-- 8ch indent, no tabs
+- 8ch indent, no tabs, except for files in man/ which are 2ch indent,
+ and still no tabs
- Don't break code lines too eagerly. We do *not* force line breaks at
80ch, all of today's screens should be much larger than that. But
- For robustness reasons, destructors should be able to destruct
half-initialized objects, too
-- Error codes are returned as negative Exxx. i.e. return -EINVAL. There
+- Error codes are returned as negative Exxx. e.g. return -EINVAL. There
are some exceptions: for constructors, it is OK to return NULL on
OOM. For lookup functions, NULL is fine too for "not found".
doing something wrong!
- Stay uniform. For example, always use "usec_t" for time
- values. Do not usec mix msec, and usec and whatnot.
+ values. Do not mix usec and msec, and usec and whatnot.
- Make use of _cleanup_free_ and friends. It makes your code much
nicer to read!
But it is OK if you do not.
+- Single-line "if" blocks should not be enclosed in {}. Use this:
+
+ if (foobar)
+ waldo();
+
+ instead of this:
+
+ if (foobar) {
+ waldo();
+ }
+
- Do not write "foo ()", write "foo()".
- Please use streq() and strneq() instead of strcmp(), strncmp() where applicable.
is_main_thread() to detect whether the calling thread is the main
thread.
-- Option parsing:
+- Command line option parsing:
- Do not print full help() on error, be specific about the error.
- Do not print messages to stdout on error.
- Do not POSIX_ME_HARDER unless necessary, i.e. avoid "+" in option string.
+
+- Do not write functions that clobber call-by-reference variables on
+ failure. Use temporary variables for these cases and change the
+ passed in variables only on success.
+
+- When you allocate a file descriptor, it should be made O_CLOEXEC
+ right from the beginning, as none of our files should leak to forked
+ binaries by default. Hence, whenever you open a file, O_CLOEXEC must
+ be specified, right from the beginning. This also applies to
+ sockets. Effectively this means that all invocations to:
+
+ a) open() must get O_CLOEXEC passed
+ b) socket() and socketpair() must get SOCK_CLOEXEC passed
+ c) recvmsg() must get MSG_CMSG_CLOEXEC set
+ d) F_DUPFD_CLOEXEC should be used instead of F_DUPFD, and so on
+
+- We never use the XDG version of basename(). glibc defines it in
+ libgen.h. The only reason to include that file is because dirname()
+ is needed. Everytime you need that please immediately undefine
+ basename(), and add a comment about it, so that no code ever ends up
+ using the XDG version!
+
+- Use the bool type for booleans, not integers. One exception: in public
+ headers (i.e those in src/systemd/sd-*.h) use integers after all, as "bool"
+ is C99 and in our public APIs we try to stick to C89 (with a few extension).
+
+- When you invoke certain calls like unlink(), or mkdir_p() and you
+ know it is safe to ignore the error it might return (because a later
+ call would detect the failure anyway, or because the error is in an
+ error path and you thus couldn't do anything about it anyway), then
+ make this clear by casting the invocation explicitly to (void). Code
+ checks like Coverity understand that, and will not complain about
+ ignored error codes. Hence, please use this:
+
+ (void) unlink("/foo/bar/baz");
+
+ instead of just this:
+
+ unlink("/foo/bar/baz");
+
+- Don't invoke exit(), ever. It is not replacement for proper error
+ handling. Please escalate errors up your call chain, and use normal
+ "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.
~ianmdlvl / elogind.git / blobdiff