vendor: update buildkit to master@31c870e82a48

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/in-toto/in-toto-golang/in_toto/rulelib.go

@@ -0,0 +1,131 @@
+package in_toto
+
+import (
+	"fmt"
+	"strings"
+)
+
+// An error message issued in UnpackRule if it receives a malformed rule.
+var errorMsg = "Wrong rule format, available formats are:\n" +
+	"\tMATCH <pattern> [IN <source-path-prefix>] WITH (MATERIALS|PRODUCTS)" +
+	" [IN <destination-path-prefix>] FROM <step>,\n" +
+	"\tCREATE <pattern>,\n" +
+	"\tDELETE <pattern>,\n" +
+	"\tMODIFY <pattern>,\n" +
+	"\tALLOW <pattern>,\n" +
+	"\tDISALLOW <pattern>,\n" +
+	"\tREQUIRE <filename>\n\n"
+
+/*
+UnpackRule parses the passed rule and extracts and returns the information
+required for rule processing.  It can be used to verify if a rule has a valid
+format.  Available rule formats are:
+
+	MATCH <pattern> [IN <source-path-prefix>] WITH (MATERIALS|PRODUCTS)
+		[IN <destination-path-prefix>] FROM <step>,
+	CREATE <pattern>,
+	DELETE <pattern>,
+	MODIFY <pattern>,
+	ALLOW <pattern>,
+	DISALLOW <pattern>
+
+Rule tokens are normalized to lower case before returning.  The returned map
+has the following format:
+
+	{
+		"type": "match" | "create" | "delete" |"modify" | "allow" | "disallow"
+		"pattern": "<file name pattern>",
+		"srcPrefix": "<path or empty string>", // MATCH rule only
+		"dstPrefix": "<path or empty string>", // MATCH rule only
+		"dstType": "materials" | "products">, // MATCH rule only
+		"dstName": "<step name>", // Match rule only
+	}
+
+If the rule does not match any of the available formats the first return value
+is nil and the second return value is the error.
+*/
+func UnpackRule(rule []string) (map[string]string, error) {
+	// Cache rule len
+	ruleLen := len(rule)
+
+	// Create all lower rule copy to case-insensitively parse out tokens whose
+	// position we don't know yet. We keep the original rule to retain the
+	// non-token elements' case.
+	ruleLower := make([]string, ruleLen)
+	for i, val := range rule {
+		ruleLower[i] = strings.ToLower(val)
+	}
+
+	switch ruleLower[0] {
+	case "create", "modify", "delete", "allow", "disallow", "require":
+		if ruleLen != 2 {
+			return nil,
+				fmt.Errorf("%s Got:\n\t %s", errorMsg, rule)
+		}
+
+		return map[string]string{
+			"type":    ruleLower[0],
+			"pattern": rule[1],
+		}, nil
+
+	case "match":
+		var srcPrefix string
+		var dstType string
+		var dstPrefix string
+		var dstName string
+
+		// MATCH <pattern> IN <source-path-prefix> WITH (MATERIALS|PRODUCTS) \
+		// IN <destination-path-prefix> FROM <step>
+		if ruleLen == 10 && ruleLower[2] == "in" &&
+			ruleLower[4] == "with" && ruleLower[6] == "in" &&
+			ruleLower[8] == "from" {
+			srcPrefix = rule[3]
+			dstType = ruleLower[5]
+			dstPrefix = rule[7]
+			dstName = rule[9]
+			// MATCH <pattern> IN <source-path-prefix> WITH (MATERIALS|PRODUCTS) \
+			// FROM <step>
+		} else if ruleLen == 8 && ruleLower[2] == "in" &&
+			ruleLower[4] == "with" && ruleLower[6] == "from" {
+			srcPrefix = rule[3]
+			dstType = ruleLower[5]
+			dstPrefix = ""
+			dstName = rule[7]
+
+			// MATCH <pattern> WITH (MATERIALS|PRODUCTS) IN <destination-path-prefix>
+			// FROM <step>
+		} else if ruleLen == 8 && ruleLower[2] == "with" &&
+			ruleLower[4] == "in" && ruleLower[6] == "from" {
+			srcPrefix = ""
+			dstType = ruleLower[3]
+			dstPrefix = rule[5]
+			dstName = rule[7]
+
+			// MATCH <pattern> WITH (MATERIALS|PRODUCTS) FROM <step>
+		} else if ruleLen == 6 && ruleLower[2] == "with" &&
+			ruleLower[4] == "from" {
+			srcPrefix = ""
+			dstType = ruleLower[3]
+			dstPrefix = ""
+			dstName = rule[5]
+
+		} else {
+			return nil,
+				fmt.Errorf("%s Got:\n\t %s", errorMsg, rule)
+
+		}
+
+		return map[string]string{
+			"type":      ruleLower[0],
+			"pattern":   rule[1],
+			"srcPrefix": srcPrefix,
+			"dstPrefix": dstPrefix,
+			"dstType":   dstType,
+			"dstName":   dstName,
+		}, nil
+
+	default:
+		return nil,
+			fmt.Errorf("%s Got:\n\t %s", errorMsg, rule)
+	}
+}