ephiperfifo.c

/***************************************************************************
 * _ _ ____ _
 * Project ___| | | | _ \| |
 * / __| | | | |_) | |
 * | (__| |_| | _ <| |___
 * \___|\___/|_| \_\_____|
 *
 * Copyright (C) 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.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/
/* <DESC>
 * multi socket API usage with epoll and timerfd
 * </DESC>
 */
/* Example application source code using the multi socket interface to
 * download many files at once.
 *
 * This example features the same basic functionality as hiperfifo.c does,
 * but this uses epoll and timerfd instead of libevent.
 *
 * Written by Jeff Pohlmeyer, converted to use epoll by Josh Bialkowski
 
Requires a Linux system with epoll
 
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 <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/timerfd.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
 
#include <curl/curl.h>
 
#define MSG_OUT stdout /* Send info to stdout, change to stderr if you want */
 
 
/* Global information, common to all connections */
struct GlobalInfo {
 int epfd; /* epoll filedescriptor */
 int tfd; /* timer filedescriptor */
 int fifofd; /* fifo filedescriptor */
 CURLM *multi;
 int still_running;
 FILE *input;
};
 
/* Information associated with a specific easy handle */
struct ConnInfo {
 CURL *easy;
 char *url;
 struct GlobalInfo *global;
 char error[CURL_ERROR_SIZE];
};
 
/* Information associated with a specific socket */
struct SockInfo {
 curl_socket_t sockfd;
 CURL *easy;
 int action;
 long timeout;
 struct GlobalInfo *global;
};
 
#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);
 }
}
 
static void timer_cb(struct GlobalInfo *g, int revents);
 
/* Update the timer after curl_multi library does its thing. Curl informs the
 * application through this callback what it wants the new timeout to be,
 * after it does some work. */
static int multi_timer_cb(CURLM *multi, long timeout_ms, struct GlobalInfo *g)
{
 struct itimerspec its;
 
 fprintf(MSG_OUT, "multi_timer_cb: Setting timeout to %ld ms\n", timeout_ms);
 
 if(timeout_ms > 0) {
 its.it_interval.tv_sec = 0;
 its.it_interval.tv_nsec = 0;
 its.it_value.tv_sec = timeout_ms / 1000;
 its.it_value.tv_nsec = (timeout_ms % 1000) * 1000 * 1000;
 }
 else if(timeout_ms == 0) {
 /* libcurl wants us to timeout now, however setting both fields of
 * new_value.it_value to zero disarms the timer. The closest we can
 * do is to schedule the timer to fire in 1 ns. */
 its.it_interval.tv_sec = 0;
 its.it_interval.tv_nsec = 0;
 its.it_value.tv_sec = 0;
 its.it_value.tv_nsec = 1;
 }
 else {
 memset(&its, 0, sizeof(its));
 }
 
 timerfd_settime(g->tfd, /* flags= */0, &its, NULL);
 return 0;
}
 
/* Check for completed transfers, and remove their easy handles */
static void check_multi_info(struct GlobalInfo *g)
{
 char *eff_url;
 CURLMsg *msg;
 int msgs_left;
 struct 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);
 }
 }
}
 
/* Called by libevent when we get action on a multi socket filedescriptor */
static void event_cb(struct GlobalInfo *g, int fd, int revents)
{
 CURLMcode rc;
 struct itimerspec its;
 
 int action = ((revents & EPOLLIN) ? CURL_CSELECT_IN : 0) |
 ((revents & EPOLLOUT) ? 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");
 memset(&its, 0, sizeof(its));
 timerfd_settime(g->tfd, 0, &its, NULL);
 }
}
 
/* Called by main loop when our timeout expires */
static void timer_cb(struct GlobalInfo *g, int revents)
{
 CURLMcode rc;
 uint64_t count = 0;
 ssize_t err = 0;
 
 err = read(g->tfd, &count, sizeof(uint64_t));
 if(err == -1) {
 /* Note that we may call the timer callback even if the timerfd is not
 * readable. It's possible that there are multiple events stored in the
 * epoll buffer (i.e. the timer may have fired multiple times). The event
 * count is cleared after the first call so future events in the epoll
 * buffer fails to read from the timer. */
 if(errno == EAGAIN) {
 fprintf(MSG_OUT, "EAGAIN on tfd %d\n", g->tfd);
 return;
 }
 }
 if(err != sizeof(uint64_t)) {
 fprintf(stderr, "read(tfd) == %ld", err);
 perror("read(tfd)");
 }
 
 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(struct SockInfo *f, struct GlobalInfo *g)
{
 if(f) {
 if(f->sockfd) {
 if(epoll_ctl(g->epfd, EPOLL_CTL_DEL, f->sockfd, NULL))
 fprintf(stderr, "EPOLL_CTL_DEL failed for fd: %d : %s\n",
 f->sockfd, strerror(errno));
 }
 free(f);
 }
}
 
/* Assign information to a SockInfo structure */
static void setsock(struct SockInfo *f, curl_socket_t s, CURL *e, int act,
 struct GlobalInfo *g)
{
 struct epoll_event ev;
 int kind = ((act & CURL_POLL_IN) ? EPOLLIN : 0) |
 ((act & CURL_POLL_OUT) ? EPOLLOUT : 0);
 
 if(f->sockfd) {
 if(epoll_ctl(g->epfd, EPOLL_CTL_DEL, f->sockfd, NULL))
 fprintf(stderr, "EPOLL_CTL_DEL failed for fd: %d : %s\n",
 f->sockfd, strerror(errno));
 }
 
 f->sockfd = s;
 f->action = act;
 f->easy = e;
 
 ev.events = kind;
 ev.data.fd = s;
 if(epoll_ctl(g->epfd, EPOLL_CTL_ADD, s, &ev))
 fprintf(stderr, "EPOLL_CTL_ADD failed for fd: %d : %s\n",
 s, strerror(errno));
}
 
/* Initialize a new SockInfo structure */
static void addsock(curl_socket_t s, CURL *easy, int action,
 struct GlobalInfo *g)
{
 struct SockInfo *fdp = (struct SockInfo*)calloc(1, sizeof(struct SockInfo));
 
 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)
{
 struct GlobalInfo *g = (struct GlobalInfo*) cbp;
 struct SockInfo *fdp = (struct 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, g);
 }
 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)
{
 struct ConnInfo *conn = (struct 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(const char *url, struct GlobalInfo *g)
{
 struct ConnInfo *conn;
 CURLMcode rc;
 
 conn = (struct ConnInfo*)calloc(1, sizeof(*conn));
 conn->error[0] = '0円';
 
 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);
 curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_TIME, 3L);
 curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_LIMIT, 10L);
 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() sets a timeout to trigger soon so that the
 * necessary socket_action() call gets called by this app */
}
 
/* This gets called whenever data is received from the fifo */
static void fifo_cb(struct GlobalInfo *g, int revents)
{
 char s[1024];
 long int rv = 0;
 int n = 0;
 
 do {
 s[0]='0円';
 rv = fscanf(g->input, "%1023s%n", s, &n);
 s[n]='0円';
 if(n && s[0]) {
 new_conn(s, g); /* 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(struct GlobalInfo *g)
{
 struct stat st;
 curl_socket_t sockfd;
 struct epoll_event epev;
 
 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");
 return 1;
 }
 }
 unlink(fifo);
 if(mkfifo(fifo, 0600) == -1) {
 perror("mkfifo");
 return 1;
 }
 sockfd = open(fifo, O_RDWR | O_NONBLOCK, 0);
 if(sockfd == -1) {
 perror("open");
 return 1;
 }
 
 g->fifofd = sockfd;
 g->input = fdopen(sockfd, "r");
 
 epev.events = EPOLLIN;
 epev.data.fd = sockfd;
 epoll_ctl(g->epfd, EPOLL_CTL_ADD, sockfd, &epev);
 
 fprintf(MSG_OUT, "Now, pipe some URL's into > %s\n", fifo);
 return 0;
}
 
static void clean_fifo(struct GlobalInfo *g)
{
 epoll_ctl(g->epfd, EPOLL_CTL_DEL, g->fifofd, NULL);
 fclose(g->input);
 unlink(fifo);
}
 
 
int g_should_exit_ = 0;
 
void sigint_handler(int signo)
{
 g_should_exit_ = 1;
}
 
int main(int argc, char **argv)
{
 CURLcode res;
 struct GlobalInfo g;
 struct itimerspec its;
 struct epoll_event ev;
 struct epoll_event events[10];
 (void)argc;
 (void)argv;
 
 res = curl_global_init(CURL_GLOBAL_ALL);
 if(res)
 return (int)res;
 
 g_should_exit_ = 0;
 signal(SIGINT, sigint_handler);
 
 memset(&g, 0, sizeof(g));
 g.epfd = epoll_create1(EPOLL_CLOEXEC);
 if(g.epfd == -1) {
 perror("epoll_create1 failed");
 curl_global_cleanup();
 return 1;
 }
 
 g.tfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
 if(g.tfd == -1) {
 perror("timerfd_create failed");
 curl_global_cleanup();
 return 1;
 }
 
 memset(&its, 0, sizeof(its));
 its.it_interval.tv_sec = 0;
 its.it_value.tv_sec = 1;
 timerfd_settime(g.tfd, 0, &its, NULL);
 
 ev.events = EPOLLIN;
 ev.data.fd = g.tfd;
 epoll_ctl(g.epfd, EPOLL_CTL_ADD, g.tfd, &ev);
 
 if(init_fifo(&g)) {
 curl_global_cleanup();
 return 1;
 }
 g.multi = curl_multi_init();
 
 /* 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 do not call any curl_multi_socket*() function yet as we have no handles
 added! */
 
 fprintf(MSG_OUT, "Entering wait loop\n");
 fflush(MSG_OUT);
 while(!g_should_exit_) {
 int idx;
 int err = epoll_wait(g.epfd, events,
 sizeof(events)/sizeof(struct epoll_event), 10000);
 if(err == -1) {
 /* !checksrc! disable ERRNOVAR 1 */
 if(errno == EINTR) {
 fprintf(MSG_OUT, "note: wait interrupted\n");
 continue;
 }
 else {
 perror("epoll_wait");
 curl_global_cleanup();
 return 1;
 }
 }
 
 for(idx = 0; idx < err; ++idx) {
 if(events[idx].data.fd == g.fifofd) {
 fifo_cb(&g, events[idx].events);
 }
 else if(events[idx].data.fd == g.tfd) {
 timer_cb(&g, events[idx].events);
 }
 else {
 event_cb(&g, events[idx].data.fd, events[idx].events);
 }
 }
 }
 
 fprintf(MSG_OUT, "Exiting normally.\n");
 fflush(MSG_OUT);
 
 curl_multi_cleanup(g.multi);
 clean_fifo(&g);
 curl_global_cleanup();
 return 0;
}

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