apache-api/8498: ap_send_fd doesn't seem to send the file; no error reported

[Shamim Mohamed <sp...@languid.org>]

>Number:         8498
>Category:       apache-api
>Synopsis:       ap_send_fd doesn't seem to send the file; no error reported
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    apache
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Tue Oct 09 15:00:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     spmap@languid.org
>Release:        2.0.16-beta
>Organization:
apache
>Environment:
$   uname -a
Linux artemis.rubiconproject.com 2.4.3-20mdk #1 Sun Apr 15 23:03:10 CEST 2001 i686 unknown
$  gcc --version
2.96
>Description:
I'm porting a module from 1.3.20 that has a content handler. The sequence of ops is:

    /*
     * File exists?
     */
    if (stat(filename, &st) < 0)
        return ... ;

    /* Readable? */
    err = apr_file_open(&fp, filename, APR_READ, APR_OS_DEFAULT, r->pool);
    if (err != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_NOERRNO | APLOG_DEBUG, err, r->server,
                     "couldn't open file \"%s\"", filename);
        return ... ;
    }

    /* Get file type and size */
    filesize = st.st_size;
    filetype = slFileType(filename);

    /* Send HTTP header */
    r->content_type = filetype;
    ap_set_content_length(r, filesize);
    r->status = HTTP_OK;
    r->status_line = "200 OK";
    /*ap_send_http_header(r);*/
 
    /* Write the content */
    err = ap_send_fd(fp, r, 0, filesize, &sent);
    if (err != APR_SUCCESS || sent != filesize)
        ap_log_error(APLOG_MARK, APLOG_NOERRNO | APLOG_DEBUG, err, r->server,
                     "short write (%d/%d) for file \"%s\"",
                     sent, filesize, filename);

    apr_file_close(fp);

No errors are reported - I'm running httpd at LogLevel debug. But no data is
actually sent by ap_send_fd:

$ telnet localhost 6060
Trying 63.95.167.73...
Connected to localhost.localdomain
Escape character is '^]'.
GET /content?pid=4078&f=/some/long/path/foo.txt&vc=23&t=1002662916&ttl=3600&k=1&a=nbGw0cZtf90iHTO0tp6AJg HTTP/1.0
 
HTTP/1.1 200 OK
Date: Tue, 09 Oct 2001 21:29:12 GMT
Server: Apache/2.0.16 (Unix)
Content-Length: 68
Connection: close
Content-Type: text/plain; charset=ISO-8859-1
 
Connection closed by foreign host.

As you can see, Content-type and Content-length are set correctly, but no data.

The server was built with:

./configure  --prefix=/usr/local/apache2 --enable-so --with-mpm=threaded --disable-cgid

and it's running on port 6060 as a non-root user.
>How-To-Repeat:
I'm trying to trim down the DSO to reproduce the problem.
>Fix:
In the next few days I shall try to trace ap_send_fd() and try to figure out what's
going on.
>Release-Note:
>Audit-Trail:
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