Implement Popen() execv helper to avoid popen()

2 files changed, 67 insertions, 0 deletions

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index de73a7fd8..8d15baad2 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -2057,3 +2057,58 @@ bool Rename(std::string From, std::string To)
    }   
    return true;
 }
+
+bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode)
+{
+   int fd;
+   if (Mode != FileFd::ReadOnly && Mode != FileFd::WriteOnly)
+      return _error->Error("Popen supports ReadOnly (x)or WriteOnly mode only");
+
+   int Pipe[2] = {-1, -1};
+   if(pipe(Pipe) != 0)
+   {
+      return _error->Errno("pipe", _("Failed to create subprocess IPC"));
+      return NULL;
+   }
+   std::set<int> keep_fds;
+   keep_fds.insert(Pipe[0]);
+   keep_fds.insert(Pipe[1]);
+   Child = ExecFork(keep_fds);
+   if(Child < 0)
+      return _error->Errno("fork", "Failed to fork");
+   if(Child == 0)
+   {
+      if(Mode == FileFd::ReadOnly)
+      {
+         close(Pipe[0]);
+         fd = Pipe[1];
+      }
+      else if(Mode == FileFd::WriteOnly)
+      {
+         close(Pipe[1]);
+         fd = Pipe[0];
+      }
+
+      if(Mode == FileFd::ReadOnly)
+      {
+         dup2(fd, 1);
+         dup2(fd, 2);
+      } else if(Mode == FileFd::WriteOnly)
+         dup2(fd, 0);
+
+      execv(Args[0], (char**)Args);
+      _exit(100);
+   }
+   if(Mode == FileFd::ReadOnly)
+   {
+      close(Pipe[1]);
+      fd = Pipe[0];
+   } else if(Mode == FileFd::WriteOnly)
+   {
+      close(Pipe[0]);
+      fd = Pipe[1];
+   }
+   Fd.OpenDescriptor(fd, Mode, FileFd::None, true);
+
+   return true;
+}
diff --git a/apt-pkg/contrib/fileutl.h b/apt-pkg/contrib/fileutl.h
index cc1a98eae..b7812ac56 100644
--- a/apt-pkg/contrib/fileutl.h
+++ b/apt-pkg/contrib/fileutl.h
@@ -201,4 +201,16 @@ std::string flCombine(std::string Dir,std::string File);
 // simple c++ glob
 std::vector<std::string> Glob(std::string const &pattern, int flags=0);
 
+/** \brief Popen() implementation that execv() instead of using a shell
+ *
+ * \param Args the execv style command to run
+ * \param FileFd is a referenz to the FileFd to use for input or output
+ * \param Child a reference to the integer that stores the child pid
+ *        Note that you must call ExecWait() or similar to cleanup
+ * \param Mode is either FileFd::ReadOnly or FileFd::WriteOnly
+ * \return true on success, false on failure with _error set
+ */
+bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode);
+
+
 #endif