MB-8102: Switched from using select(..) to poll(..) within mcs_io_read

This prevent segfaults when more than 1024 fd's are used.

Change-Id: I5513af3fdeca6d807d14d5977e9ca2cb5b2c8719
Reviewed-on: http://review.couchbase.org/30345
Reviewed-by: Steve Yen <[email protected]>
Tested-by: Bin Cui <[email protected]>

Author: stevenh

mcs.c

@@ -8,6 +8,10 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <assert.h>
+#ifndef WIN32
+#include <poll.h>
+#include <limits.h>
+#endif
 #include "memcached.h"
 #include "cproxy.h"
 #include "mcs.h"
@@ -16,6 +20,9 @@
 /* TODO: This timeout is inherited from zstored, but use it where? */
 
 #define DOWNSTREAM_DEFAULT_LINGER 1000
+#ifndef INFTIM
+#define INFTIM -1
+#endif
 
 /* The lvb stands for libvbucket. */
 
@@ -584,6 +591,7 @@ ssize_t mcs_io_write(int fd, const void *buffer, size_t length) {
     return write(fd, buffer, length);
 }
 
+#ifdef WIN32
 mcs_return mcs_io_read(int fd, void *dta, size_t size, struct timeval *timeout_in) {
     struct timeval my_timeout; /* Linux select() modifies its timeout param. */
     struct timeval *timeout = NULL;
@@ -626,6 +634,77 @@ mcs_return mcs_io_read(int fd, void *dta, size_t size, struct timeval *timeout_i
 
     return MCS_SUCCESS;
 }
+#else
+
+static unsigned long long __get_time_ms(const struct timeval *tv) {
+    struct timeval now;
+
+    if (tv == NULL) {
+        if (gettimeofday(&now, NULL) != 0) {
+            return 0;
+        }
+        tv = &now;
+    }
+    return (unsigned long long)tv->tv_sec * 1000 + (unsigned long long)tv->tv_usec / 1000;
+}
+
+mcs_return mcs_io_read(int fd, void *dta, size_t size, struct timeval *timeout_in) {
+    unsigned long long start_ms = 0;
+    unsigned long long timeout_ms = 0;
+    unsigned long long now_ms = 0;
+
+    if (timeout_in != NULL) {
+        start_ms = __get_time_ms(NULL);
+        timeout_ms = __get_time_ms(timeout_in);
+        now_ms = start_ms;
+    }
+
+    char *data = dta;
+    size_t done = 0;
+    struct pollfd pfd[1];
+
+    while (done < size) {
+        pfd[0].fd = fd;
+        pfd[0].events = POLLIN;
+        pfd[0].revents = 0;
+
+        int timeout = INFTIM;
+        if (timeout_in != NULL) {
+            if (timeout_ms == 0) {
+                /* ensure we poll at least once */
+                timeout = 0;
+            } else {
+                unsigned long long taken_ms = now_ms - start_ms;
+                if (taken_ms >= timeout_ms) {
+                    /* just check (boundary case) */
+                    timeout = 0;
+                } else {
+                    unsigned long long left_ms = timeout_ms - taken_ms;
+                    timeout = (left_ms > INT_MAX) ? INT_MAX : left_ms;
+                }
+            }
+        }
+        int s = poll(pfd, 1, timeout);
+        if (s == 0) {
+            return MCS_TIMEOUT;
+        }
+
+        if (s != 1 || (pfd[0].revents & (POLLERR|POLLHUP|POLLNVAL)) || !(pfd[0].revents & POLLIN)) {
+            return MCS_FAILURE;
+        }
+
+        ssize_t n = read(fd, data + done, 1);
+        if (n == -1 || n == 0) {
+            return MCS_FAILURE;
+        }
+
+        done += (size_t) n;
+        now_ms = __get_time_ms(NULL);
+    }
+
+    return MCS_SUCCESS;
+}
+#endif
 
 void mcs_io_reset(int fd) {
     (void) fd;