Next to including several files, our "common.h" header also declares various macros which are then used throughout the project. As such, we have to make sure to always include this file first in all implementation files. Otherwise, we might encounter problems or even silent behavioural differences due to macros or defines not being defined as they should be. So in fact, our header and implementation files should make sure to always include "common.h" first. This commit does so by establishing a common include pattern. Header files inside of "src" will now always include "common.h" as its first other file, separated by a newline from all the other includes to make it stand out as special. There are two cases for the implementation files. If they do have a matching header file, they will always include this one first, leading to "common.h" being transitively included as first file. If they do not have a matching header file, they instead include "common.h" as first file themselves. This fixes the outlined problems and will become our standard practice for header and source files inside of the "src/" from now on.
Short-circuit the call to `git_path_resolve_relative` in case `git_buf_joinpath` returns an error. While this does not fix any immediate errors, the resulting code is easier to read and handles potential new error conditions raised by `git_buf_joinpath`.
In the `_check_dir_contents` function, we first allocate memory for joining the directory and subdirectory together and afterwards use `git_buf_joinpath`. While this function in fact should not fail as memory is already allocated, err on the safe side and check for returned errors.
When calling `git_path_dirname_r` on a Win32 prefix, e.g. a drive or network share prefix, we always want to return the trailing '/'. This does not work currently when passing in a path like 'C:', where the '/' would not be appended correctly. Fix this by appending a '/' if we try to normalize a Win32 prefix and there is no trailing '/'.
Getting the dirname of a filesystem root should return the filesystem root itself. E.g. the dirname of "/" is always "/". On Windows, we emulate this behavior and as such, we should return e.g. "C:/" if calling dirname on "C:/". But we currently fail to do so and instead return ".", as we do not check if we actually have a Windows prefix before stripping off the last directory component. Fix this by calling out to `win32_prefix_length` immediately after stripping trailing slashes, returning early if we have a prefix.
Extract code which determines if a path is at a Windows system's root. This incluses drive prefixes (e.g. "C:\") as well as network computer names (e.g. "//computername/").
Error messages should be sentence fragments, and therefore: 1. Should not begin with a capital letter, 2. Should not conclude with punctuation, and 3. Should not end a sentence and begin a new one
On Windows we can find locked files even when reading a reference or the packed-refs file. Bubble up the error in this case as well to allow callers on Windows to retry more intelligently.