Add log message if LLProcessLauncher child fails to execv().

On a Posix platform (vfork()/execv() implementation), if for any reason the
execv() failed (e.g. executable not on PATH), the viewer would never know, nor
the user: the vfork() child produced no output, and terminated with rc 0! Add
logging, make child terminate with nonzero rc.
Remove pointless addArgument(const char*) overload: this does nothing for you
that the compiler won't do implicitly.
In llupdateinstaller.cpp, remove pointless c_str() call in addArgument() arg:
we were starting with a std::string, then extracting its c_str(), only to
construct a whole new std::string from it!

1 files changed, 11 insertions, 9 deletions

diff --git a/indra/llcommon/llprocesslauncher.cpp b/indra/llcommon/llprocesslauncher.cpp
index 10950181fd..25d64e9e28 100644
--- a/indra/llcommon/llprocesslauncher.cpp
+++ b/indra/llcommon/llprocesslauncher.cpp
@@ -73,11 +73,6 @@ void LLProcessLauncher::addArgument(const std::string &arg)
 	mLaunchArguments.push_back(arg);
 }
 
-void LLProcessLauncher::addArgument(const char *arg)
-{
-	mLaunchArguments.push_back(std::string(arg));
-}
-
 #if LL_WINDOWS
 
 int LLProcessLauncher::launch(void)
@@ -262,12 +257,19 @@ int LLProcessLauncher::launch(void)
 	if(id == 0)
 	{
 		// child process
-		
 		::execv(mExecutable.c_str(), (char * const *)fake_argv);
-		
+
 		// If we reach this point, the exec failed.
-		// Use _exit() instead of exit() per the vfork man page.
-		_exit(0);
+        LL_WARNS("LLProcessLauncher") << "failed to launch: ";
+        for (const char * const * ai = fake_argv; *ai; ++ai)
+        {
+            LL_CONT << *ai << ' ';
+        }
+        LL_CONT << LL_ENDL;
+		// Use _exit() instead of exit() per the vfork man page. Exit with a
+		// distinctive rc: someday soon we'll be able to retrieve it, and it
+		// would be nice to be able to tell that the child process failed!
+		_exit(249);
 	}
 
 	// parent process