Version 4 (modified by 7 years ago) (diff) | ,
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This coding style is not final and not yet in effect. Discussion ongoing in #openvpn-devel. Right before branching of the release/2.4 branch, we will have The Great Reformatting where we switch to this coding style.
Introduction
The OpenVPN coding style is based on the Allman style, e.g.:
void myfunction(int a, int b) { if (a == b) { something_equals(); } else { does_not_equal(); } }
Summarizing:
- Indentation is 4 spaces, no tabs ever.
- Opening and closing brackets get their own line, and must match indentation.
Open question: do we allow
} else {
and} else if () {
as exceptions?
- Line length is 80 characters.
- C99 is allowed. E.g.
for (int i = 0; i < max; i++)
. - Only use
/* */
-style comments
Open question: should we also allow
//
for single-line comments now that we can write C99?
Line wrapping
The maximum line length is 80 characters. When lines exceed this length, wrap them using a double indent (ie 8 spaces) on the new line. For example:
void my_function(void) { if (variable_with_artificially_long_name_1 != 0 && variable_with_artificially_long_name_2 != 0) { return variable_with_artificially_long_name_1 + variable_with_artificially_long_name_2 + variable_with_artificially_long_name_3; } }
If you find yourself continuously exceeding the line limit, you might want to consider breaking up your function into smaller functions to reduce nesting.
Some additional secure coding style rules
This are style rules, not general secure coding guide lines. See e.g. https://www.securecoding.cert.org/confluence/display/c/SEI+CERT+C+Coding+Standard for useful guidelines on writing secure C.
All branches should use braces
For example:
if (a) { return true; }
We wouldn't be the first to not spot missing braces in an if statement, like what happened in Apple's goto fail; bug. Always using braces prevents this kind of mistake.
Cases in a switch statement should break or explicitly fall through
The only exception to this rule are empty case statements, to not overly clutter the code with comments.
For example:
switch (a) { case ONE: case TWO: one_or_two = true; /* Fall through */ case THREE: now_do_something(); break; default: ASSERT(0); }
This makes the intent immediately clear to the reader / reviewer.