init: support wait timeout with more precision

A one second timeout is so coarse and can affect boot time when
the possibility that the file does not exist.  Switch to accepting
a floating point number for seconds for the wait for file command.

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 151950334
Test: wait_for_file sleep 0.05 reports an appropriate delay
Change-Id: I8d8ed386519ab54270b05ce91663d0add30f12e7
diff --git a/init/builtins.cpp b/init/builtins.cpp
index 200bfff..149a766 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -49,6 +49,7 @@
 #include <android-base/chrono_utils.h>
 #include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/parsedouble.h>
 #include <android-base/parseint.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
@@ -1065,11 +1066,12 @@
 static Result<void> do_wait(const BuiltinArguments& args) {
     auto timeout = kCommandRetryTimeout;
     if (args.size() == 3) {
-        int timeout_int;
-        if (!android::base::ParseInt(args[2], &timeout_int)) {
+        double timeout_double;
+        if (!android::base::ParseDouble(args[2], &timeout_double, 0)) {
             return Error() << "failed to parse timeout";
         }
-        timeout = std::chrono::seconds(timeout_int);
+        timeout = std::chrono::duration_cast<std::chrono::nanoseconds>(
+                std::chrono::duration<double>(timeout_double));
     }
 
     if (wait_for_file(args[1].c_str(), timeout) != 0) {