From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 3 Apr 2015 12:26:22 +0000 (+0200)
Subject: CODING_STYLE: mention that dup() should not be used
X-Git-Tag: v219.0~194
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=9ff3e22aa93fe461f8971f2468c65dc928fadc9e;ds=sidebyside

CODING_STYLE: mention that dup() should not be used
---

diff --git a/CODING_STYLE b/CODING_STYLE
index 1748dc4bc..feb1a9dd6 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -232,3 +232,10 @@
   "return" to exit from the main function of a process. If you
   fork()ed off a child process, please use _exit() instead of exit(),
   so that the exit handlers are not run.
+
+- Please never use dup(). Use fcntl(fd, F_DUPFD_CLOEXEC, 3)
+  instead. For two reason: first, you want O_CLOEXEC set on the new fd
+  (see above). Second, dup() will happily duplicate your fd as 0, 1,
+  2, i.e. stdin, stdout, stderr, should those fds be closed. Given the
+  special semantics of those fds, it's probably a good idea to avoid
+  them. F_DUPFD_CLOEXEC with "3" as parameter avoids them.