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curl/docs/examples/hiperfifo.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2021, 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
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
/* <DESC>
* multi socket API usage with libevent 2
* </DESC>
*/
/* Example application source code using the multi socket interface to
download many files at once.
Written by Jeff Pohlmeyer
Requires libevent version 2 and a (POSIX?) system that has mkfifo().
This is an adaptation of libcurl's "hipev.c" and libevent's "event-test.c"
sample programs.
When running, the program creates the named pipe "hiper.fifo"
Whenever there is input into the fifo, the program reads the input as a list
of URL's and creates some new easy handles to fetch each URL via the
curl_multi "hiper" API.
Thus, you can try a single URL:
% echo http://www.yahoo.com > hiper.fifo
Or a whole bunch of them:
% cat my-url-list > hiper.fifo
The fifo buffer is handled almost instantly, so you can even add more URL's
while the previous requests are still being downloaded.
Note:
For the sake of simplicity, URL length is limited to 1023 char's !
This is purely a demo app, all retrieved data is simply discarded by the write
callback.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <sys/poll.h>
#include <curl/curl.h>
#include <event2/event.h>
#include <event2/event_struct.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include <sys/cdefs.h>
#define MSG_OUT stdout /* Send info to stdout, change to stderr if you want */
/* Global information, common to all connections */
typedef struct _GlobalInfo
{
struct event_base *evbase;
struct event fifo_event;
struct event timer_event;
CURLM *multi;
int still_running;
FILE *input;
int stopped;
} GlobalInfo;
/* Information associated with a specific easy handle */
typedef struct _ConnInfo
{
CURL *easy;
char *url;
GlobalInfo *global;
char error[CURL_ERROR_SIZE];
} ConnInfo;
/* Information associated with a specific socket */
typedef struct _SockInfo
{
curl_socket_t sockfd;
CURL *easy;
int action;
long timeout;
struct event ev;
GlobalInfo *global;
} SockInfo;
#define mycase(code) \
case code: s = __STRING(code)
/* Die if we get a bad CURLMcode somewhere */
static void mcode_or_die(const char *where, CURLMcode code)
{
if(CURLM_OK != code) {
const char *s;
switch(code) {
mycase(CURLM_BAD_HANDLE); break;
mycase(CURLM_BAD_EASY_HANDLE); break;
mycase(CURLM_OUT_OF_MEMORY); break;
mycase(CURLM_INTERNAL_ERROR); break;
mycase(CURLM_UNKNOWN_OPTION); break;
mycase(CURLM_LAST); break;
default: s = "CURLM_unknown"; break;
mycase(CURLM_BAD_SOCKET);
fprintf(MSG_OUT, "ERROR: %s returns %s\n", where, s);
/* ignore this error */
return;
}
fprintf(MSG_OUT, "ERROR: %s returns %s\n", where, s);
exit(code);
}
}
/* Update the event timer after curl_multi library calls */
static int multi_timer_cb(CURLM *multi, long timeout_ms, GlobalInfo *g)
{
struct timeval timeout;
(void)multi;
timeout.tv_sec = timeout_ms/1000;
timeout.tv_usec = (timeout_ms%1000)*1000;
fprintf(MSG_OUT, "multi_timer_cb: Setting timeout to %ld ms\n", timeout_ms);
/*
* if timeout_ms is -1, just delete the timer
*
* For all other values of timeout_ms, this should set or *update* the timer
* to the new value
*/
if(timeout_ms == -1)
evtimer_del(&g->timer_event);
else /* includes timeout zero */
evtimer_add(&g->timer_event, &timeout);
return 0;
}
/* Check for completed transfers, and remove their easy handles */
static void check_multi_info(GlobalInfo *g)
{
char *eff_url;
CURLMsg *msg;
int msgs_left;
ConnInfo *conn;
CURL *easy;
CURLcode res;
fprintf(MSG_OUT, "REMAINING: %d\n", g->still_running);
while((msg = curl_multi_info_read(g->multi, &msgs_left))) {
if(msg->msg == CURLMSG_DONE) {
easy = msg->easy_handle;
res = msg->data.result;
curl_easy_getinfo(easy, CURLINFO_PRIVATE, &conn);
curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &eff_url);
fprintf(MSG_OUT, "DONE: %s => (%d) %s\n", eff_url, res, conn->error);
curl_multi_remove_handle(g->multi, easy);
free(conn->url);
curl_easy_cleanup(easy);
free(conn);
}
}
if(g->still_running == 0 && g->stopped)
event_base_loopbreak(g->evbase);
}
/* Called by libevent when we get action on a multi socket */
static void event_cb(int fd, short kind, void *userp)
{
GlobalInfo *g = (GlobalInfo*) userp;
CURLMcode rc;
int action =
((kind & EV_READ) ? CURL_CSELECT_IN : 0) |
((kind & EV_WRITE) ? CURL_CSELECT_OUT : 0);
rc = curl_multi_socket_action(g->multi, fd, action, &g->still_running);
mcode_or_die("event_cb: curl_multi_socket_action", rc);
check_multi_info(g);
if(g->still_running <= 0) {
fprintf(MSG_OUT, "last transfer done, kill timeout\n");
if(evtimer_pending(&g->timer_event, NULL)) {
evtimer_del(&g->timer_event);
}
}
}
/* Called by libevent when our timeout expires */
static void timer_cb(int fd, short kind, void *userp)
{
GlobalInfo *g = (GlobalInfo *)userp;
CURLMcode rc;
(void)fd;
(void)kind;
rc = curl_multi_socket_action(g->multi,
CURL_SOCKET_TIMEOUT, 0, &g->still_running);
mcode_or_die("timer_cb: curl_multi_socket_action", rc);
check_multi_info(g);
}
/* Clean up the SockInfo structure */
static void remsock(SockInfo *f)
{
if(f) {
if(event_initialized(&f->ev)) {
event_del(&f->ev);
}
free(f);
}
}
/* Assign information to a SockInfo structure */
static void setsock(SockInfo *f, curl_socket_t s, CURL *e, int act,
GlobalInfo *g)
{
int kind =
((act & CURL_POLL_IN) ? EV_READ : 0) |
((act & CURL_POLL_OUT) ? EV_WRITE : 0) | EV_PERSIST;
f->sockfd = s;
f->action = act;
f->easy = e;
if(event_initialized(&f->ev)) {
event_del(&f->ev);
}
event_assign(&f->ev, g->evbase, f->sockfd, kind, event_cb, g);
event_add(&f->ev, NULL);
}
/* Initialize a new SockInfo structure */
static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *g)
{
SockInfo *fdp = calloc(sizeof(SockInfo), 1);
fdp->global = g;
setsock(fdp, s, easy, action, g);
curl_multi_assign(g->multi, s, fdp);
}
/* CURLMOPT_SOCKETFUNCTION */
static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
{
GlobalInfo *g = (GlobalInfo*) cbp;
SockInfo *fdp = (SockInfo*) sockp;
const char *whatstr[]={ "none", "IN", "OUT", "INOUT", "REMOVE" };
fprintf(MSG_OUT,
"socket callback: s=%d e=%p what=%s ", s, e, whatstr[what]);
if(what == CURL_POLL_REMOVE) {
fprintf(MSG_OUT, "\n");
remsock(fdp);
}
else {
if(!fdp) {
fprintf(MSG_OUT, "Adding data: %s\n", whatstr[what]);
addsock(s, e, what, g);
}
else {
fprintf(MSG_OUT,
"Changing action from %s to %s\n",
whatstr[fdp->action], whatstr[what]);
setsock(fdp, s, e, what, g);
}
}
return 0;
}
/* CURLOPT_WRITEFUNCTION */
static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *data)
{
(void)ptr;
(void)data;
return size * nmemb;
}
/* CURLOPT_PROGRESSFUNCTION */
static int prog_cb(void *p, double dltotal, double dlnow, double ult,
double uln)
{
ConnInfo *conn = (ConnInfo *)p;
(void)ult;
(void)uln;
fprintf(MSG_OUT, "Progress: %s (%g/%g)\n", conn->url, dlnow, dltotal);
return 0;
}
/* Create a new easy handle, and add it to the global curl_multi */
static void new_conn(char *url, GlobalInfo *g)
{
ConnInfo *conn;
CURLMcode rc;
conn = calloc(1, sizeof(ConnInfo));
conn->error[0]='\0';
conn->easy = curl_easy_init();
if(!conn->easy) {
fprintf(MSG_OUT, "curl_easy_init() failed, exiting!\n");
exit(2);
}
conn->global = g;
conn->url = strdup(url);
curl_easy_setopt(conn->easy, CURLOPT_URL, conn->url);
curl_easy_setopt(conn->easy, CURLOPT_WRITEFUNCTION, write_cb);
curl_easy_setopt(conn->easy, CURLOPT_WRITEDATA, conn);
curl_easy_setopt(conn->easy, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error);
curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn);
curl_easy_setopt(conn->easy, CURLOPT_NOPROGRESS, 0L);
curl_easy_setopt(conn->easy, CURLOPT_PROGRESSFUNCTION, prog_cb);
curl_easy_setopt(conn->easy, CURLOPT_PROGRESSDATA, conn);
curl_easy_setopt(conn->easy, CURLOPT_FOLLOWLOCATION, 1L);
fprintf(MSG_OUT,
"Adding easy %p to multi %p (%s)\n", conn->easy, g->multi, url);
rc = curl_multi_add_handle(g->multi, conn->easy);
mcode_or_die("new_conn: curl_multi_add_handle", rc);
/* note that the add_handle() will set a time-out to trigger very soon so
that the necessary socket_action() call will be called by this app */
}
/* This gets called whenever data is received from the fifo */
static void fifo_cb(int fd, short event, void *arg)
{
char s[1024];
long int rv = 0;
int n = 0;
GlobalInfo *g = (GlobalInfo *)arg;
(void)fd;
(void)event;
do {
s[0]='\0';
rv = fscanf(g->input, "%1023s%n", s, &n);
s[n]='\0';
if(n && s[0]) {
if(!strcmp(s, "stop")) {
g->stopped = 1;
if(g->still_running == 0)
event_base_loopbreak(g->evbase);
}
else
new_conn(s, arg); /* if we read a URL, go get it! */
}
else
break;
} while(rv != EOF);
}
/* Create a named pipe and tell libevent to monitor it */
static const char *fifo = "hiper.fifo";
static int init_fifo(GlobalInfo *g)
{
struct stat st;
curl_socket_t sockfd;
fprintf(MSG_OUT, "Creating named pipe \"%s\"\n", fifo);
if(lstat (fifo, &st) == 0) {
if((st.st_mode & S_IFMT) == S_IFREG) {
errno = EEXIST;
perror("lstat");
exit(1);
}
}
unlink(fifo);
if(mkfifo (fifo, 0600) == -1) {
perror("mkfifo");
exit(1);
}
sockfd = open(fifo, O_RDWR | O_NONBLOCK, 0);
if(sockfd == -1) {
perror("open");
exit(1);
}
g->input = fdopen(sockfd, "r");
fprintf(MSG_OUT, "Now, pipe some URL's into > %s\n", fifo);
event_assign(&g->fifo_event, g->evbase, sockfd, EV_READ|EV_PERSIST,
fifo_cb, g);
event_add(&g->fifo_event, NULL);
return (0);
}
static void clean_fifo(GlobalInfo *g)
{
event_del(&g->fifo_event);
fclose(g->input);
unlink(fifo);
}
int main(int argc, char **argv)
{
GlobalInfo g;
(void)argc;
(void)argv;
memset(&g, 0, sizeof(GlobalInfo));
g.evbase = event_base_new();
init_fifo(&g);
g.multi = curl_multi_init();
evtimer_assign(&g.timer_event, g.evbase, timer_cb, &g);
/* setup the generic multi interface options we want */
curl_multi_setopt(g.multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
curl_multi_setopt(g.multi, CURLMOPT_SOCKETDATA, &g);
curl_multi_setopt(g.multi, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
curl_multi_setopt(g.multi, CURLMOPT_TIMERDATA, &g);
/* we don't call any curl_multi_socket*() function yet as we have no handles
added! */
event_base_dispatch(g.evbase);
/* this, of course, won't get called since only way to stop this program is
via ctrl-C, but it is here to show how cleanup /would/ be done. */
clean_fifo(&g);
event_del(&g.timer_event);
event_base_free(g.evbase);
curl_multi_cleanup(g.multi);
return 0;
}
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