view src/os/unix/ngx_channel.c @ 6949:ff0c8e11edbc

Simplified and improved sendfile() code on Linux. The ngx_linux_sendfile() function is now used for both normal sendfile() and sendfile in threads. The ngx_linux_sendfile_thread() function was modified to use the same interface as ngx_linux_sendfile(), and is simply called from ngx_linux_sendfile() when threads are enabled. Special return code NGX_DONE is used to indicate that a thread task was posted and no further actions are needed. If number of bytes sent is less that what we were sending, we now always retry sending. This is needed for sendfile() in threads as the number of bytes we are sending might have been changed since the thread task was posted. And this is also needed for Linux 4.3+, as sendfile() might be interrupted at any time and provides no indication if it was interrupted or not (ticket #1174).
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 28 Mar 2017 18:15:39 +0300
parents 3377f9459e99
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_channel.h>


ngx_int_t
ngx_write_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size,
    ngx_log_t *log)
{
    ssize_t             n;
    ngx_err_t           err;
    struct iovec        iov[1];
    struct msghdr       msg;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

    union {
        struct cmsghdr  cm;
        char            space[CMSG_SPACE(sizeof(int))];
    } cmsg;

    if (ch->fd == -1) {
        msg.msg_control = NULL;
        msg.msg_controllen = 0;

    } else {
        msg.msg_control = (caddr_t) &cmsg;
        msg.msg_controllen = sizeof(cmsg);

        ngx_memzero(&cmsg, sizeof(cmsg));

        cmsg.cm.cmsg_len = CMSG_LEN(sizeof(int));
        cmsg.cm.cmsg_level = SOL_SOCKET;
        cmsg.cm.cmsg_type = SCM_RIGHTS;

        /*
         * We have to use ngx_memcpy() instead of simple
         *   *(int *) CMSG_DATA(&cmsg.cm) = ch->fd;
         * because some gcc 4.4 with -O2/3/s optimization issues the warning:
         *   dereferencing type-punned pointer will break strict-aliasing rules
         *
         * Fortunately, gcc with -O1 compiles this ngx_memcpy()
         * in the same simple assignment as in the code above
         */

        ngx_memcpy(CMSG_DATA(&cmsg.cm), &ch->fd, sizeof(int));
    }

    msg.msg_flags = 0;

#else

    if (ch->fd == -1) {
        msg.msg_accrights = NULL;
        msg.msg_accrightslen = 0;

    } else {
        msg.msg_accrights = (caddr_t) &ch->fd;
        msg.msg_accrightslen = sizeof(int);
    }

#endif

    iov[0].iov_base = (char *) ch;
    iov[0].iov_len = size;

    msg.msg_name = NULL;
    msg.msg_namelen = 0;
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

    n = sendmsg(s, &msg, 0);

    if (n == -1) {
        err = ngx_errno;
        if (err == NGX_EAGAIN) {
            return NGX_AGAIN;
        }

        ngx_log_error(NGX_LOG_ALERT, log, err, "sendmsg() failed");
        return NGX_ERROR;
    }

    return NGX_OK;
}


ngx_int_t
ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size, ngx_log_t *log)
{
    ssize_t             n;
    ngx_err_t           err;
    struct iovec        iov[1];
    struct msghdr       msg;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)
    union {
        struct cmsghdr  cm;
        char            space[CMSG_SPACE(sizeof(int))];
    } cmsg;
#else
    int                 fd;
#endif

    iov[0].iov_base = (char *) ch;
    iov[0].iov_len = size;

    msg.msg_name = NULL;
    msg.msg_namelen = 0;
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)
    msg.msg_control = (caddr_t) &cmsg;
    msg.msg_controllen = sizeof(cmsg);
#else
    msg.msg_accrights = (caddr_t) &fd;
    msg.msg_accrightslen = sizeof(int);
#endif

    n = recvmsg(s, &msg, 0);

    if (n == -1) {
        err = ngx_errno;
        if (err == NGX_EAGAIN) {
            return NGX_AGAIN;
        }

        ngx_log_error(NGX_LOG_ALERT, log, err, "recvmsg() failed");
        return NGX_ERROR;
    }

    if (n == 0) {
        ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "recvmsg() returned zero");
        return NGX_ERROR;
    }

    if ((size_t) n < sizeof(ngx_channel_t)) {
        ngx_log_error(NGX_LOG_ALERT, log, 0,
                      "recvmsg() returned not enough data: %z", n);
        return NGX_ERROR;
    }

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

    if (ch->command == NGX_CMD_OPEN_CHANNEL) {

        if (cmsg.cm.cmsg_len < (socklen_t) CMSG_LEN(sizeof(int))) {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "recvmsg() returned too small ancillary data");
            return NGX_ERROR;
        }

        if (cmsg.cm.cmsg_level != SOL_SOCKET || cmsg.cm.cmsg_type != SCM_RIGHTS)
        {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "recvmsg() returned invalid ancillary data "
                          "level %d or type %d",
                          cmsg.cm.cmsg_level, cmsg.cm.cmsg_type);
            return NGX_ERROR;
        }

        /* ch->fd = *(int *) CMSG_DATA(&cmsg.cm); */

        ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int));
    }

    if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) {
        ngx_log_error(NGX_LOG_ALERT, log, 0,
                      "recvmsg() truncated data");
    }

#else

    if (ch->command == NGX_CMD_OPEN_CHANNEL) {
        if (msg.msg_accrightslen != sizeof(int)) {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "recvmsg() returned no ancillary data");
            return NGX_ERROR;
        }

        ch->fd = fd;
    }

#endif

    return n;
}


ngx_int_t
ngx_add_channel_event(ngx_cycle_t *cycle, ngx_fd_t fd, ngx_int_t event,
    ngx_event_handler_pt handler)
{
    ngx_event_t       *ev, *rev, *wev;
    ngx_connection_t  *c;

    c = ngx_get_connection(fd, cycle->log);

    if (c == NULL) {
        return NGX_ERROR;
    }

    c->pool = cycle->pool;

    rev = c->read;
    wev = c->write;

    rev->log = cycle->log;
    wev->log = cycle->log;

    rev->channel = 1;
    wev->channel = 1;

    ev = (event == NGX_READ_EVENT) ? rev : wev;

    ev->handler = handler;

    if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) {
        if (ngx_add_conn(c) == NGX_ERROR) {
            ngx_free_connection(c);
            return NGX_ERROR;
        }

    } else {
        if (ngx_add_event(ev, event, 0) == NGX_ERROR) {
            ngx_free_connection(c);
            return NGX_ERROR;
        }
    }

    return NGX_OK;
}


void
ngx_close_channel(ngx_fd_t *fd, ngx_log_t *log)
{
    if (close(fd[0]) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed");
    }

    if (close(fd[1]) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed");
    }
}