实现SYS_LINK和SYS_LINKAT #611
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@schulice: no appropriate reviewer found, use r? to override |
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PR Description updated to latest commit (04a8ab0) |
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对于这两个建议。1. fd是否有效在user_path_at中会检查（AT_EMPTY直接使用oldfd时也有）。2. 新文件是否存在在inode的link中有检查，虽然我个人认为在do_linkat中用find检查会更合适。 |
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@dragonosbot assign @chiichen |
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@dragonosbot label S-等待审查 |
kernel/src/filesystem/vfs/syscall.rs
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| } | ||
| // TODO AT_EMPTY_PATH标志启用时，进行调用者CAP_DAC_READ_SEARCH或相似的检查 | ||
| let symlink_times = match flags & AtFlags::AT_SYMLINK_FOLLOW.bits() { | ||
| 0 => 0, |
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这里应当使用flags.contains或者if 来判断它是否等于0，而不是match。下面那个代码也一样。
kernel/src/filesystem/vfs/syscall.rs
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| .ok_or(SystemError::EBADF)?; | ||
| let old_inode = file.lock().inode(); | ||
| if old_inode.metadata().unwrap().file_type == FileType::Dir { | ||
| return Err(SystemError::EPERM); |
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返回值是eperm吗？有无linux man7的文档。看看这种情况应当返回什么内容。
kernel/src/filesystem/vfs/syscall.rs
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| old: &str, | ||
| newfd: i32, | ||
| new: &str, | ||
| flags: i32, |
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这个作为内部的函数，flags应当是Atflags类型，而不是i32
kernel/src/syscall/mod.rs
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| let old_cstr = args[0] as *const u8; | ||
| let new_cstr = args[1] as *const u8; | ||
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| let old = check_and_clone_cstr(old_cstr, Some(MAX_PATHLEN))?; |
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把这些校验的操作放到vfs的syscall里面去。不要写在这里。
| } | ||
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| #[cfg(target_arch = "x86_64")] | ||
| SYS_LINKAT => { |
kernel/src/syscall/mod.rs
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| let old = check_and_clone_cstr(old_cstr, Some(MAX_PATHLEN))?; | ||
| let new = check_and_clone_cstr(new_cstr, Some(MAX_PATHLEN))?; | ||
| if old.len() >= MAX_PATHLEN || new.len() >= MAX_PATHLEN { |
kernel/src/syscall/mod.rs
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| return Err(SystemError::ENAMETOOLONG); | ||
| } | ||
| // old.len() 根据flags & AtFlags::AT_EMPTY_PATH判空 | ||
| if new.len() <= 0 || (old.len() <= 0 && flags & AtFlags::AT_EMPTY_PATH.bits() == 0) |
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@dragonosbot label +S-等待作者修改 |
| pub fn link(old: *const u8, new: *const u8) -> Result<usize, SystemError> { | ||
| let get_path = |cstr: *const u8| -> Result<String, SystemError> { | ||
| let res = check_and_clone_cstr(cstr, Some(MAX_PATHLEN))?; | ||
| if res.len() >= MAX_PATHLEN { |
| let old = check_and_clone_cstr(old, Some(MAX_PATHLEN))?; | ||
| let new = check_and_clone_cstr(new, Some(MAX_PATHLEN))?; | ||
| if old.len() >= MAX_PATHLEN || new.len() >= MAX_PATHLEN { | ||
| return Err(SystemError::ENAMETOOLONG); |
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同理，因为check_and_clone_str会自动截断。
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我个人认为这个只检查是否等于MAX_PATHLEN，写成>=的形式是参考了unlink的写法。
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有些小疑问。 |
也许这个确实需要改改。 |
这个我在主线刚才改好了，返回EFAULT 然后合并一下主线代码进来，这个PR感觉无问题 |
kernel/src/filesystem/vfs/syscall.rs
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| let new_parent = new_begin_inode | ||
| .lookup_follow_symlink(&new_parent_path.unwrap_or("/"), symlink_times)?; | ||
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| // 在下层检查是否处于同一文件系统 |
User description
目的
希望提供一个方便在用户态测试文件系统link的接口。
实现了才想起来应当先提个issue，索性测完交个pr。
实现方法
实现do_linkat()，在link()及linkat()中直接调用。
do_linkat()调用inode的link()
可能不合规范的行为
功能测试
在/ramte上挂载了ramfs，并使用shell的echo向文件写入内容进行测试。
其他杂项
#596 在SYS_RMDIR上加了个判空。
Type
Bug fix, Enhancement
Description
此PR实现了SYS_LINK和SYS_LINKAT系统调用，允许用户在文件系统中创建硬链接。同时，对SYS_RMDIR函数进行了增强，现在可以正确处理空路径的情况。
Changes walkthrough
syscall.rs
- 实现SYS_LINK和SYS_LINKAT系统调用 - 完善SYS_RMDIR功能kernel/src/filesystem/vfs/syscall.rs
do_linkat()和link()函数，实现了创建硬链接的系统调用。rmdir()函数进行了完善，增加了对空路径的处理。✨ Usage guide:
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