* def HAVE_SENDFILE */
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