feat(debug): add named buffer allocation with pattern filling

cmd/gasm/debug_linux_amd64.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"os"
 	"sort"
+	"strings"
 
 	"sourcedock.dev/petrbalvin/gasm-devkit/debug"
 	"sourcedock.dev/petrbalvin/gasm-devkit/verify"
@@ -32,6 +33,7 @@ REPL commands:
 	target := fs.Bool("target", false, "") // hidden: debuggee subprocess mode
 	funcName := fs.String("func", "", "function to debug")
 	argsFile := fs.String("args", "", "file containing the ABI0 argument block")
+	bufSpec := fs.String("buf", "", "buffer specification: name:size:pattern[,name:size:pattern...] where pattern is zero, ones, seq, or hex")
 	fs.Parse(args)
 
 	// --- Debuggee mode (internal, spawned by the debugger) ---
@@ -76,12 +78,79 @@ REPL commands:
 	}
 	sort.Slice(labels, func(i, j int) bool { return labels[i].Offset < labels[j].Offset })
 
-	// Launch the debuggee with a zeroed argument block.
-	argBlock := make([]byte, fl.Args)
-	sess, err := debug.Launch("", path, *funcName, argBlock)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "gasm debug: %v\n", err)
-		return 1
+	// Launch the debuggee with the argument block.
+	var argBlock []byte
+	var bufAddrs []uint64
+	var sess *debug.Session
+	if *bufSpec != "" {
+		// Parse the function signature to determine argument layout.
+		src, err := readSource(path)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm debug: %v\n", err)
+			return 1
+		}
+		sig, ok := verify.ExtractFuncSig(src, *funcName)
+		if !ok {
+			fmt.Fprintf(os.Stderr, "gasm debug: no // func signature found for %s\n", *funcName)
+			return 1
+		}
+		layout := verify.ArgLayout(sig)
+
+		// Parse the buffer spec to get buffer names.
+		bufNames := parseBufNames(*bufSpec)
+
+		// Allocate buffers in the debuggee.
+		argBlock = make([]byte, fl.Args)
+		sess, bufAddrs, err = debug.LaunchWithBuffers("", path, *funcName, argBlock, *bufSpec)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm debug: %v\n", err)
+			return 1
+		}
+
+		// Construct the argument block with buffer pointers at the correct positions.
+		bufIdx := 0
+		for _, arg := range layout {
+			if !arg.IsPtr {
+				continue
+			}
+			// Find the buffer that matches this argument.
+			for i, name := range bufNames {
+				if i < len(bufAddrs) && (name == arg.Name || strings.HasPrefix(arg.Name, name)) {
+					addr := bufAddrs[i]
+					off := arg.Offset
+					if off+8 <= len(argBlock) {
+						argBlock[off] = byte(addr)
+						argBlock[off+1] = byte(addr >> 8)
+						argBlock[off+2] = byte(addr >> 16)
+						argBlock[off+3] = byte(addr >> 24)
+						argBlock[off+4] = byte(addr >> 32)
+						argBlock[off+5] = byte(addr >> 40)
+						argBlock[off+6] = byte(addr >> 48)
+						argBlock[off+7] = byte(addr >> 56)
+					}
+					// For slices, also set the length and capacity.
+					if strings.HasPrefix(arg.Typ, "[]") && off+24 <= len(argBlock) {
+						// Find the buffer size from the spec.
+						size := parseBufSize(*bufSpec, name)
+						// Length at offset+8, capacity at offset+16.
+						for j := 0; j < 8; j++ {
+							argBlock[off+8+j] = byte(size >> (j * 8))
+							argBlock[off+16+j] = byte(size >> (j * 8))
+						}
+					}
+					bufIdx++
+					break
+				}
+			}
+		}
+		_ = bufIdx
+	} else {
+		argBlock = make([]byte, fl.Args)
+		sess, err = debug.Launch("", path, *funcName, argBlock)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "gasm debug: %v\n", err)
+			return 1
+		}
 	}
 	defer sess.Kill()
 
@@ -96,3 +165,29 @@ REPL commands:
 	debug.REPL(sess, bm, sess.CodeBase(), fl.Offset, fl.Size, fl.Args, labels, srcLines)
 	return 0
 }
+
+// parseBufNames extracts buffer names from a buffer specification.
+// Format: name:size:pattern[,name:size:pattern...]
+func parseBufNames(spec string) []string {
+	var names []string
+	for _, part := range strings.Split(spec, ",") {
+		fields := strings.SplitN(part, ":", 3)
+		if len(fields) >= 1 && fields[0] != "" {
+			names = append(names, fields[0])
+		}
+	}
+	return names
+}
+
+// parseBufSize extracts the size of a named buffer from a buffer specification.
+func parseBufSize(spec, name string) int {
+	for _, part := range strings.Split(spec, ",") {
+		fields := strings.SplitN(part, ":", 3)
+		if len(fields) >= 2 && fields[0] == name {
+			var size int
+			fmt.Sscanf(fields[1], "%d", &size)
+			return size
+		}
+	}
+	return 0
+}