Commit 1e486db9 authored by Daniel Stenberg's avatar Daniel Stenberg
Browse files

file: try reading from files with no size 

Some systems have special files that report as 0 bytes big, but still
contain data that can be read (for example /proc/cpuinfo on
Linux). Starting now, a zero byte size is considered "unknown" size and
will be read as far as possible anyway.

Reported-by: Jesse Tan

Closes #681
parent 3ae77f07

lib/file.c

+18 −8
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.

 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms
@@ -426,6 +426,7 @@ static CURLcode file_do(struct connectdata *conn, bool *done) 
                          Windows version to have a different struct without

                          having to redefine the simple word 'stat' */

  curl_off_t expected_size=0;

  bool size_known;

  bool fstated=FALSE;

  ssize_t nread;

  struct SessionHandle *data = conn->data;
@@ -531,8 +532,10 @@ static CURLcode file_do(struct connectdata *conn, bool *done) 
  if(data->req.maxdownload > 0)

    expected_size = data->req.maxdownload;



  if(fstated && (expected_size == 0))

    return CURLE_OK;

  if(!fstated || (expected_size == 0))

    size_known = FALSE;

  else

    size_known = TRUE;



  /* The following is a shortcut implementation of file reading

     this is both more efficient than the former call to download() and
@@ -551,19 +554,26 @@ static CURLcode file_do(struct connectdata *conn, bool *done) 


  while(!result) {

    /* Don't fill a whole buffer if we want less than all data */

    size_t bytestoread =

    size_t bytestoread;



    if(size_known) {

      bytestoread =

        (expected_size < CURL_OFF_T_C(BUFSIZE) - CURL_OFF_T_C(1)) ?

        curlx_sotouz(expected_size) : BUFSIZE - 1;

    }

    else

      bytestoread = BUFSIZE-1;



    nread = read(fd, buf, bytestoread);



    if(nread > 0)

      buf[nread] = 0;



    if(nread <= 0 || expected_size == 0)

    if(nread <= 0 || (size_known && (expected_size == 0)))

      break;



    bytecount += nread;

    if(size_known)

      expected_size -= nread;



    result = Curl_client_write(conn, CLIENTWRITE_BODY, buf, nread);