The new ftpuploadresume.c example by Philip Bock

docs/examples/Makefile.am

@@ -11,7 +11,7 @@ EXTRA_DIST = README curlgtk.c sepheaders.c simple.c postit2.c		\
  multi-post.c fopen.c simplepost.c makefile.dj curlx.c https.c		\
  multi-debugcallback.c fileupload.c getinfo.c ftp3rdparty.c debug.c	\
  anyauthput.c htmltitle.cc htmltidy.c opensslthreadlock.c		\
- cookie_interface.c cacertinmem.c synctime.c sampleconv.c
+ cookie_interface.c cacertinmem.c synctime.c sampleconv.c ftpuploadresume.c
 
 all:
 	@echo "done"

docs/examples/ftpuploadresume.c

+/*****************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * $Id$
+ *
+ * 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>
+
+
+/* The MinGW headers are missing a few Win32 function definitions,
+   you shouldn't need this if you use VC++ */
+int __cdecl _snscanf(const char * input, size_t length, const char * format, ...);
+
+
+/* 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, TRUE);
+
+	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, TRUE);
+
+	curl_easy_setopt(curlhandle, CURLOPT_VERBOSE, TRUE);
+
+	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, TRUE);
+			curl_easy_setopt(curlhandle, CURLOPT_HEADER, TRUE);
+
+			r = curl_easy_perform(curlhandle);
+			if (r != CURLE_OK)
+				continue;
+
+			curl_easy_setopt(curlhandle, CURLOPT_NOBODY, FALSE);
+			curl_easy_setopt(curlhandle, CURLOPT_HEADER, FALSE);
+
+			fseek(f, uploaded_len, SEEK_SET);
+
+			curl_easy_setopt(curlhandle, CURLOPT_FTPAPPEND, TRUE);
+		}
+		else { /* no */
+			curl_easy_setopt(curlhandle, CURLOPT_FTPAPPEND, FALSE);
+		}
+
+		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;
+}