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package cmd
import (
"fmt"
"io"
"log"
"net/http"
"os"
"path/filepath"
"strings"
"github.com/direnv/direnv/v2/pkg/sri"
"github.com/mattn/go-isatty"
)
// CmdFetchURL is `direnv fetchurl <url> [<integrity-hash>]`
var CmdFetchURL = &Cmd{
Name: "fetchurl",
Desc: "Fetches a given URL into direnv's CAS",
Args: []string{"<url>", "[<integrity-hash>]"},
Action: actionWithConfig(cmdFetchURL),
}
func cmdFetchURL(_ Env, args []string, config *Config) (err error) {
if len(args) < 2 {
return fmt.Errorf("missing URL argument")
}
var (
algo = sri.SHA256
url string
integrityHash string
)
casDir := casDir(config)
isTTY := isatty.IsTerminal(os.Stdout.Fd())
url = args[1]
// Validate the SRI hash if it exists
if len(args) > 2 {
// Support Base64 where '/' have been replaced by '_'
integrityHash = strings.ReplaceAll(args[2], "_", "/")
hash, err := sri.Parse(integrityHash)
if err != nil {
return err
}
// Shortcut if the cache already has the file
casFile := casPath(casDir, hash)
if fileExists(casFile) {
fmt.Println(casFile)
return nil
}
}
// Create the CAS directory if it doesn't exist
if err = os.MkdirAll(casDir, os.FileMode(0755)); err != nil {
return err
}
// Create a temporary file to copy the content into, before the CAS file
// location can be calculated.
tmpfile, err := os.CreateTemp(casDir, "tmp")
if err != nil {
return err
}
defer func() {
if err := os.Remove(tmpfile.Name()); err != nil {
log.Printf("Warning: failed to remove temp file %s: %v", tmpfile.Name(), err)
}
}() // clean up
defer func() {
if err := tmpfile.Close(); err != nil {
log.Printf("Warning: failed to close temp file: %v", err)
}
}()
// Get the URL
// G107: Potential HTTP request made with variable url
// #nosec
resp, err := http.Get(url)
if err != nil {
return err
}
defer func() {
if err := resp.Body.Close(); err != nil {
log.Printf("Warning: failed to close response body: %v", err)
}
}()
// Abort if we don't get a 200 back
if resp.StatusCode != 200 {
return fmt.Errorf("expected status code 200 but got %d", resp.StatusCode)
}
// While copying the content into the temporary location, also calculate the
// SRI hash.
w := sri.NewWriter(tmpfile, algo)
if _, err = io.Copy(w, resp.Body); err != nil {
return err
}
// Here is the new SRI hash
calculatedHash := w.Sum()
// Make the file read-only and executable for later
if err = os.Chmod(tmpfile.Name(), os.FileMode(0500)); err != nil {
return err
}
// Validate if a comparison hash was given
if integrityHash != "" && calculatedHash.String() != integrityHash {
return fmt.Errorf("hash mismatch. Expected '%s' but got '%s'", integrityHash, calculatedHash.String())
}
// Derive the CAS file location from the SRI hash
casFile := casPath(casDir, calculatedHash)
// Put the file into the CAS store if it's not already there
if !fileExists(casFile) {
err = tmpfile.Close()
if err != nil {
return err
}
// Move the temporary file to the CAS location.
if err = os.Rename(tmpfile.Name(), casFile); err != nil {
return err
}
}
if integrityHash == "" {
if isTTY {
// Print an example for terminal users
fmt.Printf(`Found hash: %s
Invoke fetchurl again with the hash as an argument to get the disk location:
direnv fetchurl "%s" "%s"
#=> %s
`, calculatedHash, url, calculatedHash.String(), casFile)
} else {
// Only print the hash in scripting mode. Add one extra hurdle on
// purpose to use fetchurl without the SRI hash.
_, err = fmt.Println(calculatedHash)
}
} else {
// Print the location to the CAS file
_, err = fmt.Println(casFile)
}
return err
}
func casDir(c *Config) string {
return filepath.Join(c.CacheDir, "cas")
}
// casPath returns filesystem path for SRI hashes
func casPath(dir string, integrityHash *sri.Hash) string {
// Use Hex encoding for the filesystem to avoid issues
sriFile := integrityHash.Hex()
return filepath.Join(dir, sriFile)
}
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