From d72ce9d0bbc6c1f8366477d90036295847526d46 Mon Sep 17 00:00:00 2001
From: Kevin Larke <kevin@larke.org>
Date: Fri, 22 May 2015 13:55:38 -0700
Subject: [PATCH] cmExec.h/c, Makefile.am : Initial commit.

---
 Makefile.am |  4 +--
 cmExec.c    | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 cmExec.h    | 29 +++++++++++++++++++
 3 files changed, 112 insertions(+), 2 deletions(-)
 create mode 100644 cmExec.c
 create mode 100644 cmExec.h

diff --git a/Makefile.am b/Makefile.am
index fcf01ac..1a29e63 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,8 +9,8 @@ cmSRC += src/libcm/cmErr.c src/libcm/cmCtx.c src/libcm/cmRpt.c src/libcm/cmGloba
 cmHDR += src/libcm/cmSerialize.h src/libcm/cmSymTbl.h src/libcm/cmHashTbl.h src/libcm/cmFileSys.h src/libcm/cmFile.h 
 cmSRC += src/libcm/cmSerialize.c src/libcm/cmSymTbl.c src/libcm/cmHashTbl.c src/libcm/cmFileSys.c src/libcm/cmFile.c 
 
-cmHDR += src/libcm/cmMem.h src/libcm/cmTime.h src/libcm/cmPgmOpts.h
-cmSRC += src/libcm/cmMem.c src/libcm/cmTime.c src/libcm/cmPgmOpts.c
+cmHDR += src/libcm/cmMem.h src/libcm/cmTime.h src/libcm/cmExec.h src/libcm/cmPgmOpts.h
+cmSRC += src/libcm/cmMem.c src/libcm/cmTime.c src/libcm/cmExec.c src/libcm/cmPgmOpts.c
 
 cmHDR += src/libcm/cmData.h src/libcm/cmLib.h src/libcm/cmText.h src/libcm/cmTextTemplate.h
 cmSRC += src/libcm/cmData.c src/libcm/cmLib.c src/libcm/cmText.c src/libcm/cmTextTemplate.c
diff --git a/cmExec.c b/cmExec.c
new file mode 100644
index 0000000..c7b32f5
--- /dev/null
+++ b/cmExec.c
@@ -0,0 +1,81 @@
+#include "cmGlobal.h"
+#include "cmRpt.h"
+#include "cmErr.h"
+#include "cmExec.h"
+#include <sys/wait.h>
+
+cmExRC_t cmExecV( cmErr_t* err, int* returnValRef, const cmChar_t* pgmFn, va_list vl0 )
+{
+  cmExRC_t rc = kOkExRC;
+  int      n  = 0;
+  int      i  = 0;
+  pid_t    pid;
+  va_list  vl1;
+
+  if( pgmFn == NULL )
+    return cmErrMsg(err,kInvalidPgmFnExRC,"No executable program file name given in call to %s.",__FUNCTION__);
+
+  // get the count of arguments
+  va_copy(vl1,vl0);
+  while( va_arg(vl1,cmChar_t*)!=NULL )
+    ++n;
+  va_end(vl1);
+
+
+  // load argv with ptrs to the args
+  cmChar_t* argv[n+2];
+  
+  argv[0] = (cmChar_t*)pgmFn;
+  for(i=0; i<n+1; ++i)
+    argv[i+1] = va_arg(vl0,cmChar_t*);
+  argv[n+1] = NULL;
+  
+  errno = 0;
+  
+  switch( pid = fork())
+  {
+    case -1:
+      rc = cmErrSysMsg(err,kForkFailExRC,errno,"Fork failed.");
+      break;
+      
+    case 0:
+      // we are in the child process - never to return
+      execvp(pgmFn,argv);
+       
+      // under normal conditions execlp() does not return so we should never get here.
+      rc = cmErrSysMsg(err,kExecFailExRC,errno,"Fork to '%s' failed. Is '%s' installed and on the execution path?",pgmFn,pgmFn);      
+      break;
+      
+    default:
+      {
+          int rv;
+          int wrc;
+          
+          // we are in the parent process - wait for the child to return
+          if((wrc = waitpid(pid,&rv,0))==-1)
+          {
+            rc = cmErrSysMsg(err,kWaitFailExRC,errno,"Wait failed on call to '%s'.",pgmFn);
+            goto errLabel;
+          }
+
+          if( returnValRef != NULL )
+            *returnValRef = rv;
+          
+          if( WEXITSTATUS(rv) != 0 )
+            rc = cmErrMsg(err,kPgmFailExRC,"'%s' failed.",pgmFn);
+      }
+      break;
+  }
+
+ errLabel:
+  return rc;
+}
+
+cmExRC_t cmExec( cmErr_t* err, int* returnValRef, const cmChar_t* pgmFn, ... )
+{
+  va_list vl;
+  va_start(vl,pgmFn);
+  cmExRC_t rc = cmExecV(err,returnValRef,pgmFn,vl);
+  va_end(vl);
+  return rc;
+}
diff --git a/cmExec.h b/cmExec.h
new file mode 100644
index 0000000..60c69ec
--- /dev/null
+++ b/cmExec.h
@@ -0,0 +1,29 @@
+#ifndef cmExec_h
+#define cmExec_h
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+  enum
+  {
+    kOkExRC,
+    kInvalidPgmFnExRC, // pgmFn was NULL
+    kForkFailExRC,     // internal fork() failed
+    kExecFailExRC,     // internal exec() failed.
+    kPgmFailExRC,      // pgm returned a non-zero exit status
+    kWaitFailExRC      // internal waitpid() failed
+  };
+
+  typedef unsigned cmExRC_t;
+
+  // If returnValRef is non-NULL *returnValRef is set to the program return value.
+  cmExRC_t cmExecV( cmErr_t* err, int* returnValRef, const cmChar_t* pgmFn, va_list vl );
+  cmExRC_t cmExec(  cmErr_t* err, int* returnValRef, const cmChar_t* pgmFn, ... );  
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif