Update CONTRIBUTING.md

1 files changed, 188 insertions, 175 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f450563a..a5a5111f 100644
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+++ b/CONTRIBUTING.md
@@ -1,30 +1,12 @@
 # Contributing to sway
 
 Contributing just involves sending a pull request. You will probably be more
-successful with your contribution if you visit the [IRC
-channel](http://webchat.freenode.net/?channels=sway-devel&uio=d4) upfront and discuss
-your plans.
+successful with your contribution if you visit
+[#sway-devel](https://webchat.freenode.net/?channels=sway-devel) on
+irc.freenode.net upfront and discuss your plans.
 
-## Release Cycle
-
-The master branch of sway is always working towards becoming the next release.
-That release will go through each of these three stages:
-
-**In development**: during this time the release lives in the master branch and
-is considered unstable. All pull requests merged during this time will land in
-the release. Only developers are encouraged to run this version.
-
-**Release candidate**: at some point (usually when development is fairly quiet),
-SirCmpwn will announce an upcoming release candidate, often 2 weeks in
-advance. When the two weeks are up, a branch is cut (i.e. 0.8-rc1) and from
-that point only bugfixes land in this branch. Each week, if bugfixes landed
-during the week, a new RC is cut. During the RC phase, more adventurous users
-are encouraged to upgrade and start looking for and reporting bugs (especially
-in new features).
-
-**Stable release**: when no substantial changes are merged into an RC for one
-week, it's released as a new stable version of sway. At this point, all users
-are encouraged to upgrade.
+Note: rules are made to be broken. Adjust or ignore any/all of these as you see
+fit, but be prepared to justify it to your peers.
 
 ## Pull Requests
 
@@ -33,34 +15,44 @@ don't, however, allow me to make a suggestion: feature branches pulled from
 upstream. Try this:
 
 1. Fork sway
-2. Clone your fork
-3. git remote add upstream git://github.com/swaywm/sway.git
+2. `git clone https://github.com/username/sway && cd sway`
+3. `git remote add upstream https://github.com/swaywm/sway`
 
 You only need to do this once. You're never going to use your fork's master
 branch. Instead, when you start working on a feature, do this:
 
-1. git fetch upstream
-2. git checkout -b add-so-and-so-feature upstream/master
-3. work
-4. git push -u origin add-so-and-so-feature
-5. Make pull request from your feature branch
+1. `git fetch upstream`
+2. `git checkout -b add-so-and-so-feature upstream/master`
+3. Add and commit your changes
+4. `git push -u origin add-so-and-so-feature`
+5. Make a pull request from your feature branch
+
+When you submit your pull request, your commit log should do most of the talking
+when it comes to describing your changes and their motivation. In addition to
+this, your pull request's comments will ideally include a test plan that the
+reviewers can use to (1) demonstrate the problem on master, if applicable and
+(2) verify that the problem no longer exists with your changes applied (or that
+your new features work correctly). Document all of the edge cases you're aware
+of so we can adequately test them - then verify the test plan yourself before
+submitting.
 
 ## Commit Messages
 
 Please strive to write good commit messages. Here's some guidelines to follow:
 
 The first line should be limited to 50 characters and should be a sentence that
-completes the thought [When applied, this commit will...] "Implement cmd_move"
-or "Fix #742" or "Improve performance of arrange_windows on ARM" or similar.
+completes the thought [When applied, this commit will...] *"Implement
+cmd_move"* or *"Fix #742"* or *"Improve performance of arrange_windows on ARM"*
+or similar.
 
-The subsequent lines should be seperated from the subject line by a single
+The subsequent lines should be separated from the subject line by a single
 blank line, and include optional details. In this you can give justification
 for the change, [reference Github
 issues](https://help.github.com/articles/closing-issues-via-commit-messages/),
 or explain some of the subtler details of your patch. This is important because
 when someone finds a line of code they don't understand later, they can use the
 `git blame` command to find out what the author was thinking when they wrote
-it. It's also easier to review your pull requests if they're seperated into
+it. It's also easier to review your pull requests if they're separated into
 logical commits that have good commit messages and justify themselves in the
 extended commit description.
 
@@ -68,157 +60,178 @@ As a good rule of thumb, anything you might put into the pull request
 description on Github is probably fair game for going into the extended commit
 message as well.
 
-## Coding Style
-
-Sway is written in C. The style guidelines is [kernel
-style](https://www.kernel.org/doc/Documentation/process/coding-style.rst), but all braces go
-on the same line (*"but K&R says so!" is a silly way of justifying something*).
-Some points to note:
-
-* Do not use typedefs unless you have a good reason
-* Do not use macros unless you have a *really* good reason
-* Align `case` with `switch`
-* Tabs, not spaces
-* `char *pointer` - note position of `*`
-* Use logging with reckless abandon
-* Always include braces for if/for/while/etc, even for one-liners
-
-An example of well formatted code:
-
-```C
-#include <stdio.h>
-#include <stdlib.h>
-#include "log.h"
-#include "example.h"
-
-struct foobar {
-        char *foo;
-        int bar;
-        long baz;
-}; // Do not typedef without a good reason
-
-int main(int argc, const char **argv) {
-        if (argc != 4) {
-                sway_abort("Do not run this program manually. See man 5 sway and look for output options.");
+See [here](https://chris.beams.io/posts/git-commit/) for more details.
+
+## Code Review
+
+When your changes are submitted for review, one or more core committers will
+look over them. Smaller changes might be merged with little fanfare, but larger
+changes will typically see review from several people. Be prepared to receive
+some feedback - you may be asked to make changes to your work. Our code review
+process is:
+
+1. **Triage** the pull request. Do the commit messages make sense? Is a test
+   plan necessary and/or present? Add anyone as reviewers that you think should
+   be there (using the relevant GitHub feature, if you have the permissions, or
+   with an @mention if necessary).
+2. **Review** the code. Look for code style violations, naming convention
+   violations, buffer overflows, memory leaks, logic errors, non-portable code
+   (including GNU-isms), etc. For significant changes to the public API, loop in
+   a couple more people for discussion.
+3. **Execute** the test plan, if present.
+4. **Merge** the pull request when all reviewers approve.
+5. **File** follow-up tickets if appropriate.
+
+## Style Reference
+
+Sway is written in C with a style similar to the [kernel
+style](https://www.kernel.org/doc/Documentation/process/coding-style.rst), but
+with a few notable differences.
+
+Try to keep your code conforming to C11 and POSIX as much as possible, and do
+not use GNU extensions.
+
+### Brackets
+
+Brackets always go on the same line, including in functions.
+Always include brackets for if/while/for, even if it's a single statement.
+```c
+void function(void) {
+        if (condition1) {
+                do_thing1();
         }
 
-        if (!registry->desktop_shell) {
-                sway_abort("swaybg requires the compositor to support the desktop-shell extension.");
+        if (condition2) {
+                do_thing2();
+        } else {
+                do_thing3();
         }
+}
+```
+
+### Indentation
+
+Indentations are a single tab.
+
+For long lines that need to be broken, the continuation line should be indented
+with an additional tab.
+
+If the line being broken is opening a new block (functions, if, while, etc.),
+the continuation line should be indented with two tabs, so they can't be
+misread as being part of the block.
+
+```c
+really_long_function(argument1, argument2, ...,
+        argument3, argument4);
+
+if (condition1 && condition2 && ...
+                condition3 && condition4) {
+        do_thing();
+}
+```
+
+Try to break the line in the place which you think is the most appropriate to
+balance the lines.
+
+### Line Length
+
+Try to keep your lines under 80 columns, but you can go up to 100 if it
+improves readability. Don't break lines indiscriminately, try to find nice
+breaking points so your code is easy to read.
+
+### Names
+
+Global function and type names should be prefixed with `sway_submodule_` (e.g.
+`struct sway_output`, `sway_output_destroy`).  For static functions and
+types local to a file, the names chosen aren't as important. Static functions
+shouldn't have a `sway_` prefix.
+
+For include guards, use the header's filename relative to include.  Uppercase
+all of the characters, and replace any invalid characters with an underscore.
 
-        int desired_output = atoi(argv[1]);
-        sway_log(WLR_INFO, "Using output %d of %d", desired_output, registry->outputs->length);
-        int i;
-        struct output_state *output = registry->outputs->items[desired_output];
-        struct window *window = window_setup(registry, 100, 100, false);
-        if (!window) {
-                sway_abort("Failed to create surfaces.");
+### Construction/Destruction Functions
+
+For functions that are responsible for constructing and destructing an object,
+they should be written as a pair of one of two forms:
+
+* `init`/`finish`: These initialize/deinitialize a type, but are **NOT**
+  responsible for allocating it. They should accept a pointer to some
+  pre-allocated memory (e.g. a member of a struct).
+* `create`/`destroy`: These also initialize/deinitialize, but will return a
+  pointer to a `malloc`ed chunk of memory, and will `free` it in `destroy`.
+
+A destruction function should always be able to accept a NULL pointer or a
+zeroed value and exit cleanly; this simplifies error handling a lot.
+
+### Error Codes
+
+For functions not returning a value, they should return a (stdbool.h) bool to
+indicated if they succeeded or not.
+
+### Macros
+
+Keep the use of macros to a minimum, especially if a function can do the job. If
+you do need to use them, try to keep them close to where they're being used and
+`#undef` them after.
+
+### Example
+
+```c
+struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
+        struct wlr_backend *backend;
+        if (getenv("WAYLAND_DISPLAY") || getenv("_WAYLAND_DISPLAY")) {
+                backend = attempt_wl_backend(display);
+                if (backend) {
+                        return backend;
+                }
         }
-        window->width = output->width;
-        window->height = output->height;
-        desktop_shell_set_background(registry->desktop_shell, output->output, window->surface);
-        list_add(surfaces, window);
-
-        cairo_surface_t *image = cairo_image_surface_create_from_png(argv[2]);
-        double width = cairo_image_surface_get_width(image);
-        double height = cairo_image_surface_get_height(image);
-
-        const char *scaling_mode_str = argv[3];
-        enum scaling_mode scaling_mode;
-        if (strcmp(scaling_mode_str, "stretch") == 0) {
-                scaling_mode = SCALING_MODE_STRETCH;
-        } else if (strcmp(scaling_mode_str, "fill") == 0) {
-                scaling_mode = SCALING_MODE_FILL;
-        } else if (strcmp(scaling_mode_str, "fit") == 0) {
-                scaling_mode = SCALING_MODE_FIT;
-        } else if (strcmp(scaling_mode_str, "center") == 0) {
-                scaling_mode = SCALING_MODE_CENTER;
-        } else if (strcmp(scaling_mode_str, "tile") == 0) {
-                scaling_mode = SCALING_MODE_TILE;
-        } else {
-                sway_abort("Unsupported scaling mode: %s", scaling_mode_str);
+
+        const char *x11_display = getenv("DISPLAY");
+        if (x11_display) {
+                return wlr_x11_backend_create(display, x11_display);
         }
 
-        for (i = 0; i < surfaces->length; ++i) {
-                struct window *window = surfaces->items[i];
-                if (window_prerender(window) && window->cairo) {
-                        switch (scaling_mode) {
-                        case SCALING_MODE_STRETCH:
-                                cairo_scale(window->cairo,
-                                                (double) window->width / width,
-                                                (double) window->height / height);
-                                cairo_set_source_surface(window->cairo, image, 0, 0);
-                                break;
-                        case SCALING_MODE_FILL:
-                        {
-                                double window_ratio = (double) window->width / window->height;
-                                double bg_ratio = width / height;
-
-                                if (window_ratio > bg_ratio) {
-                                        double scale = (double) window->width / width;
-                                        cairo_scale(window->cairo, scale, scale);
-                                        cairo_set_source_surface(window->cairo, image,
-                                                        0,
-                                                        (double) window->height/2 / scale - height/2);
-                                } else {
-                                        double scale = (double) window->height / height;
-                                        cairo_scale(window->cairo, scale, scale);
-                                        cairo_set_source_surface(window->cairo, image,
-                                                        (double) window->width/2 / scale - width/2,
-                                                        0);
-                                }
-                                break;
-                        }
-                        case SCALING_MODE_FIT:
-                        {
-                                double window_ratio = (double) window->width / window->height;
-                                double bg_ratio = width / height;
-
-                                if (window_ratio > bg_ratio) {
-                                        double scale = (double) window->height / height;
-                                        cairo_scale(window->cairo, scale, scale);
-                                        cairo_set_source_surface(window->cairo, image,
-                                                        (double) window->width/2 / scale - width/2,
-                                                        0);
-                                } else {
-                                        double scale = (double) window->width / width;
-                                        cairo_scale(window->cairo, scale, scale);
-                                        cairo_set_source_surface(window->cairo, image,
-                                                        0,
-                                                        (double) window->height/2 / scale - height/2);
-                                }
-                                break;
-                        }
-                        case SCALING_MODE_CENTER:
-                                cairo_set_source_surface(window->cairo, image,
-                                                (double) window->width/2 - width/2,
-                                                (double) window->height/2 - height/2);
-                                break;
-                        case SCALING_MODE_TILE:
-                        {
-                                cairo_pattern_t *pattern = cairo_pattern_create_for_surface(image);
-                                cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REPEAT);
-                                cairo_set_source(window->cairo, pattern);
-                                break;
-                        }
-                        default:
-                                sway_abort("Scaling mode '%s' not implemented yet!", scaling_mode_str);
-                        }
-
-                        cairo_paint(window->cairo);
-
-                        window_render(window);
-                }
+        // Attempt DRM+libinput
+
+        struct wlr_session *session = wlr_session_create(display);
+        if (!session) {
+                wlr_log(WLR_ERROR, "Failed to start a DRM session");
+                return NULL;
+        }
+
+        int gpu = wlr_session_find_gpu(session);
+        if (gpu == -1) {
+                wlr_log(WLR_ERROR, "Failed to open DRM device");
+                goto error_session;
         }
 
-        while (wl_display_dispatch(registry->display) != -1);
+        backend = wlr_multi_backend_create(session);
+        if (!backend) {
+                goto error_gpu;
+        }
 
-        for (i = 0; i < surfaces->length; ++i) {
-                struct window *window = surfaces->items[i];
-                window_teardown(window);
+        struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
+        if (!libinput) {
+                goto error_multi;
         }
-        list_free(surfaces);
-        registry_teardown(registry);
-        return 0;
+
+        struct wlr_backend *drm = wlr_drm_backend_create(display, session, gpu);
+        if (!drm) {
+                goto error_libinput;
+        }
+
+        wlr_multi_backend_add(backend, libinput);
+        wlr_multi_backend_add(backend, drm);
+        return backend;
+
+error_libinput:
+        wlr_backend_destroy(libinput);
+error_multi:
+        wlr_backend_destroy(backend);
+error_gpu:
+        wlr_session_close_file(session, gpu);
+error_session:
+        wlr_session_destroy(session);
+        return NULL;
 }
 ```