Unverified Commit 12e78939 authored by Daniel Stenberg's avatar Daniel Stenberg
Browse files

examples/post-callback: stop returning one byte at a time 

... since people copy and paste code from this example and thus they get
an inefficient POST operation without a good reason and sometimes
without understanding why.

Instead this now returns as much data as possible.
parent b081f2ad

docs/examples/post-callback.c

+32 −23
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 - 2017, 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
@@ -20,33 +20,42 @@ 
 *

 ***************************************************************************/

/* <DESC>

 * An example source code that issues a HTTP POST and we provide the actual

 * data through a read callback.

 * Issue an HTTP POST and provide the data through the read callback.

 * </DESC>

 */

#include <stdio.h>

#include <string.h>

#include <curl/curl.h>



static const char data[]="this is what we post to the silly web server";

/* silly test data to POST */

static const char data[]="Lorem ipsum dolor sit amet, consectetur adipiscing "

  "elit. Sed vel urna neque. Ut quis leo metus. Quisque eleifend, ex at "

  "laoreet rhoncus, odio ipsum semper metus, at tempus ante urna in mauris. "

  "Suspendisse ornare tempor venenatis. Ut dui neque, pellentesque a varius "

  "eget, mattis vitae ligula. Fusce ut pharetra est. Ut ullamcorper mi ac "

  "sollicitudin semper. Praesent sit amet tellus varius, posuere nulla non, "

  "rhoncus ipsum.";



struct WriteThis {

  const char *readptr;

  long sizeleft;

  size_t sizeleft;

};



static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp)

static size_t read_callback(void *dest, size_t size, size_t nmemb, void *userp)

{

  struct WriteThis *pooh = (struct WriteThis *)userp;



  if(size*nmemb < 1)

    return 0;



  if(pooh->sizeleft) {

    *(char *)ptr = pooh->readptr[0]; /* copy one single byte */

    pooh->readptr++;                 /* advance pointer */

    pooh->sizeleft--;                /* less data left */

    return 1;                        /* we return 1 byte at a time! */

  struct WriteThis *wt = (struct WriteThis *)userp;

  size_t buffer_size = size*nmemb;



  if(wt->sizeleft) {

    /* copy as much as possible from the source to the destination */

    size_t copy_this_much = wt->sizeleft;

    if(copy_this_much > buffer_size)

      copy_this_much = buffer_size;

    memcpy(dest, wt->readptr, copy_this_much);



    wt->readptr += copy_this_much;

    wt->sizeleft -= copy_this_much;

    return copy_this_much; /* we copied this many bytes */

  }



  return 0; /* no more data left to deliver */
@@ -57,10 +66,10 @@ int main(void) 
  CURL *curl;

  CURLcode res;



  struct WriteThis pooh;

  struct WriteThis wt;



  pooh.readptr = data;

  pooh.sizeleft = (long)strlen(data);

  wt.readptr = data;

  wt.sizeleft = strlen(data);



  /* In windows, this will init the winsock stuff */

  res = curl_global_init(CURL_GLOBAL_DEFAULT);
@@ -75,7 +84,7 @@ int main(void) 
  curl = curl_easy_init();

  if(curl) {

    /* First set the URL that is about to receive our POST. */

    curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/index.cgi");

    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/index.cgi");



    /* Now specify we want to POST data */

    curl_easy_setopt(curl, CURLOPT_POST, 1L);
@@ -84,7 +93,7 @@ int main(void) 
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);



    /* pointer to pass to our read function */

    curl_easy_setopt(curl, CURLOPT_READDATA, &pooh);

    curl_easy_setopt(curl, CURLOPT_READDATA, &wt);



    /* get verbose debug output please */

    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
@@ -108,7 +117,7 @@ int main(void) 
#else

    /* Set the expected POST size. If you want to POST large amounts of data,

       consider CURLOPT_POSTFIELDSIZE_LARGE */

    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, pooh.sizeleft);

    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, wt.sizeleft);

#endif



#ifdef DISABLE_EXPECT