linux-user: implement pipe2 [v3]

implement pipe2 syscall.

[v2] fix do_pipe on mips and sh4
[v3] use pipe2 to ensure atomicity, but only when it is available.

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>

2 files changed, 58 insertions, 18 deletions

diff --git a/configure b/configure
index d3c91408cb..7961bb30ff 100755
--- a/configure
+++ b/configure
@@ -1304,6 +1304,24 @@ if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
   utimens=yes
 fi
 
+# check if pipe2 is there
+pipe2=no
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+
+int main(void)
+{
+    int pipefd[2];
+    pipe2(pipefd, O_CLOEXEC);
+    return 0;
+}
+EOF
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+  pipe2=yes
+fi
+
 # Check if tools are available to build documentation.
 if test "$build_docs" = "yes" -a \( ! -x "`which texi2html 2>/dev/null`" -o ! -x "`which pod2man 2>/dev/null`" \) ; then
   build_docs="no"
@@ -1704,6 +1722,9 @@ fi
 if test "$utimens" = "yes" ; then
   echo "#define CONFIG_UTIMENSAT 1" >> $config_h
 fi
+if test "$pipe2" = "yes" ; then
+  echo "#define CONFIG_PIPE2 1" >> $config_h
+fi
 if test "$inotify" = "yes" ; then
   echo "#define CONFIG_INOTIFY 1" >> $config_h
 fi
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 3fc6cbc7ca..36eb9f5b53 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -944,6 +944,37 @@ static abi_long do_select(int n,
     return ret;
 }
 
+static abi_long do_pipe2(int host_pipe[], int flags)
+{
+#ifdef CONFIG_PIPE2
+    return pipe2(host_pipe, flags);
+#else
+    return -ENOSYS;
+#endif
+}
+
+static abi_long do_pipe(void *cpu_env, int pipedes, int flags)
+{
+    int host_pipe[2];
+    abi_long ret;
+    ret = flags ? do_pipe2(host_pipe, flags) : pipe(host_pipe);
+
+    if (is_error(ret))
+        return get_errno(ret);
+#if defined(TARGET_MIPS)
+    ((CPUMIPSState*)cpu_env)->active_tc.gpr[3] = host_pipe[1];
+    ret = host_pipe[0];
+#elif defined(TARGET_SH4)
+    ((CPUSH4State*)cpu_env)->gregs[1] = host_pipe[1];
+    ret = host_pipe[0];
+#else
+    if (put_user_s32(host_pipe[0], pipedes)
+        || put_user_s32(host_pipe[1], pipedes + sizeof(host_pipe[0])))
+        return -TARGET_EFAULT;
+#endif
+    return get_errno(ret);
+}
+
 static inline abi_long target_to_host_ip_mreq(struct ip_mreqn *mreqn,
                                               abi_ulong target_addr,
                                               socklen_t len)
@@ -4529,25 +4560,13 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         ret = get_errno(dup(arg1));
         break;
     case TARGET_NR_pipe:
-        {
-            int host_pipe[2];
-            ret = get_errno(pipe(host_pipe));
-            if (!is_error(ret)) {
-#if defined(TARGET_MIPS)
-                CPUMIPSState *env = (CPUMIPSState*)cpu_env;
-		env->active_tc.gpr[3] = host_pipe[1];
-		ret = host_pipe[0];
-#elif defined(TARGET_SH4)
-		((CPUSH4State*)cpu_env)->gregs[1] = host_pipe[1];
-		ret = host_pipe[0];
-#else
-                if (put_user_s32(host_pipe[0], arg1)
-                    || put_user_s32(host_pipe[1], arg1 + sizeof(host_pipe[0])))
-                    goto efault;
-#endif
-            }
-        }
+        ret = do_pipe(cpu_env, arg1, 0);
+        break;
+#ifdef TARGET_NR_pipe2
+    case TARGET_NR_pipe2:
+        ret = do_pipe(cpu_env, arg1, arg2);
         break;
+#endif
     case TARGET_NR_times:
         {
             struct target_tms *tmsp;