X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=CODING_STYLE;h=feb1a9dd6715ef3731830e99c4b8bf6019d42773;hp=ca3b5183f901037a1e6b201e13f231f86fa8b9db;hb=92947a0878c5d129adb37ddbfdef35274ef5c6ae;hpb=601185b43da638b1c74153deae01dbd518680889

diff --git a/CODING_STYLE b/CODING_STYLE
index ca3b5183f..feb1a9dd6 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -1,5 +1,9 @@
+- 8ch indent, no tabs, except for files in man/ which are 2ch indent,
+  and still no tabs
 
-- 8ch indent, 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
+  then again, don't overdo it, ~140ch should be enough really.
 
 - Variables and functions *must* be static, unless they have a
   prototype, and are supposed to be exported.
@@ -15,7 +19,7 @@
 - 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".
 
@@ -54,7 +58,7 @@
   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!
@@ -76,6 +80,17 @@
 
   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.
@@ -152,7 +167,7 @@
   function or a "non-logging" function. "Logging" functions do logging
   on their own, "non-logging" function never log on their own and
   expect their callers to log. All functions in "library" code,
-  i.e. in src/shared/ and suchlike must be "non-logging". Everytime a
+  i.e. in src/shared/ and suchlike must be "non-logging". Every time a
   "logging" function calls a "non-logging" function, it should log
   about the resulting errors. If a "logging" function calls another
   "logging" function, then it should not generate log messages, so
@@ -168,7 +183,59 @@
   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.