[PATCH xorg-gtest 06/11] process: require NULL as last argument to Start()

[Peter Hutterer]

And handle empty arguments and NULL_terminated arguments. This is a better
API than require the user to pass empty strings, especially since in some
cases an empty string may be a valid argument.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 include/xorg/gtest/xorg-gtest-process.h |  7 ++++---
 src/process.cpp                         | 13 ++++++++-----
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/xorg/gtest/xorg-gtest-process.h b/include/xorg/gtest/xorg-gtest-process.h
index 48f387b..b4ac0d9 100644
--- a/include/xorg/gtest/xorg-gtest-process.h
+++ b/include/xorg/gtest/xorg-gtest-process.h
@@ -30,6 +30,7 @@
 #define XORG_GTEST_PROCESS_H
 
 #include <stdarg.h>
+#include <X11/Xfuncproto.h> /* for _X_SENTINEL */
 
 #include <memory>
 #include <string>
@@ -114,7 +115,7 @@ class Process {
    *
    * @param program The program to start.
    * @param args Variadic list of arguments passed to the program. This list
-   * must end in a zero-length string ("", not NULL).
+   * must end with NULL.
    *
    * @throws std::runtime_error on failure.
    *
@@ -127,7 +128,7 @@ class Process {
    * Starts a program as a child process.
    *
    * Takes a variadic list of arguments passed to the program. This list
-   * must end in a zero-length string ("", not NULL).
+   * must end with NULL.
    * See 'man execvp' for further information on the variadic argument list.
    *
    * @param program The program to start.
@@ -137,7 +138,7 @@ class Process {
    * @post If successful: Child process forked and program started.
    * @post If successful: Subsequent calls to Pid() return child process pid.
    */
-  void Start(const std::string& program, ...);
+  void Start(const std::string& program, ...) _X_SENTINEL(0);
 
   /**
    * Terminates (SIGTERM) this child process and waits a given timeout for
diff --git a/src/process.cpp b/src/process.cpp
index 03dbc42..b85170b 100644
--- a/src/process.cpp
+++ b/src/process.cpp
@@ -69,7 +69,6 @@ void xorg::testing::Process::Start(const std::string &program, const std::vector
     args.push_back(strdup(program.c_str()));
 
     for (it = argv.begin(); it != argv.end(); it++)
-      if (!it->empty())
         args.push_back(strdup(it->c_str()));
     args.push_back(NULL);
 
@@ -82,10 +81,14 @@ void xorg::testing::Process::Start(const std::string &program, const std::vector
 void xorg::testing::Process::Start(const std::string& program, va_list args) {
   std::vector<std::string> argv;
 
-  do {
-    std::string arg(va_arg(args, char*));
-    argv.push_back(arg);
-  } while (!argv.back().empty());
+  if (args) {
+    char *arg;
+    do {
+      arg = va_arg(args, char*);
+      if (arg)
+        argv.push_back(std::string(arg));
+    } while (arg);
+  }
 
   Start(program, argv);
 }
-- 
1.7.11.2