* Don't call getnameinfo() if we've already populated the addr_buf.

[rsync.git] / io.c

/* -*- c-file-style: "linux" -*-
 * 
 * Copyright (C) 1996-2001 by Andrew Tridgell 
 * Copyright (C) Paul Mackerras 1996
 * Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
 * 
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/**
 * @file io.c
 *
 * Socket and pipe IO utilities used in rsync.
 *
 * rsync provides its own multiplexing system, which is used to send
 * stderr and stdout over a single socket.  We need this because
 * stdout normally carries the binary data stream, and stderr all our
 * error messages.
 *
 * For historical reasons this is off during the start of the
 * connection, but it's switched on quite early using
 * io_start_multiplex_out() and io_start_multiplex_in().
 **/

#include "rsync.h"

/** If no timeout is specified then use a 60 second select timeout */
#define SELECT_TIMEOUT 60

static int io_multiplexing_out;
static int io_multiplexing_in;
static int multiplex_in_fd;
static int multiplex_out_fd;
static time_t last_io;
static int no_flush;

extern int bwlimit;
extern int verbose;
extern int io_timeout;
extern struct stats stats;


const char phase_unknown[] = "unknown";

/**
 * The connection might be dropped at some point; perhaps because the
 * remote instance crashed.  Just giving the offset on the stream is
 * not very helpful.  So instead we try to make io_phase_name point to
 * something useful.
 *
 * For buffered/multiplexed IO these names will be somewhat
 * approximate; perhaps for ease of support we would rather make the
 * buffer always flush when a single application-level IO finishes.
 *
 * @todo Perhaps we want some simple stack functionality, but there's
 * no need to overdo it.
 **/
const char *io_write_phase = phase_unknown;
const char *io_read_phase = phase_unknown;

/** Ignore EOF errors while reading a module listing if the remote
    version is 24 or less. */
int kludge_around_eof = False;


static int io_error_fd = -1;

static void read_loop(int fd, char *buf, size_t len);

static void check_timeout(void)
{
        extern int am_server, am_daemon;
        time_t t;

        err_list_push();
        
        if (!io_timeout) return;

        if (!last_io) {
                last_io = time(NULL);
                return;
        }

        t = time(NULL);

        if (last_io && io_timeout && (t-last_io) >= io_timeout) {
                if (!am_server && !am_daemon) {
                        rprintf(FERROR,"io timeout after %d seconds - exiting\n", 
                                (int)(t-last_io));
                }
                exit_cleanup(RERR_TIMEOUT);
        }
}

/** Setup the fd used to propagate errors */
void io_set_error_fd(int fd)
{
        io_error_fd = fd;
}

/** Read some data from the error fd and write it to the write log code */
static void read_error_fd(void)
{
        char buf[200];
        size_t n;
        int fd = io_error_fd;
        int tag, len;

        /* io_error_fd is temporarily disabled -- is this meant to
         * prevent indefinite recursion? */
        io_error_fd = -1;

        read_loop(fd, buf, 4);
        tag = IVAL(buf, 0);

        len = tag & 0xFFFFFF;
        tag = tag >> 24;
        tag -= MPLEX_BASE;

        while (len) {
                n = len;
                if (n > (sizeof(buf)-1))
                        n = sizeof(buf)-1;
                read_loop(fd, buf, n);
                rwrite((enum logcode)tag, buf, n);
                len -= n;
        }

        io_error_fd = fd;
}


/**
 * It's almost always an error to get an EOF when we're trying to read
 * from the network, because the protocol is self-terminating.
 *
 * However, there is one unfortunate cases where it is not, which is
 * rsync <2.4.6 sending a list of modules on a server, since the list
 * is terminated by closing the socket. So, for the section of the
 * program where that is a problem (start_socket_client),
 * kludge_around_eof is True and we just exit.
 */
static void whine_about_eof (void)
{
        if (kludge_around_eof)
                exit_cleanup (0);
        else {
                rprintf (FERROR,
                         "%s: connection unexpectedly closed "
                         "(%.0f bytes read so far)\n",
                         RSYNC_NAME, (double)stats.total_read);
        
                exit_cleanup (RERR_STREAMIO);
        }
}


static void die_from_readerr (int err)
{
        /* this prevents us trying to write errors on a dead socket */
        io_multiplexing_close();
                                
        rprintf(FERROR, "%s: read error: %s\n",
                RSYNC_NAME, strerror (err));
        exit_cleanup(RERR_STREAMIO);
}


/**
 * Read from a socket with IO timeout. return the number of bytes
 * read. If no bytes can be read then exit, never return a number <= 0.
 *
 * TODO: If the remote shell connection fails, then current versions
 * actually report an "unexpected EOF" error here.  Since it's a
 * fairly common mistake to try to use rsh when ssh is required, we
 * should trap that: if we fail to read any data at all, we should
 * give a better explanation.  We can tell whether the connection has
 * started by looking e.g. at whether the remote version is known yet.
 */
static int read_timeout (int fd, char *buf, size_t len)
{
        int n, ret=0;

        io_flush();

        while (ret == 0) {
                /* until we manage to read *something* */
                fd_set fds;
                struct timeval tv;
                int fd_count = fd+1;
                int count;

                FD_ZERO(&fds);
                FD_SET(fd, &fds);
                if (io_error_fd != -1) {
                        FD_SET(io_error_fd, &fds);
                        if (io_error_fd > fd) fd_count = io_error_fd+1;
                }

                tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
                tv.tv_usec = 0;

                errno = 0;

                count = select(fd_count, &fds, NULL, NULL, &tv);

                if (count == 0) {
                        check_timeout();
                }

                if (count <= 0) {
                        if (errno == EBADF) {
                                exit_cleanup(RERR_SOCKETIO);
                        }
                        continue;
                }

                if (io_error_fd != -1 && FD_ISSET(io_error_fd, &fds)) {
                        read_error_fd();
                }

                if (!FD_ISSET(fd, &fds)) continue;

                n = read(fd, buf, len);

                if (n > 0) {
                        buf += n;
                        len -= n;
                        ret += n;
                        if (io_timeout)
                                last_io = time(NULL);
                        continue;
                } else if (n == 0) {
                        whine_about_eof ();
                        return -1; /* doesn't return */
                } else if (n == -1) {
                        if (errno == EINTR || errno == EWOULDBLOCK ||
                            errno == EAGAIN) 
                                continue;
                        else
                                die_from_readerr (errno);
                }
        }

        return ret;
}




/**
 * Continue trying to read len bytes - don't return until len has been
 * read.
 **/
static void read_loop (int fd, char *buf, size_t len)
{
        while (len) {
                int n = read_timeout(fd, buf, len);

                buf += n;
                len -= n;
        }
}


/**
 * Read from the file descriptor handling multiplexing - return number
 * of bytes read.
 * 
 * Never returns <= 0. 
 */
static int read_unbuffered(int fd, char *buf, size_t len)
{
        static size_t remaining;
        int tag, ret = 0;
        char line[1024];

        if (!io_multiplexing_in || fd != multiplex_in_fd)
                return read_timeout(fd, buf, len);

        while (ret == 0) {
                if (remaining) {
                        len = MIN(len, remaining);
                        read_loop(fd, buf, len);
                        remaining -= len;
                        ret = len;
                        continue;
                }

                read_loop(fd, line, 4);
                tag = IVAL(line, 0);

                remaining = tag & 0xFFFFFF;
                tag = tag >> 24;

                if (tag == MPLEX_BASE)
                        continue;

                tag -= MPLEX_BASE;

                if (tag != FERROR && tag != FINFO) {
                        rprintf(FERROR, "unexpected tag %d\n", tag);
                        exit_cleanup(RERR_STREAMIO);
                }

                if (remaining > sizeof(line) - 1) {
                        rprintf(FERROR, "multiplexing overflow %d\n\n",
                                remaining);
                        exit_cleanup(RERR_STREAMIO);
                }

                read_loop(fd, line, remaining);
                line[remaining] = 0;

                rprintf((enum logcode) tag, "%s", line);
                remaining = 0;
        }

        return ret;
}



/**
 * Do a buffered read from @p fd.  Don't return until all @p n bytes
 * have been read.  If all @p n can't be read then exit with an
 * error.
 **/
static void readfd (int fd, char *buffer, size_t N)
{
        int  ret;
        size_t total=0;  
        
        while (total < N) {
                io_flush();

                ret = read_unbuffered (fd, buffer + total, N-total);
                total += ret;
        }

        stats.total_read += total;
}


int32 read_int(int f)
{
        char b[4];
        int32 ret;

        readfd(f,b,4);
        ret = IVAL(b,0);
        if (ret == (int32)0xffffffff) return -1;
        return ret;
}

int64 read_longint(int f)
{
        extern int remote_version;
        int64 ret;
        char b[8];
        ret = read_int(f);

        if ((int32)ret != (int32)0xffffffff) {
                return ret;
        }

#ifdef NO_INT64
        rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
        exit_cleanup(RERR_UNSUPPORTED);
#else
        if (remote_version >= 16) {
                readfd(f,b,8);
                ret = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
        }
#endif

        return ret;
}

void read_buf(int f,char *buf,size_t len)
{
        readfd(f,buf,len);
}

void read_sbuf(int f,char *buf,size_t len)
{
        read_buf (f,buf,len);
        buf[len] = 0;
}

unsigned char read_byte(int f)
{
        unsigned char c;
        read_buf (f, (char *)&c, 1);
        return c;
}


/**
 * Sleep after writing to limit I/O bandwidth usage.
 *
 * @todo Rather than sleeping after each write, it might be better to
 * use some kind of averaging.  The current algorithm seems to always
 * use a bit less bandwidth than specified, because it doesn't make up
 * for slow periods.  But arguably this is a feature.  In addition, we
 * ought to take the time used to write the data into account.
 **/
static void sleep_for_bwlimit(int bytes_written)
{
        struct timeval tv;

        if (!bwlimit)
                return;

        assert(bytes_written > 0);
        assert(bwlimit > 0);
        
        tv.tv_usec = bytes_written * 1000 / bwlimit;
        tv.tv_sec  = tv.tv_usec / 1000000;
        tv.tv_usec = tv.tv_usec % 1000000;

        select(0, NULL, NULL, NULL, &tv);
}


/**
 * Write len bytes to the file descriptor @p fd.
 *
 * This function underlies the multiplexing system.  The body of the
 * application never calls this function directly.
 **/
static void writefd_unbuffered(int fd,char *buf,size_t len)
{
        size_t total = 0;
        fd_set w_fds, r_fds;
        int fd_count, count;
        struct timeval tv;

        err_list_push();

        no_flush++;

        while (total < len) {
                FD_ZERO(&w_fds);
                FD_ZERO(&r_fds);
                FD_SET(fd,&w_fds);
                fd_count = fd;

                if (io_error_fd != -1) {
                        FD_SET(io_error_fd,&r_fds);
                        if (io_error_fd > fd_count) 
                                fd_count = io_error_fd;
                }

                tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
                tv.tv_usec = 0;

                errno = 0;

                count = select(fd_count+1,
                               io_error_fd != -1?&r_fds:NULL,
                               &w_fds,NULL,
                               &tv);

                if (count == 0) {
                        check_timeout();
                }

                if (count <= 0) {
                        if (errno == EBADF) {
                                exit_cleanup(RERR_SOCKETIO);
                        }
                        continue;
                }

                if (io_error_fd != -1 && FD_ISSET(io_error_fd, &r_fds)) {
                        read_error_fd();
                }

                if (FD_ISSET(fd, &w_fds)) {
                        int ret;
                        size_t n = len-total;
                        ret = write(fd,buf+total,n);

                        if (ret == -1 && errno == EINTR) {
                                continue;
                        }

                        if (ret == -1 && 
                            (errno == EWOULDBLOCK || errno == EAGAIN)) {
                                msleep(1);
                                continue;
                        }

                        if (ret <= 0) {
                                /* Don't try to write errors back
                                 * across the stream */
                                io_multiplexing_close();
                                rprintf(FERROR, RSYNC_NAME
                                        ": writefd_unbuffered failed to write %ld bytes: phase \"%s\": %s\n",
                                        (long) len, io_write_phase, 
                                        strerror(errno));
                                exit_cleanup(RERR_STREAMIO);
                        }

                        sleep_for_bwlimit(ret);
 
                        total += ret;

                        if (io_timeout)
                                last_io = time(NULL);
                }
        }

        no_flush--;
}


static char *io_buffer;
static int io_buffer_count;

void io_start_buffering(int fd)
{
        if (io_buffer) return;
        multiplex_out_fd = fd;
        io_buffer = (char *)malloc(IO_BUFFER_SIZE);
        if (!io_buffer) out_of_memory("writefd");
        io_buffer_count = 0;
}

/**
 * Write an message to a multiplexed stream. If this fails then rsync
 * exits.
 **/
static void mplex_write(int fd, enum logcode code, char *buf, size_t len)
{
        char buffer[4096];
        size_t n = len;

        SIVAL(buffer, 0, ((MPLEX_BASE + (int)code)<<24) + len);

        if (n > (sizeof(buffer)-4)) {
                n = sizeof(buffer)-4;
        }

        memcpy(&buffer[4], buf, n);
        writefd_unbuffered(fd, buffer, n+4);

        len -= n;
        buf += n;

        if (len) {
                writefd_unbuffered(fd, buf, len);
        }
}


void io_flush(void)
{
        int fd = multiplex_out_fd;

        err_list_push();

        if (!io_buffer_count || no_flush) return;

        if (io_multiplexing_out) {
                mplex_write(fd, FNONE, io_buffer, io_buffer_count);
        } else {
                writefd_unbuffered(fd, io_buffer, io_buffer_count);
        }
        io_buffer_count = 0;
}


void io_end_buffering(void)
{
        io_flush();
        if (!io_multiplexing_out) {
                free(io_buffer);
                io_buffer = NULL;
        }
}

static void writefd(int fd,char *buf,size_t len)
{
        stats.total_written += len;

        err_list_push();

        if (!io_buffer || fd != multiplex_out_fd) {
                writefd_unbuffered(fd, buf, len);
                return;
        }

        while (len) {
                int n = MIN((int) len, IO_BUFFER_SIZE-io_buffer_count);
                if (n > 0) {
                        memcpy(io_buffer+io_buffer_count, buf, n);
                        buf += n;
                        len -= n;
                        io_buffer_count += n;
                }
                
                if (io_buffer_count == IO_BUFFER_SIZE) io_flush();
        }
}


void write_int(int f,int32 x)
{
        char b[4];
        SIVAL(b,0,x);
        writefd(f,b,4);
}


void write_int_named(int f, int32 x, const char *phase)
{
        io_write_phase = phase;
        write_int(f, x);
        io_write_phase = phase_unknown;
}


/*
 * Note: int64 may actually be a 32-bit type if ./configure couldn't find any
 * 64-bit types on this platform.
 */
void write_longint(int f, int64 x)
{
        extern int remote_version;
        char b[8];

        if (remote_version < 16 || x <= 0x7FFFFFFF) {
                write_int(f, (int)x);
                return;
        }

        write_int(f, (int32)0xFFFFFFFF);
        SIVAL(b,0,(x&0xFFFFFFFF));
        SIVAL(b,4,((x>>32)&0xFFFFFFFF));

        writefd(f,b,8);
}

void write_buf(int f,char *buf,size_t len)
{
        writefd(f,buf,len);
}

/** Write a string to the connection */
static void write_sbuf(int f,char *buf)
{
        write_buf(f, buf, strlen(buf));
}


void write_byte(int f,unsigned char c)
{
        write_buf(f,(char *)&c,1);
}



/**
 * Read a line of up to @p maxlen characters into @p buf.  Does not
 * contain a trailing newline or carriage return.
 *
 * @return 1 for success; 0 for io error or truncation.
 **/
int read_line(int f, char *buf, size_t maxlen)
{
        while (maxlen) {
                buf[0] = 0;
                read_buf(f, buf, 1);
                if (buf[0] == 0)
                        return 0;
                if (buf[0] == '\n') {
                        buf[0] = 0;
                        break;
                }
                if (buf[0] != '\r') {
                        buf++;
                        maxlen--;
                }
        }
        if (maxlen == 0) {
                *buf = 0;
                return 0;
        }

        return 1;
}


void io_printf(int fd, const char *format, ...)
{
        va_list ap;  
        char buf[1024];
        int len;
        
        va_start(ap, format);
        len = vsnprintf(buf, sizeof(buf), format, ap);
        va_end(ap);

        if (len < 0) exit_cleanup(RERR_STREAMIO);

        write_sbuf(fd, buf);
}


/** Setup for multiplexing an error stream with the data stream */
void io_start_multiplex_out(int fd)
{
        multiplex_out_fd = fd;
        io_flush();
        io_start_buffering(fd);
        io_multiplexing_out = 1;
}

/** Setup for multiplexing an error stream with the data stream */
void io_start_multiplex_in(int fd)
{
        multiplex_in_fd = fd;
        io_flush();
        io_multiplexing_in = 1;
}

/** Write an message to the multiplexed error stream */
int io_multiplex_write(enum logcode code, char *buf, size_t len)
{
        if (!io_multiplexing_out) return 0;

        io_flush();
        stats.total_written += (len+4);
        mplex_write(multiplex_out_fd, code, buf, len);
        return 1;
}

/** Stop output multiplexing */
void io_multiplexing_close(void)
{
        io_multiplexing_out = 0;
}