initial implementation of subprocess execution. currently is merging child STDOUT and child STDERR into parent STDOUT. Next effort.

conf/units/all_test.units

@@ -2,7 +2,7 @@
   "units": [
     {
       "name":       "independent test 1",
-      "target":     "/usr/bin/true",
+      "target":     "(>&2 echo 'error is a doodle day')",
       "rectifier":  "/usr/bin/true",
       "active":     true,
       "required":   true,

src/sproc/Sproc.cpp

@@ -1,10 +1,111 @@
 #include "Sproc.h"
+#include <unistd.h>
+#include <cstring>
 
-
+/// Sproc::execute
-
+///
-int Sproc::execute( std::string input )
+/// \param input - The commandline input to execute.
-{
+/// \return - The return code of the execution of input in the calling shell.
+int Sproc::execute(std::string input) {
     std::cout << std::endl << "made it to subprocess execution but not implemented yet" << std::endl << std::endl;
-    return EXIT_SUCCESS;
 
+    int PIPE_READ = 0;
+    int PIPE_WRITE = 1;
+
+    int stdin_pipe[2];
+    // int aStderrPipe[2];
+    int stdout_pipe[2];
+    int child_pid;
+    char nChar;
+    int child_exit_code;
+
+    if (pipe(stdin_pipe) < 0)
+    {
+        perror("allocating pipe for child input redirect");
+        return -1;
+    }
+
+/*
+    if (pipe(aStderrPipe < 0)) {
+        close(aStderrPipe[PIPE_READ]);
+        close(aStderrPipe[PIPE_WRITE]);
+        perror("allocating pipe for error redirect");
+        return -1;
+    }
+*/
+
+    if (pipe(stdout_pipe) < 0)
+    {
+        close(stdin_pipe[PIPE_READ]);
+        close(stdin_pipe[PIPE_WRITE]);
+        perror("allocating pipe for child output redirect");
+        return -1;
+    }
+
+    child_pid = fork();
+    if (0 == child_pid)
+    {
+        // child continues here
+
+        // redirect stdin
+        if (dup2(stdin_pipe[PIPE_READ], STDIN_FILENO) == -1) {
+            exit(errno);
+        }
+
+        // redirect stdout
+        if (dup2(stdout_pipe[PIPE_WRITE], STDOUT_FILENO) == -1) {
+            exit(errno);
+        }
+
+        // redirect stderr
+        if (dup2(stdout_pipe[PIPE_WRITE], STDERR_FILENO) == -1) {
+            exit(errno);
+        }
+
+        // all these are for use by parent only
+        close(stdin_pipe[PIPE_READ]);
+        close(stdin_pipe[PIPE_WRITE]);
+        close(stdout_pipe[PIPE_READ]);
+        close(stdout_pipe[PIPE_WRITE]);
+
+        // run child process image
+        // replace this with any exec* function find easier to use ("man exec")
+        child_exit_code = system( input.c_str() );
+
+        // if we get here at all, an error occurred, but we are in the child
+        // process, so just exit
+        exit(child_exit_code);
+    } else if (child_pid > 0) {
+        // parent continues here
+
+        // close unused file descriptors, these are for child only
+        close(stdin_pipe[PIPE_READ]);
+        close(stdout_pipe[PIPE_WRITE]);
+
+        // da fuq?
+/*        // Include error check here
+        if (NULL != szMessage)
+        {
+            write(stdin_pipe[PIPE_WRITE], szMessage, strlen(szMessage));
+        }
+*/
+
+        // Just a char by char read here, you can change it accordingly
+        while (read(stdout_pipe[PIPE_READ], &nChar, 1) == 1)
+        {
+            write(STDOUT_FILENO, &nChar, 1);
+        }
+
+        // done with these in this example program, you would normally keep these
+        // open of course as long as you want to talk to the child
+        close(stdin_pipe[PIPE_WRITE]);
+        close(stdout_pipe[PIPE_READ]);
+    } else {
+        // failed to create child
+        close(stdin_pipe[PIPE_READ]);
+        close(stdin_pipe[PIPE_WRITE]);
+        close(stdout_pipe[PIPE_READ]);
+        close(stdout_pipe[PIPE_WRITE]);
+    }
+    return child_exit_code;
 }