源码快照 @ 2026-09-01 (source-only, 剔除非源码素材)

packages/agent/runtimeprep/codex_user_instructions.go

@@ -0,0 +1,110 @@
+package runtimeprep
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// exposeUserCodexAgentsFile seeds the run-scoped instruction file with the
+// user's global Codex instructions. The session-owned file must be a copy:
+// WriteManagedBlock adds Tutti's managed policy to it and must never mutate the
+// user's real ~/.codex/AGENTS.md.
+func exposeUserCodexAgentsFile(codexHome string, userCodexHome string) error {
+	source := filepath.Join(userCodexHome, "AGENTS.md")
+	sourceContent, sourceExists, err := readRegularCodexAgentsFile(source)
+	if err != nil {
+		return err
+	}
+
+	target := filepath.Join(codexHome, "AGENTS.md")
+	targetInfo, err := os.Lstat(target)
+	if os.IsNotExist(err) {
+		if !sourceExists {
+			return nil
+		}
+		if err := writeRegularCodexAgentsFile(target, sourceContent); err != nil {
+			return fmt.Errorf("copy user codex AGENTS.md: %w", err)
+		}
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("inspect session codex AGENTS.md: %w", err)
+	}
+
+	// Always replace a pre-existing link with a private regular file. This
+	// prevents WriteManagedBlock from following a symlink or mutating a hardlink
+	// to the user's real ~/.codex/AGENTS.md on the next line of Prepare.
+	if targetInfo.Mode()&os.ModeSymlink != 0 {
+		if sourceExists {
+			if err := writeRegularCodexAgentsFile(target, sourceContent); err != nil {
+				return fmt.Errorf("replace session codex AGENTS.md link: %w", err)
+			}
+			return nil
+		}
+		if err := os.Remove(target); err != nil {
+			return fmt.Errorf("remove session codex AGENTS.md link: %w", err)
+		}
+		return nil
+	}
+	if !targetInfo.Mode().IsRegular() {
+		return fmt.Errorf("session codex AGENTS.md is not a regular file")
+	}
+
+	// Re-materialize an existing regular file too. A hardlink has regular-file
+	// mode, so an atomic replacement is what guarantees a new inode without
+	// discarding any session-local content already present in the file.
+	existing, err := os.ReadFile(target)
+	if err != nil {
+		return fmt.Errorf("read session codex AGENTS.md: %w", err)
+	}
+	if err := writeRegularCodexAgentsFile(target, existing); err != nil {
+		return fmt.Errorf("isolate session codex AGENTS.md: %w", err)
+	}
+	return nil
+}
+
+func readRegularCodexAgentsFile(path string) ([]byte, bool, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, false, nil
+		}
+		return nil, false, fmt.Errorf("inspect user codex AGENTS.md: %w", err)
+	}
+	if !info.Mode().IsRegular() {
+		// AGENTS.md is optional. Ignore directories, FIFOs, and other special
+		// files instead of blocking runtime preparation while reading them.
+		return nil, false, nil
+	}
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return nil, false, fmt.Errorf("read user codex AGENTS.md: %w", err)
+	}
+	return content, true, nil
+}
+
+func writeRegularCodexAgentsFile(path string, content []byte) error {
+	temporary, err := os.CreateTemp(filepath.Dir(path), ".codex-agents-*.tmp")
+	if err != nil {
+		return err
+	}
+	temporaryPath := temporary.Name()
+	defer func() {
+		_ = temporary.Close()
+		_ = os.Remove(temporaryPath)
+	}()
+	if err := temporary.Chmod(0o600); err != nil {
+		return err
+	}
+	if _, err := temporary.Write(content); err != nil {
+		return err
+	}
+	if err := temporary.Sync(); err != nil {
+		return err
+	}
+	if err := temporary.Close(); err != nil {
+		return err
+	}
+	return os.Rename(temporaryPath, path)
+}