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package main
import (
"io"
"os"
"path/filepath"
"time"
"github.com/tinygo-org/tinygo/goenv"
)
// Return the newest timestamp of all the file paths passed in. Used to check
// for stale caches.
func cacheTimestamp(paths []string) (time.Time, error) {
var timestamp time.Time
for _, path := range paths {
st, err := os.Stat(path)
if err != nil {
return time.Time{}, err
}
if timestamp.IsZero() {
timestamp = st.ModTime()
} else if timestamp.Before(st.ModTime()) {
timestamp = st.ModTime()
}
}
return timestamp, nil
}
// Try to load a given file from the cache. Return "", nil if no cached file can
// be found (or the file is stale), return the absolute path if there is a cache
// and return an error on I/O errors.
//
// TODO: the configKey is currently ignored. It is supposed to be used as extra
// data for the cache key, like the compiler version and arguments.
func cacheLoad(name, configKey string, sourceFiles []string) (string, error) {
cachepath := filepath.Join(goenv.Get("GOCACHE"), name)
cacheStat, err := os.Stat(cachepath)
if os.IsNotExist(err) {
return "", nil // does not exist
} else if err != nil {
return "", err // cannot stat cache file
}
sourceTimestamp, err := cacheTimestamp(sourceFiles)
if err != nil {
return "", err // cannot stat source files
}
if cacheStat.ModTime().After(sourceTimestamp) {
return cachepath, nil
} else {
os.Remove(cachepath)
// stale cache
return "", nil
}
}
// Store the file located at tmppath in the cache with the given name. The
// tmppath may or may not be gone afterwards.
//
// Note: the configKey is ignored, see cacheLoad.
func cacheStore(tmppath, name, configKey string, sourceFiles []string) (string, error) {
// get the last modified time
if len(sourceFiles) == 0 {
panic("cache: no source files")
}
// TODO: check the config key
dir := goenv.Get("GOCACHE")
err := os.MkdirAll(dir, 0777)
if err != nil {
return "", err
}
cachepath := filepath.Join(dir, name)
err = moveFile(tmppath, cachepath)
if err != nil {
return "", err
}
return cachepath, nil
}
// moveFile renames the file from src to dst. If renaming doesn't work (for
// example, the rename crosses a filesystem boundary), the file is copied and
// the old file is removed.
func moveFile(src, dst string) error {
err := os.Rename(src, dst)
if err == nil {
// Success!
return nil
}
// Failed to move, probably a different filesystem.
// Do a copy + remove.
inf, err := os.Open(src)
if err != nil {
return err
}
defer inf.Close()
outpath := dst + ".tmp"
outf, err := os.Create(outpath)
if err != nil {
return err
}
_, err = io.Copy(outf, inf)
if err != nil {
os.Remove(outpath)
return err
}
err = outf.Close()
if err != nil {
return err
}
return os.Rename(dst+".tmp", dst)
}
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