add mac value when get the seed, avoid get the same seed between different machine

[yansendao]

diff --git a/src/platform.cpp b/src/platform.cpp
index d1ef1f9..c85e613 100644
--- a/src/platform.cpp
+++ b/src/platform.cpp
@@ -47,6 +47,10 @@
 #include "platform.h"
 #include <stdlib.h>
 #include <sys/time.h>
+#include <net/if.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
 #if HAVE_BSD_STDLIB_H
 #  include <bsd/stdlib.h>
 #endif
@@ -110,12 +114,62 @@ unsigned long platform_gen_seed()
        return seed;
 }
 #else
+unsigned long getMacValue(void) {
+    int fd;
+    int interfaceNum = 0;
+    struct ifreq buf[16];
+    struct ifconf ifc;
+    struct ifreq ifrcopy;
+
+    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+        perror("socket");
+        close(fd);
+        return (unsigned long)1;
+    }
+
+    ifc.ifc_len = sizeof(buf);
+    ifc.ifc_buf = (caddr_t)buf;
+    if (!ioctl(fd, SIOCGIFCONF, (char *)&ifc)) {
+        interfaceNum = ifc.ifc_len / sizeof(struct ifreq);
+        while (interfaceNum-- > 0) {
+            // ignore the interface that not up or not runing
+            ifrcopy = buf[interfaceNum];
+            if (ioctl(fd, SIOCGIFFLAGS, &ifrcopy)) {
+                continue;
+            }
+
+            // get the mac of this interface
+            if (!ioctl(fd, SIOCGIFHWADDR, (char *)(&buf[interfaceNum]))) {
+                unsigned long value = 0;
+                int j=0;
+                for(int i=5; i>=0; i--) {
+                    value += ((unsigned long)(buf[interfaceNum].ifr_hwaddr.sa_data[i]) << (j*8));
+                    j++;
+                }
+                if( value == 0 ) {
+                    continue;
+                } else {
+                    return value;
+                }
+            } else {
+                close(fd);
+                return (unsigned long)2;
+            }
+        }
+    } else {
+        close(fd);
+        return (unsigned long)3;
+    }
+    close(fd);
+    return (unsigned long)0;
+}
+
 unsigned long platform_gen_seed()
 {
        //return (long) read_time();
        struct timeval tp;
        gettimeofday(&tp, nullptr);
-       return tp.tv_sec * 1000000 + tp.tv_usec;
+       return getMacValue() + (unsigned long)(tp.tv_sec * 1000000 + tp.tv_usec);
 }
 #endif

mac.patch.txt

[jxyang]

We want Csmith to work across platforms with minimum dependency on the environment. The proposed solution is not ideal because it requires Unix and a network stack.

If you are using a script to launch Csmith on different machines, wouldn't it be easier to add a different delay for each machine in your script? @yansendao