code review 7523043: lib9: add mktempdir, removeall, runprog

src/lib9/run_plan9.c

+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <u.h>
+#include <libc.h>
+
+int
+runcmd(char **argv)
+{
+        int pid;
+        Waitmsg *w;
+········
+        switch(pid = fork()) {
+        case -1:
+                return -1;
+        case 0:
+                execvp(argv[0], argv);
+                fprint(2, "exec %s: %r", argv[0]);
+                _exit(1);
+        }
+········
+        w = wait();
+        if(w == nil)
+                return -1;
+        if(w->pid != pid) {
+                werrstr("unexpected pid in wait");
+                free(w);
+                return -1;
+        }
+        if(w->msg[0]) {
+                werrstr("unsuccessful exit status: %s", w->msg);
+                free(w);
+                return -1;
+        }
+        free(w);
+        return 0;
+}