Add comments and function descriptions

1 files changed, 21 insertions, 0 deletions

diff --git a/verifysetup/cmd/setup.go b/verifysetup/cmd/setup.go
index c2ba790..e946dd7 100644
--- a/verifysetup/cmd/setup.go
+++ b/verifysetup/cmd/setup.go
@@ -28,12 +28,15 @@ func NewSetupCommand() *cobra.Command {
 	return cmd
 }
 
+// checksumBlock is a function to create a chain of Nodes to verify an area of a block device.
+// It is meant to be run as a goroutine, taking a waitGroup as a parameter.
 func checksumBlock(blockStart int, blockEnd int, bundleSize int, diskBytes []byte, nodeChannel chan verify.Node, n int, waitGroup *sync.WaitGroup) {
 	defer waitGroup.Done()
 	defer close(nodeChannel)
 	var reader *bytes.Reader
 	node := verify.Node{}
 
+	// A block is 2000 bytes big
 	blockCount := math.Floor(float64(bundleSize / 2000))
 
 	for i := 0; i < int(blockCount); i++ {
@@ -51,6 +54,8 @@ func checksumBlock(blockStart int, blockEnd int, bundleSize int, diskBytes []byt
 		nodeChannel <- node
 	}
 
+	// Since it is unlikely that the bundleSize is perfectly divisible by 2000
+	// a final node has to be created that includes the last amount of bytes
 	block, err := core.ReadBlock(int(blockCount*2000), len(diskBytes), reader)
 	if err != nil {
 		fmt.Printf("%d:: final attempted reading from %d to %d. Error %s\n", blockStart, int(blockCount*2000)+2000, len(diskBytes), err)
@@ -65,6 +70,10 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 	if len(args) != 3 && len(args) != 4 {
 		return fmt.Errorf("Usage: verifysetup setup [partition] [procCount] [fsverify partition output] <minisign directory>")
 	}
+
+	// The minisign directory argument is optional
+	// which is why the existence of the argument is checked
+	// before minisignDir is set to a directory
 	var minisignDir string
 	if len(args) != 4 {
 		minisignDir = "./minisign/"
@@ -75,6 +84,7 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
+
 	fmt.Println("Using partition: ", args[0])
 	disk, err := os.Open(args[0])
 	if err != nil {
@@ -86,6 +96,7 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
+
 	diskSize := diskInfo.Size()
 	bundleSize := math.Floor(float64(diskSize / int64(procCount)))
 	blockCount := math.Ceil(float64(bundleSize / 2000))
@@ -95,10 +106,14 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 		return err
 	}
 
+	// To decrease the amount of file operations
+	// a single reader is created that gets used for the goroutines
 	reader := bytes.NewReader(diskBytes)
 	var waitGroup sync.WaitGroup
 	nodeChannels := make([]chan verify.Node, procCount+1)
 	for i := 0; i < procCount; i++ {
+		// Ensuring that each thread only reads the area it is meant to read
+		// by making a copy of the area which it gets access to
 		diskBytesCopy, err := verify.CopyByteArea(i*(int(bundleSize)), (i+1)*(int(bundleSize)), reader)
 		if err != nil {
 			return err
@@ -115,6 +130,10 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 		return err
 	}
 
+	// All generated nodes are written to the database at once
+	// while this is worse for the speed of verifysetup.
+	// it ensures that no write conflicts happen
+	// which could be caused by multiple threads accessing the same database
 	for i := 0; i < procCount; i++ {
 		channel := nodeChannels[i]
 		err = db.Batch(func(tx *bolt.Tx) error {
@@ -141,6 +160,8 @@ func SetupCommand(_ *cobra.Command, args []string) error {
 		return err
 	}
 
+	// The untrusted Signature is stored in a special way
+	// requiring special decoding of it to represent it as a string
 	var UntrustedSignature [2 + 8 + ed25519.SignatureSize]byte
 	binary.LittleEndian.PutUint16(UntrustedSignature[:2], sig.Algorithm)
 	binary.LittleEndian.PutUint64(UntrustedSignature[2:10], sig.KeyID)