style revision 1.43
1/* $NetBSD: style,v 1.43 2008/07/20 00:51:19 lukem 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 1.43 2008/07/20 00:51:19 lukem 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); 125int main(int, char *[]); 126 127/* 128 * Macros are capitalized, parenthesized, and should avoid side-effects. 129 * Spacing before and after the macro name may be any whitespace, though 130 * use of TABs should be consistent through a file. 131 * If they are an inline expansion of a function, the function is defined 132 * all in lowercase, the macro has the same name all in uppercase. 133 * If the macro is an expression, wrap the expression in parenthesis. 134 * If the macro is more than a single statement, use ``do { ... } while (0)'', 135 * so that a trailing semicolon works. Right-justify the backslashes; it 136 * makes it easier to read. The CONSTCOND comment is to satisfy lint(1). 137 */ 138#define MACRO(v, w, x, y) \ 139do { \ 140 v = (x) + (y); \ 141 w = (y) + 2; \ 142} while (/* CONSTCOND */ 0) 143 144#define DOUBLE(x) ((x) * 2) 145 146/* Enum types are capitalized. No comma on the last element. */ 147enum enumtype { 148 ONE, 149 TWO 150} et; 151 152/* 153 * When declaring variables in structures, declare them organized by use in 154 * a manner to attempt to minimize memory wastage because of compiler alignment 155 * issues, then by size, and then by alphabetical order. E.g, don't use 156 * ``int a; char *b; int c; char *d''; use ``int a; int b; char *c; char *d''. 157 * Each variable gets its own type and line, although an exception can be made 158 * when declaring bitfields (to clarify that it's part of the one bitfield). 159 * Note that the use of bitfields in general is discouraged. 160 * 161 * Major structures should be declared at the top of the file in which they 162 * are used, or in separate header files, if they are used in multiple 163 * source files. Use of the structures should be by separate declarations 164 * and should be "extern" if they are declared in a header file. 165 * 166 * It may be useful to use a meaningful prefix for each member name. 167 * E.g, for ``struct softc'' the prefix could be ``sc_''. 168 */ 169struct foo { 170 struct foo *next; /* List of active foo */ 171 struct mumble amumble; /* Comment for mumble */ 172 int bar; 173 unsigned int baz:1, /* Bitfield; line up entries if desired */ 174 fuz:5, 175 zap:2; 176 uint8_t flag; 177}; 178struct foo *foohead; /* Head of global foo list */ 179 180/* Make the structure name match the typedef. */ 181typedef struct BAR { 182 int level; 183} BAR; 184 185/* C99 uintN_t is preferred over u_intN_t. */ 186uint32_t zero; 187 188/* 189 * All major routines should have a comment briefly describing what 190 * they do. The comment before the "main" routine should describe 191 * what the program does. 192 */ 193int 194main(int argc, char *argv[]) 195{ 196 long num; 197 int ch; 198 char *ep; 199 200 /* 201 * At the start of main(), call setprogname() to set the program 202 * name. This does nothing on NetBSD, but increases portability 203 * to other systems. 204 */ 205 setprogname(argv[0]); 206 207 /* 208 * For consistency, getopt should be used to parse options. 209 * Options should be sorted in the getopt call and the switch 210 * statement, unless parts of the switch cascade. For the 211 * sorting order, see the usage() example below. Don't forget 212 * to add option descriptions to the usage and the manpage. 213 * Elements in a switch statement that cascade should have a 214 * FALLTHROUGH comment. Numerical arguments should be checked 215 * for accuracy. Code that cannot be reached should have a 216 * NOTREACHED comment. 217 */ 218 while ((ch = getopt(argc, argv, "abn:")) != -1) { 219 switch (ch) { /* Indent the switch. */ 220 case 'a': /* Don't indent the case. */ 221 aflag = 1; 222 /* FALLTHROUGH */ 223 case 'b': 224 bflag = 1; 225 break; 226 case 'n': 227 errno = 0; 228 num = strtol(optarg, &ep, 10); 229 if (num <= 0 || *ep != '\0' || (errno == ERANGE && 230 (num == LONG_MAX || num == LONG_MIN)) ) 231 errx(1, "illegal number -- %s", optarg); 232 break; 233 case '?': 234 default: 235 usage(); 236 /* NOTREACHED */ 237 } 238 } 239 argc -= optind; 240 argv += optind; 241 242 /* 243 * Space after keywords (while, for, return, switch). No braces are 244 * required for control statements with only a single statement, 245 * unless it's a long statement. 246 * 247 * Forever loops are done with for's, not while's. 248 */ 249 for (p = buf; *p != '\0'; ++p) 250 continue; /* Explicit no-op */ 251 for (;;) 252 stmt; 253 254 /* 255 * Braces are required for control statements with a single statement 256 * that may expand to nothing. 257 */ 258#ifdef DEBUG_FOO 259#define DPRINTF(a) printf a 260#else 261#define DPRINTF(a) 262#endif 263 if (broken) { 264 DPRINTF(("broken is %d\n", broken)); 265 } 266 267 /* 268 * Parts of a for loop may be left empty. Don't put declarations 269 * inside blocks unless the routine is unusually complicated. 270 */ 271 for (; cnt < 15; cnt++) { 272 stmt1; 273 stmt2; 274 } 275 276 /* Second level indents are four spaces. */ 277 while (cnt < 20) 278 z = a + really + long + statement + that + needs + two + lines + 279 gets + indented + four + spaces + on + the + second + 280 and + subsequent + lines; 281 282 /* 283 * Closing and opening braces go on the same line as the else. 284 * Don't add braces that aren't necessary except in cases where 285 * there are ambiguity or readability issues. 286 */ 287 if (test) { 288 /* 289 * I have a long comment here. 290 */ 291#ifdef zorro 292 z = 1; 293#else 294 b = 3; 295#endif 296 } else if (bar) { 297 stmt; 298 stmt; 299 } else 300 stmt; 301 302 /* No spaces after function names. */ 303 if ((result = function(a1, a2, a3, a4)) == NULL) 304 exit(1); 305 306 /* 307 * Unary operators don't require spaces, binary operators do. 308 * Don't excessively use parenthesis, but they should be used if 309 * statement is really confusing without them, such as: 310 * a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 311 */ 312 a = ((b->c[0] + ~d == (e || f)) || (g && h)) ? i : (j >> 1); 313 k = !(l & FLAGS); 314 315 /* 316 * Exits should be EXIT_SUCCESS on success, and EXIT_FAILURE on 317 * failure. Don't denote all the possible exit points, using the 318 * integers 1 through 127. Avoid obvious comments such as "Exit 319 * 0 on success.". Since main is a function that returns an int, 320 * prefer returning from it, than calling exit. 321 */ 322 return EXIT_SUCCESS; 323} 324 325/* 326 * The function type must be declared on a line by itself 327 * preceding the function. 328 */ 329static char * 330function(int a1, int a2, float fl, int a4) 331{ 332 /* 333 * When declaring variables in functions declare them sorted by size, 334 * then in alphabetical order; multiple ones per line are okay. 335 * Function prototypes should go in the include file "extern.h". 336 * If a line overflows reuse the type keyword. 337 * 338 * DO NOT initialize variables in the declarations. 339 */ 340 extern u_char one; 341 extern char two; 342 struct foo three, *four; 343 double five; 344 int *six, seven; 345 char *eight, *nine, ten, eleven, twelve, thirteen; 346 char fourteen, fifteen, sixteen; 347 348 /* 349 * Casts and sizeof's are not followed by a space. NULL is any 350 * pointer type, and doesn't need to be cast, so use NULL instead 351 * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers 352 * against NULL. I.e. use: 353 * 354 * (p = f()) == NULL 355 * not: 356 * !(p = f()) 357 * 358 * Don't use `!' for tests unless it's a boolean. 359 * E.g. use "if (*p == '\0')", not "if (!*p)". 360 * 361 * Routines returning ``void *'' should not have their return 362 * values cast to more specific pointer types. 363 * 364 * Use err/warn(3), don't roll your own! 365 */ 366 if ((four = malloc(sizeof(struct foo))) == NULL) 367 err(1, NULL); 368 if ((six = (int *)overflow()) == NULL) 369 errx(1, "Number overflowed."); 370 371 /* No parentheses are needed around the return value. */ 372 return eight; 373} 374 375/* 376 * Use ANSI function declarations. ANSI function braces look like 377 * old-style (K&R) function braces. 378 * As per the wrapped prototypes, use your discretion on how to format 379 * the subsequent lines. 380 */ 381static int 382dirinfo(const char *p, struct stat *sb, struct dirent *de, struct statfs *sf, 383 int *rargc, char **rargv[]) 384{ /* Insert an empty line if the function has no local variables. */ 385 386 /* 387 * In system libraries, catch obviously invalid function arguments 388 * using _DIAGASSERT(3). 389 */ 390 _DIAGASSERT(p != NULL); 391 _DIAGASSERT(filedesc != -1); 392 393 if (stat(p, sb) < 0) 394 err(1, "Unable to stat %s", p); 395 396 /* 397 * To printf quantities that might be larger that "long", include 398 * <inttypes.h>, cast quantities to intmax_t or uintmax_t and use 399 * PRI?MAX constants. 400 */ 401 (void)printf("The size of %s is %" PRIdMAX " (%#" PRIxMAX ")\n", p, 402 (intmax_t)sb->st_size, (uintmax_t)sb->st_size); 403 404 /* 405 * To printf quantities of known bit-width, use the corresponding 406 * defines (generally only done within NetBSD for quantities that 407 * exceed 32-bits). 408 */ 409 (void)printf("%s uses %" PRId64 " blocks and has flags %#" PRIx32 "\n", 410 p, sb->st_blocks, sb->st_flags); 411 412 /* 413 * There are similar constants that should be used with the *scanf(3) 414 * family of functions: SCN?MAX, SCN?64, etc. 415 */ 416} 417 418/* 419 * Functions that support variable numbers of arguments should look like this. 420 * (With the #include <stdarg.h> appearing at the top of the file with the 421 * other include files). 422 */ 423#include <stdarg.h> 424 425void 426vaf(const char *fmt, ...) 427{ 428 va_list ap; 429 430 va_start(ap, fmt); 431 STUFF; 432 va_end(ap); 433 /* No return needed for void functions. */ 434} 435 436static void 437usage(void) 438{ 439 440 /* 441 * Use printf(3), not fputs/puts/putchar/whatever, it's faster and 442 * usually cleaner, not to mention avoiding stupid bugs. 443 * Use snprintf(3) or strlcpy(3)/strlcat(3) instead of sprintf(3); 444 * again to avoid stupid bugs. 445 * 446 * Usage statements should look like the manual pages. 447 * Options w/o operands come first, in alphabetical order 448 * inside a single set of braces, upper case before lower case 449 * (AaBbCc...). Next are options with operands, in the same 450 * order, each in braces. Then required arguments in the 451 * order they are specified, followed by optional arguments in 452 * the order they are specified. A bar (`|') separates 453 * either/or options/arguments, and multiple options/arguments 454 * which are specified together are placed in a single set of 455 * braces. 456 * 457 * Use getprogname() instead of hardcoding the program name. 458 * 459 * "usage: f [-aDde] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n" 460 * "usage: f [-a | -b] [-c [-de] [-n number]]\n" 461 */ 462 (void)fprintf(stderr, "usage: %s [-ab]\n", getprogname()); 463 exit(EXIT_FAILURE); 464} 465