Added piped process support to Util::Procs

util/proc.cpp

@@ -24,22 +24,11 @@ void Util::Procs::childsig_handler(int signum){
   plist.erase(ret);
 }
 
-/// Starts a new process if the name is not already active.
+/// Attempts to run the command cmd.
-/// \return 0 if process was not started, process PID otherwise.
+/// Replaces the current process - use after forking first!
-/// \arg name Name for this process - only used internally.
+/// This function will never return - it will either run the given
-/// \arg cmd Commandline for this process.
+/// command or kill itself with return code 42.
-pid_t Util::Procs::Start(std::string name, std::string cmd){
+void Util::Procs::runCmd(std::string & cmd){
-  if (isActive(name)){return getPid(name);}
-  if (!handler_set){
-    struct sigaction new_action;
-    new_action.sa_handler = Util::Procs::childsig_handler;
-    sigemptyset(&new_action.sa_mask);
-    new_action.sa_flags = 0;
-    sigaction(SIGCHLD, &new_action, NULL);
-    handler_set = true;
-  }
-  pid_t ret = fork();
-  if (ret == 0){
   //split cmd into arguments
   //supports a maximum of 20 arguments
   char * tmp = (char*)cmd.c_str();
@@ -57,9 +46,28 @@ pid_t Util::Procs::Start(std::string name, std::string cmd){
   //execute the command
   execvp(args[0], args);
   #if DEBUG >= 1
-    std::cerr << "Error: " << strerror(errno) << std::endl;
+  std::cerr << "Error running \"" << cmd << "\": " << strerror(errno) << std::endl;
   #endif
   _exit(42);
+}
+
+/// Starts a new process if the name is not already active.
+/// \return 0 if process was not started, process PID otherwise.
+/// \arg name Name for this process - only used internally.
+/// \arg cmd Commandline for this process.
+pid_t Util::Procs::Start(std::string name, std::string cmd){
+  if (isActive(name)){return getPid(name);}
+  if (!handler_set){
+    struct sigaction new_action;
+    new_action.sa_handler = Util::Procs::childsig_handler;
+    sigemptyset(&new_action.sa_mask);
+    new_action.sa_flags = 0;
+    sigaction(SIGCHLD, &new_action, NULL);
+    handler_set = true;
+  }
+  pid_t ret = fork();
+  if (ret == 0){
+    runCmd(cmd);
   }else{
     if (ret > 0){
       #if DEBUG >= 1
@@ -76,6 +84,63 @@ pid_t Util::Procs::Start(std::string name, std::string cmd){
   return ret;
 }
 
+/// Starts two piped processes if the name is not already active.
+/// \return 0 if process was not started, main (receiving) process PID otherwise.
+/// \arg name Name for this process - only used internally.
+/// \arg cmd Commandline for sub (sending) process.
+/// \arg cmd2 Commandline for main (receiving) process.
+pid_t Util::Procs::Start(std::string name, std::string cmd, std::string cmd2){
+  if (isActive(name)){return getPid(name);}
+  if (!handler_set){
+    struct sigaction new_action;
+    new_action.sa_handler = Util::Procs::childsig_handler;
+    sigemptyset(&new_action.sa_mask);
+    new_action.sa_flags = 0;
+    sigaction(SIGCHLD, &new_action, NULL);
+    handler_set = true;
+  }
+  pid_t ret = fork();
+  if (ret == 0){
+    int pfildes[2];
+    if (pipe(pfildes) == -1){
+      #if DEBUG >= 1
+      std::cerr << "Process " << name << " could not be started. Pipe creation failed." << std::endl;
+      #endif
+      _exit(41);
+    }
+    pid_t pid;
+    if ((pid = fork()) == -1){
+      #if DEBUG >= 1
+      std::cerr << "Process " << name << " could not be started. Second fork() failed." << std::endl;
+      #endif
+      _exit(41);
+    }else if (pid == 0){
+      close(pfildes[0]);
+      dup2(pfildes[1],1);
+      close(pfildes[1]);
+      runCmd(cmd);
+    }else{
+      close(pfildes[1]);
+      dup2(pfildes[0],0);
+      close(pfildes[0]);
+      runCmd(cmd2);
+    }
+  }else{
+    if (ret > 0){
+      #if DEBUG >= 1
+      std::cerr << "Process " << name << " started, PID " << ret << ": " << cmd << " | " << cmd2 << std::endl;
+      #endif
+      plist.insert(std::pair<pid_t, std::string>(ret, name));
+    }else{
+      #if DEBUG >= 1
+      std::cerr << "Process " << name << " could not be started. fork() failed." << std::endl;
+      #endif
+      return 0;
+    }
+  }
+  return ret;
+}
+
 /// Stops the named process, if running.
 /// \arg name (Internal) name of process to stop
 void Util::Procs::Stop(std::string name){

util/proc.h

@@ -14,8 +14,10 @@ namespace Util{
       static std::map<pid_t, std::string> plist; ///< Holds active processes
       static bool handler_set; ///< If true, the sigchld handler has been setup.
       static void childsig_handler(int signum);
+      static void runCmd(std::string & cmd);
     public:
       static pid_t Start(std::string name, std::string cmd);
+      static pid_t Start(std::string name, std::string cmd, std::string cmd2);
       static void Stop(std::string name);
       static void Stop(pid_t name);
       static void StopAll();