auto merge of #9280 : alexcrichton/rust/less-c++, r=brson

Some of the functions could be converted to rust, but the functions dealing with
signals were moved to rust_builtin.cpp instead (no reason to keep the original
file around for one function).

Closes #2674

Because less C++ is better C++!

Author: bors

mk/rt.mk

@@ -71,7 +71,6 @@ RUNTIME_CXXS_$(1)_$(2) := \
               rt/sync/lock_and_signal.cpp \
               rt/sync/rust_thread.cpp \
               rt/rust_builtin.cpp \
-              rt/rust_run_program.cpp \
               rt/rust_rng.cpp \
               rt/rust_upcall.cpp \
               rt/rust_uv.cpp \

src/libstd/run.rs

@@ -643,15 +643,28 @@ fn spawn_process_os(prog: &str, args: &[~str],
     use libc::funcs::bsd44::getdtablesize;
 
     mod rustrt {
-        use libc::c_void;
-
         #[abi = "cdecl"]
         extern {
             pub fn rust_unset_sigprocmask();
-            pub fn rust_set_environ(envp: *c_void);
         }
     }
 
+    #[cfg(windows)]
+    unsafe fn set_environ(_envp: *c_void) {}
+    #[cfg(target_os = "macos")]
+    unsafe fn set_environ(envp: *c_void) {
+        externfn!(fn _NSGetEnviron() -> *mut *c_void);
+
+        *_NSGetEnviron() = envp;
+    }
+    #[cfg(not(target_os = "macos"), not(windows))]
+    unsafe fn set_environ(envp: *c_void) {
+        extern {
+            static mut environ: *c_void;
+        }
+        environ = envp;
+    }
+
     unsafe {
 
         let pid = fork();
@@ -685,7 +698,7 @@ fn spawn_process_os(prog: &str, args: &[~str],
 
         do with_envp(env) |envp| {
             if !envp.is_null() {
-                rustrt::rust_set_environ(envp);
+                set_environ(envp);
             }
             do with_argv(prog, args) |argv| {
                 execvp(*argv, argv);

src/rt/rust_builtin.cpp

@@ -643,6 +643,29 @@ rust_valgrind_stack_deregister(unsigned int id) {
   VALGRIND_STACK_DEREGISTER(id);
 }
 
+#if defined(__WIN32__)
+
+extern "C" CDECL void
+rust_unset_sigprocmask() {
+    // empty stub for windows to keep linker happy
+}
+
+#else
+
+#include <signal.h>
+#include <unistd.h>
+
+extern "C" CDECL void
+rust_unset_sigprocmask() {
+    // this can't be safely converted to rust code because the
+    // representation of sigset_t is platform-dependent
+    sigset_t sset;
+    sigemptyset(&sset);
+    sigprocmask(SIG_SETMASK, &sset, NULL);
+}
+
+#endif
+
 //
 // Local Variables:
 // mode: C++

src/rt/rust_run_program.cpp

@@ -25,7 +25,6 @@ rust_list_dir_wfd_fp_buf
 rust_log_console_on
 rust_log_console_off
 rust_should_log_console
-rust_set_environ
 rust_unset_sigprocmask
 rust_env_pairs
 upcall_rust_personality