liblog: fix fd leakage

File descriptors remain open across an exec unless FD_CLOEXEC is
set.  Add O_CLOEXEC to the open() call to prevent file descriptor
leakage.

In particular, the following program will eventually run out of
file descriptors:

int main(int argc, char **argv) {
  printf("===== entering main =====\n");
  ALOGW("entering main");
  system("ls -l /proc/self/fd/");

  execv(argv[0], argv);
  printf("exec failed\n");
  return -1;
}

Change-Id: I5be43ab3b9f82a05f242b1f586454c50568af388

liblog/logd_write.c

@@ -24,6 +24,8 @@
 #include <string.h>
 #include <stdlib.h>
 #include <stdarg.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 #include <cutils/logger.h>
 #include <cutils/logd.h>
@@ -37,7 +39,7 @@
 #define log_writev(filedes, vector, count) fakeLogWritev(filedes, vector, count)
 #define log_close(filedes) fakeLogClose(filedes)
 #else
-#define log_open(pathname, flags) open(pathname, flags)
+#define log_open(pathname, flags) open(pathname, (flags) | O_CLOEXEC)
 #define log_writev(filedes, vector, count) writev(filedes, vector, count)
 #define log_close(filedes) close(filedes)
 #endif