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https://github.com/sipeed/picoclaw.git
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mosir
98 lines
2.7 KiB
Go
98 lines
2.7 KiB
Go
// PicoClaw - Ultra-lightweight personal AI agent
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// Inspired by and based on nanobot: https://github.com/HKUDS/nanobot
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// License: MIT
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//
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// Copyright (c) 2026 PicoClaw contributors
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package utils
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import (
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"fmt"
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"os"
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"path/filepath"
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)
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// WriteFileAtomic atomically writes data to a file using a temp file + rename pattern.
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//
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// This guarantees that the target file is either:
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// - Completely written with the new data
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// - Unchanged (if write fails or power loss during write)
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//
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// The function:
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// 1. Creates a temp file in the same directory
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// 2. Writes data to temp file
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// 3. Syncs to disk (critical for SD cards/flash storage)
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// 4. Sets file permissions
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// 5. Atomically renames temp file to target path
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//
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// Parameters:
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// - path: Target file path
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// - data: Data to write
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// - perm: File permission mode (e.g., 0o600 for secure, 0o644 for readable)
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//
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// Returns:
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// - Error if any step fails, nil on success
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//
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// Example:
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//
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// // Secure config file (owner read/write only)
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// err := utils.WriteFileAtomic("config.json", data, 0o600)
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//
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// // Public readable file
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// err := utils.WriteFileAtomic("public.txt", data, 0o644)
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func WriteFileAtomic(path string, data []byte, perm os.FileMode) error {
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dir := filepath.Dir(path)
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if err := os.MkdirAll(dir, 0o755); err != nil {
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return fmt.Errorf("failed to create directory: %w", err)
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}
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// Create temp file in the same directory (ensures atomic rename works)
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tmpFile, err := os.CreateTemp(dir, ".tmp-*.tmp")
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if err != nil {
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return fmt.Errorf("failed to create temp file: %w", err)
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}
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tmpPath := tmpFile.Name()
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// Cleanup on error: ensure temp file is removed if anything fails
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cleanup := true
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defer func() {
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if cleanup {
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_ = os.Remove(tmpPath)
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}
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}()
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// Write data to temp file
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if _, err := tmpFile.Write(data); err != nil {
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tmpFile.Close()
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return fmt.Errorf("failed to write temp file: %w", err)
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}
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// CRITICAL: Force sync to storage medium before rename.
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// This ensures data is physically written to disk, not just cached.
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// Essential for SD cards, eMMC, and other flash storage on edge devices.
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if err := tmpFile.Sync(); err != nil {
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tmpFile.Close()
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return fmt.Errorf("failed to sync temp file: %w", err)
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}
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// Set file permissions
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if err := tmpFile.Chmod(perm); err != nil {
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tmpFile.Close()
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return fmt.Errorf("failed to set permissions: %w", err)
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}
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// Close file before rename
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if err := tmpFile.Close(); err != nil {
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return fmt.Errorf("failed to close temp file: %w", err)
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}
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// Atomic rename: temp file becomes the target
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if err := os.Rename(tmpPath, path); err != nil {
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return fmt.Errorf("failed to rename temp file: %w", err)
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}
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// Success: skip cleanup
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cleanup = false
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return nil
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}
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