vcs: version int 32 and revision method v0.7.6

Author: TobiasGleiter

vcs/vcs.go

@@ -7,11 +7,13 @@ package vcs
 import (
 	"fmt"
 	"runtime/debug"
+	"strconv"
 )
 
-// Version returns the build time and revision information.
-// The returned string format is "time-revision" or "time-revision-dirty"
+// Version returns the build time, revision hash, and revision integer.
+// The returned string format is "time-revision-int" or "time-revision-int-dirty"
 // if the working directory had uncommitted changes at build time.
+// The integer is derived from the first 4 bytes of the git revision hash.
 func Version() string {
 	var (
 		time     string
@@ -35,9 +37,79 @@ func Version() string {
 		}
 	}
 
+	revInt, err := revisionToInt(revision)
+	if err != nil {
+		revInt = 0
+	}
+
 	if modified {
-		return fmt.Sprintf("%s-%s-dirty", time, revision)
+		return fmt.Sprintf("%s-%s-%d-dirty", time, revision, revInt)
+	}
+
+	return fmt.Sprintf("%s-%s-%d", time, revision, revInt)
+}
+
+// revisionToInt converts the first 4 bytes (8 hex characters) of a git revision hash
+// to a signed 32-bit integer suitable for use as SQLite user_version.
+// The conversion uses the first 8 hex characters of the hash, which are
+// cryptographically random and uniformly distributed.
+//
+// Example: "abc123def456..." -> 0xabc123de -> -1412567330
+//
+// Returns an error if the revision is too short (< 8 characters) or contains
+// invalid hexadecimal characters.
+func revisionToInt(revision string) (int32, error) {
+	if len(revision) < 8 {
+		return 0, fmt.Errorf("revision too short: need at least 8 characters, got %d", len(revision))
+	}
+
+	// Take first 8 hex characters (4 bytes)
+	hexStr := revision[:8]
+
+	// Parse as uint32 first to handle the full range
+	val, err := strconv.ParseUint(hexStr, 16, 32)
+	if err != nil {
+		return 0, fmt.Errorf("failed to parse revision hex: %w", err)
+	}
+
+	// Convert to int32 (may be negative due to sign bit)
+	return int32(val), nil
+}
+
+// VersionInt32 returns the git revision hash and its integer representation.
+// The integer is derived from the first 4 bytes (8 hex characters) of the
+// revision hash and is suitable for use as SQLite user_version (signed 32-bit integer).
+//
+// This function extracts the vcs.revision value from the build information
+// embedded in the binary during compilation with -buildvcs flag.
+//
+// Returns:
+//   - revision: The full git commit hash (e.g., "abc123def456...")
+//   - revisionInt: A signed 32-bit integer representation (e.g., -1412567330)
+//   - error: Non-nil if build info is unavailable, revision not found, or parsing fails
+func VersionInt32() (string, int32, error) {
+	var revision string
+
+	bi, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", 0, fmt.Errorf("build info not available")
+	}
+
+	for _, s := range bi.Settings {
+		if s.Key == "vcs.revision" {
+			revision = s.Value
+			break
+		}
+	}
+
+	if revision == "" {
+		return "", 0, fmt.Errorf("vcs.revision not found in build info")
+	}
+
+	revInt, err := revisionToInt(revision)
+	if err != nil {
+		return revision, 0, err
 	}
 
-	return fmt.Sprintf("%s-%s", time, revision)
+	return revision, revInt, nil
 }