internal/pkg: populate substitute status

These are not created when taking the fast path, but should be inherited from the alternative.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg.go

@@ -509,36 +509,32 @@ const (
 )
 
 const (
-	// fileLock is the file name appended to Cache.base for guaranteeing
-	// exclusive access to the cache directory.
+	// fileLock is the lock file for exclusive access to the cache directory.
 	fileLock = "lock"
-	// fileVariant is the file name appended to Cache.base holding the variant
-	// identification string set by a prior call to [SetExtension].
+	// fileVariant is a file holding the variant identification string set by a
+	// prior call to [SetExtension].
 	fileVariant = "variant"
 
-	// dirSubstitute is the directory name appended to Cache.base for linking
-	// artifacts named after their substitute identifier.
+	// dirSubstitute holds symlinks to artifacts by checksum, named after their
+	// substitute identifier.
 	dirSubstitute = "substitute"
-	// dirIdentifier is the directory name appended to Cache.base for storing
-	// artifacts named after their [ID].
+	// dirIdentifier holds symlinks to artifacts by checksum,  named after their
+	// IR-based identifier.
 	dirIdentifier = "identifier"
-	// dirChecksum is the directory name appended to Cache.base for storing
-	// artifacts named after their [Checksum].
+	// dirChecksum holds artifacts named after their [Checksum].
 	dirChecksum = "checksum"
-	// dirStatus is the directory name appended to Cache.base for storing
-	// artifact metadata and logs named after their [ID].
+	// dirStatus holds artifact metadata and logs named after their IR-based
+	// identifier. For [FloodArtifact], the same file is also available under
+	// its substitute identifier.
 	dirStatus = "status"
 
-	// dirWork is the directory name appended to Cache.base for working
-	// pathnames set up during [Cache.Cure].
+	// dirWork holds working pathnames set up during [Cache.Cure].
 	dirWork = "work"
-	// dirTemp is the directory name appended to Cache.base for scratch space
-	// pathnames allocated during [Cache.Cure].
+	// dirTemp holds scratch space allocated during [Cache.Cure].
 	dirTemp = "temp"
 
-	// dirExecScratch is the directory name appended to Cache.base for scratch
-	// space setting up the container started by [Cache.EnterExec]. Exclusivity
-	// via Cache.inExec.
+	// dirExecScratch is scratch space set up for the container started by
+	// [Cache.EnterExec]. Exclusivity via Cache.inExec.
 	dirExecScratch = "scratch"
 
 	// checksumLinknamePrefix is prepended to the encoded [Checksum] value
@@ -1995,10 +1991,11 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 		buf := c.getIdentBuf()
 		sh.Sum(buf[wordSize:wordSize])
 		substitute = unique.Make(ID(buf[wordSize:]))
+		substitutes := Encode(substitute.Value())
 		c.putIdentBuf(buf)
 		alternative = c.base.Append(
 			dirSubstitute,
-			Encode(substitute.Value()),
+			substitutes,
 		)
 
 		if c.flags&CIgnoreSubstitutes == 0 {
@@ -2014,6 +2011,17 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 					dirChecksum,
 					checksums,
 				)
+				if _, err = os.Lstat(c.base.Append(
+					dirStatus,
+					substitutes,
+				).String()); err == nil {
+					err = os.Symlink(substitutes, c.base.Append(
+						dirStatus,
+						ids,
+					).String())
+				} else if errors.Is(err, os.ErrNotExist) {
+					err = nil
+				}
 				return
 			}
 		}
@@ -2023,6 +2031,15 @@ func (c *Cache) cure(a Artifact, curesExempt bool) (
 			return
 		}
 		err = ca.Cure(&f)
+		if err == nil && f.status != nil {
+			err = os.Link(c.base.Append(
+				dirStatus,
+				ids,
+			).String(), c.base.Append(
+				dirStatus,
+				substitutes,
+			).String())
+		}
 		c.exitCure(a, curesExempt)
 		if err != nil {
 			return

internal/pkg/pkg_test.go

@@ -1059,8 +1059,14 @@ func TestCache(t *testing.T) {
 						"_EmV5nsYZ2UWHgRmLDMU8i-rJWDx-kv5_1pFrzQI7vMMCM5mAXivO8UZtVfOqMR_",
 					), want, nil},
 				})
-
 			}
+
+			if dents, err := os.ReadDir(base.Append("status").String()); err != nil {
+				t.Fatal(err)
+			} else if len(dents) > 0 {
+				t.Errorf("ReadDir: %v", dents)
+			}
+
 		}, expectsFS{
 			".": {Mode: fs.ModeDir | 0700},