krino: planning — chains, placeholders, conflicts, JSON

1 files changed, 41 insertions, 0 deletions

diff --git a/internal/dup/dup.go b/internal/dup/dup.go
index 502ef31..e3c7424 100644
--- a/internal/dup/dup.go
+++ b/internal/dup/dup.go
@@ -381,6 +381,47 @@ func readAt(f *os.File, off int64) ([]byte, error) {
 	return buf[:n], nil
 }
 
+// SameContent reports whether a and b hold identical content: a stat and
+// size check first, then the same partial/full hash comparison Lookup uses
+// for scanned candidates. Neither file needs to have been scanned or
+// indexed; this is the one place content identity is decided, so callers
+// outside this package must not hash a second way.
+func SameContent(a, b string) (bool, error) {
+	ai, err := os.Stat(a)
+	if err != nil {
+		return false, err
+	}
+	bi, err := os.Stat(b)
+	if err != nil {
+		return false, err
+	}
+	if ai.Size() != bi.Size() {
+		return false, nil
+	}
+
+	aPartial, err := computePartialHash(a)
+	if err != nil {
+		return false, err
+	}
+	bPartial, err := computePartialHash(b)
+	if err != nil {
+		return false, err
+	}
+	if aPartial != bPartial {
+		return false, nil
+	}
+
+	aFull, err := computeFullHash(a)
+	if err != nil {
+		return false, err
+	}
+	bFull, err := computeFullHash(b)
+	if err != nil {
+		return false, err
+	}
+	return aFull == bFull, nil
+}
+
 // computeFullHash hashes the whole file.
 func computeFullHash(path string) ([sha256.Size]byte, error) {
 	f, err := os.Open(path)