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curl/lib/select.c
Yang Tse f7690db37d Some systems poll function sets POLLHUP in revents without setting 
POLLIN, and sets POLLERR without setting POLLIN and POLLOUT. In some
libcurl code execution paths this could trigger busy wait loops with
high CPU usage until a timeout condition aborted the loop.

This fix for Curl_poll adresses the above in a libcurl-wide mode.
2009-09-15 00:07:56 +00:00

508 lines
13 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2008, 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.
*
* $Id$
***************************************************************************/
#include "setup.h"
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.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"
/* 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 dependant, 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
*/
static int 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,
int 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 = 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
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 = 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 = 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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