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curl/lib/select.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2011, 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 http://curl.haxx.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.
*
***************************************************************************/
#include "setup.h"
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#if !defined(HAVE_SELECT) && !defined(HAVE_POLL_FINE)
#error "We can't compile without select() or poll() support."
#endif
#if defined(__BEOS__) && !defined(__HAIKU__)
/* BeOS has FD_SET defined in socket.h */
#include <socket.h>
#endif
#ifdef MSDOS
#include <dos.h> /* delay() */
#endif
#include <curl/curl.h>
#include "urldata.h"
#include "connect.h"
#include "select.h"
#include "warnless.h"
/* Winsock and TPF sockets are not in range [0..FD_SETSIZE-1] */
#if defined(USE_WINSOCK) || defined(TPF)
#define VERIFY_SOCK(x) do { } while(0)
#else
#define VALID_SOCK(s) (((s) >= 0) && ((s) < FD_SETSIZE))
#define VERIFY_SOCK(x) do { \
if(!VALID_SOCK(x)) { \
SET_SOCKERRNO(EINVAL); \
return -1; \
} \
} while(0)
#endif
/* Convenience local macros */
#define elapsed_ms (int)curlx_tvdiff(curlx_tvnow(), initial_tv)
#ifdef CURL_ACKNOWLEDGE_EINTR
#define error_not_EINTR (1)
#else
#define error_not_EINTR (error != EINTR)
#endif
/*
* Internal function used for waiting a specific amount of ms
* in Curl_socket_ready() and Curl_poll() when no file descriptor
* is provided to wait on, just being used to delay execution.
* WinSock select() and poll() timeout mechanisms need a valid
* socket descriptor in a not null file descriptor set to work.
* Waiting indefinitely with this function is not allowed, a
* zero or negative timeout value will return immediately.
* Timeout resolution, accuracy, as well as maximum supported
* value is system dependent, neither factor is a citical issue
* for the intended use of this function in the library.
* On non-DOS and non-Winsock platforms, when compiled with
* CURL_ACKNOWLEDGE_EINTR defined, EINTR condition is honored
* and function might exit early without awaiting full timeout,
* otherwise EINTR will be ignored and full timeout will elapse.
*
* Return values:
* -1 = system call error, invalid timeout value, or interrupted
* 0 = specified timeout has elapsed
*/
int Curl_wait_ms(int timeout_ms)
{
#if !defined(MSDOS) && !defined(USE_WINSOCK)
#ifndef HAVE_POLL_FINE
struct timeval pending_tv;
#endif
struct timeval initial_tv;
int pending_ms;
int error;
#endif
int r = 0;
if(!timeout_ms)
return 0;
if(timeout_ms < 0) {
SET_SOCKERRNO(EINVAL);
return -1;
}
#if defined(MSDOS)
delay(timeout_ms);
#elif defined(USE_WINSOCK)
Sleep(timeout_ms);
#else
pending_ms = timeout_ms;
initial_tv = curlx_tvnow();
do {
#if defined(HAVE_POLL_FINE)
r = poll(NULL, 0, pending_ms);
#else
pending_tv.tv_sec = pending_ms / 1000;
pending_tv.tv_usec = (pending_ms % 1000) * 1000;
r = select(0, NULL, NULL, NULL, &pending_tv);
#endif /* HAVE_POLL_FINE */
if(r != -1)
break;
error = SOCKERRNO;
if(error && error_not_EINTR)
break;
pending_ms = timeout_ms - elapsed_ms;
if(pending_ms <= 0)
break;
} while(r == -1);
#endif /* USE_WINSOCK */
if(r)
r = -1;
return r;
}
/*
* This is an internal function used for waiting for read or write
* events on a pair of file descriptors. It uses poll() when a fine
* poll() is available, in order to avoid limits with FD_SETSIZE,
* otherwise select() is used. An error is returned if select() is
* being used and a file descriptor is too large for FD_SETSIZE.
* A negative timeout value makes this function wait indefinitely,
* unles no valid file descriptor is given, when this happens the
* negative timeout is ignored and the function times out immediately.
* When compiled with CURL_ACKNOWLEDGE_EINTR defined, EINTR condition
* is honored and function might exit early without awaiting timeout,
* otherwise EINTR will be ignored.
*
* Return values:
* -1 = system call error or fd >= FD_SETSIZE
* 0 = timeout
* CURL_CSELECT_IN | CURL_CSELECT_OUT | CURL_CSELECT_ERR
*/
int Curl_socket_ready(curl_socket_t readfd, curl_socket_t writefd,
long timeout_ms)
{
#ifdef HAVE_POLL_FINE
struct pollfd pfd[2];
int num;
#else
struct timeval pending_tv;
struct timeval *ptimeout;
fd_set fds_read;
fd_set fds_write;
fd_set fds_err;
curl_socket_t maxfd;
#endif
struct timeval initial_tv = {0,0};
int pending_ms = 0;
int error;
int r;
int ret;
if((readfd == CURL_SOCKET_BAD) && (writefd == CURL_SOCKET_BAD)) {
r = Curl_wait_ms((int)timeout_ms);
return r;
}
/* Avoid initial timestamp, avoid curlx_tvnow() call, when elapsed
time in this function does not need to be measured. This happens
when function is called with a zero timeout or a negative timeout
value indicating a blocking call should be performed. */
if(timeout_ms > 0) {
pending_ms = (int)timeout_ms;
initial_tv = curlx_tvnow();
}
#ifdef HAVE_POLL_FINE
num = 0;
if(readfd != CURL_SOCKET_BAD) {
pfd[num].fd = readfd;
pfd[num].events = POLLRDNORM|POLLIN|POLLRDBAND|POLLPRI;
pfd[num].revents = 0;
num++;
}
if(writefd != CURL_SOCKET_BAD) {
pfd[num].fd = writefd;
pfd[num].events = POLLWRNORM|POLLOUT;
pfd[num].revents = 0;
num++;
}
do {
if(timeout_ms < 0)
pending_ms = -1;
else if(!timeout_ms)
pending_ms = 0;
r = poll(pfd, num, pending_ms);
if(r != -1)
break;
error = SOCKERRNO;
if(error && error_not_EINTR)
break;
if(timeout_ms > 0) {
pending_ms = (int)(timeout_ms - elapsed_ms);
if(pending_ms <= 0)
break;
}
} while(r == -1);
if(r < 0)
return -1;
if(r == 0)
return 0;
ret = 0;
num = 0;
if(readfd != CURL_SOCKET_BAD) {
if(pfd[num].revents & (POLLRDNORM|POLLIN|POLLERR|POLLHUP))
ret |= CURL_CSELECT_IN;
if(pfd[num].revents & (POLLRDBAND|POLLPRI|POLLNVAL))
ret |= CURL_CSELECT_ERR;
num++;
}
if(writefd != CURL_SOCKET_BAD) {
if(pfd[num].revents & (POLLWRNORM|POLLOUT))
ret |= CURL_CSELECT_OUT;
if(pfd[num].revents & (POLLERR|POLLHUP|POLLNVAL))
ret |= CURL_CSELECT_ERR;
}
return ret;
#else /* HAVE_POLL_FINE */
FD_ZERO(&fds_err);
maxfd = (curl_socket_t)-1;
FD_ZERO(&fds_read);
if(readfd != CURL_SOCKET_BAD) {
VERIFY_SOCK(readfd);
FD_SET(readfd, &fds_read);
FD_SET(readfd, &fds_err);
maxfd = readfd;
}
FD_ZERO(&fds_write);
if(writefd != CURL_SOCKET_BAD) {
VERIFY_SOCK(writefd);
FD_SET(writefd, &fds_write);
FD_SET(writefd, &fds_err);
if(writefd > maxfd)
maxfd = writefd;
}
ptimeout = (timeout_ms < 0) ? NULL : &pending_tv;
do {
if(timeout_ms > 0) {
pending_tv.tv_sec = pending_ms / 1000;
pending_tv.tv_usec = (pending_ms % 1000) * 1000;
}
else if(!timeout_ms) {
pending_tv.tv_sec = 0;
pending_tv.tv_usec = 0;
}
r = select((int)maxfd + 1, &fds_read, &fds_write, &fds_err, ptimeout);
if(r != -1)
break;
error = SOCKERRNO;
if(error && error_not_EINTR)
break;
if(timeout_ms > 0) {
pending_ms = timeout_ms - elapsed_ms;
if(pending_ms <= 0)
break;
}
} while(r == -1);
if(r < 0)
return -1;
if(r == 0)
return 0;
ret = 0;
if(readfd != CURL_SOCKET_BAD) {
if(FD_ISSET(readfd, &fds_read))
ret |= CURL_CSELECT_IN;
if(FD_ISSET(readfd, &fds_err))
ret |= CURL_CSELECT_ERR;
}
if(writefd != CURL_SOCKET_BAD) {
if(FD_ISSET(writefd, &fds_write))
ret |= CURL_CSELECT_OUT;
if(FD_ISSET(writefd, &fds_err))
ret |= CURL_CSELECT_ERR;
}
return ret;
#endif /* HAVE_POLL_FINE */
}
/*
* This is a wrapper around poll(). If poll() does not exist, then
* select() is used instead. An error is returned if select() is
* being used and a file descriptor is too large for FD_SETSIZE.
* A negative timeout value makes this function wait indefinitely,
* unles no valid file descriptor is given, when this happens the
* negative timeout is ignored and the function times out immediately.
* When compiled with CURL_ACKNOWLEDGE_EINTR defined, EINTR condition
* is honored and function might exit early without awaiting timeout,
* otherwise EINTR will be ignored.
*
* Return values:
* -1 = system call error or fd >= FD_SETSIZE
* 0 = timeout
* N = number of structures with non zero revent fields
*/
int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
{
#ifndef HAVE_POLL_FINE
struct timeval pending_tv;
struct timeval *ptimeout;
fd_set fds_read;
fd_set fds_write;
fd_set fds_err;
curl_socket_t maxfd;
#endif
struct timeval initial_tv = {0,0};
bool fds_none = TRUE;
unsigned int i;
int pending_ms = 0;
int error;
int r;
if(ufds) {
for(i = 0; i < nfds; i++) {
if(ufds[i].fd != CURL_SOCKET_BAD) {
fds_none = FALSE;
break;
}
}
}
if(fds_none) {
r = Curl_wait_ms(timeout_ms);
return r;
}
/* Avoid initial timestamp, avoid curlx_tvnow() call, when elapsed
time in this function does not need to be measured. This happens
when function is called with a zero timeout or a negative timeout
value indicating a blocking call should be performed. */
if(timeout_ms > 0) {
pending_ms = timeout_ms;
initial_tv = curlx_tvnow();
}
#ifdef HAVE_POLL_FINE
do {
if(timeout_ms < 0)
pending_ms = -1;
else if(!timeout_ms)
pending_ms = 0;
r = poll(ufds, nfds, pending_ms);
if(r != -1)
break;
error = SOCKERRNO;
if(error && error_not_EINTR)
break;
if(timeout_ms > 0) {
pending_ms = timeout_ms - elapsed_ms;
if(pending_ms <= 0)
break;
}
} while(r == -1);
if(r < 0)
return -1;
if(r == 0)
return 0;
for(i = 0; i < nfds; i++) {
if(ufds[i].fd == CURL_SOCKET_BAD)
continue;
if(ufds[i].revents & POLLHUP)
ufds[i].revents |= POLLIN;
if(ufds[i].revents & POLLERR)
ufds[i].revents |= (POLLIN|POLLOUT);
}
#else /* HAVE_POLL_FINE */
FD_ZERO(&fds_read);
FD_ZERO(&fds_write);
FD_ZERO(&fds_err);
maxfd = (curl_socket_t)-1;
for(i = 0; i < nfds; i++) {
ufds[i].revents = 0;
if(ufds[i].fd == CURL_SOCKET_BAD)
continue;
VERIFY_SOCK(ufds[i].fd);
if(ufds[i].events & (POLLIN|POLLOUT|POLLPRI|
POLLRDNORM|POLLWRNORM|POLLRDBAND)) {
if(ufds[i].fd > maxfd)
maxfd = ufds[i].fd;
if(ufds[i].events & (POLLRDNORM|POLLIN))
FD_SET(ufds[i].fd, &fds_read);
if(ufds[i].events & (POLLWRNORM|POLLOUT))
FD_SET(ufds[i].fd, &fds_write);
if(ufds[i].events & (POLLRDBAND|POLLPRI))
FD_SET(ufds[i].fd, &fds_err);
}
}
ptimeout = (timeout_ms < 0) ? NULL : &pending_tv;
do {
if(timeout_ms > 0) {
pending_tv.tv_sec = pending_ms / 1000;
pending_tv.tv_usec = (pending_ms % 1000) * 1000;
}
else if(!timeout_ms) {
pending_tv.tv_sec = 0;
pending_tv.tv_usec = 0;
}
r = select((int)maxfd + 1, &fds_read, &fds_write, &fds_err, ptimeout);
if(r != -1)
break;
error = SOCKERRNO;
if(error && error_not_EINTR)
break;
if(timeout_ms > 0) {
pending_ms = timeout_ms - elapsed_ms;
if(pending_ms <= 0)
break;
}
} while(r == -1);
if(r < 0)
return -1;
if(r == 0)
return 0;
r = 0;
for(i = 0; i < nfds; i++) {
ufds[i].revents = 0;
if(ufds[i].fd == CURL_SOCKET_BAD)
continue;
if(FD_ISSET(ufds[i].fd, &fds_read))
ufds[i].revents |= POLLIN;
if(FD_ISSET(ufds[i].fd, &fds_write))
ufds[i].revents |= POLLOUT;
if(FD_ISSET(ufds[i].fd, &fds_err))
ufds[i].revents |= POLLPRI;
if(ufds[i].revents != 0)
r++;
}
#endif /* HAVE_POLL_FINE */
return r;
}
#ifdef TPF
/*
* This is a replacement for select() on the TPF platform.
* It is used whenever libcurl calls select().
* The call below to tpf_process_signals() is required because
* TPF's select calls are not signal interruptible.
*
* Return values are the same as select's.
*/
int tpf_select_libcurl(int maxfds, fd_set* reads, fd_set* writes,
fd_set* excepts, struct timeval* tv)
{
int rc;
rc = tpf_select_bsd(maxfds, reads, writes, excepts, tv);
tpf_process_signals();
return(rc);
}
#endif /* TPF */
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