srs/trunk/3rdparty/st-srs/io.c

/* 
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape Portable Runtime library.
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1994-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):  Silicon Graphics, Inc.
 * 
 * Portions created by SGI are Copyright (C) 2000-2001 Silicon
 * Graphics, Inc.  All Rights Reserved.
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */

/*
 * This file is derived directly from Netscape Communications Corporation,
 * and consists of extensive modifications made during the year(s) 1999-2000.
 */

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include "common.h"

// Global stat.
#if defined(DEBUG) && defined(DEBUG_STATS)
unsigned long long _st_stat_recvfrom = 0;
unsigned long long _st_stat_recvfrom_eagain = 0;
unsigned long long _st_stat_sendto = 0;
unsigned long long _st_stat_sendto_eagain = 0;
unsigned long long _st_stat_read = 0;
unsigned long long _st_stat_read_eagain = 0;
unsigned long long _st_stat_readv = 0;
unsigned long long _st_stat_readv_eagain = 0;
unsigned long long _st_stat_writev = 0;
unsigned long long _st_stat_writev_eagain = 0;
unsigned long long _st_stat_recvmsg = 0;
unsigned long long _st_stat_recvmsg_eagain = 0;
unsigned long long _st_stat_sendmsg = 0;
unsigned long long _st_stat_sendmsg_eagain = 0;
#endif

#if EAGAIN != EWOULDBLOCK
    #define _IO_NOT_READY_ERROR  ((errno == EAGAIN) || (errno == EWOULDBLOCK))
#else
    #define _IO_NOT_READY_ERROR  (errno == EAGAIN)
#endif

#define _LOCAL_MAXIOV  16

/* File descriptor object free list */
static _st_netfd_t *_st_netfd_freelist = NULL;
/* Maximum number of file descriptors that the process can open */
static int _st_osfd_limit = -1;

static void _st_netfd_free_aux_data(_st_netfd_t *fd);

int _st_io_init(void)
{
    struct sigaction sigact;
    struct rlimit rlim;
    int fdlim;

    /* Ignore SIGPIPE */
    sigact.sa_handler = SIG_IGN;
    sigemptyset(&sigact.sa_mask);
    sigact.sa_flags = 0;
    if (sigaction(SIGPIPE, &sigact, NULL) < 0)
        return -1;

    /* Set maximum number of open file descriptors */
    if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
        return -1;

    fdlim = (*_st_eventsys->fd_getlimit)();
    if (fdlim > 0 && rlim.rlim_max > (rlim_t) fdlim) {
        rlim.rlim_max = fdlim;
    }
    
    /**
     * by SRS, for osx.
     * when rlimit max is negative, for example, osx, use cur directly.
     * @see https://github.com/winlinvip/simple-rtmp-server/issues/336
     */
    if ((int)rlim.rlim_max < 0) {
        _st_osfd_limit = (int)(fdlim > 0? fdlim : rlim.rlim_cur);
        return 0;
    }
    
    rlim.rlim_cur = rlim.rlim_max;
    if (setrlimit(RLIMIT_NOFILE, &rlim) < 0)
        return -1;
    _st_osfd_limit = (int) rlim.rlim_max;

    return 0;
}


int st_getfdlimit(void)
{
    return _st_osfd_limit;
}


void st_netfd_free(_st_netfd_t *fd)
{
    if (!fd->inuse)
        return;

    fd->inuse = 0;
    if (fd->aux_data)
        _st_netfd_free_aux_data(fd);
    if (fd->private_data && fd->destructor)
        (*(fd->destructor))(fd->private_data);
    fd->private_data = NULL;
    fd->destructor = NULL;
    fd->next = _st_netfd_freelist;
    _st_netfd_freelist = fd;
}


static _st_netfd_t *_st_netfd_new(int osfd, int nonblock, int is_socket)
{
    _st_netfd_t *fd;
    int flags = 1;

    if ((*_st_eventsys->fd_new)(osfd) < 0)
        return NULL;

    if (_st_netfd_freelist) {
        fd = _st_netfd_freelist;
        _st_netfd_freelist = _st_netfd_freelist->next;
    } else {
        fd = calloc(1, sizeof(_st_netfd_t));
        if (!fd)
            return NULL;
    }

    fd->osfd = osfd;
    fd->inuse = 1;
    fd->next = NULL;
    
    if (nonblock) {
        /* Use just one system call */
        if (is_socket && ioctl(osfd, FIONBIO, &flags) != -1)
            return fd;
        /* Do it the Posix way */
        if ((flags = fcntl(osfd, F_GETFL, 0)) < 0 ||
            fcntl(osfd, F_SETFL, flags | O_NONBLOCK) < 0) {
            st_netfd_free(fd);
            return NULL;
        }
    }

    return fd;
}


_st_netfd_t *st_netfd_open(int osfd)
{
    return _st_netfd_new(osfd, 1, 0);
}


_st_netfd_t *st_netfd_open_socket(int osfd)
{
    return _st_netfd_new(osfd, 1, 1);
}


int st_netfd_close(_st_netfd_t *fd)
{
    if ((*_st_eventsys->fd_close)(fd->osfd) < 0)
        return -1;
    
    st_netfd_free(fd);
    return close(fd->osfd);
}


int st_netfd_fileno(_st_netfd_t *fd)
{
    return (fd->osfd);
}


void st_netfd_setspecific(_st_netfd_t *fd, void *value, _st_destructor_t destructor)
{
  if (value != fd->private_data) {
    /* Free up previously set non-NULL data value */
    if (fd->private_data && fd->destructor)
      (*(fd->destructor))(fd->private_data);
  }
  fd->private_data = value;
  fd->destructor = destructor;
}


void *st_netfd_getspecific(_st_netfd_t *fd)
{
    return (fd->private_data);
}


/*
 * Wait for I/O on a single descriptor.
 */
int st_netfd_poll(_st_netfd_t *fd, int how, st_utime_t timeout)
{
    struct pollfd pd;
    int n;
    
    pd.fd = fd->osfd;
    pd.events = (short) how;
    pd.revents = 0;
    
    if ((n = st_poll(&pd, 1, timeout)) < 0)
        return -1;
    if (n == 0) {
        /* Timed out */
        errno = ETIME;
        return -1;
    }
    if (pd.revents & POLLNVAL) {
        errno = EBADF;
        return -1;
    }
    
    return 0;
}


#ifdef MD_ALWAYS_UNSERIALIZED_ACCEPT
/* No-op */
int st_netfd_serialize_accept(_st_netfd_t *fd)
{
    fd->aux_data = NULL;
    return 0;
}

/* No-op */
static void _st_netfd_free_aux_data(_st_netfd_t *fd)
{
    fd->aux_data = NULL;
}

_st_netfd_t *st_accept(_st_netfd_t *fd, struct sockaddr *addr, int *addrlen, st_utime_t timeout)
{
    int osfd, err;
    _st_netfd_t *newfd;
    
    while ((osfd = accept(fd->osfd, addr, (socklen_t *)addrlen)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return NULL;
        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return NULL;
    }
    
    /* On some platforms the new socket created by accept() inherits */
    /* the nonblocking attribute of the listening socket */
#if defined (MD_ACCEPT_NB_INHERITED)
    newfd = _st_netfd_new(osfd, 0, 1);
#elif defined (MD_ACCEPT_NB_NOT_INHERITED)
    newfd = _st_netfd_new(osfd, 1, 1);
#else
    #error Unknown OS
#endif
    
    if (!newfd) {
        err = errno;
        close(osfd);
        errno = err;
    }
    
    return newfd;
}

#else /* MD_ALWAYS_UNSERIALIZED_ACCEPT */
/*
 * On some platforms accept() calls from different processes
 * on the same listen socket must be serialized.
 * The following code serializes accept()'s without process blocking.
 * A pipe is used as an inter-process semaphore.
 */
int st_netfd_serialize_accept(_st_netfd_t *fd)
{
    _st_netfd_t **p;
    int osfd[2], err;
    
    if (fd->aux_data) {
        errno = EINVAL;
        return -1;
    }
    if ((p = (_st_netfd_t **)calloc(2, sizeof(_st_netfd_t *))) == NULL)
        return -1;
    if (pipe(osfd) < 0) {
        free(p);
        return -1;
    }
    if ((p[0] = st_netfd_open(osfd[0])) != NULL && (p[1] = st_netfd_open(osfd[1])) != NULL && write(osfd[1], " ", 1) == 1) {
        fd->aux_data = p;
        return 0;
    }
    /* Error */
    err = errno;
    if (p[0])
        st_netfd_free(p[0]);
    if (p[1])
        st_netfd_free(p[1]);
    close(osfd[0]);
    close(osfd[1]);
    free(p);
    errno = err;
    
    return -1;
}

static void _st_netfd_free_aux_data(_st_netfd_t *fd)
{
    _st_netfd_t **p = (_st_netfd_t **) fd->aux_data;
    
    st_netfd_close(p[0]);
    st_netfd_close(p[1]);
    free(p);
    fd->aux_data = NULL;
}

_st_netfd_t *st_accept(_st_netfd_t *fd, struct sockaddr *addr, int *addrlen, st_utime_t timeout)
{
    int osfd, err;
    _st_netfd_t *newfd;
    _st_netfd_t **p = (_st_netfd_t **) fd->aux_data;
    ssize_t n;
    char c;
    
    for ( ; ; ) {
        if (p == NULL) {
            osfd = accept(fd->osfd, addr, (socklen_t *)addrlen);
        } else {
            /* Get the lock */
            n = st_read(p[0], &c, 1, timeout);
            if (n < 0)
                return NULL;
            ST_ASSERT(n == 1);
            /* Got the lock */
            osfd = accept(fd->osfd, addr, (socklen_t *)addrlen);
            /* Unlock */
            err = errno;
            n = st_write(p[1], &c, 1, timeout);
            ST_ASSERT(n == 1);
            errno = err;
        }
        if (osfd >= 0)
            break;
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return NULL;
        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return NULL;
    }
    
    /* On some platforms the new socket created by accept() inherits */
    /* the nonblocking attribute of the listening socket */
#if defined (MD_ACCEPT_NB_INHERITED)
    newfd = _st_netfd_new(osfd, 0, 1);
#elif defined (MD_ACCEPT_NB_NOT_INHERITED)
    newfd = _st_netfd_new(osfd, 1, 1);
#else
#error Unknown OS
#endif
    
    if (!newfd) {
        err = errno;
        close(osfd);
        errno = err;
    }
    
    return newfd;
}
#endif /* MD_ALWAYS_UNSERIALIZED_ACCEPT */


int st_connect(_st_netfd_t *fd, const struct sockaddr *addr, int addrlen, st_utime_t timeout)
{
    int n, err = 0;
    
    while (connect(fd->osfd, addr, addrlen) < 0) {
        if (errno != EINTR) {
            /*
             * On some platforms, if connect() is interrupted (errno == EINTR)
             * after the kernel binds the socket, a subsequent connect()
             * attempt will fail with errno == EADDRINUSE.  Ignore EADDRINUSE
             * iff connect() was previously interrupted.  See Rich Stevens'
             * "UNIX Network Programming," Vol. 1, 2nd edition, p. 413
             * ("Interrupted connect").
             */
            if (errno != EINPROGRESS && (errno != EADDRINUSE || err == 0))
                return -1;
            /* Wait until the socket becomes writable */
            if (st_netfd_poll(fd, POLLOUT, timeout) < 0)
                return -1;
            /* Try to find out whether the connection setup succeeded or failed */
            n = sizeof(int);
            if (getsockopt(fd->osfd, SOL_SOCKET, SO_ERROR, (char *)&err, (socklen_t *)&n) < 0)
                return -1;
            if (err) {
                errno = err;
                return -1;
            }
            break;
        }
        err = 1;
    }
    
    return 0;
}


ssize_t st_read(_st_netfd_t *fd, void *buf, size_t nbyte, st_utime_t timeout)
{
    ssize_t n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_read;
    #endif
    
    while ((n = read(fd->osfd, buf, nbyte)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_read_eagain;
        #endif

        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return -1;
    }
    
    return n;
}


int st_read_resid(_st_netfd_t *fd, void *buf, size_t *resid, st_utime_t timeout)
{
    struct iovec iov, *riov;
    int riov_size, rv;
    
    iov.iov_base = buf;
    iov.iov_len = *resid;
    riov = &iov;
    riov_size = 1;
    rv = st_readv_resid(fd, &riov, &riov_size, timeout);
    *resid = iov.iov_len;
    return rv;
}


ssize_t st_readv(_st_netfd_t *fd, const struct iovec *iov, int iov_size, st_utime_t timeout)
{
    ssize_t n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_readv;
    #endif
    
    while ((n = readv(fd->osfd, iov, iov_size)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_readv_eagain;
        #endif

        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return -1;
    }
    
    return n;
}

int st_readv_resid(_st_netfd_t *fd, struct iovec **iov, int *iov_size, st_utime_t timeout)
{
    ssize_t n;
    
    while (*iov_size > 0) {
        if (*iov_size == 1)
            n = read(fd->osfd, (*iov)->iov_base, (*iov)->iov_len);
        else
            n = readv(fd->osfd, *iov, *iov_size);
        if (n < 0) {
            if (errno == EINTR)
                continue;
            if (!_IO_NOT_READY_ERROR)
                return -1;
        } else if (n == 0)
            break;
        else {
            while ((size_t) n >= (*iov)->iov_len) {
                n -= (*iov)->iov_len;
                (*iov)->iov_base = (char *) (*iov)->iov_base + (*iov)->iov_len;
                (*iov)->iov_len = 0;
                (*iov)++;
                (*iov_size)--;
                if (n == 0)
                    break;
            }
            if (*iov_size == 0)
                break;
            (*iov)->iov_base = (char *) (*iov)->iov_base + n;
            (*iov)->iov_len -= n;
        }
        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return -1;
    }
    
    return 0;
}


ssize_t st_read_fully(_st_netfd_t *fd, void *buf, size_t nbyte, st_utime_t timeout)
{
    size_t resid = nbyte;
    return st_read_resid(fd, buf, &resid, timeout) == 0 ?
    (ssize_t) (nbyte - resid) : -1;
}


int st_write_resid(_st_netfd_t *fd, const void *buf, size_t *resid, st_utime_t timeout)
{
    struct iovec iov, *riov;
    int riov_size, rv;
    
    iov.iov_base = (void *) buf;        /* we promise not to modify buf */
    iov.iov_len = *resid;
    riov = &iov;
    riov_size = 1;
    rv = st_writev_resid(fd, &riov, &riov_size, timeout);
    *resid = iov.iov_len;
    return rv;
}


ssize_t st_write(_st_netfd_t *fd, const void *buf, size_t nbyte, st_utime_t timeout)
{
    size_t resid = nbyte;
    return st_write_resid(fd, buf, &resid, timeout) == 0 ?
    (ssize_t) (nbyte - resid) : -1;
}


ssize_t st_writev(_st_netfd_t *fd, const struct iovec *iov, int iov_size, st_utime_t timeout)
{
    ssize_t n, rv;
    size_t nleft, nbyte;
    int index, iov_cnt;
    struct iovec *tmp_iov;
    struct iovec local_iov[_LOCAL_MAXIOV];
    
    /* Calculate the total number of bytes to be sent */
    nbyte = 0;
    for (index = 0; index < iov_size; index++)
        nbyte += iov[index].iov_len;
    
    rv = (ssize_t)nbyte;
    nleft = nbyte;
    tmp_iov = (struct iovec *) iov;    /* we promise not to modify iov */
    iov_cnt = iov_size;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_writev;
    #endif
    
    while (nleft > 0) {
        if (iov_cnt == 1) {
            if (st_write(fd, tmp_iov[0].iov_base, nleft, timeout) != (ssize_t) nleft)
                rv = -1;
            break;
        }
        if ((n = writev(fd->osfd, tmp_iov, iov_cnt)) < 0) {
            if (errno == EINTR)
                continue;
            if (!_IO_NOT_READY_ERROR) {
                rv = -1;
                break;
            }
        } else {
            if ((size_t) n == nleft)
                break;
            nleft -= n;
            /* Find the next unwritten vector */
            n = (ssize_t)(nbyte - nleft);
            for (index = 0; (size_t) n >= iov[index].iov_len; index++)
                n -= iov[index].iov_len;
            
            if (tmp_iov == iov) {
                /* Must copy iov's around */
                if (iov_size - index <= _LOCAL_MAXIOV) {
                    tmp_iov = local_iov;
                } else {
                    tmp_iov = calloc(1, (iov_size - index) * sizeof(struct iovec));
                    if (tmp_iov == NULL)
                        return -1;
                }
            }
            
            /* Fill in the first partial read */
            tmp_iov[0].iov_base = &(((char *)iov[index].iov_base)[n]);
            tmp_iov[0].iov_len = iov[index].iov_len - n;
            index++;
            /* Copy the remaining vectors */
            for (iov_cnt = 1; index < iov_size; iov_cnt++, index++) {
                tmp_iov[iov_cnt].iov_base = iov[index].iov_base;
                tmp_iov[iov_cnt].iov_len = iov[index].iov_len;
            }
        }

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_writev_eagain;
        #endif

        /* Wait until the socket becomes writable */
        if (st_netfd_poll(fd, POLLOUT, timeout) < 0) {
            rv = -1;
            break;
        }
    }
    
    if (tmp_iov != iov && tmp_iov != local_iov)
        free(tmp_iov);
    
    return rv;
}


int st_writev_resid(_st_netfd_t *fd, struct iovec **iov, int *iov_size, st_utime_t timeout)
{
    ssize_t n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_writev;
    #endif
    
    while (*iov_size > 0) {
        if (*iov_size == 1)
            n = write(fd->osfd, (*iov)->iov_base, (*iov)->iov_len);
        else
            n = writev(fd->osfd, *iov, *iov_size);
        if (n < 0) {
            if (errno == EINTR)
                continue;
            if (!_IO_NOT_READY_ERROR)
                return -1;
        } else {
            while ((size_t) n >= (*iov)->iov_len) {
                n -= (*iov)->iov_len;
                (*iov)->iov_base = (char *) (*iov)->iov_base + (*iov)->iov_len;
                (*iov)->iov_len = 0;
                (*iov)++;
                (*iov_size)--;
                if (n == 0)
                    break;
            }
            if (*iov_size == 0)
                break;
            (*iov)->iov_base = (char *) (*iov)->iov_base + n;
            (*iov)->iov_len -= n;
        }

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_writev_eagain;
        #endif

        /* Wait until the socket becomes writable */
        if (st_netfd_poll(fd, POLLOUT, timeout) < 0)
            return -1;
    }
    
    return 0;
}


/*
 * Simple I/O functions for UDP.
 */
int st_recvfrom(_st_netfd_t *fd, void *buf, int len, struct sockaddr *from, int *fromlen, st_utime_t timeout)
{
    int n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_recvfrom;
    #endif

    while ((n = recvfrom(fd->osfd, buf, len, 0, from, (socklen_t *)fromlen)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_recvfrom_eagain;
        #endif

        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return -1;
    }
    
    return n;
}


int st_sendto(_st_netfd_t *fd, const void *msg, int len, const struct sockaddr *to, int tolen, st_utime_t timeout)
{
    int n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_sendto;
    #endif
    
    while ((n = sendto(fd->osfd, msg, len, 0, to, tolen)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_sendto_eagain;
        #endif

        /* Wait until the socket becomes writable */
        if (st_netfd_poll(fd, POLLOUT, timeout) < 0)
            return -1;
    }
    
    return n;
}


int st_recvmsg(_st_netfd_t *fd, struct msghdr *msg, int flags, st_utime_t timeout)
{
    int n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_recvmsg;
    #endif
    
    while ((n = recvmsg(fd->osfd, msg, flags)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_recvmsg_eagain;
        #endif

        /* Wait until the socket becomes readable */
        if (st_netfd_poll(fd, POLLIN, timeout) < 0)
            return -1;
    }
    
    return n;
}


int st_sendmsg(_st_netfd_t *fd, const struct msghdr *msg, int flags, st_utime_t timeout)
{
    int n;

    #if defined(DEBUG) && defined(DEBUG_STATS)
    ++_st_stat_sendmsg;
    #endif
    
    while ((n = sendmsg(fd->osfd, msg, flags)) < 0) {
        if (errno == EINTR)
            continue;
        if (!_IO_NOT_READY_ERROR)
            return -1;

        #if defined(DEBUG) && defined(DEBUG_STATS)
        ++_st_stat_sendmsg_eagain;
        #endif

        /* Wait until the socket becomes writable */
        if (st_netfd_poll(fd, POLLOUT, timeout) < 0)
            return -1;
    }
    
    return n;
}


/*
 * To open FIFOs or other special files.
 */
_st_netfd_t *st_open(const char *path, int oflags, mode_t mode)
{
    int osfd, err;
    _st_netfd_t *newfd;
    
    while ((osfd = open(path, oflags | O_NONBLOCK, mode)) < 0) {
        if (errno != EINTR)
            return NULL;
    }
    
    newfd = _st_netfd_new(osfd, 0, 0);
    if (!newfd) {
        err = errno;
        close(osfd);
        errno = err;
    }
    
    return newfd;
}