How can I CURL POST a file using file pointer in C++ - c++

Question

I have a file pointer, such as the following:
FILE* f = tmpfile()
How do I use libcurl to do a HTTP POST to a URL as a field named F1?
I tried reading the file contents into a char* array but and used the following to upload:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
char* dump_buffer(void *buffer, int buffer_size){
int i;
char *ch = malloc(buffer_size);
for(i = 0;i < buffer_size;++i){
ch[i] = ((char *)buffer)[i];
//printf("%c",((char *)buffer)[i]);
}
return ch;
}
char* readFileBytes(const char *name){
FILE *file;
char *buffer;
unsigned long fileLen;
int i;
file = fopen("index.tar", "rb");
if (!file)
{
fprintf(stderr, "can't open file %s", "1.m4v");
exit(1);
}
fseek(file, 0, SEEK_END);
fileLen=ftell(file);
fseek(file, 0, SEEK_SET);
buffer=(char *)malloc(fileLen+1);
if (!buffer)
{
fprintf(stderr, "Memory error!");
fclose(file);
exit(1);
}
fread(buffer, fileLen, 1, file);
fclose(file);
char* ret = dump_buffer(&buffer, fileLen);
for(i = 0;i < fileLen;++i){
//printf("%c",ret[i]);
}
return ret;
}
int main(int argc, char *argv[])
{
CURL *curl;
CURLcode res;
struct curl_httppost *formpost=NULL;
struct curl_httppost *lastptr=NULL;
struct curl_slist *headers=NULL;
headers = curl_slist_append(headers, "Content-Type: multipart/form-data");
curl_global_init(CURL_GLOBAL_ALL);
/* Fill in the filename field */
char* p = readFileBytes("index.tar");
curl_formadd(&formpost,
&lastptr,
CURLFORM_COPYNAME, "F2",
CURLFORM_FILE, "index.tar",
CURLFORM_END);
curl_formadd(&formpost,
&lastptr,
CURLFORM_COPYNAME, "F1",
CURLFORM_COPYCONTENTS, (char*)p,
CURLFORM_END);
curl = curl_easy_init();
/* initalize custom header list (stating that Expect: 100-continue is not
wanted */
if(curl) {
/* what URL that receives this POST */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(curl, CURLOPT_URL, "http://oceanfizz.usc.edu/upload.php");
curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
res = curl_easy_perform(curl);
/* always cleanup */
curl_easy_cleanup(curl);
/* then cleanup the formpost chain */
curl_formfree(formpost);
/* free slist */
}
return 0;
}
The output that I get is
guest-wireless-207-151-246-070:Desktop ankurcha$ ./postit2
* About to connect() to oceanfizz.usc.edu port 80 (#0)
* Trying 128.125.49.29... * connected
* Connected to oceanfizz.usc.edu (128.125.49.29) port 80 (#0)
> POST /upload.php HTTP/1.1
Host: oceanfizz.usc.edu
Accept: */*
Content-Length: 20770
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------e04b6194f620
< HTTP/1.1 100 Continue
< HTTP/1.1 200 OK
< Date: Mon, 19 Apr 2010 03:51:04 GMT
< Server: Apache/2.2.12 (Ubuntu)
< X-Powered-By: PHP/5.2.10-2ubuntu6.4
< Vary: Accept-Encoding
< Content-Length: 335
< Content-Type: text/html
<
array(1) {
["F2"]=>
array(5) {
["name"]=>
string(9) "index.tar"
["type"]=>
string(24) "application/octet-stream"
["tmp_name"]=>
string(14) "/tmp/phpyOiqXh"
["error"]=>
int(0)
["size"]=>
int(20480)
}
}
array(1) {
["F1"]=>
string(0) ""
}
Sorry, there was a problem uploading your file.
* Connection #0 to host oceanfizz.usc.edu left intact
* Closing connection #0
I was expecting F1 to have binary content.

Answer 1

A HTTP POST can be done in many ways so there's not a single answer unless you specify more details in the question. One way to do POST programmatically with libcurl is as shown in this example:
http://curl.haxx.se/libcurl/c/post-callback.html
If you rather want to do a multipart formpost upload, possibly a better example is this:
http://curl.haxx.se/libcurl/c/postit2.html

Answer 2

You upload code works fine. The file uploaded is stored in a temporary file /tmp/phpyOiqXh. PHP won't store the content of uploaded file to a variable, just store the temp file's path.