List command, diff command, and snapshot search infrastructure

4 files changed, 214 insertions, 10 deletions

diff --git a/cmd/cat.go b/cmd/cat.go
index d5a275d..186f7da 100644
--- a/cmd/cat.go
+++ b/cmd/cat.go
@@ -3,19 +3,63 @@ package cmd
 import (
 	"fmt"
 	"golang.flu0r1ne.net/zfdiff/snap"
+	"os"
+	"io"
 )
 
 func Cat(params []string) {
-	if(len(params) == 0) {
+	n_params := len(params)
+
+	if(n_params == 0) {
 		die.Fatal("Reference file is required")
 	}
 
-	if(len(params) > 3) {
+	if(n_params > 3) {
 		die.Fatal("Too many arguments provided")
 	}
 
-	snapRef := snap.ToRelative(params[0])
-	reference := params[1]
+	var reference string
+	snapish := ""
+
+	if(n_params == 1) {
+		reference = params[0]
+	} else {
+		snapish, reference = params[0], params[1]
+	}
+
+	snapRef := snap.ToRelative(snapish)
+
+	oracle := snap.GetOracle(reference)
+
+	path := oracle.ResolveRelative(snapRef)
+
+	file, err := os.Open(path)
+
+	if err != nil {
+		die.Fatal("Could not open snapshot %s\nError: %v", path, err)
+	}
+
+	defer func() {
+        if err = file.Close(); err != nil {
+            die.Fatal("Could not close file %s\nError: %v", path, err)
+        }
+    }()
+
+	buf := make([]byte, 10*1024*1024) //10Ki
+
+    for {
+        n, err := file.Read(buf)
+
+        if n > 0 {
+            fmt.Printf("%s", buf[:n])
+        }
+
+        if err == io.EOF {
+            break
+        }
 
-	fmt.Println(snapRef, reference);
+        if err != nil {
+            die.Fatal("Encountered error while reading file: %v", err)
+        }
+    }
 }
\ No newline at end of file
diff --git a/cmd/list.go b/cmd/list.go
index 99d5f24..5849975 100644
--- a/cmd/list.go
+++ b/cmd/list.go
@@ -3,13 +3,14 @@ package cmd
 import (
 	"fmt"
 	"flag"
+	"golang.flu0r1ne.net/zfdiff/snap"
 )
 
 func List(params []string) {
 	flags := flag.NewFlagSet("list", flag.ExitOnError)
 
 	var withPaths bool
-
+	
 	withName := aliasedBoolVar(
 		flags,
 		&withPaths,
@@ -32,6 +33,19 @@ func List(params []string) {
 	
 	reference := flags.Arg(0)
 
-	fmt.Printf(reference)
-	fmt.Printf("Your flag is: %t", withPaths);
+	snaps := snap.GetTimeseries(reference)
+
+	for _, s := range snaps {
+		if s.Reference == "" {
+			continue
+		}
+
+		fmt.Printf("%s", s.Name)
+
+		if withPaths {
+			fmt.Printf(", %s", s.Reference)
+		}
+
+		fmt.Println("")
+	}
 }
diff --git a/snap/fs.go b/snap/fs.go
new file mode 100644
index 0000000..d0dc83d
--- /dev/null
+++ b/snap/fs.go
@@ -0,0 +1,147 @@
+package snap
+
+import (
+	"time"
+	"path/filepath"
+	"os"
+	"sort"
+)
+
+type Snapshot struct {
+	Name      string
+	ModTime   time.Time
+	Reference string
+}
+
+func getZFSRoot(reference string) string {
+	cursor := filepath.Dir(reference)
+	zfsNotFound := false
+
+	for !zfsNotFound {
+		zfsDir := filepath.Join(cursor, ".zfs")
+		
+		if _, err := os.Stat(zfsDir); !os.IsNotExist(err) {
+			break
+		} 
+
+		cursor = filepath.Join(cursor, "..")
+
+		zfsNotFound = filepath.ToSlash(cursor) == "/"
+	}
+
+	if(zfsNotFound) {
+		die.Fatal("Could not find a .zfs directory. Are you within a zfs dataset?")
+	}
+
+	return cursor
+}
+
+func getSnapshots(reference string) []*Snapshot {
+	zfsRoot := getZFSRoot(reference)
+
+	snapshotDir := filepath.Join(zfsRoot, ".zfs", "snapshot");
+
+	files, err := os.ReadDir(snapshotDir)
+	if err != nil {
+		die.Fatalf("Could not find the snapshots directory inside %s", snapshotDir);
+	}
+
+	relPath, err := filepath.Rel(zfsRoot, reference)
+	if err != nil {
+		die.Fatal("Could not find relative path to reference file: %v", err)
+	}
+
+	snaps := make([]*Snapshot, len(files))
+
+	for i, file := range files {
+
+		info, err := file.Info()
+		if(err != nil) {
+			die.Fatalf("Could not read file %v", err)
+		}
+
+		name := file.Name()
+		snaps[i] = &Snapshot{
+			Name: name,
+			ModTime: info.ModTime(),
+		}
+
+		pathInSnap := filepath.Join(snapshotDir, name, relPath)
+
+		if _, err := os.Stat(pathInSnap); err != nil {
+			if !os.IsNotExist(err) {
+				die.Fatalf("Error encountered while attempting to read reference file in snapshot:\n%v", err)
+			}
+		} else {
+			snaps[i].Reference = pathInSnap
+		}
+
+	}
+
+	return snaps
+}
+
+func GetTimeseries(reference string) []*Snapshot {
+	reference, err := filepath.Abs(reference)
+
+	if err != nil {
+	  die.Fatal(err)
+	}
+	
+	snaps := getSnapshots(reference)
+
+	sort.Slice(snaps, func(i, j int) bool {
+		return snaps[i].ModTime.Before(snaps[j].ModTime)
+	})
+
+	return snaps
+}
+
+func buildNameMap(snapTs []*Snapshot) map[string] int {
+	namemap := make(map[string] int)
+
+	for i, snap := range snapTs {
+		namemap[snap.Name] = i
+	}
+
+	return namemap
+}
+
+type SnapshotOracle struct {
+	timeseries []*Snapshot
+	namemap    map[string] int
+};
+
+func GetOracle(reference string) *SnapshotOracle {
+	timeseries := GetTimeseries(reference)
+	namemap := buildNameMap(timeseries)
+
+
+	return &SnapshotOracle {
+		timeseries,
+		namemap,
+	}
+}
+
+func (oracle *SnapshotOracle) ResolveRelative(ref *Relative) string {
+	n_ts := len(oracle.timeseries)
+	wanted := n_ts - 1
+
+	if ref.snapshot != "" {
+		id, ok := oracle.namemap[ref.snapshot]
+
+		if !ok {
+			die.Fatal("Could not find the snapshot %s", ref.snapshot)
+		}
+
+		wanted = id
+	}
+
+	wanted += ref.offset
+
+	if wanted < 0 || wanted >= n_ts {
+		die.Fatal("The snapshot you requested is out of range.")
+	}
+
+	return oracle.timeseries[wanted].Reference
+}
\ No newline at end of file
diff --git a/snap/parsing.go b/snap/parsing.go
index e878077..fcacec9 100644
--- a/snap/parsing.go
+++ b/snap/parsing.go
@@ -78,7 +78,7 @@ func ToRelative(snapish string) * Relative {
 		return ref;
 	}
 
-	if ref := parseRelativeSyntax(snapish, "~"); ref != nil {
+	if ref := parseRelativeSyntax(snapish, "^"); ref != nil {
 		ref.offset = -ref.offset;
 		return ref;
 	}
@@ -88,7 +88,6 @@ func ToRelative(snapish string) * Relative {
 	};
 }
 
-// FROM, TO
 func ParseDiff(snapdiff string) (fromRel, toRel *Relative) {
 	snapishes := strings.Split(snapdiff, "..")