From d2d2b5d96121ba427f6b23b64aa38a77d6bf7ace Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 11 Apr 2013 16:52:24 +0200 Subject: docs: move some of them to the root directory Lets move CodingStyle, SubmittingPatches, and Sponsors into the root directory of netsniff-ng and remove the Documentation folder. Some of those files are quite bloated, and most of these things should be in the man-pages anyway. They should be the only big sources of documentation, nothing else. The rest is currently put here: http://pub.netsniff-ng.org/docs/ Signed-off-by: Daniel Borkmann --- Documentation/CodingStyle | 833 ---------------------------------------------- 1 file changed, 833 deletions(-) delete mode 100644 Documentation/CodingStyle (limited to 'Documentation/CodingStyle') diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle deleted file mode 100644 index 31265b4..0000000 --- a/Documentation/CodingStyle +++ /dev/null @@ -1,833 +0,0 @@ - The coding conventions of the netsniff-ng toolkit match with the Linux kernel - style guidelines. So here we go with a copy of linux/Documentation/CodingStyle - written by Linus. - - In general, keep this in mind: (i) simplicity, (ii) brevity, (iii) elegance. - You are also obliged to treat files in Documentation/ in same quality as code. - - Daniel Borkmann - -------------------------------------------------------------------------------- - - Linux kernel coding style - -This is a short document describing the preferred coding style for the -linux kernel. Coding style is very personal, and I won't _force_ my -views on anybody, but this is what goes for anything that I have to be -able to maintain, and I'd prefer it for most other things too. Please -at least consider the points made here. - -First off, I'd suggest printing out a copy of the GNU coding standards, -and NOT read it. Burn them, it's a great symbolic gesture. - -Anyway, here goes: - - - Chapter 1: Indentation - -Tabs are 8 characters, and thus indentations are also 8 characters. -There are heretic movements that try to make indentations 4 (or even 2!) -characters deep, and that is akin to trying to define the value of PI to -be 3. - -Rationale: The whole idea behind indentation is to clearly define where -a block of control starts and ends. Especially when you've been looking -at your screen for 20 straight hours, you'll find it a lot easier to see -how the indentation works if you have large indentations. - -Now, some people will claim that having 8-character indentations makes -the code move too far to the right, and makes it hard to read on a -80-character terminal screen. The answer to that is that if you need -more than 3 levels of indentation, you're screwed anyway, and should fix -your program. - -In short, 8-char indents make things easier to read, and have the added -benefit of warning you when you're nesting your functions too deep. -Heed that warning. - -The preferred way to ease multiple indentation levels in a switch statement is -to align the "switch" and its subordinate "case" labels in the same column -instead of "double-indenting" the "case" labels. E.g.: - - switch (suffix) { - case 'G': - case 'g': - mem <<= 30; - break; - case 'M': - case 'm': - mem <<= 20; - break; - case 'K': - case 'k': - mem <<= 10; - /* fall through */ - default: - break; - } - - -Don't put multiple statements on a single line unless you have -something to hide: - - if (condition) do_this; - do_something_everytime; - -Don't put multiple assignments on a single line either. Kernel coding style -is super simple. Avoid tricky expressions. - -Outside of comments, documentation and except in Kconfig, spaces are never -used for indentation, and the above example is deliberately broken. - -Get a decent editor and don't leave whitespace at the end of lines. - - - Chapter 2: Breaking long lines and strings - -Coding style is all about readability and maintainability using commonly -available tools. - -The limit on the length of lines is 80 columns and this is a strongly -preferred limit. - -Statements longer than 80 columns will be broken into sensible chunks. -Descendants are always substantially shorter than the parent and are placed -substantially to the right. The same applies to function headers with a long -argument list. Long strings are as well broken into shorter strings. The -only exception to this is where exceeding 80 columns significantly increases -readability and does not hide information. - -void fun(int a, int b, int c) -{ - if (condition) - printk(KERN_WARNING "Warning this is a long printk with " - "3 parameters a: %u b: %u " - "c: %u \n", a, b, c); - else - next_statement; -} - - Chapter 3: Placing Braces and Spaces - -The other issue that always comes up in C styling is the placement of -braces. Unlike the indent size, there are few technical reasons to -choose one placement strategy over the other, but the preferred way, as -shown to us by the prophets Kernighan and Ritchie, is to put the opening -brace last on the line, and put the closing brace first, thusly: - - if (x is true) { - we do y - } - -This applies to all non-function statement blocks (if, switch, for, -while, do). E.g.: - - switch (action) { - case KOBJ_ADD: - return "add"; - case KOBJ_REMOVE: - return "remove"; - case KOBJ_CHANGE: - return "change"; - default: - return NULL; - } - -However, there is one special case, namely functions: they have the -opening brace at the beginning of the next line, thus: - - int function(int x) - { - body of function - } - -Heretic people all over the world have claimed that this inconsistency -is ... well ... inconsistent, but all right-thinking people know that -(a) K&R are _right_ and (b) K&R are right. Besides, functions are -special anyway (you can't nest them in C). - -Note that the closing brace is empty on a line of its own, _except_ in -the cases where it is followed by a continuation of the same statement, -ie a "while" in a do-statement or an "else" in an if-statement, like -this: - - do { - body of do-loop - } while (condition); - -and - - if (x == y) { - .. - } else if (x > y) { - ... - } else { - .... - } - -Rationale: K&R. - -Also, note that this brace-placement also minimizes the number of empty -(or almost empty) lines, without any loss of readability. Thus, as the -supply of new-lines on your screen is not a renewable resource (think -25-line terminal screens here), you have more empty lines to put -comments on. - -Do not unnecessarily use braces where a single statement will do. - -if (condition) - action(); - -This does not apply if one branch of a conditional statement is a single -statement. Use braces in both branches. - -if (condition) { - do_this(); - do_that(); -} else { - otherwise(); -} - - 3.1: Spaces - -Linux kernel style for use of spaces depends (mostly) on -function-versus-keyword usage. Use a space after (most) keywords. The -notable exceptions are sizeof, typeof, alignof, and __attribute__, which look -somewhat like functions (and are usually used with parentheses in Linux, -although they are not required in the language, as in: "sizeof info" after -"struct fileinfo info;" is declared). - -So use a space after these keywords: - if, switch, case, for, do, while -but not with sizeof, typeof, alignof, or __attribute__. E.g., - s = sizeof(struct file); - -Do not add spaces around (inside) parenthesized expressions. This example is -*bad*: - - s = sizeof( struct file ); - -When declaring pointer data or a function that returns a pointer type, the -preferred use of '*' is adjacent to the data name or function name and not -adjacent to the type name. Examples: - - char *linux_banner; - unsigned long long memparse(char *ptr, char **retptr); - char *match_strdup(substring_t *s); - -Use one space around (on each side of) most binary and ternary operators, -such as any of these: - - = + - < > * / % | & ^ <= >= == != ? : - -but no space after unary operators: - & * + - ~ ! sizeof typeof alignof __attribute__ defined - -no space before the postfix increment & decrement unary operators: - ++ -- - -no space after the prefix increment & decrement unary operators: - ++ -- - -and no space around the '.' and "->" structure member operators. - -Do not leave trailing whitespace at the ends of lines. Some editors with -"smart" indentation will insert whitespace at the beginning of new lines as -appropriate, so you can start typing the next line of code right away. -However, some such editors do not remove the whitespace if you end up not -putting a line of code there, such as if you leave a blank line. As a result, -you end up with lines containing trailing whitespace. - -Git will warn you about patches that introduce trailing whitespace, and can -optionally strip the trailing whitespace for you; however, if applying a series -of patches, this may make later patches in the series fail by changing their -context lines. - - - Chapter 4: Naming - -C is a Spartan language, and so should your naming be. Unlike Modula-2 -and Pascal programmers, C programmers do not use cute names like -ThisVariableIsATemporaryCounter. A C programmer would call that -variable "tmp", which is much easier to write, and not the least more -difficult to understand. - -HOWEVER, while mixed-case names are frowned upon, descriptive names for -global variables are a must. To call a global function "foo" is a -shooting offense. - -GLOBAL variables (to be used only if you _really_ need them) need to -have descriptive names, as do global functions. If you have a function -that counts the number of active users, you should call that -"count_active_users()" or similar, you should _not_ call it "cntusr()". - -Encoding the type of a function into the name (so-called Hungarian -notation) is brain damaged - the compiler knows the types anyway and can -check those, and it only confuses the programmer. No wonder MicroSoft -makes buggy programs. - -LOCAL variable names should be short, and to the point. If you have -some random integer loop counter, it should probably be called "i". -Calling it "loop_counter" is non-productive, if there is no chance of it -being mis-understood. Similarly, "tmp" can be just about any type of -variable that is used to hold a temporary value. - -If you are afraid to mix up your local variable names, you have another -problem, which is called the function-growth-hormone-imbalance syndrome. -See chapter 6 (Functions). - - - Chapter 5: Typedefs - -Please don't use things like "vps_t". - -It's a _mistake_ to use typedef for structures and pointers. When you see a - - vps_t a; - -in the source, what does it mean? - -In contrast, if it says - - struct virtual_container *a; - -you can actually tell what "a" is. - -Lots of people think that typedefs "help readability". Not so. They are -useful only for: - - (a) totally opaque objects (where the typedef is actively used to _hide_ - what the object is). - - Example: "pte_t" etc. opaque objects that you can only access using - the proper accessor functions. - - NOTE! Opaqueness and "accessor functions" are not good in themselves. - The reason we have them for things like pte_t etc. is that there - really is absolutely _zero_ portably accessible information there. - - (b) Clear integer types, where the abstraction _helps_ avoid confusion - whether it is "int" or "long". - - u8/u16/u32 are perfectly fine typedefs, although they fit into - category (d) better than here. - - NOTE! Again - there needs to be a _reason_ for this. If something is - "unsigned long", then there's no reason to do - - typedef unsigned long myflags_t; - - but if there is a clear reason for why it under certain circumstances - might be an "unsigned int" and under other configurations might be - "unsigned long", then by all means go ahead and use a typedef. - - (c) when you use sparse to literally create a _new_ type for - type-checking. - - (d) New types which are identical to standard C99 types, in certain - exceptional circumstances. - - Although it would only take a short amount of time for the eyes and - brain to become accustomed to the standard types like 'uint32_t', - some people object to their use anyway. - - Therefore, the Linux-specific 'u8/u16/u32/u64' types and their - signed equivalents which are identical to standard types are - permitted -- although they are not mandatory in new code of your - own. - - When editing existing code which already uses one or the other set - of types, you should conform to the existing choices in that code. - - (e) Types safe for use in userspace. - - In certain structures which are visible to userspace, we cannot - require C99 types and cannot use the 'u32' form above. Thus, we - use __u32 and similar types in all structures which are shared - with userspace. - -Maybe there are other cases too, but the rule should basically be to NEVER -EVER use a typedef unless you can clearly match one of those rules. - -In general, a pointer, or a struct that has elements that can reasonably -be directly accessed should _never_ be a typedef. - - - Chapter 6: Functions - -Functions should be short and sweet, and do just one thing. They should -fit on one or two screenfuls of text (the ISO/ANSI screen size is 80x24, -as we all know), and do one thing and do that well. - -The maximum length of a function is inversely proportional to the -complexity and indentation level of that function. So, if you have a -conceptually simple function that is just one long (but simple) -case-statement, where you have to do lots of small things for a lot of -different cases, it's OK to have a longer function. - -However, if you have a complex function, and you suspect that a -less-than-gifted first-year high-school student might not even -understand what the function is all about, you should adhere to the -maximum limits all the more closely. Use helper functions with -descriptive names (you can ask the compiler to in-line them if you think -it's performance-critical, and it will probably do a better job of it -than you would have done). - -Another measure of the function is the number of local variables. They -shouldn't exceed 5-10, or you're doing something wrong. Re-think the -function, and split it into smaller pieces. A human brain can -generally easily keep track of about 7 different things, anything more -and it gets confused. You know you're brilliant, but maybe you'd like -to understand what you did 2 weeks from now. - -In source files, separate functions with one blank line. If the function is -exported, the EXPORT* macro for it should follow immediately after the closing -function brace line. E.g.: - -int system_is_up(void) -{ - return system_state == SYSTEM_RUNNING; -} -EXPORT_SYMBOL(system_is_up); - -In function prototypes, include parameter names with their data types. -Although this is not required by the C language, it is preferred in Linux -because it is a simple way to add valuable information for the reader. - - - Chapter 7: Centralized exiting of functions - -Albeit deprecated by some people, the equivalent of the goto statement is -used frequently by compilers in form of the unconditional jump instruction. - -The goto statement comes in handy when a function exits from multiple -locations and some common work such as cleanup has to be done. - -The rationale is: - -- unconditional statements are easier to understand and follow -- nesting is reduced -- errors by not updating individual exit points when making - modifications are prevented -- saves the compiler work to optimize redundant code away ;) - -int fun(int a) -{ - int result = 0; - char *buffer = kmalloc(SIZE); - - if (buffer == NULL) - return -ENOMEM; - - if (condition1) { - while (loop1) { - ... - } - result = 1; - goto out; - } - ... -out: - kfree(buffer); - return result; -} - - Chapter 8: Commenting - -Comments are good, but there is also a danger of over-commenting. NEVER -try to explain HOW your code works in a comment: it's much better to -write the code so that the _working_ is obvious, and it's a waste of -time to explain badly written code. - -Generally, you want your comments to tell WHAT your code does, not HOW. -Also, try to avoid putting comments inside a function body: if the -function is so complex that you need to separately comment parts of it, -you should probably go back to chapter 6 for a while. You can make -small comments to note or warn about something particularly clever (or -ugly), but try to avoid excess. Instead, put the comments at the head -of the function, telling people what it does, and possibly WHY it does -it. - -When commenting the kernel API functions, please use the kernel-doc format. -See the files Documentation/kernel-doc-nano-HOWTO.txt and scripts/kernel-doc -for details. - -Linux style for comments is the C89 "/* ... */" style. -Don't use C99-style "// ..." comments. - -The preferred style for long (multi-line) comments is: - - /* - * This is the preferred style for multi-line - * comments in the Linux kernel source code. - * Please use it consistently. - * - * Description: A column of asterisks on the left side, - * with beginning and ending almost-blank lines. - */ - -It's also important to comment data, whether they are basic types or derived -types. To this end, use just one data declaration per line (no commas for -multiple data declarations). This leaves you room for a small comment on each -item, explaining its use. - - - Chapter 9: You've made a mess of it - -That's OK, we all do. You've probably been told by your long-time Unix -user helper that "GNU emacs" automatically formats the C sources for -you, and you've noticed that yes, it does do that, but the defaults it -uses are less than desirable (in fact, they are worse than random -typing - an infinite number of monkeys typing into GNU emacs would never -make a good program). - -So, you can either get rid of GNU emacs, or change it to use saner -values. To do the latter, you can stick the following in your .emacs file: - -(defun c-lineup-arglist-tabs-only (ignored) - "Line up argument lists by tabs, not spaces" - (let* ((anchor (c-langelem-pos c-syntactic-element)) - (column (c-langelem-2nd-pos c-syntactic-element)) - (offset (- (1+ column) anchor)) - (steps (floor offset c-basic-offset))) - (* (max steps 1) - c-basic-offset))) - -(add-hook 'c-mode-common-hook - (lambda () - ;; Add kernel style - (c-add-style - "linux-tabs-only" - '("linux" (c-offsets-alist - (arglist-cont-nonempty - c-lineup-gcc-asm-reg - c-lineup-arglist-tabs-only)))))) - -(add-hook 'c-mode-hook - (lambda () - (let ((filename (buffer-file-name))) - ;; Enable kernel mode for the appropriate files - (when (and filename - (string-match (expand-file-name "~/src/linux-trees") - filename)) - (setq indent-tabs-mode t) - (c-set-style "linux-tabs-only"))))) - -This will make emacs go better with the kernel coding style for C -files below ~/src/linux-trees. - -But even if you fail in getting emacs to do sane formatting, not -everything is lost: use "indent". - -Now, again, GNU indent has the same brain-dead settings that GNU emacs -has, which is why you need to give it a few command line options. -However, that's not too bad, because even the makers of GNU indent -recognize the authority of K&R (the GNU people aren't evil, they are -just severely misguided in this matter), so you just give indent the -options "-kr -i8" (stands for "K&R, 8 character indents"), or use -"scripts/Lindent", which indents in the latest style. - -"indent" has a lot of options, and especially when it comes to comment -re-formatting you may want to take a look at the man page. But -remember: "indent" is not a fix for bad programming. - - - Chapter 10: Kconfig configuration files - -For all of the Kconfig* configuration files throughout the source tree, -the indentation is somewhat different. Lines under a "config" definition -are indented with one tab, while help text is indented an additional two -spaces. Example: - -config AUDIT - bool "Auditing support" - depends on NET - help - Enable auditing infrastructure that can be used with another - kernel subsystem, such as SELinux (which requires this for - logging of avc messages output). Does not do system-call - auditing without CONFIG_AUDITSYSCALL. - -Features that might still be considered unstable should be defined as -dependent on "EXPERIMENTAL": - -config SLUB - depends on EXPERIMENTAL && !ARCH_USES_SLAB_PAGE_STRUCT - bool "SLUB (Unqueued Allocator)" - ... - -while seriously dangerous features (such as write support for certain -filesystems) should advertise this prominently in their prompt string: - -config ADFS_FS_RW - bool "ADFS write support (DANGEROUS)" - depends on ADFS_FS - ... - -For full documentation on the configuration files, see the file -Documentation/kbuild/kconfig-language.txt. - - - Chapter 11: Data structures - -Data structures that have visibility outside the single-threaded -environment they are created and destroyed in should always have -reference counts. In the kernel, garbage collection doesn't exist (and -outside the kernel garbage collection is slow and inefficient), which -means that you absolutely _have_ to reference count all your uses. - -Reference counting means that you can avoid locking, and allows multiple -users to have access to the data structure in parallel - and not having -to worry about the structure suddenly going away from under them just -because they slept or did something else for a while. - -Note that locking is _not_ a replacement for reference counting. -Locking is used to keep data structures coherent, while reference -counting is a memory management technique. Usually both are needed, and -they are not to be confused with each other. - -Many data structures can indeed have two levels of reference counting, -when there are users of different "classes". The subclass count counts -the number of subclass users, and decrements the global count just once -when the subclass count goes to zero. - -Examples of this kind of "multi-level-reference-counting" can be found in -memory management ("struct mm_struct": mm_users and mm_count), and in -filesystem code ("struct super_block": s_count and s_active). - -Remember: if another thread can find your data structure, and you don't -have a reference count on it, you almost certainly have a bug. - - - Chapter 12: Macros, Enums and RTL - -Names of macros defining constants and labels in enums are capitalized. - -#define CONSTANT 0x12345 - -Enums are preferred when defining several related constants. - -CAPITALIZED macro names are appreciated but macros resembling functions -may be named in lower case. - -Generally, inline functions are preferable to macros resembling functions. - -Macros with multiple statements should be enclosed in a do - while block: - -#define macrofun(a, b, c) \ - do { \ - if (a == 5) \ - do_this(b, c); \ - } while (0) - -Things to avoid when using macros: - -1) macros that affect control flow: - -#define FOO(x) \ - do { \ - if (blah(x) < 0) \ - return -EBUGGERED; \ - } while(0) - -is a _very_ bad idea. It looks like a function call but exits the "calling" -function; don't break the internal parsers of those who will read the code. - -2) macros that depend on having a local variable with a magic name: - -#define FOO(val) bar(index, val) - -might look like a good thing, but it's confusing as hell when one reads the -code and it's prone to breakage from seemingly innocent changes. - -3) macros with arguments that are used as l-values: FOO(x) = y; will -bite you if somebody e.g. turns FOO into an inline function. - -4) forgetting about precedence: macros defining constants using expressions -must enclose the expression in parentheses. Beware of similar issues with -macros using parameters. - -#define CONSTANT 0x4000 -#define CONSTEXP (CONSTANT | 3) - -The cpp manual deals with macros exhaustively. The gcc internals manual also -covers RTL which is used frequently with assembly language in the kernel. - - - Chapter 13: Printing kernel messages - -Kernel developers like to be seen as literate. Do mind the spelling -of kernel messages to make a good impression. Do not use crippled -words like "dont"; use "do not" or "don't" instead. Make the messages -concise, clear, and unambiguous. - -Kernel messages do not have to be terminated with a period. - -Printing numbers in parentheses (%d) adds no value and should be avoided. - -There are a number of driver model diagnostic macros in -which you should use to make sure messages are matched to the right device -and driver, and are tagged with the right level: dev_err(), dev_warn(), -dev_info(), and so forth. For messages that aren't associated with a -particular device, defines pr_debug() and pr_info(). - -Coming up with good debugging messages can be quite a challenge; and once -you have them, they can be a huge help for remote troubleshooting. Such -messages should be compiled out when the DEBUG symbol is not defined (that -is, by default they are not included). When you use dev_dbg() or pr_debug(), -that's automatic. Many subsystems have Kconfig options to turn on -DDEBUG. -A related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to the -ones already enabled by DEBUG. - - - Chapter 14: Allocating memory - -The kernel provides the following general purpose memory allocators: -kmalloc(), kzalloc(), kcalloc(), and vmalloc(). Please refer to the API -documentation for further information about them. - -The preferred form for passing a size of a struct is the following: - - p = kmalloc(sizeof(*p), ...); - -The alternative form where struct name is spelled out hurts readability and -introduces an opportunity for a bug when the pointer variable type is changed -but the corresponding sizeof that is passed to a memory allocator is not. - -Casting the return value which is a void pointer is redundant. The conversion -from void pointer to any other pointer type is guaranteed by the C programming -language. - - - Chapter 15: The inline disease - -There appears to be a common misperception that gcc has a magic "make me -faster" speedup option called "inline". While the use of inlines can be -appropriate (for example as a means of replacing macros, see Chapter 12), it -very often is not. Abundant use of the inline keyword leads to a much bigger -kernel, which in turn slows the system as a whole down, due to a bigger -icache footprint for the CPU and simply because there is less memory -available for the pagecache. Just think about it; a pagecache miss causes a -disk seek, which easily takes 5 miliseconds. There are a LOT of cpu cycles -that can go into these 5 miliseconds. - -A reasonable rule of thumb is to not put inline at functions that have more -than 3 lines of code in them. An exception to this rule are the cases where -a parameter is known to be a compiletime constant, and as a result of this -constantness you *know* the compiler will be able to optimize most of your -function away at compile time. For a good example of this later case, see -the kmalloc() inline function. - -Often people argue that adding inline to functions that are static and used -only once is always a win since there is no space tradeoff. While this is -technically correct, gcc is capable of inlining these automatically without -help, and the maintenance issue of removing the inline when a second user -appears outweighs the potential value of the hint that tells gcc to do -something it would have done anyway. - - - Chapter 16: Function return values and names - -Functions can return values of many different kinds, and one of the -most common is a value indicating whether the function succeeded or -failed. Such a value can be represented as an error-code integer -(-Exxx = failure, 0 = success) or a "succeeded" boolean (0 = failure, -non-zero = success). - -Mixing up these two sorts of representations is a fertile source of -difficult-to-find bugs. If the C language included a strong distinction -between integers and booleans then the compiler would find these mistakes -for us... but it doesn't. To help prevent such bugs, always follow this -convention: - - If the name of a function is an action or an imperative command, - the function should return an error-code integer. If the name - is a predicate, the function should return a "succeeded" boolean. - -For example, "add work" is a command, and the add_work() function returns 0 -for success or -EBUSY for failure. In the same way, "PCI device present" is -a predicate, and the pci_dev_present() function returns 1 if it succeeds in -finding a matching device or 0 if it doesn't. - -All EXPORTed functions must respect this convention, and so should all -public functions. Private (static) functions need not, but it is -recommended that they do. - -Functions whose return value is the actual result of a computation, rather -than an indication of whether the computation succeeded, are not subject to -this rule. Generally they indicate failure by returning some out-of-range -result. Typical examples would be functions that return pointers; they use -NULL or the ERR_PTR mechanism to report failure. - - - Chapter 17: Don't re-invent the kernel macros - -The header file include/linux/kernel.h contains a number of macros that -you should use, rather than explicitly coding some variant of them yourself. -For example, if you need to calculate the length of an array, take advantage -of the macro - - #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) - -Similarly, if you need to calculate the size of some structure member, use - - #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) - -There are also min() and max() macros that do strict type checking if you -need them. Feel free to peruse that header file to see what else is already -defined that you shouldn't reproduce in your code. - - - Chapter 18: Editor modelines and other cruft - -Some editors can interpret configuration information embedded in source files, -indicated with special markers. For example, emacs interprets lines marked -like this: - --*- mode: c -*- - -Or like this: - -/* -Local Variables: -compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c" -End: -*/ - -Vim interprets markers that look like this: - -/* vim:set sw=8 noet */ - -Do not include any of these in source files. People have their own personal -editor configurations, and your source files should not override them. This -includes markers for indentation and mode configuration. People may use their -own custom mode, or may have some other magic method for making indentation -work correctly. - - - - Appendix I: References - -The C Programming Language, Second Edition -by Brian W. Kernighan and Dennis M. Ritchie. -Prentice Hall, Inc., 1988. -ISBN 0-13-110362-8 (paperback), 0-13-110370-9 (hardback). -URL: http://cm.bell-labs.com/cm/cs/cbook/ - -The Practice of Programming -by Brian W. Kernighan and Rob Pike. -Addison-Wesley, Inc., 1999. -ISBN 0-201-61586-X. -URL: http://cm.bell-labs.com/cm/cs/tpop/ - -GNU manuals - where in compliance with K&R and this text - for cpp, gcc, -gcc internals and indent, all available from http://www.gnu.org/manual/ - -WG14 is the international standardization working group for the programming -language C, URL: http://www.open-std.org/JTC1/SC22/WG14/ - -Kernel CodingStyle, by greg@kroah.com at OLS 2002: -http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/ - --- -Last updated on 2007-July-13. -- cgit v1.2.3-54-g00ecf