fix: cp时kernel panic和rmdir输出错误信息

[1037827920]

Type

Bug fix, Enhancement

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Description

此 PR 包含了对文件系统 VFS 相关的多个修复和增强。在 open、syscall 和 utils 模块中，针对 cp、rmdir 等命令的错误处理进行了优化，减少了内核恐慌的风险，并提高了错误信息的可读性。同时，对路径解析功能进行了修复，确保在处理空路径时能够返回正确的错误码。

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Changes walkthrough

	Relevant files
Bug fix	open.rs 修复 `cp` 和 `rmdir` 命令相关错误                                                                                  kernel/src/filesystem/vfs/open.rs 修复了在执行 cp 命令时可能导致的内核恐慌问题。 修复了 rmdir 命令的错误信息输出。 utils.rs 优化路径解析功能                                                                                                                  kernel/src/filesystem/vfs/utils.rs 增加了对空路径的处理，避免在路径为空时执行 lookup。
Enhancement	syscall.rs 完善文件权限设置和目录删除功能的错误处理                                                                                          kernel/src/filesystem/vfs/syscall.rs 完善了 do_fchmodat 函数的错误处理。 在删除目录的 syscall 处理中，增加了错误日志的输出。

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[dragonos-community-ai-pr-reviewer]

PR Description updated to latest commit (d5f440d)

[dragonos-community-ai-pr-reviewer]

PR Analysis

• 🎯 Main theme: 此PR主要包含了对文件系统VFS相关的多个修复和增强，包括优化cp、rmdir等命令的错误处理，减少内核恐慌的风险，并提高错误信息的可读性。同时，对路径解析功能进行了修复，确保在处理空路径时能够返回正确的错误码。
• 📝 PR summary: 这是一个包含多个修复和增强的PR，主要针对文件系统VFS进行优化，提高了系统的稳定性和错误处理能力。
• 📌 Type of PR: Bug fix, Enhancement
• 🧪 Relevant tests added: False
• ⏱️ Estimated effort to review [1-5]: 3，因为需要仔细检查修复的代码是否正确，以及是否有潜在的问题。
• 🔒 Security concerns: No，这个PR代码没有引入可能的漏洞。

PR Feedback

💡 General suggestions: 修复和增强的代码应该能够解决实际问题，并且代码质量高。建议在提交PR前，对修复的代码进行充分的测试，以确保其正确性和稳定性。

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[dragonos-community-ai-pr-reviewer]

PR Code Suggestions

	Suggestions
bug	检查文件路径长度和有效性，避免无效路径带来的错误。                                                     在处理文件路径时，应确保路径有效，避免无效路径带来的错误。建议检查路径长度是否超过限制，以及路径是否为空。 kernel/src/filesystem/vfs/open.rs [36] let path = check_and_clone_cstr(path, Some(MAX_PATHLEN))?; -if path.len() == 0 { +if path.is_empty() { return Err(SystemError::EINVAL); } 检查路径是否为空，避免空路径带来的错误。                                                          在解析路径时，应检查路径是否为空，避免空路径带来的错误。 kernel/src/filesystem/vfs/utils.rs [38] +if path.is_empty() { + return Err(SystemError::EINVAL); +} let mut inode = ROOT_INODE(); let ret_path; // 如果path不是绝对路径，则需要拼接
enhancement	记录文件系统操作的错误信息。                                                                当文件系统操作失败时，应记录详细的错误信息，以便于调试。 kernel/src/filesystem/vfs/syscall.rs [554] match do_remove_dir(dirfd, &pathname) { Err(err) => { + kerror!("Failed to Remove Directory, Error Code = {:?}", err); return Err(err); } Ok(_) => {

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[fslongjin]

#568

[schulice]

如果把判空逻辑写在user_path_at的话，把unlink进来的c字符串空判定也改了吧。不过我查了下linux的实现，它在fs/namei.c:130下的getname_flags中判空和其他判定，最后返回一个path的结构体。或许我们可以实现类似的函数，在syscall的match时调用，可以先只检查len的长度和trim，返回一个不用再判定的str，后续也方便扩展。

[schulice]

错误码可能也要改下，贴一段在linux代码中的说明。
POSIX.1 2.4: an empty pathname is invalid (ENOENT). PATH_MAX includes the nul terminator --RR