chore: refactor sha validation

Signed-off-by: Abiola Ibrahim <[email protected]>

util/downloader/download.go

@@ -5,7 +5,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"strconv"
 	"strings"
 
 	"github.com/abiosoft/colima/config"
@@ -19,57 +18,6 @@ type (
 	guestActions = environment.GuestActions
 )
 
-type SHA struct {
-	URL    string // url to download the shasum file (if Digest is empty)
-	Size   int    // one of 256 or 512
-	Digest string // shasum
-}
-
-func (s SHA) validate(host hostActions, url, cacheFilename string) error {
-	if s.URL == "" && s.Digest == "" {
-		return fmt.Errorf("error validating SHA: one of Digest or URL must be set")
-	}
-
-	if s.Digest != "" {
-		s.Digest = strings.TrimPrefix(s.Digest, fmt.Sprintf("sha%d:", s.Size))
-	}
-
-	filename := func() string {
-		if url == "" {
-			return ""
-		}
-		split := strings.Split(url, "/")
-		return split[len(split)-1]
-	}()
-	dir, cacheFilename := filepath.Split(cacheFilename)
-
-	var script string
-
-	if s.Digest == "" {
-		script = strings.NewReplacer(
-			"{dir}", dir,
-			"{url}", s.URL,
-			"{filename}", filename,
-			"{size}", strconv.Itoa(s.Size),
-			"{cache_filename}", cacheFilename,
-		).Replace(
-			`cd {dir} && echo "$(curl -sL {url} | grep '  {filename}$' | awk -F' ' '{print $1}')  {cache_filename}" | shasum -a {size} --check --status`,
-		)
-	} else {
-		script = strings.NewReplacer(
-			"{dir}", dir,
-			"{digest}", s.Digest,
-			"{filename}", filename,
-			"{size}", strconv.Itoa(s.Size),
-			"{cache_filename}", cacheFilename,
-		).Replace(
-			`cd {dir} && echo "{digest}  {cache_filename}" | shasum -a {size} --check --status`,
-		)
-	}
-
-	return host.Run("sh", "-c", script)
-}
-
 // Request is download request
 type Request struct {
 	URL string // request URL
@@ -146,7 +94,7 @@ func (d downloader) downloadFile(r Request) (err error) {
 
 	// validate download if sha is present
 	if r.SHA != nil {
-		if err := r.SHA.validate(d.host, r.URL, cacheDownloadingFilename); err != nil {
+		if err := r.SHA.validateDownload(d.host, r.URL, cacheDownloadingFilename); err != nil {
 
 			// move file to allow subsequent re-download
 			// error discarded, would not be actioned anyways

util/downloader/sha.go

@@ -0,0 +1,75 @@
+package downloader
+
+import (
+	"fmt"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// SHA is the shasum of a file.
+type SHA struct {
+	Digest string // shasum
+	URL    string // url to download the shasum file (if Digest is empty)
+	Size   int    // one of 256 or 512
+}
+
+// Validate validates the SHA of the file.
+func (s SHA) Validate(host hostActions, file string) error {
+	dir, filename := filepath.Split(file)
+
+	script := strings.NewReplacer(
+		"{dir}", dir,
+		"{digest}", s.Digest,
+		"{size}", strconv.Itoa(s.Size),
+		"{filename}", filename,
+	).Replace(
+		`cd {dir} && echo "{digest}  {filename}" | shasum -a {size} --check --status`,
+	)
+
+	return host.Run("sh", "-c", script)
+}
+
+func (s SHA) validateDownload(host hostActions, url string, filename string) error {
+	if s.URL == "" && s.Digest == "" {
+		return fmt.Errorf("error validating SHA: one of Digest or URL must be set")
+	}
+
+	if s.Digest != "" {
+		s.Digest = strings.TrimPrefix(s.Digest, fmt.Sprintf("sha%d:", s.Size))
+	}
+
+	// fetch digest from URL if empty
+	if s.Digest == "" {
+		// retrieve the filename from the download url.
+		filename := func() string {
+			if url == "" {
+				return ""
+			}
+			split := strings.Split(url, "/")
+			return split[len(split)-1]
+		}()
+
+		digest, err := fetchSHAFromURL(host, s.URL, filename)
+		if err != nil {
+			return err
+		}
+		s.Digest = digest
+	}
+
+	return s.Validate(host, filename)
+}
+
+func fetchSHAFromURL(host hostActions, url, filename string) (string, error) {
+	script := strings.NewReplacer(
+		"{url}", url,
+		"{filename}", filename,
+	).Replace(
+		"curl -sL {url} | grep '  {filename}$' | awk -F' ' '{print $1}'",
+	)
+	sha, err := host.RunOutput("sh", "-c", script)
+	if err != nil {
+		return "", fmt.Errorf("error retrieving sha from url '%s': %w", url, err)
+	}
+	return strings.TrimSpace(sha), nil
+}