import RT-Thread@9217865c without bsp, libcpu and components/net

components/libc/posix/io/poll/select.c

@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2016-12-28     Bernard      first version
+ */
+
+#include <rtthread.h>
+#include <poll.h>
+#include <sys/select.h>
+
+static void fdszero(fd_set *set, int nfds)
+{
+    fd_mask *m;
+    int n;
+
+    /*
+      The 'sizeof(fd_set)' of the system space may differ from user space,
+      so the actual size of the 'fd_set' is determined here with the parameter 'nfds'
+    */
+    m = (fd_mask *)set;
+    for (n = 0; n < nfds; n += (sizeof(fd_mask) * 8))
+    {
+        rt_memset(m, 0, sizeof(fd_mask));
+        m ++;
+    }
+}
+
+int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
+{
+    int fd;
+    int npfds;
+    int msec;
+    int ndx;
+    int ret;
+    struct pollfd *pollset = RT_NULL;
+
+    /* How many pollfd structures do we need to allocate? */
+    for (fd = 0, npfds = 0; fd < nfds; fd++)
+    {
+        /* Check if any monitor operation is requested on this fd */
+        if ((readfds   && FD_ISSET(fd, readfds))  ||
+            (writefds  && FD_ISSET(fd, writefds)) ||
+            (exceptfds && FD_ISSET(fd, exceptfds)))
+        {
+            npfds++;
+        }
+    }
+
+    /* Allocate the descriptor list for poll() */
+    if (npfds > 0)
+    {
+        pollset = (struct pollfd *)rt_calloc(npfds, sizeof(struct pollfd));
+        if (!pollset)
+        {
+            return -1;
+        }
+    }
+
+    /* Initialize the descriptor list for poll() */
+    for (fd = 0, ndx = 0; fd < nfds; fd++)
+    {
+        int incr = 0;
+
+        /* The readfs set holds the set of FDs that the caller can be assured
+         * of reading from without blocking.  Note that POLLHUP is included as
+         * a read-able condition.  POLLHUP will be reported at the end-of-file
+         * or when a connection is lost.  In either case, the read() can then
+         * be performed without blocking.
+         */
+
+        if (readfds && FD_ISSET(fd, readfds))
+        {
+            pollset[ndx].fd         = fd;
+            pollset[ndx].events |= POLLIN;
+            incr = 1;
+        }
+
+        if (writefds && FD_ISSET(fd, writefds))
+        {
+            pollset[ndx].fd      = fd;
+            pollset[ndx].events |= POLLOUT;
+            incr = 1;
+        }
+
+        if (exceptfds && FD_ISSET(fd, exceptfds))
+        {
+            pollset[ndx].fd = fd;
+            incr = 1;
+        }
+
+        ndx += incr;
+    }
+
+    RT_ASSERT(ndx == npfds);
+
+    /* Convert the timeout to milliseconds */
+    if (timeout)
+    {
+        msec = (int)timeout->tv_sec * 1000 + (int)timeout->tv_usec / 1000;
+    }
+    else
+    {
+        msec = -1;
+    }
+
+    /* Then let poll do all of the real work. */
+
+    ret = poll(pollset, npfds, msec);
+
+    /* Now set up the return values */
+    if (readfds)
+    {
+        fdszero(readfds, nfds);
+    }
+
+    if (writefds)
+    {
+        fdszero(writefds, nfds);
+    }
+
+    if (exceptfds)
+    {
+        fdszero(exceptfds, nfds);
+    }
+
+    /* Convert the poll descriptor list back into selects 3 bitsets */
+
+    if (ret > 0)
+    {
+        ret = 0;
+        for (ndx = 0; ndx < npfds; ndx++)
+        {
+            /* Check for read conditions.  Note that POLLHUP is included as a
+             * read condition.  POLLHUP will be reported when no more data will
+             * be available (such as when a connection is lost).  In either
+             * case, the read() can then be performed without blocking.
+             */
+
+            if (readfds)
+            {
+                if (pollset[ndx].revents & (POLLIN | POLLHUP))
+                {
+                    FD_SET(pollset[ndx].fd, readfds);
+                    ret++;
+                }
+            }
+
+            /* Check for write conditions */
+            if (writefds)
+            {
+                if (pollset[ndx].revents & POLLOUT)
+                {
+                    FD_SET(pollset[ndx].fd, writefds);
+                    ret++;
+                }
+            }
+
+            /* Check for exceptions */
+            if (exceptfds)
+            {
+                if (pollset[ndx].revents & POLLERR)
+                {
+                    FD_SET(pollset[ndx].fd, exceptfds);
+                    ret++;
+                }
+            }
+        }
+    }
+
+    if (pollset) rt_free(pollset);
+
+    return ret;
+}