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Icecast is free server software for streaming multimedia.


C Coding Style

Proposal for Icecast



Indent with (4) spaces, no tabs.
A Line Should Not Exceed 80 Characters.

Brace Placement

All if, while, for and do statements should either have braces or be on a single line. Do not put braces next to keywords. Put a space between.

if (foo == 1) {
    /* code */
} else {
    /* code */

For complex conditions you can put spaces in the start and the end of the statement, if it helps readability:

if ( (a > 5) && (b < 3) || (a < 7) && (!b) && (func(test_var) << 7) == 5 ) {
    /* code */

One line form:

if (somevalue == 1) somevalue = 2;

(Should be used only where it really makes sense and stays readable)

If Then Else Formatting

Recommended way:

if (condition) {
    /* code */
} else if (condition) {
    /* code */
} else {
    /* code */
switch Formatting

Falling through a case statement into the next case statement shall be permitted as long as a comment is included.

switch (something) {
    case 1:
        /* code */
    case 2:
        /* code */
    /* fall through */
    case 3:
        /* code */
        /* code */
(condition) ? funct1() : func2();


    ? long statement
    : another long statement;

Functions should limit themselves to a single page of code. Unlike conditions, functions should have the curly brace on a newline. No whitespace between function name and brace.

static void test(client_t *client, const char *mount)
    /* code */

If variable list is too long, break it as follow

static void test(client_t	*client,
                 const char	*mount)
    /* code */

Macros and inline functions

Don’t change syntax via macro substitution. Macros for small tasks are ok, longer ones should be, when possible, inline functions

inline int max(int a, int b)
    return (a > b) ? a : b;

When putting expressions in macros always wrap the expression in parenthesis

#define ADD(x,y) ((x) + (y))


Placement and formating

Variable declarations should always go to the begin of the current scope. Each block of declarations is terminated by a single blank line. Variables are never declared mixed with code.

static void test(void)
    char *str;
    int i;

    /* code */

    if (expr) {
        const char *msg = getmsg();

        printf("Message: %s\n", msg);

Types should be chosen by there definition. Generic or native types should be avoided as they are often defined in a way that can result in portability problems.

Common errors include assumptions about the size or data structure of types. Examples include the use of short when a 16 bit integer type is required. The correct type here is int16_t from <stdint.h>.

Good types include:

Type Usage
intN_t signed integer type of fixed size (N bits)
uintN_t unsigned integer type of fixed size (N bits)
size_t Unsigned type used for counting objects in memory. Such as results of sizeof(), array sizes and indices, string lengths, or as counter loops iterating over arrays.
ssize_t Similar to size_t but can in addition hold the value -1 (often used to indicate an error).
char * Strings, 0-terminated
void * Blocks of memory, not 0-terminated. Often accompanied by length parameters which should have a type of size_t.


For comments, // should never be used but instead /* comment here */.

If the comment is about what a special if case does, it should be on the next line:

if (ret == 0) {
    /* nothing to do */

Multiline comment should have text on the first line, but not on the last:

/* This is text on the first line
 * an here is even more cool text

TAGs for Comments

The following tags should be used in comments, when necessary, for easier finding stuff that needs to be reviewed or handled in future release.

Extra Tags
/* BEFORE RELEASE 2.5.3 REVIEW #1234: Should we convert A to B?
 * A is according to standard REF0. This standard was superseded by
 * standard REF1 which could be implemented with option B.
 * This may break early clients of standard REF0 not being aware of SOMETHING.
/* IN YEAR 2022 REWRITE: Change copyright statement as license expires. */
/* LEAK FIXME #1234: Fix case object can not be added to queue. */
 * on authentication failure of backend server
/* AFTER RELEASE 2.5.3 REMOVE: Remove support for Icecast 1.x style SOURCE requests */