pump.c

distcc编译器的源代码.好像是readhat公司开发的.

/* -*- c-file-style: "java"; indent-tabs-mode: nil; fill-column: 78 -*-
 * 
 * distcc -- A simple distributed compiler system
 *
 * Copyright (C) 2003, 2004 by Martin Pool
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */


/* pump.c - Transfer of bulk data (source, object code) */


#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>
#include <sys/types.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SELECT_H
#  include <sys/select.h>
#endif
#include <sys/time.h>
#ifdef HAVE_SYS_MMAN_H
#  include <sys/mman.h>
#endif

#include <netinet/in.h>
#include <netinet/tcp.h>

#include "distcc.h"
#include "trace.h"
#include "util.h"
#include "exitcode.h"


/*
 * Receive either compressed or uncompressed bulk data.
 */
int dcc_r_bulk(int ofd,
               int ifd,
               unsigned f_size,
               enum dcc_compress compression)
{
    if (f_size == 0)
        return 0;               /* don't decompress nothing */
    
    if (compression == DCC_COMPRESS_NONE) {
        return dcc_pump_readwrite(ofd, ifd, f_size);
    } else if (compression == DCC_COMPRESS_LZO1X) {
        return dcc_r_bulk_lzo1x(ofd, ifd, f_size);
    } else {
        rs_log_error("impossible compression %d", compression);
        return EXIT_PROTOCOL_ERROR;
    }    
}



/**
 * Copy @p n bytes from @p ifd to @p ofd.
 *
 * Does not use sendfile(), so either one may be a socket.
 *
 * In the current code at least one of the files will always be a regular
 * (disk) file, even though it may not be mmapable.  That should mean that
 * writes to it will always complete immediately.  That in turn means that on
 * each pass through the main loop we ought to either completely fill our
 * buffer, or completely drain it, depending on which one is the disk.
 *
 * In future we may put back the ability to feed the compiler from a fifo, in
 * which case it may be that the writes don't complete.
 *
 * We might try selecting on both buffers and handling whichever is ready.
 * This would require some approximation to a circular buffer though, which
 * might be more complex.
 **/
int
dcc_pump_readwrite(int ofd, int ifd, size_t n)
{
    static char buf[262144];    /* we're not recursive */
    char *p;
    ssize_t r_in, r_out, wanted;
    int ret;

    while (n > 0) {
        wanted = (n > sizeof buf) ? (sizeof buf) : n;
        r_in = read(ifd, buf, (size_t) wanted);

        if (r_in == -1 && errno == EAGAIN) {
            if ((ret = dcc_select_for_read(ifd, dcc_io_timeout)) != 0)
                return ret;
            else
                continue;
        } else if (r_in == -1 && errno == EINTR) {
            continue;
        } else if (r_in == -1) {
            rs_log_error("failed to read %ld bytes: %s",
                         (long) wanted, strerror(errno));
            return EXIT_IO_ERROR;
        } else if (r_in == 0) {
            rs_log_error("unexpected eof on fd%d", ifd);
            return EXIT_IO_ERROR;
        }
        
        n -= r_in;
        p = buf;

        /* We now have r_in bytes waiting to go out, starting at p.  Keep
         * going until they're all written out. */

        while (r_in > 0) {
            r_out = write(ofd, p, (size_t) r_in);
            
            if (r_out == -1 && errno == EAGAIN) {
                if ((ret = dcc_select_for_write(ofd, dcc_io_timeout)) != 0)
                    return ret;
                else
                    continue;
            } else if (r_out == -1 && errno == EINTR) {
                continue;
            } else if (r_out == -1  ||  r_out == 0) {
                rs_log_error("failed to write: %s", strerror(errno));
                return EXIT_IO_ERROR;
            }
            r_in -= r_out;
            p += r_out;
        }
    }

    return 0;
}