PR go/47515

runtime: If no MAP_ANON, use /dev/zero.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@169388 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/libgo/runtime/mem.c b/libgo/runtime/mem.c
index 29cf495..4d6c742 100644 (file)
--- a/libgo/runtime/mem.c
+++ b/libgo/runtime/mem.c
@@ -3,13 +3,39 @@
 #include "runtime.h"
 #include "malloc.h"
 
+#ifndef MAP_ANON
+#ifdef MAP_ANONYMOUS
+#define MAP_ANON MAP_ANONYMOUS
+#else
+#define USE_DEV_ZERO
+#define MAP_ANON 0
+#endif
+#endif
+
+#ifdef USE_DEV_ZERO
+static int dev_zero = -1;
+#endif
+
 void*
 runtime_SysAlloc(uintptr n)
 {
        void *p;
+       int fd = -1;
 
        mstats.sys += n;
-       p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
+
+#ifdef USE_DEV_ZERO
+       if (dev_zero == -1) {
+               dev_zero = open("/dev/zero", O_RDONLY);
+               if (dev_zero < 0) {
+                       printf("open /dev/zero: errno=%d\n", errno);
+                       exit(2);
+               }
+       }
+       fd = dev_zero;
+#endif
+
+       p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
        if (p == MAP_FAILED) {
                if(errno == EACCES) {
                        printf("mmap: access denied\n");

diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index e43177f..95216e4 100644 (file)
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -12,6 +12,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <pthread.h>
 #include <semaphore.h>