1/* 2 * Style guide for BSD's KNF (Kernel Normal Form). 3 * 4 * @(#)style 1.10 (Berkeley) 02/11/92 5 */ 6 7/* 8 * VERY important single-line comments look like this. 9 */ 10 11/* Most single-line comments look like this. */ 12 13/* 14 * Multi-line comments look like this. Make them real sentences. Fill 15 * them so they look like real paragraphs. 16 */ 17 18/* Include files go at the top of the source module. */ 19#include <stdio.h> /* Non-local includes in brackets. */ 20 21/* 22 * Global pathnames are defined in /usr/include/paths.h. Pathnames local 23 * to the program go in pathnames.h in the local directory. 24 */ 25#include <paths.h> /* Non-local includes in brackets. */ 26#include "pathnames.h" /* Local includes in quotes. */ 27 28/* 29 * All ANSI function decls go at the top of the source module. Use the 30 * __P macro from include file <sys/cdefs.h>. Only the kernel has a name 31 * associated with the types, i.e. in the kernel use: 32 * 33 * void function __P((int a)); 34 * 35 * in user land use: 36 * 37 * void function __P((int)); 38 */ 39void function __P((int, const char *)); 40 41/* 42 * Macros are capitalized, parenthesized, and should avoid side-effects. 43 * If they are an inline expansion of a function, the function is defined 44 * all in lowercase, the macro has the same name all in uppercase. If the 45 * macro needs more than a single line, use braces. Put a space before 46 * the backslashes. 47 */ 48#define MACRO(x, y) { \ 49 variable = (x) + (y); \ 50 line two; \ 51} 52 53/* Enum types are capitalized. */ 54enum enumtype { ONE, TWO } et; 55 56/* 57 * When declaring variables in structures, declare them sorted by use, then 58 * by size, and then by alphabetical order. The first category normally 59 * doesn't apply, but there are exceptions. Each one gets its own line. 60 * Put a tab after the first word, i.e. use "int^Ix;" and "struct^Ifoo *x;". 61 * 62 * Major structures should be declared at the top of the file they are 63 * used in, or in separate header files, if they are used in multiple 64 * source files. Use of the structures should be by separate declarations 65 * and should be "extern" if they are declared in a header file. 66 */ 67struct foo { 68 struct foo *next; /* List of active foo */ 69 struct mumble amumble; /* Comment for mumble */ 70 int bar; 71}; 72struct foo *foohead; /* Head of global foo list */ 73 74/* 75 * All major routines should have a comment briefly describing what 76 * they do. The comment before the "main" routine should describe 77 * what the program does. 78 */ 79main(argc, argv) 80 int argc; 81 char *argv[]; 82{ 83 extern char *optarg; 84 extern int optind; 85 long num; 86 int ch; 87 char *ep; 88 89 /* 90 * For consistency, getopt should be used to parse options. 91 * Options should be sorted in the getopt call and the switch 92 * statement, unless they fall through. Elements in a switch 93 * statement that fall through should have a FALLTHROUGH comment. 94 * Numerical arguments should be checked for accuracy. 95 */ 96 while ((ch = getopt(argc, argv, "abn")) != EOF) 97 switch (ch) { /* Indent the switch. */ 98 case 'a': /* Don't indent the case. */ 99 aflag = 1; 100 /* FALLTHROUGH */ 101 case 'b': 102 bflag = 1; 103 break; 104 case 'n': 105 num = strtol(optarg, &ep, 10); 106 if (num <= 0 || *ep) 107 err("illegal number -- %s", optarg); 108 break; 109 case '?': 110 default: 111 usage(); 112 } 113 argc -= optind; 114 argv += optind; 115 116 /* 117 * Space after keywords (while, for, return, switch). No braces are 118 * used for single statement block. 119 * 120 * Forever loops are done with for's, not while's. 121 */ 122 for (;;) 123 stmt; 124 125 /* 126 * Parts of a for loop may be left empty. Avoid declarations in 127 * blocks unless the routine is unusually complicated. 128 */ 129 for (; cnt < 15; cnt++) { 130 stmt1; 131 stmt2; 132 } 133 134 while (cnt < 20) { 135 stmt1; /* Second level indents are four spaces. */ 136 z = a + really + long + statment + that + needs + two lines + 137 gets + indented + four + spaces + on + the + second + 138 and + subsequent + lines. 139 } 140 141 /* 142 * Try to put shorter part first. The closing and opening braces 143 * go on the same line as the else. 144 */ 145 if (test) 146 stmt; 147 else if (bar) { 148 stmt; 149 stmt; 150 } else 151 stmt; 152 153 /* No space after function names. */ 154 if (error = function(a1, a2)) 155 exit(error); 156 157 /* 158 * Unary operators do not require spaces, binary operators do. 159 * Try not to use too many parenthesis unless the statement is 160 * really confusing without them. 161 */ 162 a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 163 k = l & FLAGS; 164 165 /* 166 * Exits should be 0 on success, and 1 on failure. Don't denote 167 * all the possible exit points, using the integers 1 through 300. 168 */ 169 exit(0); /* Avoid obvious comments such as "Exit 0 on success." */ 170} 171 172/* 173 * If a function type is declared, it should be on a line 174 * by itself preceeding the function. 175 */ 176static char * 177function(a1, a2, a3, a4) 178 int a1, a2, a4; /* Declare ints too. */ 179 float a3; /* List in order declared, as much as possible. */ 180{ 181 /* 182 * When declaring variables in functions declare them sorted by size, 183 * then in alphabetical order; multiple ones per line are okay. Old 184 * style function declarations can go on the same line. ANSI style 185 * function declarations should go in the include file "externs.h". 186 * If a line overflows reuse the type keyword. 187 * 188 * Try not to initialize variables in the declarations. 189 */ 190 extern u_char one; 191 extern char two; 192 struct foo three, *four; 193 double five; 194 int *six, seven, eight(); 195 char *nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen; 196 char *overflow __P((void)); 197 void *mymalloc __P((u_int)); 198 199 /* 200 * Casts and sizeof's are not followed by a space. NULL is any 201 * pointer type, and doesn't need to be cast, so use NULL instead 202 * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers 203 * against NULL, i.e. use: 204 * 205 * (p = f()) == NULL 206 * not: 207 * !(p = f()) 208 * 209 * Routines returning void * should not have their return values cast 210 * to any pointer type. 211 */ 212 if ((four = malloc(sizeof(struct foo))) == NULL) 213 return (NULL); 214 if ((six = (int *)overflow()) == NULL) 215 return (NULL); 216 return (eight); 217} 218 219/* ANSI function braces look like regular function braces. */ 220function(int a1, int a2) 221{ 222 ... 223} 224 225static void 226usage() 227{ /* Insert an empty line if the function has no local variables. */ 228 229 /* 230 * Use printf(3), not fputs/puts/putchar/whatever, it's faster and 231 * usually cleaner, not to mention avoiding stupid bugs. 232 * 233 * Usage statements should look like the manual pages. Options w/o 234 * operands come first, in alphabetical order inside a single set of 235 * braces. Followed by options with operands, in alphabetical order, 236 * each in braces. Followed by required arguments in the order they 237 * are specified, followed by optional arguments in the order they 238 * are specified. A bar ('|') separates either/or options/arguments, 239 * and multiple options/arguments which are specified together are 240 * placed in a single set of braces. 241 * 242 * "usage: f [-ade] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n" 243 * "usage: f [-a | -b] [-c [-de] [-n number]]\n" 244 */ 245 (void)fprintf(stderr, "usage: f [-ab]\n"); 246 exit(1); 247} 248