cmd/docker: fix stringSliceReplaceAt with overlapping matches

Inline the sub-slice lookup into stringSliceReplaceAt and use
slices.Equal to compare candidate ranges. When a specific index is
required, check that position directly instead of searching the full
slice.

This also fixes overlapping matches and uses slices.Concat to construct
the replacement result.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cmd/docker/aliases_utils.go

@@ -1,32 +1,26 @@
 package main
 
-func stringSliceIndex(s, subs []string) int {
-	j := 0
-	if len(subs) > 0 {
-		for i, x := range s {
-			if j < len(subs) && subs[j] == x {
-				j++
-			} else {
-				j = 0
-			}
-			if len(subs) == j {
-				return i + 1 - j
-			}
-		}
-	}
-	return -1
-}
+import "slices"
 
-// stringSliceReplaceAt replaces the sub-slice find, with the sub-slice replace, in the string
-// slice s, returning a new slice and a boolean indicating if the replacement happened.
-// requireIdx is the index at which old needs to be found at (or -1 to disregard that).
+// stringSliceReplaceAt replaces the sub-slice find with the sub-slice replace in s,
+// returning a new slice and a boolean indicating whether the replacement happened.
+// requireIndex is the index at which find must be found, or -1 to disregard it.
 func stringSliceReplaceAt(s, find, replace []string, requireIndex int) ([]string, bool) {
-	idx := stringSliceIndex(s, find)
-	if (requireIndex != -1 && requireIndex != idx) || idx == -1 {
+	if len(find) == 0 {
 		return s, false
 	}
-	out := append([]string{}, s[:idx]...)
-	out = append(out, replace...)
-	out = append(out, s[idx+len(find):]...)
-	return out, true
+
+	if requireIndex >= 0 {
+		if requireIndex+len(find) > len(s) || !slices.Equal(s[requireIndex:requireIndex+len(find)], find) {
+			return s, false
+		}
+		return slices.Concat(s[:requireIndex], replace, s[requireIndex+len(find):]), true
+	}
+
+	for i := range len(s) - len(find) + 1 {
+		if slices.Equal(s[i:i+len(find)], find) {
+			return slices.Concat(s[:i], replace, s[i+len(find):]), true
+		}
+	}
+	return s, false
 }

cmd/docker/aliases_utils_test.go

@@ -65,6 +65,15 @@ func TestStringSliceReplaceAt(t *testing.T) {
 			requireIndex: -1,
 			expected:     []string{"foo"},
 		},
+		{
+			name:         "overlapping match",
+			s:            []string{"a", "a", "b"},
+			find:         []string{"a", "b"},
+			replace:      []string{"c"},
+			requireIndex: -1,
+			expected:     []string{"a", "c"},
+			ok:           true,
+		},
 	}
 
 	for _, tc := range tests {