-##
-## Coding conventions in the Samba 3.0 tree
-##
+Coding conventions in the Samba tree
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. contents::
===========
Quick Start
===========
Coding style guidelines are about reducing the number of unnecessary
-reformatting patches and making things easier developers to work together.
+reformatting patches and making things easier for developers to work
+together.
You don't have to like them or even agree with them, but once put in place
we all have to abide by them (or vote to change them). However, coding
-style should never outweigh coding itself and so the the guidelines
-described here are hopefully easier enough to follow as they are very
+style should never outweigh coding itself and so the guidelines
+described here are hopefully easy enough to follow as they are very
common and supported by tools and editors.
-The basic style, also mentioned in the SAMBA_4_0/prog_guide.txt is the
-Linux kernel coding style (See Documentation/CodingStyle in the kernel
-source tree). The closely matches what most Samba developers use already
-anyways.
+The basic style for C code, also mentioned in prog_guide4.txt, is the Linux kernel
+coding style (See Documentation/CodingStyle in the kernel source tree). This
+closely matches what most Samba developers use already anyways, with a few
+exceptions as mentioned below.
+
+The coding style for Python code is documented in PEP8,
+http://www.python.org/pep/pep8 (with spaces).
+If you have ever worked on another free software Python project, you are
+probably already familiar with it.
But to save you the trouble of reading the Linux kernel style guide, here
are the highlights.
-
* Maximum Line Width is 80 Characters
- The reason is not for people with low-res screens but rather sticking
+ The reason is not about people with low-res screens but rather sticking
to 80 columns prevents you from easily nesting more than one level of
- if statements or other code blocks. Use source/script/count_80_col.pl
+ if statements or other code blocks. Use source3/script/count_80_col.pl
to check your changes.
* Use 8 Space Tabs to Indent
- No whitespace filler.
+ No whitespace fillers.
* No Trailing Whitespace
- Use source/script/strip_trail_ws.pl to clean you files before committing.
+ Use source3/script/strip_trail_ws.pl to clean up your files before
+ committing.
-* Follow the K&R guidelines. We won't go throw them all here. You have
- a copy of "The C Programming Language" anyways right? You can also use
- the format_indent.sh script found in source/script/ if all else fails.
+* Follow the K&R guidelines. We won't go through all of them here. Do you
+ have a copy of "The C Programming Language" anyways right? You can also use
+ the format_indent.sh script found in source3/script/ if all else fails.
--
(Thanks to SATOH Fumiyasu <fumiyas@osstech.jp> for these hints):
-For the basic vi eitor including with all variants of *nix, add the
+For the basic vi editor included with all variants of \*nix, add the
following to $HOME/.exrc:
set tabstop=8
set shiftwidth=8
-For Vim, the following settings in $HOME/.vimrc will also deal with
-disaplaying trailing whitespace:
+For Vim, the following settings in $HOME/.vimrc will also deal with
+displaying trailing whitespace:
if has("syntax") && (&t_Co > 2 || has("gui_running"))
syntax on
endf
autocmd BufNewFile,BufRead * call ActivateInvisibleCharIndicator()
endif
+ " Show tabs, trailing whitespace, and continued lines visually
+ set list listchars=tab:»·,trail:·,extends:…
+
+ " highlight overly long lines same as TODOs.
+ set textwidth=80
+ autocmd BufNewFile,BufRead *.c,*.h exec 'match Todo /\%>' . &textwidth . 'v.\+/'
+
+clang-format
+------------
+BasedOnStyle: LLVM
+IndentWidth: 8
+UseTab: true
+BreakBeforeBraces: Linux
+AllowShortIfStatementsOnASingleLine: false
+IndentCaseLabels: false
+BinPackParameters: false
+
+
+=========================
+FAQ & Statement Reference
+=========================
+
+Comments
+--------
+
+Comments should always use the standard C syntax. C++
+style comments are not currently allowed.
+
+The lines before a comment should be empty. If the comment directly
+belongs to the following code, there should be no empty line
+after the comment, except if the comment contains a summary
+of multiple following code blocks.
+
+This is good:
+
+ ...
+ int i;
+
+ /*
+ * This is a multi line comment,
+ * which explains the logical steps we have to do:
+ *
+ * 1. We need to set i=5, because...
+ * 2. We need to call complex_fn1
+ */
+
+ /* This is a one line comment about i = 5. */
+ i = 5;
+
+ /*
+ * This is a multi line comment,
+ * explaining the call to complex_fn1()
+ */
+ ret = complex_fn1();
+ if (ret != 0) {
+ ...
+
+ /**
+ * @brief This is a doxygen comment.
+ *
+ * This is a more detailed explanation of
+ * this simple function.
+ *
+ * @param[in] param1 The parameter value of the function.
+ *
+ * @param[out] result1 The result value of the function.
+ *
+ * @return 0 on success and -1 on error.
+ */
+ int example(int param1, int *result1);
+
+This is bad:
+
+ ...
+ int i;
+ /*
+ * This is a multi line comment,
+ * which explains the logical steps we have to do:
+ *
+ * 1. We need to set i=5, because...
+ * 2. We need to call complex_fn1
+ */
+ /* This is a one line comment about i = 5. */
+ i = 5;
+ /*
+ * This is a multi line comment,
+ * explaining the call to complex_fn1()
+ */
+ ret = complex_fn1();
+ if (ret != 0) {
+ ...
+
+ /*This is a one line comment.*/
+
+ /* This is a multi line comment,
+ with some more words...*/
+
+ /*
+ * This is a multi line comment,
+ * with some more words...*/
+
+Indention & Whitespace & 80 columns
+-----------------------------------
+
+To avoid confusion, indentations have to be tabs with length 8 (not 8
+' ' characters). When wrapping parameters for function calls,
+align the parameter list with the first parameter on the previous line.
+Use tabs to get as close as possible and then fill in the final 7
+characters or less with whitespace. For example,
+
+ var1 = foo(arg1, arg2,
+ arg3);
+
+The previous example is intended to illustrate alignment of function
+parameters across lines and not as encourage for gratuitous line
+splitting. Never split a line before columns 70 - 79 unless you
+have a really good reason. Be smart about formatting.
+
+One exception to the previous rule is function declarations and
+definitions. In function declarations and definitions, either the
+declaration is a one-liner, or each parameter is listed on its own
+line. The rationale is that if there are many parameters, each one
+should be on its own line to make tracking interface changes easier.
+
+
+If, switch, & Code blocks
+-------------------------
+
+Always follow an 'if' keyword with a space but don't include additional
+spaces following or preceding the parentheses in the conditional.
+This is good:
+
+ if (x == 1)
+
+This is bad:
+
+ if ( x == 1 )
+
+Yes we have a lot of code that uses the second form and we are trying
+to clean it up without being overly intrusive.
+
+Note that this is a rule about parentheses following keywords and not
+functions. Don't insert a space between the name and left parentheses when
+invoking functions.
+
+Braces for code blocks used by for, if, switch, while, do..while, etc.
+should begin on the same line as the statement keyword and end on a line
+of their own. You should always include braces, even if the block only
+contains one statement. NOTE: Functions are different and the beginning left
+brace should be located in the first column on the next line.
+
+If the beginning statement has to be broken across lines due to length,
+the beginning brace should be on a line of its own.
+
+The exception to the ending rule is when the closing brace is followed by
+another language keyword such as else or the closing while in a do..while
+loop.
+
+Good examples:
+
+ if (x == 1) {
+ printf("good\n");
+ }
+
+ for (x=1; x<10; x++) {
+ print("%d\n", x);
+ }
+
+ for (really_really_really_really_long_var_name=0;
+ really_really_really_really_long_var_name<10;
+ really_really_really_really_long_var_name++)
+ {
+ print("%d\n", really_really_really_really_long_var_name);
+ }
+
+ do {
+ printf("also good\n");
+ } while (1);
+
+Bad examples:
+
+ while (1)
+ {
+ print("I'm in a loop!\n"); }
+
+ for (x=1;
+ x<10;
+ x++)
+ {
+ print("no good\n");
+ }
+
+ if (i < 10)
+ print("I should be in braces.\n");
+
+
+Goto
+----
+
+While many people have been academically taught that "goto"s are
+fundamentally evil, they can greatly enhance readability and reduce memory
+leaks when used as the single exit point from a function. But in no Samba
+world what so ever is a goto outside of a function or block of code a good
+idea.
+
+Good Examples:
+
+ int function foo(int y)
+ {
+ int *z = NULL;
+ int ret = 0;
+
+ if (y < 10) {
+ z = malloc(sizeof(int) * y);
+ if (z == NULL) {
+ ret = 1;
+ goto done;
+ }
+ }
+
+ print("Allocated %d elements.\n", y);
+
+ done:
+ if (z != NULL) {
+ free(z);
+ }
+
+ return ret;
+ }
+
+
+Primitive Data Types
+--------------------
+
+Samba has large amounts of historical code which makes use of data types
+commonly supported by the C99 standard. However, at the time such types
+as boolean and exact width integers did not exist and Samba developers
+were forced to provide their own. Now that these types are guaranteed to
+be available either as part of the compiler C99 support or from
+lib/replace/, new code should adhere to the following conventions:
+
+ * Booleans are of type "bool" (not BOOL)
+ * Boolean values are "true" and "false" (not True or False)
+ * Exact width integers are of type [u]int[8|16|32|64]_t
+
+Most of the time a good name for a boolean variable is 'ok'. Here is an
+example we often use:
+
+ bool ok;
+
+ ok = foo();
+ if (!ok) {
+ /* do something */
+ }
+
+It makes the code more readable and is easy to debug.
+
+Typedefs
+--------
+
+Samba tries to avoid "typedef struct { .. } x_t;" so we do always try to use
+"struct x { .. };". We know there are still such typedefs in the code,
+but for new code, please don't do that anymore.
+
+Initialize pointers
+-------------------
+
+All pointer variables MUST be initialized to NULL. History has
+demonstrated that uninitialized pointer variables have lead to various
+bugs and security issues.
+
+Pointers MUST be initialized even if the assignment directly follows
+the declaration, like pointer2 in the example below, because the
+instructions sequence may change over time.
+
+Good Example:
+
+ char *pointer1 = NULL;
+ char *pointer2 = NULL;
+
+ pointer2 = some_func2();
+
+ ...
+
+ pointer1 = some_func1();
+
+Bad Example:
+
+ char *pointer1;
+ char *pointer2;
+
+ pointer2 = some_func2();
+
+ ...
+
+ pointer1 = some_func1();
+
+Make use of helper variables
+----------------------------
+
+Please try to avoid passing function calls as function parameters
+in new code. This makes the code much easier to read and
+it's also easier to use the "step" command within gdb.
+
+Good Example:
+
+ char *name = NULL;
+ int ret;
+
+ name = get_some_name();
+ if (name == NULL) {
+ ...
+ }
+
+ ret = some_function_my_name(name);
+ ...
+
+
+Bad Example:
+
+ ret = some_function_my_name(get_some_name());
+ ...
+
+Please try to avoid passing function return values to if- or
+while-conditions. The reason for this is better handling of code under a
+debugger.
+
+Good example:
+
+ x = malloc(sizeof(short)*10);
+ if (x == NULL) {
+ fprintf(stderr, "Unable to alloc memory!\n");
+ }
+
+Bad example:
+
+ if ((x = malloc(sizeof(short)*10)) == NULL ) {
+ fprintf(stderr, "Unable to alloc memory!\n");
+ }
+
+There are exceptions to this rule. One example is walking a data structure in
+an iterator style:
+
+ while ((opt = poptGetNextOpt(pc)) != -1) {
+ ... do something with opt ...
+ }
+
+But in general, please try to avoid this pattern.
+
+
+Control-Flow changing macros
+----------------------------
+
+Macros like NT_STATUS_NOT_OK_RETURN that change control flow
+(return/goto/etc) from within the macro are considered bad, because
+they look like function calls that never change control flow. Please
+do not use them in new code.
+
+The only exception is the test code that depends repeated use of calls
+like CHECK_STATUS, CHECK_VAL and others.
+
+
+DEBUG statements
+----------------
+Use these following macros instead of DEBUG:
-===================
-Statement Reference
-===================
+DBG_ERR log level 0 error conditions
+DBG_WARNING log level 1 warning conditions
+DBG_NOTICE log level 3 normal, but significant, condition
+DBG_INFO log level 5 informational message
+DBG_DEBUG log level 10 debug-level message
-To be filled later in as needed.
+Example usage:
+DBG_ERR("Memory allocation failed\n");
+DBG_DEBUG("Received %d bytes\n", count);
+The messages from these macros are automatically prefixed with the
+function name.
git.samba.org / sfrench / samba-autobuild / .git / blobdiff