1.\"- 2.\" Copyright (c) 1995-2005 The FreeBSD Project 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL [your name] OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" From: @(#)style 1.14 (Berkeley) 4/28/95 27.\" $FreeBSD$ 28.\" 29.Dd January 25, 2018 30.Dt STYLE 9 31.Os 32.Sh NAME 33.Nm style 34.Nd "kernel source file style guide" 35.Sh DESCRIPTION 36This file specifies the preferred style for kernel source files in the 37.Fx 38source tree. 39It is also a guide for the preferred userland code style. 40Many of the style rules are implicit in the examples. 41Be careful to check the examples before assuming that 42.Nm 43is silent on an issue. 44.Bd -literal 45/* 46 * Style guide for FreeBSD. Based on the CSRG's KNF (Kernel Normal Form). 47 * 48 * @(#)style 1.14 (Berkeley) 4/28/95 49 * $FreeBSD$ 50 */ 51 52/* 53 * VERY important single-line comments look like this. 54 */ 55 56/* Most single-line comments look like this. */ 57 58/* 59 * Multi-line comments look like this. Make them real sentences. Fill 60 * them so they look like real paragraphs. 61 */ 62.Ed 63.Pp 64The copyright header should be a multi-line comment, with the first 65line of the comment having a dash after the star like so: 66.Bd -literal 67/*- 68 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 69 * 70 * Copyright (c) 1984-2025 John Q. Public 71 * All rights reserved. 72 * 73 * Long, boring license goes here, but trimmed for brevity 74 */ 75.Ed 76.Pp 77An automatic script collects license information from the tree for 78all comments that start in the first column with 79.Dq Li "/*-" . 80If you desire to flag 81.Xr indent 1 82to not reformat a comment that starts in the first column which is not a 83license or copyright notice, change the dash to a star for those 84comments. 85Comments starting in columns other than the first are never 86considered license statements. 87Use the appropriate SPDX-License-Identifier line before the copyright. 88.Pp 89After any copyright header, there is a blank line, and the 90.Li $\&FreeBSD$ 91for non C/C++ language source files. 92Version control system ID tags should only exist once in a file 93(unlike in this one). 94Non-C/C++ source files follow the example above, while C/C++ source files 95follow the one below. 96All VCS (version control system) revision identification in files obtained 97from elsewhere should be maintained, including, where applicable, multiple IDs 98showing a file's history. 99In general, do not edit foreign IDs or their infrastructure. 100Unless otherwise wrapped (such as 101.Dq Li "#if defined(LIBC_SCCS)" ) , 102enclose both in 103.Dq Li "#if 0 ... #endif" 104to hide any uncompilable bits 105and to keep the IDs out of object files. 106Only add 107.Dq Li "From: " 108in front of foreign VCS IDs if the file is renamed. 109.Bd -literal 110/* From: @(#)style 1.14 (Berkeley) 4/28/95 */ 111 112#include <sys/cdefs.h> 113__FBSDID("$FreeBSD$"); 114.Ed 115.Pp 116Leave one blank line before the header files. 117.Pp 118Kernel include files 119.Pa ( sys/*.h ) 120come first. 121If 122.In sys/cdefs.h 123is needed for 124.Fn __FBSDID , 125include it first. 126If either 127.In sys/types.h 128or 129.In sys/param.h 130is needed, include it before other include files. 131.Po 132.In sys/param.h 133includes 134.In sys/types.h ; 135do not include both. 136.Pc 137The remaining kernel headers should be sorted alphabetically. 138.Bd -literal 139#include <sys/types.h> /* Non-local includes in angle brackets. */ 140#include <sys/endian.h> 141#include <sys/lock.h> 142#include <sys/queue.h> 143.Ed 144.Pp 145For a network program, put the network include files next. 146.Bd -literal 147#include <net/if.h> 148#include <net/if_dl.h> 149#include <net/route.h> 150#include <netinet/in.h> 151#include <protocols/rwhod.h> 152.Ed 153.Pp 154Do not include files from 155.Pa /usr/include 156in the kernel. 157.Pp 158Leave a blank line before the next group, the 159.Pa /usr/include 160files, 161which should be sorted alphabetically by name. 162.Bd -literal 163#include <stdio.h> 164.Ed 165.Pp 166Global pathnames are defined in 167.In paths.h . 168Pathnames local 169to the program go in 170.Qq Pa pathnames.h 171in the local directory. 172.Bd -literal 173#include <paths.h> 174.Ed 175.Pp 176Leave another blank line before the local include files. 177.Bd -literal 178#include "pathnames.h" /* Local includes in double quotes. */ 179.Ed 180.Pp 181Do not 182.Ic #define 183or declare names in the implementation namespace except 184for implementing application interfaces. 185.Pp 186The names of 187.Dq unsafe 188macros (ones that have side effects), and the names of macros for 189manifest constants, are all in uppercase. 190The expansions of expression-like macros are either a single token 191or have outer parentheses. 192Put a single tab character between the 193.Ic #define 194and the macro name. 195If a macro is an inline expansion of a function, the function name is 196all in lowercase and the macro has the same name all in uppercase. 197.\" XXX the above conflicts with ANSI style where the names are the 198.\" same and you #undef the macro (if any) to get the function. 199.\" It is not followed for MALLOC(), and not very common if inline 200.\" functions are used. 201Right-justify the 202backslashes; it makes it easier to read. 203If the macro encapsulates a compound statement, enclose it in a 204.Ic do 205loop, 206so that it can safely be used in 207.Ic if 208statements. 209Any final statement-terminating semicolon should be 210supplied by the macro invocation rather than the macro, to make parsing easier 211for pretty-printers and editors. 212.Bd -literal 213#define MACRO(x, y) do { \e 214 variable = (x) + (y); \e 215 (y) += 2; \e 216} while (0) 217.Ed 218.Pp 219When code is conditionally compiled using 220.Ic #ifdef 221or 222.Ic #if , 223a comment may be added following the matching 224.Ic #endif 225or 226.Ic #else 227to permit the reader to easily discern where conditionally compiled code 228regions end. 229This comment should be used only for (subjectively) long regions, regions 230greater than 20 lines, or where a series of nested 231.Ic #ifdef 's 232may be confusing to the reader. 233The comment should be separated from the 234.Ic #endif 235or 236.Ic #else 237by a single space. 238For short conditionally compiled regions, a closing comment should not be 239used. 240.Pp 241The comment for 242.Ic #endif 243should match the expression used in the corresponding 244.Ic #if 245or 246.Ic #ifdef . 247The comment for 248.Ic #else 249and 250.Ic #elif 251should match the inverse of the expression(s) used in the preceding 252.Ic #if 253and/or 254.Ic #elif 255statements. 256In the comments, the subexpression 257.Dq Li defined(FOO) 258is abbreviated as 259.Dq Li FOO . 260For the purposes of comments, 261.Dq Ic #ifndef Li FOO 262is treated as 263.Dq Ic #if Li !defined(FOO) . 264.Bd -literal 265#ifdef KTRACE 266#include <sys/ktrace.h> 267#endif 268 269#ifdef COMPAT_43 270/* A large region here, or other conditional code. */ 271#else /* !COMPAT_43 */ 272/* Or here. */ 273#endif /* COMPAT_43 */ 274 275#ifndef COMPAT_43 276/* Yet another large region here, or other conditional code. */ 277#else /* COMPAT_43 */ 278/* Or here. */ 279#endif /* !COMPAT_43 */ 280.Ed 281.Pp 282The project is slowly moving to use the 283.St -isoC-99 284unsigned integer identifiers of the form 285.Vt uintXX_t 286in preference to the older 287.Bx Ns -style 288integer identifiers of the form 289.Vt u_intXX_t . 290New code should use the former, and old code should be converted to 291the new form if other major work is being done in that area and 292there is no overriding reason to prefer the older 293.Bx Ns -style . 294Like white-space commits, care should be taken in making 295.Vt uintXX_t 296only commits. 297.Pp 298Similarly, the project is slowly moving to use the 299.St -isoC-99 300.Vt bool 301in preference to the older 302.Vt int 303or 304.Vt boolean_t . 305New code should use 306.Vt bool , 307and old code may be converted if it is 308reasonable to do so. 309Literal values are named 310.Dv true 311and 312.Dv false . 313These are preferred to the old spellings 314.Dv TRUE 315and 316.Dv FALSE . 317Userspace code should include 318.In stdbool.h , 319while kernel code should include 320.In sys/types.h . 321.Pp 322Likewise, the project is moving to using the 323.St -isoC-99 324designated initializers when it makes sense to do so. 325.Pp 326Enumeration values are all uppercase. 327.Bd -literal 328enum enumtype { ONE, TWO } et; 329.Ed 330.Pp 331The use of internal_underscores in identifiers is preferred over 332camelCase or TitleCase. 333.Pp 334In declarations, do not put any whitespace between asterisks and 335adjacent tokens, except for tokens that are identifiers related to 336types. 337(These identifiers are the names of basic types, type 338qualifiers, and 339.Ic typedef Ns -names 340other than the one being declared.) 341Separate these identifiers from asterisks using a single space. 342.Pp 343When declaring variables in structures, declare them sorted by use, then 344by size (largest to smallest), and then in alphabetical order. 345The first category normally does not apply, but there are exceptions. 346Each one gets its own line. 347Try to make the structure 348readable by aligning the member names using either one or two tabs 349depending upon your judgment. 350You should use one tab only if it suffices to align at least 90% of 351the member names. 352Names following extremely long types 353should be separated by a single space. 354.Pp 355Major structures should be declared at the top of the file in which they 356are used, or in separate header files if they are used in multiple 357source files. 358Use of the structures should be by separate declarations 359and should be 360.Ic extern 361if they are declared in a header file. 362.Bd -literal 363struct foo { 364 struct foo *next; /* List of active foo. */ 365 struct mumble amumble; /* Comment for mumble. */ 366 int bar; /* Try to align the comments. */ 367 struct verylongtypename *baz; /* Does not fit in 2 tabs. */ 368}; 369struct foo *foohead; /* Head of global foo list. */ 370.Ed 371.Pp 372Use 373.Xr queue 3 374macros rather than rolling your own lists, whenever possible. 375Thus, 376the previous example would be better written: 377.Bd -literal 378#include <sys/queue.h> 379 380struct foo { 381 LIST_ENTRY(foo) link; /* Use queue macros for foo lists. */ 382 struct mumble amumble; /* Comment for mumble. */ 383 int bar; /* Try to align the comments. */ 384 struct verylongtypename *baz; /* Does not fit in 2 tabs. */ 385}; 386LIST_HEAD(, foo) foohead; /* Head of global foo list. */ 387.Ed 388.Pp 389Avoid using typedefs for structure types. 390Typedefs are problematic because they do not properly hide their 391underlying type; for example you need to know if the typedef is 392the structure itself or a pointer to the structure. 393In addition they must be declared exactly once, whereas an 394incomplete structure type can be mentioned as many times as 395necessary. 396Typedefs are difficult to use in stand-alone header files: 397the header that defines the typedef must be included 398before the header that uses it, or by the header that uses 399it (which causes namespace pollution), or there must be a 400back-door mechanism for obtaining the typedef. 401.Pp 402When convention requires a 403.Ic typedef , 404make its name match the struct tag. 405Avoid typedefs ending in 406.Dq Li _t , 407except as specified in Standard C or by POSIX. 408.Bd -literal 409/* Make the structure name match the typedef. */ 410typedef struct bar { 411 int level; 412} BAR; 413typedef int foo; /* This is foo. */ 414typedef const long baz; /* This is baz. */ 415.Ed 416.Pp 417All functions are prototyped somewhere. 418.Pp 419Function prototypes for private functions (i.e., functions not used 420elsewhere) go at the top of the first source module. 421Functions 422local to one source module should be declared 423.Ic static . 424.Pp 425Functions used from other parts of the kernel are prototyped in the 426relevant include file. 427Function prototypes should be listed in a logical order, preferably 428alphabetical unless there is a compelling reason to use a different 429ordering. 430.Pp 431Functions that are used locally in more than one module go into a 432separate header file, e.g., 433.Qq Pa extern.h . 434.Pp 435Do not use the 436.Dv __P 437macro. 438.Pp 439In general code can be considered 440.Dq "new code" 441when it makes up about 50% or more of the file(s) involved. 442This is enough 443to break precedents in the existing code and use the current 444.Nm 445guidelines. 446.Pp 447The kernel has a name associated with parameter types, e.g., in the kernel 448use: 449.Bd -literal 450void function(int fd); 451.Ed 452.Pp 453In header files visible to userland applications, prototypes that are 454visible must use either 455.Dq protected 456names (ones beginning with an underscore) 457or no names with the types. 458It is preferable to use protected names. 459E.g., use: 460.Bd -literal 461void function(int); 462.Ed 463.Pp 464or: 465.Bd -literal 466void function(int _fd); 467.Ed 468.Pp 469Prototypes may have an extra space after a tab to enable function names 470to line up: 471.Bd -literal 472static char *function(int _arg, const char *_arg2, struct foo *_arg3, 473 struct bar *_arg4); 474static void usage(void); 475 476/* 477 * All major routines should have a comment briefly describing what 478 * they do. The comment before the "main" routine should describe 479 * what the program does. 480 */ 481int 482main(int argc, char *argv[]) 483{ 484 char *ep; 485 long num; 486 int ch; 487.Ed 488.Pp 489For consistency, 490.Xr getopt 3 491should be used to parse options. 492Options 493should be sorted in the 494.Xr getopt 3 495call and the 496.Ic switch 497statement, unless 498parts of the 499.Ic switch 500cascade. 501Elements in a 502.Ic switch 503statement that cascade should have a 504.Li FALLTHROUGH 505comment. 506Numerical arguments should be checked for accuracy. 507Code which is unreachable for non-obvious reasons may be marked /* 508.Li NOTREACHED 509*/. 510.Bd -literal 511 while ((ch = getopt(argc, argv, "abNn:")) != -1) 512 switch (ch) { /* Indent the switch. */ 513 case 'a': /* Do not indent the case. */ 514 aflag = 1; /* Indent case body one tab. */ 515 /* FALLTHROUGH */ 516 case 'b': 517 bflag = 1; 518 break; 519 case 'N': 520 Nflag = 1; 521 break; 522 case 'n': 523 num = strtol(optarg, &ep, 10); 524 if (num <= 0 || *ep != '\e0') { 525 warnx("illegal number, -n argument -- %s", 526 optarg); 527 usage(); 528 } 529 break; 530 case '?': 531 default: 532 usage(); 533 } 534 argc -= optind; 535 argv += optind; 536.Ed 537.Pp 538Space after keywords 539.Pq Ic if , while , for , return , switch . 540Two styles of braces 541.Ql ( \&{ 542and 543.Ql \&} ) 544are allowed for single line statements. 545Either they are used for all single statements, or 546they are used only where needed for clarity. 547Usage within a function should be consistent. 548Forever loops are done with 549.Ic for Ns 's , 550not 551.Ic while Ns 's . 552.Bd -literal 553 for (p = buf; *p != '\e0'; ++p) 554 ; /* nothing */ 555 for (;;) 556 stmt; 557 for (;;) { 558 z = a + really + long + statement + that + needs + 559 two + lines + gets + indented + four + spaces + 560 on + the + second + and + subsequent + lines; 561 } 562 for (;;) { 563 if (cond) 564 stmt; 565 } 566 if (val != NULL) 567 val = realloc(val, newsize); 568.Ed 569.Pp 570Parts of a 571.Ic for 572loop may be left empty. 573Do not put declarations 574inside blocks unless the routine is unusually complicated. 575.Bd -literal 576 for (; cnt < 15; cnt++) { 577 stmt1; 578 stmt2; 579 } 580.Ed 581.Pp 582Indentation is an 8 character tab. 583Second level indents are four spaces. 584If you have to wrap a long statement, put the operator at the end of the 585line. 586.Bd -literal 587 while (cnt < 20 && this_variable_name_is_too_long && 588 ep != NULL) 589 z = a + really + long + statement + that + needs + 590 two + lines + gets + indented + four + spaces + 591 on + the + second + and + subsequent + lines; 592.Ed 593.Pp 594Do not add whitespace at the end of a line, and only use tabs 595followed by spaces 596to form the indentation. 597Do not use more spaces than a tab will produce 598and do not use spaces in front of tabs. 599.Pp 600Closing and opening braces go on the same line as the 601.Ic else . 602Braces that are not necessary may be left out. 603.Bd -literal 604 if (test) 605 stmt; 606 else if (bar) { 607 stmt; 608 stmt; 609 } else 610 stmt; 611.Ed 612.Pp 613No spaces after function names. 614Commas have a space after them. 615No spaces 616after 617.Ql \&( 618or 619.Ql \&[ 620or preceding 621.Ql \&] 622or 623.Ql \&) 624characters. 625.Bd -literal 626 error = function(a1, a2); 627 if (error != 0) 628 exit(error); 629.Ed 630.Pp 631Unary operators do not require spaces, binary operators do. 632Do not use parentheses unless they are required for precedence or unless the 633statement is confusing without them. 634Remember that other people may 635confuse easier than you. 636Do YOU understand the following? 637.Bd -literal 638 a = b->c[0] + ~d == (e || f) || g && h ? i : j >> 1; 639 k = !(l & FLAGS); 640.Ed 641.Pp 642Exits should be 0 on success, or 1 on failure. 643.Bd -literal 644 exit(0); /* 645 * Avoid obvious comments such as 646 * "Exit 0 on success." 647 */ 648} 649.Ed 650.Pp 651The function type should be on a line by itself 652preceding the function. 653The opening brace of the function body should be 654on a line by itself. 655.Bd -literal 656static char * 657function(int a1, int a2, float fl, int a4) 658{ 659.Ed 660.Pp 661When declaring variables in functions declare them sorted by size, 662then in alphabetical order; multiple ones per line are okay. 663If a line overflows reuse the type keyword. 664.Pp 665Be careful to not obfuscate the code by initializing variables in 666the declarations. 667Use this feature only thoughtfully. 668DO NOT use function calls in initializers. 669.Bd -literal 670 struct foo one, *two; 671 double three; 672 int *four, five; 673 char *six, seven, eight, nine, ten, eleven, twelve; 674 675 four = myfunction(); 676.Ed 677.Pp 678Do not declare functions inside other functions; ANSI C says that 679such declarations have file scope regardless of the nesting of the 680declaration. 681Hiding file declarations in what appears to be a local 682scope is undesirable and will elicit complaints from a good compiler. 683.Pp 684Casts and 685.Ic sizeof Ns 's 686are not followed by a space. 687Note that 688.Xr indent 1 689does not understand this rule. 690.Ic sizeof Ns 's 691are written with parenthesis always. 692The redundant parenthesis rules do not apply to 693.Fn sizeof var 694instances. 695.Pp 696.Dv NULL 697is the preferred null pointer constant. 698Use 699.Dv NULL 700instead of 701.Vt ( "type *" ) Ns 0 702or 703.Vt ( "type *" ) Ns Dv NULL 704in contexts where the compiler knows the 705type, e.g., in assignments. 706Use 707.Vt ( "type *" ) Ns Dv NULL 708in other contexts, 709in particular for all function args. 710(Casting is essential for 711variadic args and is necessary for other args if the function prototype 712might not be in scope.) 713Test pointers against 714.Dv NULL , 715e.g., use: 716.Bd -literal 717(p = f()) == NULL 718.Ed 719.Pp 720not: 721.Bd -literal 722!(p = f()) 723.Ed 724.Pp 725Do not use 726.Ic \&! 727for tests unless it is a boolean, e.g., use: 728.Bd -literal 729if (*p == '\e0') 730.Ed 731.Pp 732not: 733.Bd -literal 734if (!*p) 735.Ed 736.Pp 737Routines returning 738.Vt "void *" 739should not have their return values cast 740to any pointer type. 741.Pp 742Values in 743.Ic return 744statements should be enclosed in parentheses. 745.Pp 746Use 747.Xr err 3 748or 749.Xr warn 3 , 750do not roll your own. 751.Bd -literal 752 if ((four = malloc(sizeof(struct foo))) == NULL) 753 err(1, (char *)NULL); 754 if ((six = (int *)overflow()) == NULL) 755 errx(1, "number overflowed"); 756 return (eight); 757} 758.Ed 759.Pp 760When converting K&R style declarations to ANSI style, preserve 761any comments about parameters. 762.Pp 763Long parameter lists are wrapped with a normal four space indent. 764.Pp 765Variable numbers of arguments should look like this: 766.Bd -literal 767#include <stdarg.h> 768 769void 770vaf(const char *fmt, ...) 771{ 772 va_list ap; 773 774 va_start(ap, fmt); 775 STUFF; 776 va_end(ap); 777 /* No return needed for void functions. */ 778} 779 780static void 781usage() 782{ 783 /* Insert an empty line if the function has no local variables. */ 784.Ed 785.Pp 786Use 787.Xr printf 3 , 788not 789.Xr fputs 3 , 790.Xr puts 3 , 791.Xr putchar 3 , 792whatever; it is faster and usually cleaner, not 793to mention avoiding stupid bugs. 794.Pp 795Usage statements should look like the manual pages 796.Sx SYNOPSIS . 797The usage statement should be structured in the following order: 798.Bl -enum 799.It 800Options without operands come first, 801in alphabetical order, 802inside a single set of brackets 803.Ql ( \&[ 804and 805.Ql \&] ) . 806.It 807Options with operands come next, 808also in alphabetical order, 809with each option and its argument inside its own pair of brackets. 810.It 811Required arguments 812(if any) 813are next, 814listed in the order they should be specified on the command line. 815.It 816Finally, 817any optional arguments should be listed, 818listed in the order they should be specified, 819and all inside brackets. 820.El 821.Pp 822A bar 823.Pq Ql \&| 824separates 825.Dq either-or 826options/arguments, 827and multiple options/arguments which are specified together are 828placed in a single set of brackets. 829.Bd -literal -offset 4n 830"usage: f [-aDde] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\en" 831"usage: f [-a | -b] [-c [-dEe] [-n number]]\en" 832.Ed 833.Bd -literal 834 (void)fprintf(stderr, "usage: f [-ab]\en"); 835 exit(1); 836} 837.Ed 838.Pp 839Note that the manual page options description should list the options in 840pure alphabetical order. 841That is, without regard to whether an option takes arguments or not. 842The alphabetical ordering should take into account the case ordering 843shown above. 844.Pp 845New core kernel code should be reasonably compliant with the 846.Nm 847guides. 848The guidelines for third-party maintained modules and device drivers are more 849relaxed but at a minimum should be internally consistent with their style. 850.Pp 851Stylistic changes (including whitespace changes) are hard on the source 852repository and are to be avoided without good reason. 853Code that is approximately 854.Fx 855KNF 856.Nm 857compliant in the repository must not diverge from compliance. 858.Pp 859Whenever possible, code should be run through a code checker 860(e.g., various static analyzers or 861.Nm cc Fl Wall ) 862and produce minimal warnings. 863.Sh FILES 864.Bl -tag -width indent 865.It Pa /usr/src/tools/tools/editing/freebsd.el 866An Emacs plugin to follow the 867.Fx 868.Nm 869indentation rules. 870.It Pa /usr/src/tools/tools/editing/freebsd.vim 871A Vim plugin to follow the 872.Fx 873.Nm 874indentation rules. 875.El 876.Sh SEE ALSO 877.Xr indent 1 , 878.Xr err 3 , 879.Xr warn 3 , 880.Xr style.Makefile 5 , 881.Xr style.lua 9 882.Sh HISTORY 883This manual page is largely based on the 884.Pa src/admin/style/style 885file from the 886.Bx 4.4 Lite2 887release, with occasional updates to reflect the current practice and 888desire of the 889.Fx 890project. 891.Pa src/admin/style/style 892is a codification by the CSRG of the programming style of Ken Thompson and 893Dennis Ritchie in 894.At v6 . 895