528 строки
13 KiB
C
528 строки
13 KiB
C
/*****************************************************************************
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*
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* This example source code introduces a c library buffered I/O interface to
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* URL reads it supports fopen(), fread(), fgets(), feof(), fclose(),
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* rewind(). Supported functions have identical prototypes to their normal c
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* lib namesakes and are preceaded by url_ .
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*
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* Using this code you can replace your program's fopen() with url_fopen()
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* and fread() with url_fread() and it become possible to read remote streams
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* instead of (only) local files. Local files (ie those that can be directly
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* fopened) will drop back to using the underlying clib implementations
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*
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* See the main() function at the bottom that shows an app that retrives from a
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* specified url using fgets() and fread() and saves as two output files.
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*
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* Copyright (c) 2003 Simtec Electronics
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*
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* Re-implemented by Vincent Sanders <vince@kyllikki.org> with extensive
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* reference to original curl example code
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This example requires libcurl 7.9.7 or later.
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*/
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#include <stdio.h>
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#include <string.h>
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#ifndef WIN32
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# include <sys/time.h>
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#endif
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#include <stdlib.h>
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#include <errno.h>
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#include <curl/curl.h>
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enum fcurl_type_e {
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CFTYPE_NONE=0,
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CFTYPE_FILE=1,
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CFTYPE_CURL=2
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};
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struct fcurl_data
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{
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enum fcurl_type_e type; /* type of handle */
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union {
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CURL *curl;
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FILE *file;
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} handle; /* handle */
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char *buffer; /* buffer to store cached data*/
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size_t buffer_len; /* currently allocated buffers length */
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size_t buffer_pos; /* end of data in buffer*/
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int still_running; /* Is background url fetch still in progress */
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};
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typedef struct fcurl_data URL_FILE;
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/* exported functions */
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URL_FILE *url_fopen(const char *url,const char *operation);
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int url_fclose(URL_FILE *file);
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int url_feof(URL_FILE *file);
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size_t url_fread(void *ptr, size_t size, size_t nmemb, URL_FILE *file);
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char * url_fgets(char *ptr, size_t size, URL_FILE *file);
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void url_rewind(URL_FILE *file);
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/* we use a global one for convenience */
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CURLM *multi_handle;
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/* curl calls this routine to get more data */
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static size_t write_callback(char *buffer,
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size_t size,
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size_t nitems,
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void *userp)
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{
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char *newbuff;
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size_t rembuff;
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URL_FILE *url = (URL_FILE *)userp;
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size *= nitems;
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rembuff=url->buffer_len - url->buffer_pos; /* remaining space in buffer */
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if(size > rembuff) {
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/* not enough space in buffer */
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newbuff=realloc(url->buffer,url->buffer_len + (size - rembuff));
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if(newbuff==NULL) {
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fprintf(stderr,"callback buffer grow failed\n");
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size=rembuff;
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}
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else {
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/* realloc suceeded increase buffer size*/
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url->buffer_len+=size - rembuff;
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url->buffer=newbuff;
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}
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}
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memcpy(&url->buffer[url->buffer_pos], buffer, size);
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url->buffer_pos += size;
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return size;
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}
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/* use to attempt to fill the read buffer up to requested number of bytes */
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static int fill_buffer(URL_FILE *file, size_t want)
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{
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fd_set fdread;
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fd_set fdwrite;
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fd_set fdexcep;
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struct timeval timeout;
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int rc;
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/* only attempt to fill buffer if transactions still running and buffer
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* doesnt exceed required size already
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*/
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if((!file->still_running) || (file->buffer_pos > want))
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return 0;
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/* attempt to fill buffer */
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do {
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int maxfd = -1;
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long curl_timeo = -1;
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FD_ZERO(&fdread);
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FD_ZERO(&fdwrite);
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FD_ZERO(&fdexcep);
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/* set a suitable timeout to fail on */
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timeout.tv_sec = 60; /* 1 minute */
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timeout.tv_usec = 0;
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curl_multi_timeout(multi_handle, &curl_timeo);
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if(curl_timeo >= 0) {
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timeout.tv_sec = curl_timeo / 1000;
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if(timeout.tv_sec > 1)
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timeout.tv_sec = 1;
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else
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timeout.tv_usec = (curl_timeo % 1000) * 1000;
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}
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/* get file descriptors from the transfers */
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curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
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/* In a real-world program you OF COURSE check the return code of the
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function calls. On success, the value of maxfd is guaranteed to be
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greater or equal than -1. We call select(maxfd + 1, ...), specially
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in case of (maxfd == -1), we call select(0, ...), which is basically
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equal to sleep. */
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rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);
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switch(rc) {
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case -1:
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/* select error */
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break;
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case 0:
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default:
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/* timeout or readable/writable sockets */
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curl_multi_perform(multi_handle, &file->still_running);
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break;
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}
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} while(file->still_running && (file->buffer_pos < want));
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return 1;
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}
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/* use to remove want bytes from the front of a files buffer */
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static int use_buffer(URL_FILE *file,int want)
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{
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/* sort out buffer */
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if((file->buffer_pos - want) <=0) {
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/* ditch buffer - write will recreate */
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if(file->buffer)
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free(file->buffer);
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file->buffer=NULL;
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file->buffer_pos=0;
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file->buffer_len=0;
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}
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else {
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/* move rest down make it available for later */
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memmove(file->buffer,
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&file->buffer[want],
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(file->buffer_pos - want));
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file->buffer_pos -= want;
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}
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return 0;
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}
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URL_FILE *url_fopen(const char *url,const char *operation)
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{
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/* this code could check for URLs or types in the 'url' and
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basicly use the real fopen() for standard files */
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URL_FILE *file;
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(void)operation;
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file = malloc(sizeof(URL_FILE));
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if(!file)
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return NULL;
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memset(file, 0, sizeof(URL_FILE));
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if((file->handle.file=fopen(url,operation)))
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file->type = CFTYPE_FILE; /* marked as URL */
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else {
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file->type = CFTYPE_CURL; /* marked as URL */
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file->handle.curl = curl_easy_init();
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curl_easy_setopt(file->handle.curl, CURLOPT_URL, url);
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curl_easy_setopt(file->handle.curl, CURLOPT_WRITEDATA, file);
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curl_easy_setopt(file->handle.curl, CURLOPT_VERBOSE, 0L);
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curl_easy_setopt(file->handle.curl, CURLOPT_WRITEFUNCTION, write_callback);
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if(!multi_handle)
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multi_handle = curl_multi_init();
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curl_multi_add_handle(multi_handle, file->handle.curl);
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/* lets start the fetch */
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curl_multi_perform(multi_handle, &file->still_running);
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if((file->buffer_pos == 0) && (!file->still_running)) {
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/* if still_running is 0 now, we should return NULL */
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/* make sure the easy handle is not in the multi handle anymore */
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curl_multi_remove_handle(multi_handle, file->handle.curl);
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/* cleanup */
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curl_easy_cleanup(file->handle.curl);
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free(file);
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file = NULL;
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}
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}
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return file;
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}
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int url_fclose(URL_FILE *file)
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{
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int ret=0;/* default is good return */
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switch(file->type) {
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case CFTYPE_FILE:
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ret=fclose(file->handle.file); /* passthrough */
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break;
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case CFTYPE_CURL:
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/* make sure the easy handle is not in the multi handle anymore */
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curl_multi_remove_handle(multi_handle, file->handle.curl);
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/* cleanup */
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curl_easy_cleanup(file->handle.curl);
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break;
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default: /* unknown or supported type - oh dear */
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ret=EOF;
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errno=EBADF;
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break;
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}
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if(file->buffer)
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free(file->buffer);/* free any allocated buffer space */
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free(file);
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return ret;
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}
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int url_feof(URL_FILE *file)
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{
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int ret=0;
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switch(file->type) {
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case CFTYPE_FILE:
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ret=feof(file->handle.file);
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break;
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case CFTYPE_CURL:
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if((file->buffer_pos == 0) && (!file->still_running))
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ret = 1;
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break;
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default: /* unknown or supported type - oh dear */
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ret=-1;
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errno=EBADF;
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break;
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}
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return ret;
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}
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size_t url_fread(void *ptr, size_t size, size_t nmemb, URL_FILE *file)
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{
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size_t want;
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switch(file->type) {
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case CFTYPE_FILE:
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want=fread(ptr,size,nmemb,file->handle.file);
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break;
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case CFTYPE_CURL:
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want = nmemb * size;
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fill_buffer(file,want);
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/* check if theres data in the buffer - if not fill_buffer()
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* either errored or EOF */
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if(!file->buffer_pos)
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return 0;
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/* ensure only available data is considered */
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if(file->buffer_pos < want)
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want = file->buffer_pos;
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/* xfer data to caller */
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memcpy(ptr, file->buffer, want);
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use_buffer(file,want);
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want = want / size; /* number of items */
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break;
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default: /* unknown or supported type - oh dear */
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want=0;
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errno=EBADF;
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break;
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}
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return want;
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}
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char *url_fgets(char *ptr, size_t size, URL_FILE *file)
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{
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size_t want = size - 1;/* always need to leave room for zero termination */
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size_t loop;
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switch(file->type) {
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case CFTYPE_FILE:
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ptr = fgets(ptr,size,file->handle.file);
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break;
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case CFTYPE_CURL:
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fill_buffer(file,want);
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/* check if theres data in the buffer - if not fill either errored or
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* EOF */
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if(!file->buffer_pos)
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return NULL;
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/* ensure only available data is considered */
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if(file->buffer_pos < want)
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want = file->buffer_pos;
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/*buffer contains data */
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/* look for newline or eof */
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for(loop=0;loop < want;loop++) {
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if(file->buffer[loop] == '\n') {
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want=loop+1;/* include newline */
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break;
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}
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}
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/* xfer data to caller */
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memcpy(ptr, file->buffer, want);
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ptr[want]=0;/* allways null terminate */
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use_buffer(file,want);
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break;
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default: /* unknown or supported type - oh dear */
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ptr=NULL;
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errno=EBADF;
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break;
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}
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return ptr;/*success */
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}
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void url_rewind(URL_FILE *file)
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{
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switch(file->type) {
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case CFTYPE_FILE:
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rewind(file->handle.file); /* passthrough */
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break;
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case CFTYPE_CURL:
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/* halt transaction */
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curl_multi_remove_handle(multi_handle, file->handle.curl);
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/* restart */
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curl_multi_add_handle(multi_handle, file->handle.curl);
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/* ditch buffer - write will recreate - resets stream pos*/
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if(file->buffer)
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free(file->buffer);
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file->buffer=NULL;
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file->buffer_pos=0;
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file->buffer_len=0;
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break;
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default: /* unknown or supported type - oh dear */
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break;
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}
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}
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/* Small main program to retrive from a url using fgets and fread saving the
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* output to two test files (note the fgets method will corrupt binary files if
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* they contain 0 chars */
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int main(int argc, char *argv[])
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{
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URL_FILE *handle;
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FILE *outf;
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int nread;
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char buffer[256];
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const char *url;
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if(argc < 2)
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url="http://192.168.7.3/testfile";/* default to testurl */
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else
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url=argv[1];/* use passed url */
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/* copy from url line by line with fgets */
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outf=fopen("fgets.test","w+");
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if(!outf) {
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perror("couldn't open fgets output file\n");
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return 1;
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}
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handle = url_fopen(url, "r");
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if(!handle) {
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printf("couldn't url_fopen() %s\n", url);
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fclose(outf);
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return 2;
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}
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while(!url_feof(handle)) {
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url_fgets(buffer,sizeof(buffer),handle);
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fwrite(buffer,1,strlen(buffer),outf);
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}
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url_fclose(handle);
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fclose(outf);
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/* Copy from url with fread */
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outf=fopen("fread.test","w+");
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if(!outf) {
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perror("couldn't open fread output file\n");
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return 1;
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}
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handle = url_fopen("testfile", "r");
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if(!handle) {
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printf("couldn't url_fopen() testfile\n");
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fclose(outf);
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return 2;
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}
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do {
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nread = url_fread(buffer, 1,sizeof(buffer), handle);
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fwrite(buffer,1,nread,outf);
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} while(nread);
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url_fclose(handle);
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fclose(outf);
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/* Test rewind */
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outf=fopen("rewind.test","w+");
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if(!outf) {
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perror("couldn't open fread output file\n");
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return 1;
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}
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handle = url_fopen("testfile", "r");
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if(!handle) {
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printf("couldn't url_fopen() testfile\n");
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fclose(outf);
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return 2;
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}
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nread = url_fread(buffer, 1,sizeof(buffer), handle);
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fwrite(buffer,1,nread,outf);
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url_rewind(handle);
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buffer[0]='\n';
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fwrite(buffer,1,1,outf);
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nread = url_fread(buffer, 1,sizeof(buffer), handle);
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fwrite(buffer,1,nread,outf);
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url_fclose(handle);
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fclose(outf);
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return 0;/* all done */
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}
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