nginx/src/os/unix/ngx_linux_sendfile_chain.c

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


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


static ssize_t ngx_linux_sendfile(ngx_connection_t *c, ngx_buf_t *file,
    size_t size);

#if (NGX_THREADS)
#include <ngx_thread_pool.h>

#if !(NGX_HAVE_SENDFILE64)
#error sendfile64() is required!
#endif

static ssize_t ngx_linux_sendfile_thread(ngx_connection_t *c, ngx_buf_t *file,
    size_t size);
static void ngx_linux_sendfile_thread_handler(void *data, ngx_log_t *log);
#endif


/*
 * On Linux up to 2.4.21 sendfile() (syscall #187) works with 32-bit
 * offsets only, and the including <sys/sendfile.h> breaks the compiling,
 * if off_t is 64 bit wide.  So we use own sendfile() definition, where offset
 * parameter is int32_t, and use sendfile() for the file parts below 2G only,
 * see src/os/unix/ngx_linux_config.h
 *
 * Linux 2.4.21 has the new sendfile64() syscall #239.
 *
 * On Linux up to 2.6.16 sendfile() does not allow to pass the count parameter
 * more than 2G-1 bytes even on 64-bit platforms: it returns EINVAL,
 * so we limit it to 2G-1 bytes.
 *
 * On Linux 2.6.16 and later, sendfile() silently limits the count parameter
 * to 2G minus the page size, even on 64-bit platforms.
 */

#define NGX_SENDFILE_MAXSIZE …


ngx_chain_t *
ngx_linux_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
{ … }


static ssize_t
ngx_linux_sendfile(ngx_connection_t *c, ngx_buf_t *file, size_t size)
{ … }


#if (NGX_THREADS)

typedef struct {
    ngx_buf_t     *file;
    ngx_socket_t   socket;
    size_t         size;

    size_t         sent;
    ngx_err_t      err;
} ngx_linux_sendfile_ctx_t;


static ssize_t
ngx_linux_sendfile_thread(ngx_connection_t *c, ngx_buf_t *file, size_t size)
{
    ngx_event_t               *wev;
    ngx_thread_task_t         *task;
    ngx_linux_sendfile_ctx_t  *ctx;

    ngx_log_debug3(NGX_LOG_DEBUG_CORE, c->log, 0,
                   "linux sendfile thread: %d, %uz, %O",
                   file->file->fd, size, file->file_pos);

    task = c->sendfile_task;

    if (task == NULL) {
        task = ngx_thread_task_alloc(c->pool, sizeof(ngx_linux_sendfile_ctx_t));
        if (task == NULL) {
            return NGX_ERROR;
        }

        task->event.log = c->log;
        task->handler = ngx_linux_sendfile_thread_handler;

        c->sendfile_task = task;
    }

    ctx = task->ctx;
    wev = c->write;

    if (task->event.complete) {
        task->event.complete = 0;

        if (ctx->err == NGX_EAGAIN) {
            /*
             * if wev->complete is set, this means that a write event
             * happened while we were waiting for the thread task, so
             * we have to retry sending even on EAGAIN
             */

            if (wev->complete) {
                return 0;
            }

            return NGX_AGAIN;
        }

        if (ctx->err) {
            wev->error = 1;
            ngx_connection_error(c, ctx->err, "sendfile() failed");
            return NGX_ERROR;
        }

        if (ctx->sent == 0) {
            /*
             * if sendfile returns zero, then someone has truncated the file,
             * so the offset became beyond the end of the file
             */

            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "sendfile() reported that \"%s\" was truncated at %O",
                          file->file->name.data, file->file_pos);

            return NGX_ERROR;
        }

        return ctx->sent;
    }

    ctx->file = file;
    ctx->socket = c->fd;
    ctx->size = size;

    wev->complete = 0;

    if (file->file->thread_handler(task, file->file) != NGX_OK) {
        return NGX_ERROR;
    }

    return NGX_DONE;
}


static void
ngx_linux_sendfile_thread_handler(void *data, ngx_log_t *log)
{
    ngx_linux_sendfile_ctx_t *ctx = data;

    off_t       offset;
    ssize_t     n;
    ngx_buf_t  *file;

    ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "linux sendfile thread handler");

    file = ctx->file;
    offset = file->file_pos;

again:

    n = sendfile(ctx->socket, file->file->fd, &offset, ctx->size);

    if (n == -1) {
        ctx->err = ngx_errno;

    } else {
        ctx->sent = n;
        ctx->err = 0;
    }

#if 0
    ngx_time_update();
#endif

    ngx_log_debug4(NGX_LOG_DEBUG_EVENT, log, 0,
                   "sendfile: %z (err: %d) of %uz @%O",
                   n, ctx->err, ctx->size, file->file_pos);

    if (ctx->err == NGX_EINTR) {
        goto again;
    }
}

#endif /* NGX_THREADS */