style revision 1.52
1/* $NetBSD: style,v 1.52 2015/10/24 15:46:09 christos 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 1.52 2015/10/24 15:46:09 christos 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/param.h> /* <sys/param.h> first, */ 81#include <sys/types.h> /* <sys/types.h> next, */ 82#include <sys/ioctl.h> /* and then the rest, */ 83#include <sys/socket.h> /* sorted lexicographically. */ 84#include <sys/stat.h> 85#include <sys/wait.h> /* Non-local includes in brackets. */ 86 87/* 88 * If it's a network program, put the network include files next. 89 * Group the includes files by subdirectory. 90 */ 91#include <net/if.h> 92#include <net/if_dl.h> 93#include <net/route.h> 94#include <netinet/in.h> 95#include <protocols/rwhod.h> 96 97/* 98 * Then there's a blank line, followed by the /usr include files. 99 * The /usr include files should be sorted lexicographically! 100 */ 101#include <assert.h> 102#include <errno.h> 103#include <inttypes.h> 104#include <stdio.h> 105#include <stdlib.h> 106 107/* 108 * Global pathnames are defined in /usr/include/paths.h. Pathnames local 109 * to the program go in pathnames.h in the local directory. 110 */ 111#include <paths.h> 112 113/* Then, there's a blank line, and the user include files. */ 114#include "pathnames.h" /* Local includes in double quotes. */ 115 116/* 117 * ANSI function declarations for private functions (i.e. functions not used 118 * elsewhere) and the main() function go at the top of the source module. 119 * Don't associate a name with the types. I.e. use: 120 * void function(int); 121 * Use your discretion on indenting between the return type and the name, and 122 * how to wrap a prototype too long for a single line. In the latter case, 123 * lining up under the initial left parenthesis may be more readable. 124 * In any case, consistency is important! 125 */ 126static char *function(int, int, float, int); 127static int dirinfo(const char *, struct stat *, struct dirent *, 128 struct statfs *, int *, char **[]); 129static void usage(void) __dead; /* declare functions that don't return dead */ 130 131/* 132 * Macros are capitalized, parenthesized, and should avoid side-effects. 133 * Spacing before and after the macro name may be any whitespace, though 134 * use of TABs should be consistent through a file. 135 * If they are an inline expansion of a function, the function is defined 136 * all in lowercase, the macro has the same name all in uppercase. 137 * If the macro is an expression, wrap the expression in parenthesis. 138 * If the macro is more than a single statement, use ``do { ... } while (0)'', 139 * so that a trailing semicolon works. Right-justify the backslashes; it 140 * makes it easier to read. The CONSTCOND comment is to satisfy lint(1). 141 */ 142#define MACRO(v, w, x, y) \ 143do { \ 144 v = (x) + (y); \ 145 w = (y) + 2; \ 146} while (/* CONSTCOND */ 0) 147 148#define DOUBLE(x) ((x) * 2) 149 150/* Enum types are capitalized. No comma on the last element. */ 151enum enumtype { 152 ONE, 153 TWO 154} et; 155 156/* 157 * When declaring variables in structures, declare them organized by use in 158 * a manner to attempt to minimize memory wastage because of compiler alignment 159 * issues, then by size, and then by alphabetical order. E.g, don't use 160 * ``int a; char *b; int c; char *d''; use ``int a; int b; char *c; char *d''. 161 * Each variable gets its own type and line, although an exception can be made 162 * when declaring bitfields (to clarify that it's part of the one bitfield). 163 * Note that the use of bitfields in general is discouraged. 164 * 165 * Major structures should be declared at the top of the file in which they 166 * are used, or in separate header files, if they are used in multiple 167 * source files. Use of the structures should be by separate declarations 168 * and should be "extern" if they are declared in a header file. 169 * 170 * It may be useful to use a meaningful prefix for each member name. 171 * E.g, for ``struct softc'' the prefix could be ``sc_''. 172 */ 173struct foo { 174 struct foo *next; /* List of active foo */ 175 struct mumble amumble; /* Comment for mumble */ 176 int bar; 177 unsigned int baz:1, /* Bitfield; line up entries if desired */ 178 fuz:5, 179 zap:2; 180 uint8_t flag; 181}; 182struct foo *foohead; /* Head of global foo list */ 183 184/* Make the structure name match the typedef. */ 185typedef struct BAR { 186 int level; 187} BAR; 188 189/* C99 uintN_t is preferred over u_intN_t. */ 190uint32_t zero; 191 192/* 193 * All major routines should have a comment briefly describing what 194 * they do. The comment before the "main" routine should describe 195 * what the program does. 196 */ 197int 198main(int argc, char *argv[]) 199{ 200 long num; 201 int ch; 202 char *ep; 203 204 /* 205 * At the start of main(), call setprogname() to set the program 206 * name. This does nothing on NetBSD, but increases portability 207 * to other systems. 208 */ 209 setprogname(argv[0]); 210 211 /* 212 * For consistency, getopt should be used to parse options. 213 * Options should be sorted in the getopt call and the switch 214 * statement, unless parts of the switch cascade. For the 215 * sorting order, see the usage() example below. Don't forget 216 * to add option descriptions to the usage and the manpage. 217 * Elements in a switch statement that cascade should have a 218 * FALLTHROUGH comment. Numerical arguments should be checked 219 * for accuracy. Code that cannot be reached should have a 220 * NOTREACHED comment. 221 */ 222 while ((ch = getopt(argc, argv, "abn:")) != -1) { 223 switch (ch) { /* Indent the switch. */ 224 case 'a': /* Don't indent the case. */ 225 aflag = 1; 226 /* FALLTHROUGH */ 227 case 'b': 228 bflag = 1; 229 break; 230 case 'n': 231 errno = 0; 232 num = strtol(optarg, &ep, 10); 233 if (num <= 0 || *ep != '\0' || (errno == ERANGE && 234 (num == LONG_MAX || num == LONG_MIN)) ) 235 errx(1, "illegal number -- %s", optarg); 236 break; 237 case '?': 238 default: 239 usage(); 240 /* NOTREACHED */ 241 } 242 } 243 argc -= optind; 244 argv += optind; 245 246 /* 247 * Space after keywords (while, for, return, switch). No braces are 248 * required for control statements with only a single statement, 249 * unless it's a long statement. 250 * 251 * Forever loops are done with for's, not while's. 252 */ 253 for (p = buf; *p != '\0'; ++p) 254 continue; /* Explicit no-op */ 255 for (;;) 256 stmt; 257 258 /* 259 * Braces are required for control statements with a single statement 260 * that may expand to nothing. 261 */ 262#ifdef DEBUG_FOO 263#define DPRINTF(a) printf a 264#else 265#define DPRINTF(a) 266#endif 267 if (broken) { 268 DPRINTF(("broken is %d\n", broken)); 269 } 270 271 /* 272 * Parts of a for loop may be left empty. Don't put declarations 273 * inside blocks unless the routine is unusually complicated. 274 */ 275 for (; cnt < 15; cnt++) { 276 stmt1; 277 stmt2; 278 } 279 280 /* Second level indents are four spaces. */ 281 while (cnt < 20) 282 z = a + really + long + statement + that + needs + two + lines + 283 gets + indented + four + spaces + on + the + second + 284 and + subsequent + lines; 285 286 /* 287 * Closing and opening braces go on the same line as the else. 288 * Don't add braces that aren't necessary except in cases where 289 * there are ambiguity or readability issues. 290 */ 291 if (test) { 292 /* 293 * I have a long comment here. 294 */ 295#ifdef zorro 296 z = 1; 297#else 298 b = 3; 299#endif 300 } else if (bar) { 301 stmt; 302 stmt; 303 } else 304 stmt; 305 306 /* No spaces after function names. */ 307 if ((result = function(a1, a2, a3, a4)) == NULL) 308 exit(1); 309 310 /* 311 * Unary operators don't require spaces, binary operators do. 312 * Don't excessively use parenthesis, but they should be used if 313 * statement is really confusing without them, such as: 314 * a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 315 */ 316 a = ((b->c[0] + ~d == (e || f)) || (g && h)) ? i : (j >> 1); 317 k = !(l & FLAGS); 318 319 /* 320 * Exits should be EXIT_SUCCESS on success, and EXIT_FAILURE on 321 * failure. Don't denote all the possible exit points, using the 322 * integers 1 through 127. Avoid obvious comments such as "Exit 323 * 0 on success.". Since main is a function that returns an int, 324 * prefer returning from it, than calling exit. 325 */ 326 return EXIT_SUCCESS; 327} 328 329/* 330 * The function type must be declared on a line by itself 331 * preceding the function. 332 */ 333static char * 334function(int a1, int a2, float fl, int a4) 335{ 336 /* 337 * When declaring variables in functions declare them sorted by size, 338 * then in alphabetical order; multiple ones per line are okay. 339 * Function prototypes should go in the include file "extern.h". 340 * If a line overflows reuse the type keyword. 341 * 342 * Avoid initializing variables in the declarations; move 343 * declarations next to their first use, and initialize 344 * opportunistically. This avoids over-initialization and 345 * accidental bugs caused by declaration reordering. 346 */ 347 extern u_char one; 348 extern char two; 349 struct foo three, *four; 350 double five; 351 int *six, seven; 352 char *eight, *nine, ten, eleven, twelve, thirteen; 353 char fourteen, fifteen, sixteen; 354 355 /* 356 * Casts and sizeof's are not followed by a space. NULL is any 357 * pointer type, and doesn't need to be cast, so use NULL instead 358 * of (struct foo *)0 or (struct foo *)NULL. Also, test pointers 359 * against NULL. I.e. use: 360 * 361 * (p = f()) == NULL 362 * not: 363 * !(p = f()) 364 * 365 * The notable exception here is variadic functions. Since our 366 * code is designed to compile and work on different environments 367 * where we don't have control over the NULL definition (on NetBSD 368 * it is defined as ((void *)0), but on other systems it can be 369 * defined as (0) and both definitions are valid under ANSI C), it 370 * it advised to cast NULL to a pointer on varyadic functions, 371 * because on machines where sizeof(pointer) != sizeof(int) and in 372 * the absence of a prototype in scope, passing an un-casted NULL, 373 * will result in passing an int on the stack instead of a pointer. 374 * 375 * Don't use `!' for tests unless it's a boolean. 376 * E.g. use "if (*p == '\0')", not "if (!*p)". 377 * 378 * Routines returning ``void *'' should not have their return 379 * values cast to more specific pointer types. 380 * 381 * Prefer sizeof(*var) over sizeof(type) because if type changes, 382 * the change needs to be done in one place. 383 * 384 * Use err/warn(3), don't roll your own! 385 */ 386 if ((four = malloc(sizeof(*four))) == NULL) 387 err(1, NULL); 388 if ((six = (int *)overflow()) == NULL) 389 errx(1, "Number overflowed."); 390 391 /* No parentheses are needed around the return value. */ 392 return eight; 393} 394 395/* 396 * Use ANSI function declarations. ANSI function braces look like 397 * old-style (K&R) function braces. 398 * As per the wrapped prototypes, use your discretion on how to format 399 * the subsequent lines. 400 */ 401static int 402dirinfo(const char *p, struct stat *sb, struct dirent *de, struct statfs *sf, 403 int *rargc, char **rargv[]) 404{ /* Insert an empty line if the function has no local variables. */ 405 406 /* 407 * In system libraries, catch obviously invalid function arguments 408 * using _DIAGASSERT(3). 409 */ 410 _DIAGASSERT(p != NULL); 411 _DIAGASSERT(filedesc != -1); 412 413 if (stat(p, sb) < 0) 414 err(1, "Unable to stat %s", p); 415 416 /* 417 * To printf quantities that might be larger that "long", include 418 * <inttypes.h>, cast quantities to intmax_t or uintmax_t and use 419 * PRI?MAX constants. 420 */ 421 (void)printf("The size of %s is %" PRIdMAX " (%#" PRIxMAX ")\n", p, 422 (intmax_t)sb->st_size, (uintmax_t)sb->st_size); 423 424 /* 425 * To printf quantities of known bit-width, use the corresponding 426 * defines (generally only done within NetBSD for quantities that 427 * exceed 32-bits). 428 */ 429 (void)printf("%s uses %" PRId64 " blocks and has flags %#" PRIx32 "\n", 430 p, sb->st_blocks, sb->st_flags); 431 432 /* 433 * There are similar constants that should be used with the *scanf(3) 434 * family of functions: SCN?MAX, SCN?64, etc. 435 */ 436} 437 438/* 439 * Functions that support variable numbers of arguments should look like this. 440 * (With the #include <stdarg.h> appearing at the top of the file with the 441 * other include files.) 442 */ 443#include <stdarg.h> 444 445void 446vaf(const char *fmt, ...) 447{ 448 va_list ap; 449 450 va_start(ap, fmt); 451 STUFF; 452 va_end(ap); 453 /* No return needed for void functions. */ 454} 455 456static void 457usage(void) 458{ 459 460 /* 461 * Use printf(3), not fputs/puts/putchar/whatever, it's faster and 462 * usually cleaner, not to mention avoiding stupid bugs. 463 * Use snprintf(3) or strlcpy(3)/strlcat(3) instead of sprintf(3); 464 * again to avoid stupid bugs. 465 * 466 * Usage statements should look like the manual pages. 467 * Options w/o operands come first, in alphabetical order 468 * inside a single set of braces, upper case before lower case 469 * (AaBbCc...). Next are options with operands, in the same 470 * order, each in braces. Then required arguments in the 471 * order they are specified, followed by optional arguments in 472 * the order they are specified. A bar (`|') separates 473 * either/or options/arguments, and multiple options/arguments 474 * which are specified together are placed in a single set of 475 * braces. 476 * 477 * Use getprogname() instead of hardcoding the program name. 478 * 479 * "usage: f [-aDde] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n" 480 * "usage: f [-a | -b] [-c [-de] [-n number]]\n" 481 */ 482 (void)fprintf(stderr, "usage: %s [-ab]\n", getprogname()); 483 exit(EXIT_FAILURE); 484} 485