mirror of
https://github.com/cheat/cheat.git
synced 2024-12-04 20:05:10 +01:00
111 lines
3.9 KiB
Go
111 lines
3.9 KiB
Go
package repo
|
|
|
|
import (
|
|
"fmt"
|
|
"os"
|
|
"strings"
|
|
)
|
|
|
|
// GitDir returns `true` if we are iterating over a directory contained within
|
|
// a repositories `.git` directory.
|
|
func GitDir(path string) (bool, error) {
|
|
|
|
/*
|
|
A bit of context is called for here, because this functionality has
|
|
previously caused a number of tricky, subtle bugs.
|
|
|
|
Fundamentally, here we are simply trying to avoid walking over the
|
|
contents of the `.git` directory. Doing so potentially makes
|
|
hundreds/thousands of needless syscalls, and can noticeably harm
|
|
performance on machines with slow disks.
|
|
|
|
The earliest effort to solve this problem involved simply returning
|
|
`fs.SkipDir` when the cheatsheet file path began with `.`, signifying a
|
|
hidden directory. This, however, caused two problems:
|
|
|
|
1. The `.cheat` directory was ignored
|
|
2. Cheatsheets installed by `brew` (which were by default installed to
|
|
`~/.config/cheat`) were ignored
|
|
|
|
See: https://github.com/cheat/cheat/issues/690
|
|
|
|
To remedy this, the exclusion criteria were narrowed, and the search
|
|
for a literal `.` was replaced with a search for a literal `.git`.
|
|
This, however, broke user installations that stored cheatsheets in
|
|
`git` submodules, because such an installation would contain a `.git`
|
|
file that pointed to the upstream repository.
|
|
|
|
See: https://github.com/cheat/cheat/issues/694
|
|
|
|
The next attempt at solving this was to search for a `.git` literal
|
|
string in the cheatsheet file path. If a match was not found, we would
|
|
continue to walk the directory, as before.
|
|
|
|
If a match *was* found, we determined whether `.git` referred to a file
|
|
or directory, and would only stop walking the path in the latter case.
|
|
|
|
This, however, caused crashes if a cheatpath contained a `.gitignore`
|
|
file. (Presumably, a crash would likewise occur on the presence of
|
|
`.gitattributes`, `.gitmodules`, etc.)
|
|
|
|
See: https://github.com/cheat/cheat/issues/699
|
|
|
|
Accounting for all of the above (hopefully?), the current solution is
|
|
not to search for `.git`, but `.git/` (including the directory
|
|
separator), and then only ceasing to walk the directory on a match.
|
|
|
|
To summarize, this code must account for the following possibilities:
|
|
|
|
1. A cheatpath is not a repository
|
|
2. A cheatpath is a repository
|
|
3. A cheatpath is a repository, and contains a `.git*` file
|
|
4. A cheatpath is a submodule
|
|
5. A cheatpath is a hidden directory
|
|
|
|
Care must be taken to support the above on both Unix and Windows
|
|
systems, which have different directory separators and line-endings.
|
|
|
|
There is a lot of nuance to all of this, and it would be worthwhile to
|
|
do two things to stop writing bugs here:
|
|
|
|
1. Build integration tests around all of this
|
|
2. Discard string-matching solutions entirely, and use `go-git` instead
|
|
|
|
NB: A reasonable smoke-test for ensuring that skipping is being applied
|
|
correctly is to run the following command:
|
|
|
|
make && strace ./dist/cheat -l | wc -l
|
|
|
|
That check should be run twice: once normally, and once after
|
|
commenting out the "skip" check in `sheets.Load`.
|
|
|
|
The specific line counts don't matter; what matters is that the number
|
|
of syscalls should be significantly lower with the skip check enabled.
|
|
*/
|
|
|
|
// determine if the literal string `.git` appears within `path`
|
|
pos := strings.Index(path, fmt.Sprintf(".git%s", string(os.PathSeparator)))
|
|
|
|
// if it does not, we know for certain that we are not within a `.git`
|
|
// directory.
|
|
if pos == -1 {
|
|
return false, nil
|
|
}
|
|
|
|
// If `path` does contain the string `.git`, we need to determine if we're
|
|
// inside of a `.git` directory, or if `path` points to a cheatsheet that's
|
|
// stored within a `git` submodule.
|
|
//
|
|
// See: https://github.com/cheat/cheat/issues/694
|
|
|
|
// truncate `path` to the occurrence of `.git`
|
|
f, err := os.Stat(path[:pos+5])
|
|
if err != nil {
|
|
return false, fmt.Errorf("failed to stat path %s: %v", path, err)
|
|
}
|
|
|
|
// return true or false depending on whether the truncated path is a
|
|
// directory
|
|
return f.Mode().IsDir(), nil
|
|
}
|