style revision 1.36
1/* $NetBSD: style,v 1.36 2005/08/25 17:51:58 briggs Exp $ */ 2 3/* 4 * The revision control tag appears first, with a blank line after it. 5 * Copyright text appears after the revision control tag. 6 */ 7 8/* 9 * The NetBSD source code style guide. 10 * (Previously known as KNF - Kernel Normal Form). 11 * 12 * from: @(#)style 1.12 (Berkeley) 3/18/94 13 */ 14/* 15 * An indent(1) profile approximating the style outlined in 16 * this document lives in /usr/share/misc/indent.pro. It is a 17 * useful tool to assist in converting code to KNF, but indent(1) 18 * output generated using this profile must not be considered to 19 * be an authoritative reference. 20 */ 21 22/* 23 * Source code revision control identifiers appear after any copyright 24 * text. Use the appropriate macros from <sys/cdefs.h>. Usually only one 25 * source file per program contains a __COPYRIGHT() section. 26 * Historic Berkeley code may also have an __SCCSID() section. 27 * Only one instance of each of these macros can occur in each file. 28 */ 29#include <sys/cdefs.h> 30__COPYRIGHT("@(#) Copyright (c) 2000\n\ 31 The NetBSD Foundation, inc. All rights reserved.\n"); 32__RCSID("$NetBSD: style,v 1.36 2005/08/25 17:51:58 briggs Exp $"); 33 34/* 35 * VERY important single-line comments look like this. 36 */ 37 38/* Most single-line comments look like this. */ 39 40/* 41 * Multi-line comments look like this. Make them real sentences. Fill 42 * them so they look like real paragraphs. 43 */ 44 45/* 46 * Attempt to wrap lines longer than 80 characters appropriately. 47 * Refer to the examples below for more information. 48 */ 49 50/* 51 * EXAMPLE HEADER FILE: 52 * 53 * A header file should protect itself against multiple inclusion. 54 * E.g, <sys/socket.h> would contain something like: 55 */ 56#ifndef _SYS_SOCKET_H_ 57#define _SYS_SOCKET_H_ 58/* 59 * Contents of #include file go between the #ifndef and the #endif at the end. 60 */ 61#endif /* !_SYS_SOCKET_H_ */ 62/* 63 * END OF EXAMPLE HEADER FILE. 64 */ 65 66/* 67 * Kernel include files come first. 68 */ 69#include <sys/types.h> /* Non-local includes in brackets. */ 70 71/* 72 * If it's a network program, put the network include files next. 73 * Group the includes files by subdirectory. 74 */ 75#include <net/if.h> 76#include <net/if_dl.h> 77#include <net/route.h> 78#include <netinet/in.h> 79#include <protocols/rwhod.h> 80 81/* 82 * Then there's a blank line, followed by the /usr include files. 83 * The /usr include files should be sorted! 84 */ 85#include <assert.h> 86#include <errno.h> 87#include <inttypes.h> 88#include <stdio.h> 89#include <stdlib.h> 90 91/* 92 * Global pathnames are defined in /usr/include/paths.h. Pathnames local 93 * to the program go in pathnames.h in the local directory. 94 */ 95#include <paths.h> 96 97/* Then, there's a blank line, and the user include files. */ 98#include "pathnames.h" /* Local includes in double quotes. */ 99 100/* 101 * ANSI function declarations for private functions (i.e. functions not used 102 * elsewhere) and the main() function go at the top of the source module. 103 * Don't associate a name with the types. I.e. use: 104 * void function(int); 105 * Use your discretion on indenting between the return type and the name, and 106 * how to wrap a prototype too long for a single line. In the latter case, 107 * lining up under the initial left parenthesis may be more readable. 108 * In any case, consistency is important! 109 */ 110static char *function(int, int, float, int); 111static int dirinfo(const char *, struct stat *, struct dirent *, 112 struct statfs *, int *, char **[]); 113static void usage(void); 114int main(int, char *[]); 115 116/* 117 * Macros are capitalized, parenthesized, and should avoid side-effects. 118 * Spacing before and after the macro name may be any whitespace, though 119 * use of TABs should be consistent through a file. 120 * If they are an inline expansion of a function, the function is defined 121 * all in lowercase, the macro has the same name all in uppercase. 122 * If the macro is an expression, wrap the expression in parenthesis. 123 * If the macro is more than a single statement, use ``do { ... } while (0)'', 124 * so that a trailing semicolon works. Right-justify the backslashes; it 125 * makes it easier to read. The CONSTCOND comment is to satisfy lint(1). 126 */ 127#define MACRO(v, w, x, y) \ 128do { \ 129 v = (x) + (y); \ 130 w = (y) + 2; \ 131} while (/* CONSTCOND */ 0) 132 133#define DOUBLE(x) ((x) * 2) 134 135/* Enum types are capitalized. No comma on the last element. */ 136enum enumtype { 137 ONE, 138 TWO 139} et; 140 141/* 142 * When declaring variables in structures, declare them organized by use in 143 * a manner to attempt to minimize memory wastage because of compiler alignment 144 * issues, then by size, and then by alphabetical order. E.g, don't use 145 * ``int a; char *b; int c; char *d''; use ``int a; int b; char *c; char *d''. 146 * Each variable gets its own type and line, although an exception can be made 147 * when declaring bitfields (to clarify that it's part of the one bitfield). 148 * Note that the use of bitfields in general is discouraged. 149 * 150 * Major structures should be declared at the top of the file in which they 151 * are used, or in separate header files, if they are used in multiple 152 * source files. Use of the structures should be by separate declarations 153 * and should be "extern" if they are declared in a header file. 154 * 155 * It may be useful to use a meaningful prefix for each member name. 156 * E.g, for ``struct softc'' the prefix could be ``sc_''. 157 */ 158struct foo { 159 struct foo *next; /* List of active foo */ 160 struct mumble amumble; /* Comment for mumble */ 161 int bar; 162 unsigned int baz:1, /* Bitfield; line up entries if desired */ 163 fuz:5, 164 zap:2; 165 uint8_t flag; 166}; 167struct foo *foohead; /* Head of global foo list */ 168 169/* Make the structure name match the typedef. */ 170typedef struct BAR { 171 int level; 172} BAR; 173 174/* C99 uintN_t is preferred over u_intN_t. */ 175uint32_t zero; 176 177/* 178 * All major routines should have a comment briefly describing what 179 * they do. The comment before the "main" routine should describe 180 * what the program does. 181 */ 182int 183main(int argc, char *argv[]) 184{ 185 long num; 186 int ch; 187 char *ep; 188 189 /* 190 * At the start of main(), call setprogname() to set the program 191 * name. This does nothing on NetBSD, but increases portability 192 * to other systems. 193 */ 194 setprogname(argv[0]); 195 196 /* 197 * For consistency, getopt should be used to parse options. Options 198 * should be sorted in the getopt call and the switch statement, unless 199 * parts of the switch cascade. Elements in a switch statement that 200 * cascade should have a FALLTHROUGH comment. Numerical arguments 201 * should be checked for accuracy. Code that cannot be reached should 202 * have a NOTREACHED comment. 203 */ 204 while ((ch = getopt(argc, argv, "abn")) != -1) { 205 switch (ch) { /* Indent the switch. */ 206 case 'a': /* Don't indent the case. */ 207 aflag = 1; 208 /* FALLTHROUGH */ 209 case 'b': 210 bflag = 1; 211 break; 212 case 'n': 213 errno = 0; 214 num = strtol(optarg, &ep, 10); 215 if (num <= 0 || *ep != '\0' || (errno == ERANGE && 216 (num == LONG_MAX || num == LONG_MIN)) ) 217 errx(1, "illegal number -- %s", optarg); 218 break; 219 case '?': 220 default: 221 usage(); 222 /* NOTREACHED */ 223 } 224 } 225 argc -= optind; 226 argv += optind; 227 228 /* 229 * Space after keywords (while, for, return, switch). No braces are 230 * used for control statements with zero or only a single statement, 231 * unless it's a long statement. 232 * 233 * Forever loops are done with for's, not while's. 234 */ 235 for (p = buf; *p != '\0'; ++p) 236 continue; /* Explicit no-op */ 237 for (;;) 238 stmt; 239 240 /* 241 * Parts of a for loop may be left empty. Don't put declarations 242 * inside blocks unless the routine is unusually complicated. 243 */ 244 for (; cnt < 15; cnt++) { 245 stmt1; 246 stmt2; 247 } 248 249 /* Second level indents are four spaces. */ 250 while (cnt < 20) 251 z = a + really + long + statement + that + needs + two lines + 252 gets + indented + four + spaces + on + the + second + 253 and + subsequent + lines; 254 255 /* 256 * Closing and opening braces go on the same line as the else. 257 * Don't add braces that aren't necessary except in cases where 258 * there are ambiguity or readability issues. 259 */ 260 if (test) { 261 /* 262 * I have a long comment here. 263 */ 264#ifdef zorro 265 z = 1; 266#else 267 b = 3; 268#endif 269 } else if (bar) { 270 stmt; 271 stmt; 272 } else 273 stmt; 274 275 /* No spaces after function names. */ 276 if ((result = function(a1, a2, a3, a4)) == NULL) 277 exit(1); 278 279 /* 280 * Unary operators don't require spaces, binary operators do. 281 * Don't excessively use parenthesis, but they should be used if 282 * statement is really confusing without them, such as: 283 * a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 284 */ 285 a = ((b->c[0] + ~d == (e || f)) || (g && h)) ? i : (j >> 1); 286 k = !(l & FLAGS); 287 288 /* 289 * Exits should be EXIT_SUCCESS on success, and EXIT_FAILURE on 290 * failure. Don't denote all the possible exit points, using the 291 * integers 1 through 127. Avoid obvious comments such as "Exit 292 * 0 on success.". Since main is a function that returns an int, 293 * prefer returning from it, than calling exit. 294 */ 295 return EXIT_SUCCESS; 296} 297 298/* 299 * The function type must be declared on a line by itself 300 * preceding the function. 301 */ 302static char * 303function(int a1, int a2, float fl, int a4) 304{ 305 /* 306 * When declaring variables in functions declare them sorted by size, 307 * then in alphabetical order; multiple ones per line are okay. 308 * Function prototypes should go in the include file "extern.h". 309 * If a line overflows reuse the type keyword. 310 * 311 * DO NOT initialize variables in the declarations. 312 */ 313 extern u_char one; 314 extern char two; 315 struct foo three, *four; 316 double five; 317 int *six, seven; 318 char *eight, *nine, ten, eleven, twelve, thirteen; 319 char fourteen, fifteen, sixteen; 320 321 /* 322 * Casts and sizeof's are not followed by a space. NULL is any 323 * pointer type, and doesn't need to be cast, so use NULL instead 324 * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers 325 * against NULL. I.e. use: 326 * 327 * (p = f()) == NULL 328 * not: 329 * !(p = f()) 330 * 331 * Don't use `!' for tests unless it's a boolean. 332 * E.g. use "if (*p == '\0')", not "if (!*p)". 333 * 334 * Routines returning ``void *'' should not have their return 335 * values cast to more specific pointer types. 336 * 337 * Use err/warn(3), don't roll your own! 338 */ 339 if ((four = malloc(sizeof(struct foo))) == NULL) 340 err(1, NULL); 341 if ((six = (int *)overflow()) == NULL) 342 errx(1, "Number overflowed."); 343 344 /* No parentheses are needed around the return value. */ 345 return eight; 346} 347 348/* 349 * Use ANSI function declarations. ANSI function braces look like 350 * old-style (K&R) function braces. 351 * As per the wrapped prototypes, use your discretion on how to format 352 * the subsequent lines. 353 */ 354static int 355dirinfo(const char *p, struct stat *sb, struct dirent *de, struct statfs *sf, 356 int *rargc, char **rargv[]) 357{ /* Insert an empty line if the function has no local variables. */ 358 359 /* 360 * In system libraries, catch obviously invalid function arguments 361 * using _DIAGASSERT(3). 362 */ 363 _DIAGASSERT(p != NULL); 364 _DIAGASSERT(filedesc != -1); 365 366 if (stat(p, sb) < 0) 367 err(1, "Unable to stat %s", p); 368 369 /* 370 * To printf quantities that might be larger that "long", include 371 * <inttypes.h>, cast quantities to intmax_t or uintmax_t and use 372 * PRI?MAX constants, which may be found in <machine/int_fmtio.h>. 373 */ 374 (void)printf("The size of %s is %" PRIdMAX " (%#" PRIxMAX ")\n", p, 375 (intmax_t)sb->st_size, (uintmax_t)sb->st_size); 376 377 /* 378 * To printf quantities of known bit-width, use the corresponding 379 * defines (generally only done within NetBSD for quantities that 380 * exceed 32-bits). 381 */ 382 (void)printf("%s uses %" PRId64 " blocks and has flags %#" PRIx32 "\n", 383 p, sb->st_blocks, sb->st_flags); 384 385 /* 386 * There are similar constants that should be used with the *scanf(3) 387 * family of functions: SCN?MAX, SCN?64, etc. 388 */ 389} 390 391/* 392 * Functions that support variable numbers of arguments should look like this. 393 * (With the #include <stdarg.h> appearing at the top of the file with the 394 * other include files). 395 */ 396#include <stdarg.h> 397 398void 399vaf(const char *fmt, ...) 400{ 401 va_list ap; 402 403 va_start(ap, fmt); 404 STUFF; 405 va_end(ap); 406 /* No return needed for void functions. */ 407} 408 409static void 410usage(void) 411{ 412 413 /* 414 * Use printf(3), not fputs/puts/putchar/whatever, it's faster and 415 * usually cleaner, not to mention avoiding stupid bugs. 416 * Use snprintf(3) or strlcpy(3)/strlcat(3) instead of sprintf(3); 417 * again to avoid stupid bugs. 418 * 419 * Usage statements should look like the manual pages. Options w/o 420 * operands come first, in alphabetical order inside a single set of 421 * braces. Followed by options with operands, in alphabetical order, 422 * each in braces. Followed by required arguments in the order they 423 * are specified, followed by optional arguments in the order they 424 * are specified. A bar (`|') separates either/or options/arguments, 425 * and multiple options/arguments which are specified together are 426 * placed in a single set of braces. 427 * 428 * Use getprogname() instead of hardcoding the program name. 429 * 430 * "usage: f [-ade] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n" 431 * "usage: f [-a | -b] [-c [-de] [-n number]]\n" 432 */ 433 (void)fprintf(stderr, "usage: %s [-ab]\n", getprogname()); 434 exit(EXIT_FAILURE); 435} 436