style revision 1.48
1/* $NetBSD: style,v 1.48 2011/08/27 17:48:11 joerg 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 * Don't use newlines in the identifiers. 29 */ 30#include <sys/cdefs.h> 31__COPYRIGHT("@(#) Copyright (c) 2008\ 32 The NetBSD Foundation, inc. All rights reserved."); 33__RCSID("$NetBSD: style,v 1.48 2011/08/27 17:48:11 joerg Exp $"); 34 35/* 36 * VERY important single-line comments look like this. 37 */ 38 39/* Most single-line comments look like this. */ 40 41/* 42 * Multi-line comments look like this. Make them real sentences. Fill 43 * them so they look like real paragraphs. 44 */ 45 46/* 47 * Attempt to wrap lines longer than 80 characters appropriately. 48 * Refer to the examples below for more information. 49 */ 50 51/* 52 * EXAMPLE HEADER FILE: 53 * 54 * A header file should protect itself against multiple inclusion. 55 * E.g, <sys/socket.h> would contain something like: 56 */ 57#ifndef _SYS_SOCKET_H_ 58#define _SYS_SOCKET_H_ 59/* 60 * Contents of #include file go between the #ifndef and the #endif at the end. 61 */ 62#endif /* !_SYS_SOCKET_H_ */ 63/* 64 * END OF EXAMPLE HEADER FILE. 65 */ 66 67/* 68 * If a header file requires structures, defines, typedefs, etc. from 69 * another header file it should include that header file and not depend 70 * on the including file for that header including both. If there are 71 * exceptions to this for specific headers it should be clearly documented 72 * in the headers and, if appropriate, the documentation. Nothing in this 73 * rule should suggest relaxation of the multiple inclusion rule and the 74 * application programmer should be free to include both regardless. 75 */ 76 77/* 78 * Kernel include files come first. 79 */ 80#include <sys/types.h> /* Non-local includes in brackets. */ 81 82/* 83 * If it's a network program, put the network include files next. 84 * Group the includes files by subdirectory. 85 */ 86#include <net/if.h> 87#include <net/if_dl.h> 88#include <net/route.h> 89#include <netinet/in.h> 90#include <protocols/rwhod.h> 91 92/* 93 * Then there's a blank line, followed by the /usr include files. 94 * The /usr include files should be sorted! 95 */ 96#include <assert.h> 97#include <errno.h> 98#include <inttypes.h> 99#include <stdio.h> 100#include <stdlib.h> 101 102/* 103 * Global pathnames are defined in /usr/include/paths.h. Pathnames local 104 * to the program go in pathnames.h in the local directory. 105 */ 106#include <paths.h> 107 108/* Then, there's a blank line, and the user include files. */ 109#include "pathnames.h" /* Local includes in double quotes. */ 110 111/* 112 * ANSI function declarations for private functions (i.e. functions not used 113 * elsewhere) and the main() function go at the top of the source module. 114 * Don't associate a name with the types. I.e. use: 115 * void function(int); 116 * Use your discretion on indenting between the return type and the name, and 117 * how to wrap a prototype too long for a single line. In the latter case, 118 * lining up under the initial left parenthesis may be more readable. 119 * In any case, consistency is important! 120 */ 121static char *function(int, int, float, int); 122static int dirinfo(const char *, struct stat *, struct dirent *, 123 struct statfs *, int *, char **[]); 124static void usage(void) __dead; /* declare functions that don't return dead */ 125 126/* 127 * Macros are capitalized, parenthesized, and should avoid side-effects. 128 * Spacing before and after the macro name may be any whitespace, though 129 * use of TABs should be consistent through a file. 130 * If they are an inline expansion of a function, the function is defined 131 * all in lowercase, the macro has the same name all in uppercase. 132 * If the macro is an expression, wrap the expression in parenthesis. 133 * If the macro is more than a single statement, use ``do { ... } while (0)'', 134 * so that a trailing semicolon works. Right-justify the backslashes; it 135 * makes it easier to read. The CONSTCOND comment is to satisfy lint(1). 136 */ 137#define MACRO(v, w, x, y) \ 138do { \ 139 v = (x) + (y); \ 140 w = (y) + 2; \ 141} while (/* CONSTCOND */ 0) 142 143#define DOUBLE(x) ((x) * 2) 144 145/* Enum types are capitalized. No comma on the last element. */ 146enum enumtype { 147 ONE, 148 TWO 149} et; 150 151/* 152 * When declaring variables in structures, declare them organized by use in 153 * a manner to attempt to minimize memory wastage because of compiler alignment 154 * issues, then by size, and then by alphabetical order. E.g, don't use 155 * ``int a; char *b; int c; char *d''; use ``int a; int b; char *c; char *d''. 156 * Each variable gets its own type and line, although an exception can be made 157 * when declaring bitfields (to clarify that it's part of the one bitfield). 158 * Note that the use of bitfields in general is discouraged. 159 * 160 * Major structures should be declared at the top of the file in which they 161 * are used, or in separate header files, if they are used in multiple 162 * source files. Use of the structures should be by separate declarations 163 * and should be "extern" if they are declared in a header file. 164 * 165 * It may be useful to use a meaningful prefix for each member name. 166 * E.g, for ``struct softc'' the prefix could be ``sc_''. 167 */ 168struct foo { 169 struct foo *next; /* List of active foo */ 170 struct mumble amumble; /* Comment for mumble */ 171 int bar; 172 unsigned int baz:1, /* Bitfield; line up entries if desired */ 173 fuz:5, 174 zap:2; 175 uint8_t flag; 176}; 177struct foo *foohead; /* Head of global foo list */ 178 179/* Make the structure name match the typedef. */ 180typedef struct BAR { 181 int level; 182} BAR; 183 184/* C99 uintN_t is preferred over u_intN_t. */ 185uint32_t zero; 186 187/* 188 * All major routines should have a comment briefly describing what 189 * they do. The comment before the "main" routine should describe 190 * what the program does. 191 */ 192int 193main(int argc, char *argv[]) 194{ 195 long num; 196 int ch; 197 char *ep; 198 199 /* 200 * At the start of main(), call setprogname() to set the program 201 * name. This does nothing on NetBSD, but increases portability 202 * to other systems. 203 */ 204 setprogname(argv[0]); 205 206 /* 207 * For consistency, getopt should be used to parse options. 208 * Options should be sorted in the getopt call and the switch 209 * statement, unless parts of the switch cascade. For the 210 * sorting order, see the usage() example below. Don't forget 211 * to add option descriptions to the usage and the manpage. 212 * Elements in a switch statement that cascade should have a 213 * FALLTHROUGH comment. Numerical arguments should be checked 214 * for accuracy. Code that cannot be reached should have a 215 * NOTREACHED comment. 216 */ 217 while ((ch = getopt(argc, argv, "abn:")) != -1) { 218 switch (ch) { /* Indent the switch. */ 219 case 'a': /* Don't indent the case. */ 220 aflag = 1; 221 /* FALLTHROUGH */ 222 case 'b': 223 bflag = 1; 224 break; 225 case 'n': 226 errno = 0; 227 num = strtol(optarg, &ep, 10); 228 if (num <= 0 || *ep != '\0' || (errno == ERANGE && 229 (num == LONG_MAX || num == LONG_MIN)) ) 230 errx(1, "illegal number -- %s", optarg); 231 break; 232 case '?': 233 default: 234 usage(); 235 /* NOTREACHED */ 236 } 237 } 238 argc -= optind; 239 argv += optind; 240 241 /* 242 * Space after keywords (while, for, return, switch). No braces are 243 * required for control statements with only a single statement, 244 * unless it's a long statement. 245 * 246 * Forever loops are done with for's, not while's. 247 */ 248 for (p = buf; *p != '\0'; ++p) 249 continue; /* Explicit no-op */ 250 for (;;) 251 stmt; 252 253 /* 254 * Braces are required for control statements with a single statement 255 * that may expand to nothing. 256 */ 257#ifdef DEBUG_FOO 258#define DPRINTF(a) printf a 259#else 260#define DPRINTF(a) 261#endif 262 if (broken) { 263 DPRINTF(("broken is %d\n", broken)); 264 } 265 266 /* 267 * Parts of a for loop may be left empty. Don't put declarations 268 * inside blocks unless the routine is unusually complicated. 269 */ 270 for (; cnt < 15; cnt++) { 271 stmt1; 272 stmt2; 273 } 274 275 /* Second level indents are four spaces. */ 276 while (cnt < 20) 277 z = a + really + long + statement + that + needs + two + lines + 278 gets + indented + four + spaces + on + the + second + 279 and + subsequent + lines; 280 281 /* 282 * Closing and opening braces go on the same line as the else. 283 * Don't add braces that aren't necessary except in cases where 284 * there are ambiguity or readability issues. 285 */ 286 if (test) { 287 /* 288 * I have a long comment here. 289 */ 290#ifdef zorro 291 z = 1; 292#else 293 b = 3; 294#endif 295 } else if (bar) { 296 stmt; 297 stmt; 298 } else 299 stmt; 300 301 /* No spaces after function names. */ 302 if ((result = function(a1, a2, a3, a4)) == NULL) 303 exit(1); 304 305 /* 306 * Unary operators don't require spaces, binary operators do. 307 * Don't excessively use parenthesis, but they should be used if 308 * statement is really confusing without them, such as: 309 * a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 310 */ 311 a = ((b->c[0] + ~d == (e || f)) || (g && h)) ? i : (j >> 1); 312 k = !(l & FLAGS); 313 314 /* 315 * Exits should be EXIT_SUCCESS on success, and EXIT_FAILURE on 316 * failure. Don't denote all the possible exit points, using the 317 * integers 1 through 127. Avoid obvious comments such as "Exit 318 * 0 on success.". Since main is a function that returns an int, 319 * prefer returning from it, than calling exit. 320 */ 321 return EXIT_SUCCESS; 322} 323 324/* 325 * The function type must be declared on a line by itself 326 * preceding the function. 327 */ 328static char * 329function(int a1, int a2, float fl, int a4) 330{ 331 /* 332 * When declaring variables in functions declare them sorted by size, 333 * then in alphabetical order; multiple ones per line are okay. 334 * Function prototypes should go in the include file "extern.h". 335 * If a line overflows reuse the type keyword. 336 * 337 * DO NOT initialize variables in the declarations. 338 */ 339 extern u_char one; 340 extern char two; 341 struct foo three, *four; 342 double five; 343 int *six, seven; 344 char *eight, *nine, ten, eleven, twelve, thirteen; 345 char fourteen, fifteen, sixteen; 346 347 /* 348 * Casts and sizeof's are not followed by a space. NULL is any 349 * pointer type, and doesn't need to be cast, so use NULL instead 350 * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers 351 * against NULL. I.e. use: 352 * 353 * (p = f()) == NULL 354 * not: 355 * !(p = f()) 356 * 357 * Don't use `!' for tests unless it's a boolean. 358 * E.g. use "if (*p == '\0')", not "if (!*p)". 359 * 360 * Routines returning ``void *'' should not have their return 361 * values cast to more specific pointer types. 362 * 363 * Prefer sizeof(*var) over sizeof(type) because if type changes, 364 * the change needs to be done in one place. 365 * 366 * Use err/warn(3), don't roll your own! 367 */ 368 if ((four = malloc(sizeof(*four))) == NULL) 369 err(1, NULL); 370 if ((six = (int *)overflow()) == NULL) 371 errx(1, "Number overflowed."); 372 373 /* No parentheses are needed around the return value. */ 374 return eight; 375} 376 377/* 378 * Use ANSI function declarations. ANSI function braces look like 379 * old-style (K&R) function braces. 380 * As per the wrapped prototypes, use your discretion on how to format 381 * the subsequent lines. 382 */ 383static int 384dirinfo(const char *p, struct stat *sb, struct dirent *de, struct statfs *sf, 385 int *rargc, char **rargv[]) 386{ /* Insert an empty line if the function has no local variables. */ 387 388 /* 389 * In system libraries, catch obviously invalid function arguments 390 * using _DIAGASSERT(3). 391 */ 392 _DIAGASSERT(p != NULL); 393 _DIAGASSERT(filedesc != -1); 394 395 if (stat(p, sb) < 0) 396 err(1, "Unable to stat %s", p); 397 398 /* 399 * To printf quantities that might be larger that "long", include 400 * <inttypes.h>, cast quantities to intmax_t or uintmax_t and use 401 * PRI?MAX constants. 402 */ 403 (void)printf("The size of %s is %" PRIdMAX " (%#" PRIxMAX ")\n", p, 404 (intmax_t)sb->st_size, (uintmax_t)sb->st_size); 405 406 /* 407 * To printf quantities of known bit-width, use the corresponding 408 * defines (generally only done within NetBSD for quantities that 409 * exceed 32-bits). 410 */ 411 (void)printf("%s uses %" PRId64 " blocks and has flags %#" PRIx32 "\n", 412 p, sb->st_blocks, sb->st_flags); 413 414 /* 415 * There are similar constants that should be used with the *scanf(3) 416 * family of functions: SCN?MAX, SCN?64, etc. 417 */ 418} 419 420/* 421 * Functions that support variable numbers of arguments should look like this. 422 * (With the #include <stdarg.h> appearing at the top of the file with the 423 * other include files.) 424 */ 425#include <stdarg.h> 426 427void 428vaf(const char *fmt, ...) 429{ 430 va_list ap; 431 432 va_start(ap, fmt); 433 STUFF; 434 va_end(ap); 435 /* No return needed for void functions. */ 436} 437 438static void 439usage(void) 440{ 441 442 /* 443 * Use printf(3), not fputs/puts/putchar/whatever, it's faster and 444 * usually cleaner, not to mention avoiding stupid bugs. 445 * Use snprintf(3) or strlcpy(3)/strlcat(3) instead of sprintf(3); 446 * again to avoid stupid bugs. 447 * 448 * Usage statements should look like the manual pages. 449 * Options w/o operands come first, in alphabetical order 450 * inside a single set of braces, upper case before lower case 451 * (AaBbCc...). Next are options with operands, in the same 452 * order, each in braces. Then required arguments in the 453 * order they are specified, followed by optional arguments in 454 * the order they are specified. A bar (`|') separates 455 * either/or options/arguments, and multiple options/arguments 456 * which are specified together are placed in a single set of 457 * braces. 458 * 459 * Use getprogname() instead of hardcoding the program name. 460 * 461 * "usage: f [-aDde] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n" 462 * "usage: f [-a | -b] [-c [-de] [-n number]]\n" 463 */ 464 (void)fprintf(stderr, "usage: %s [-ab]\n", getprogname()); 465 exit(EXIT_FAILURE); 466} 467