Update README.CodingStyle
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Andreas Schneider
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59
CodingStyle
59
CodingStyle
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Coding Style Conventions
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========================
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Coding style guidelines are about reducing the number of unnecessary
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reformatting patches and making things easier for developers to work together.
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You don't have to like them or even agree with them, but once put in place we
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all have to abide by them (or vote to change them). However, coding style
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should never outweigh coding itself and so the guidelines described here are
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hopefully easy enough to follow as they are very common and supported by tools
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and editors.
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The basic style for C code is the Linux kernel coding style [1] with one
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excecption, we use 4 spaces instead of tabs. This closely matches what most
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libssh developers use already anyways, with a few exceptions as mentioned
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below.
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To shorthen this here are the highlights:
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* Maximum line width is 80 characters
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The reason is not about people with low-res screens but rather sticking
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to 80 columns prevents you from easily nesting more than one level of
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if statements or other code blocks.
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* Use 4 spaces to indent
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* No trailing whitespaces
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* Follow the K&R guidelines. We won't go through all of them here. Do you
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have a copy of "The C Programming Language" anyways right?
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Editors
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========
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VIM
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----
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set ts=4 sw=4 et cindent
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For Vim, the following settings in $HOME/.vimrc will also deal with
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displaying trailing whitespace:
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if has("syntax") && (&t_Co > 2 || has("gui_running"))
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syntax on
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function! ActivateInvisibleCharIndicator()
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syntax match TrailingSpace "[ \t]\+$" display containedin=ALL
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highlight TrailingSpace ctermbg=Red
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endf
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autocmd BufNewFile,BufRead * call ActivateInvisibleCharIndicator()
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endif
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" Show tabs, trailing whitespace, and continued lines visually
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set list listchars=tab:»·,trail:·,extends:…
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" highlight overly long lines same as TODOs.
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set textwidth=80
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autocmd BufNewFile,BufRead *.c,*.h exec 'match Todo /\%>' . &textwidth . 'v.\+/'
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[1] https://www.kernel.org/doc/Documentation/CodingStyle
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354
README.CodingStyle
Обычный файл
354
README.CodingStyle
Обычный файл
@ -0,0 +1,354 @@
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Coding conventions in the libssh tree
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======================================
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===========
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Quick Start
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===========
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Coding style guidelines are about reducing the number of unnecessary
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reformatting patches and making things easier for developers to work together.
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|
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You don't have to like them or even agree with them, but once put in place we
|
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all have to abide by them (or vote to change them). However, coding style
|
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should never outweigh coding itself and so the guidelines described here are
|
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hopefully easy enough to follow as they are very common and supported by tools
|
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and editors.
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The basic style for C code, is the Linux kernel coding style (See
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Documentation/CodingStyle in the kernel source tree). This closely matches what
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libssh developers use already anyways, with a few exceptions as mentioned
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below.
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But to save you the trouble of reading the Linux kernel style guide, here
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are the highlights.
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* Maximum Line Width is 80 Characters
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The reason is not about people with low-res screens but rather sticking
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to 80 columns prevents you from easily nesting more than one level of
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if statements or other code blocks.
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* Use 4 Spaces to Indent
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* No Trailing Whitespace
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Clean up your files before committing.
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* Follow the K&R guidelines. We won't go through all of them here. Do you
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have a copy of "The C Programming Language" anyways right?
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=============
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Editor Hints
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=============
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Emacs
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------
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Add the follow to your $HOME/.emacs file:
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(add-hook 'c-mode-hook
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(lambda ()
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(c-set-style "linux")
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(c-toggle-auto-state)))
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Vim
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----
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For the basic vi editor included with all variants of \*nix, add the
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following to $HOME/.vimrc:
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set ts=4 sw=4 et cindent
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You can use the Vim gitmodline plugin to store this in the git config:
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http://git.cryptomilk.org/projects/vim-gitmodeline.git/
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For Vim, the following settings in $HOME/.vimrc will also deal with
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displaying trailing whitespace:
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if has("syntax") && (&t_Co > 2 || has("gui_running"))
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syntax on
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function! ActivateInvisibleCharIndicator()
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syntax match TrailingSpace "[ \t]\+$" display containedin=ALL
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highlight TrailingSpace ctermbg=Red
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endf
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autocmd BufNewFile,BufRead * call ActivateInvisibleCharIndicator()
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endif
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" Show tabs, trailing whitespace, and continued lines visually
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set list listchars=tab:»·,trail:·,extends:…
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" highlight overly long lines same as TODOs.
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set textwidth=80
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autocmd BufNewFile,BufRead *.c,*.h exec 'match Todo /\%>' . &textwidth . 'v.\+/'
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==========================
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FAQ & Statement Reference
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==========================
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Comments
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---------
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Comments should always use the standard C syntax. C++ style comments are not
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currently allowed.
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The lines before a comment should be empty. If the comment directly belongs to
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the following code, there should be no empty line after the comment, except if
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the comment contains a summary of multiple following code blocks.
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This is good:
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...
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int i;
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/*
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* This is a multi line comment,
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* which explains the logical steps we have to do:
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*
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* 1. We need to set i=5, because...
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* 2. We need to call complex_fn1
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*/
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/* This is a one line comment about i = 5. */
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i = 5;
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/*
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* This is a multi line comment,
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* explaining the call to complex_fn1()
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*/
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ret = complex_fn1();
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if (ret != 0) {
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...
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/**
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* @brief This is a doxygen comment.
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*
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* This is a more detailed explanation of
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* this simple function.
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*
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* @param[in] param1 The parameter value of the function.
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*
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* @param[out] result1 The result value of the function.
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*
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* @return 0 on success and -1 on error.
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*/
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int example(int param1, int *result1);
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This is bad:
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...
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int i;
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/*
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* This is a multi line comment,
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* which explains the logical steps we have to do:
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*
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* 1. We need to set i=5, because...
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* 2. We need to call complex_fn1
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*/
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/* This is a one line comment about i = 5. */
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i = 5;
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/*
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* This is a multi line comment,
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* explaining the call to complex_fn1()
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*/
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ret = complex_fn1();
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if (ret != 0) {
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...
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/*This is a one line comment.*/
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/* This is a multi line comment,
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with some more words...*/
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/*
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* This is a multi line comment,
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* with some more words...*/
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Indention & Whitespace & 80 columns
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------------------------------------
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To avoid confusion, indentations have to be 4 spaces. Do not use tabs!. When
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wrapping parameters for function calls, align the parameter list with the first
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parameter on the previous line. For example,
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var1 = foo(arg1,
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arg2,
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arg3);
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The previous example is intended to illustrate alignment of function
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parameters across lines and not as encourage for gratuitous line
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splitting. Never split a line before columns 70 - 79 unless you
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have a really good reason. Be smart about formatting.
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If, switch, & Code blocks
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--------------------------
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Always follow an 'if' keyword with a space but don't include additional
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spaces following or preceding the parentheses in the conditional.
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This is good:
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if (x == 1)
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This is bad:
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if ( x == 1 )
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or
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if (x==1)
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Yes we have a lot of code that uses the second and third form and we are trying
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to clean it up without being overly intrusive.
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Note that this is a rule about parentheses following keywords and not
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functions. Don't insert a space between the name and left parentheses when
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invoking functions.
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Braces for code blocks used by for, if, switch, while, do..while, etc. should
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begin on the same line as the statement keyword and end on a line of their own.
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You should always include braces, even if the block only contains one
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statement. NOTE: Functions are different and the beginning left brace should
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be located in the first column on the next line.
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If the beginning statement has to be broken across lines due to length, the
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beginning brace should be on a line of its own.
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The exception to the ending rule is when the closing brace is followed by
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another language keyword such as else or the closing while in a do..while loop.
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Good examples:
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if (x == 1) {
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printf("good\n");
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}
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for (x = 1; x < 10; x++) {
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print("%d\n", x);
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}
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for (really_really_really_really_long_var_name = 0;
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really_really_really_really_long_var_name < 10;
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really_really_really_really_long_var_name++)
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{
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print("%d\n", really_really_really_really_long_var_name);
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}
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do {
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printf("also good\n");
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} while (1);
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Bad examples:
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while (1)
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{
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print("I'm in a loop!\n"); }
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for (x=1;
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x<10;
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x++)
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{
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print("no good\n");
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}
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if (i < 10)
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print("I should be in braces.\n");
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Goto
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-----
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While many people have been academically taught that "goto"s are fundamentally
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evil, they can greatly enhance readability and reduce memory leaks when used as
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the single exit point from a function. But in no libssh world what so ever is a
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goto outside of a function or block of code a good idea.
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Good Examples:
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int function foo(int y)
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{
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int *z = NULL;
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int rc = 0;
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if (y < 10) {
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z = malloc(sizeof(int)*y);
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if (z == NULL) {
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rc = 1;
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goto done;
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}
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}
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print("Allocated %d elements.\n", y);
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done:
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if (z != NULL) {
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free(z);
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}
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return rc;
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}
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Typedefs
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---------
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libssh tries to avoid "typedef struct { .. } x_t;" so we do always try to use
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"struct x { .. };". We know there are still such typedefs in the code, but for
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new code, please don't do that anymore.
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Make use of helper variables
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-----------------------------
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Please try to avoid passing function calls as function parameters in new code.
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This makes the code much easier to read and it's also easier to use the "step"
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command within gdb.
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Good Example:
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char *name;
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name = get_some_name();
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if (name == NULL) {
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...
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}
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rc = some_function_my_name(name);
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...
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Bad Example:
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rc = some_function_my_name(get_some_name());
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...
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Please try to avoid passing function return values to if- or while-conditions.
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The reason for this is better handling of code under a debugger.
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Good example:
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x = malloc(sizeof(short) * 10);
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if (x == NULL) {
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fprintf(stderr, "Unable to alloc memory!\n");
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}
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Bad example:
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if ((x = malloc(sizeof(short)*10)) == NULL ) {
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fprintf(stderr, "Unable to alloc memory!\n");
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}
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There are exceptions to this rule. One example is walking a data structure in
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an iterator style:
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while ((opt = poptGetNextOpt(pc)) != -1) {
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... do something with opt ...
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}
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But in general, please try to avoid this pattern.
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Control-Flow changing macros
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-----------------------------
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Macros like STATUS_NOT_OK_RETURN that change control flow (return/goto/etc)
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from within the macro are considered bad, because they look like function calls
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that never change control flow. Please do not introduce them.
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