ftpuploadresume.c

/*****************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * $Id: ftpuploadresume.c,v 1.5 2008-08-31 12:12:35 yangtse Exp $
 *
 * Upload to FTP, resuming failed transfers
 *
 * Compile for MinGW like this:
 *  gcc -Wall -pedantic -std=c99 ftpuploadwithresume.c -o ftpuploadresume.exe
 *  -lcurl -lmsvcr70
 *
 * Written by Philip Bock
 */ 
 
#include <stdlib.h>
#include <stdio.h>
 
#include <curl/curl.h>
 
#if defined(_MSC_VER) && (_MSC_VER < 1300)
#error _snscanf requires MSVC 7.0 or later.
#endif
 
/* The MinGW headers are missing a few Win32 function definitions,
   you shouldn't need this if you use VC++ */ 
#ifdef __MINGW32__
int __cdecl _snscanf(const char * input, size_t length, const char * format, ...);
#endif
 
 
/* parse headers for Content-Length */ 
size_t getcontentlengthfunc(void *ptr, size_t size, size_t nmemb, void *stream) {
	int r;
	long len = 0;
 
	/* _snscanf() is Win32 specific */ 
	r = _snscanf(ptr, size * nmemb, "Content-Length: %ld\n", &len);
 
	if (r) /* Microsoft: we don't read the specs */ 
		*((long *) stream) = len;
 
	return size * nmemb;
}
 
/* discard downloaded data */ 
size_t discardfunc(void *ptr, size_t size, size_t nmemb, void *stream) {
	return size * nmemb;
}
 
/* read data to upload */ 
size_t readfunc(void *ptr, size_t size, size_t nmemb, void *stream)
{
	FILE *f = stream;
	size_t n;
 
	if (ferror(f))
		return CURL_READFUNC_ABORT;
 
	n = fread(ptr, size, nmemb, f) * size;
 
	return n;
}
 
 
int upload(CURL *curlhandle, const char * remotepath, const char * localpath,
           long timeout, long tries)
{
	FILE *f;
	long uploaded_len = 0;
	CURLcode r = CURLE_GOT_NOTHING;
	int c;
 
	f = fopen(localpath, "rb");
	if (f == NULL) {
		perror(NULL);
		return 0;
	}
 
	curl_easy_setopt(curlhandle, CURLOPT_UPLOAD, 1L);
 
	curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);
 
	if (timeout)
		curl_easy_setopt(curlhandle, CURLOPT_FTP_RESPONSE_TIMEOUT, timeout);
 
	curl_easy_setopt(curlhandle, CURLOPT_HEADERFUNCTION, getcontentlengthfunc);
	curl_easy_setopt(curlhandle, CURLOPT_HEADERDATA, &uploaded_len);
 
	curl_easy_setopt(curlhandle, CURLOPT_WRITEFUNCTION, discardfunc);
 
	curl_easy_setopt(curlhandle, CURLOPT_READFUNCTION, readfunc);
	curl_easy_setopt(curlhandle, CURLOPT_READDATA, f);
 
	curl_easy_setopt(curlhandle, CURLOPT_FTPPORT, "-"); /* disable passive mode */ 
	curl_easy_setopt(curlhandle, CURLOPT_FTP_CREATE_MISSING_DIRS, 1L);
 
	curl_easy_setopt(curlhandle, CURLOPT_VERBOSE, 1L);
 
	for (c = 0; (r != CURLE_OK) && (c < tries); c++) {
		/* are we resuming? */ 
		if (c) { /* yes */ 
			/* determine the length of the file already written */ 
 
			/*
			 * With NOBODY and NOHEADER, libcurl will issue a SIZE
			 * command, but the only way to retrieve the result is
			 * to parse the returned Content-Length header. Thus,
			 * getcontentlengthfunc(). We need discardfunc() above
			 * because HEADER will dump the headers to stdout
			 * without it.
			 */ 
			curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 1L);
			curl_easy_setopt(curlhandle, CURLOPT_HEADER, 1L);
 
			r = curl_easy_perform(curlhandle);
			if (r != CURLE_OK)
				continue;
 
			curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 0L);
			curl_easy_setopt(curlhandle, CURLOPT_HEADER, 0L);
 
			fseek(f, uploaded_len, SEEK_SET);
 
			curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);
		}
		else { /* no */ 
			curl_easy_setopt(curlhandle, CURLOPT_APPEND, 0L);
		}
 
		r = curl_easy_perform(curlhandle);
	}
 
	fclose(f);
 
	if (r == CURLE_OK)
		return 1;
	else {
		fprintf(stderr, "%s\n", curl_easy_strerror(r));
		return 0;
	}
}
 
int main(int c, char **argv) {
	CURL *curlhandle = NULL;
 
	curl_global_init(CURL_GLOBAL_ALL);
	curlhandle = curl_easy_init();
 
	upload(curlhandle, "ftp://user:pass@host/path/file", "C:\\file", 0, 3);
 
	curl_easy_cleanup(curlhandle);
	curl_global_cleanup();
 
	return 0;
}

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