Mark all FDs as close-on-exec

This marks all FDs which are valid after the function creating them returns
as close-on-exec, so that processes started from ZNC (e.g. through the shell
module) don't inherit a copy of all of our FDs.

Csocket already does this for its FDs.


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1004 726aef4b-f618-498e-8847-2d620e286838

FileUtils.cpp

@@ -7,6 +7,7 @@
  */
 
 #include "FileUtils.h"
+#include "Utils.h"
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -251,6 +252,9 @@ bool CFile::Open(int iFlags, mode_t iMode) {
 	if (m_iFD < 0)
 		return false;
 
+	/* Make sure this FD isn't given to childs */
+	SetFdCloseOnExec(m_iFD);
+
 	m_bClose = true;
 	return true;
 }

Utils.h

@@ -26,6 +26,15 @@ using std::vector;
 #define DEBUG_ONLY(f) ((void)0)
 #endif
 
+static inline void SetFdCloseOnExec(int fd)
+{
+	int flags = fcntl(fd, F_GETFD, 0);
+	if (flags < 0)
+		return; // Ignore errors
+	// When we execve() a new process this fd is now automatically closed.
+	fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+}
+
 static const char g_HexDigits[] = "0123456789abcdef";
 
 class CUtils {
@@ -106,11 +115,14 @@ public:
 		m_bCreated = false;
 
 		if (m_fd == -1) {
-			// i must create the file then
+			// I must create the file then
 			m_fd = open(sFile.c_str(), O_RDWR|O_CREAT, 0644);
 			m_bCreated = true;
 		}
 
+		// Thanks to broken POSIX, we shouldn't give this fd to anyone
+		SetFdCloseOnExec(m_fd);
+
 		m_pid = getpid();       // for destructor
 		m_sFileName = sFile;
 	}