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charset="US-ASCII"; x-default=true Add lseek samples in Rust MiscDevice samples Signed-off-by: Ryosuke Yasuoka --- samples/rust/rust_misc_device.rs | 68 ++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/samples/rust/rust_misc_device.rs b/samples/rust/rust_misc_device.rs index e7ab77448f75..991a59a3ea16 100644 --- a/samples/rust/rust_misc_device.rs +++ b/samples/rust/rust_misc_device.rs @@ -86,6 +86,33 @@ //! return -1; //! } //! +//! // Set a file offset +//! printf("Call lseek SEEK_SET\n"); +//! ret = lseek(fd, 10, SEEK_SET); +//! if (ret == 10) +//! printf("lseek: Succeed to SEEK_SET\n"); +//! else +//! printf("lseek: Failed to SEEK_SET\n"); +//! +//! // Change the file offset from the initial value +//! printf("Call lseek SEEK_CUR\n"); +//! ret = lseek(fd, 10, SEEK_CUR); +//! if (ret == 20) +//! printf("lseek: Succeed to SEEK_CUR\n"); +//! else +//! printf("lseek: Failed to SEEK_CUR\n"); +//! +//! // i_size is 0. So the following task always should fail. +//! printf("Call lseek SEEK_END\n"); +//! ret = lseek(fd, -10, SEEK_END); +//! if (ret < 0) +//! perror("lseek: Succeeded to fail - this was expected"); +//! else { +//! printf("lseek: Failed to fail SEEK_END\n"); +//! close(fd); +//! return -1; +//! } +//! //! // Close the device file //! printf("Closing /dev/rust-misc-device\n"); //! close(fd); @@ -114,6 +141,10 @@ const RUST_MISC_DEV_GET_VALUE: u32 = _IOR::('|' as u32, 0x81); const RUST_MISC_DEV_SET_VALUE: u32 = _IOW::('|' as u32, 0x82); +const SEEK_SET: i32 = 0; +const SEEK_CUR: i32 = 1; +const SEEK_END: i32 = 2; + module! { type: RustMiscDeviceModule, name: "rust_misc_device", @@ -173,6 +204,43 @@ fn open(_file: &File, misc: &MiscDeviceRegistration) -> Result, file: &File, offset: i64, whence: i32) -> Result { + dev_info!(me.dev, "LLSEEK Rust Misc Device Sample\n"); + let pos: i64; + let eof: i64; + + // SAFETY: + // * The file is valid for the duration of this call. + // * f_inode must be valid while the file is valid. + unsafe { + pos = (*file.as_ptr()).f_pos; + eof = (*(*file.as_ptr()).f_inode).i_size; + } + + let new_pos = match whence { + SEEK_SET => offset, + SEEK_CUR => pos + offset, + SEEK_END => eof + offset, + _ => { + dev_err!(me.dev, "LLSEEK does not recognised: {}.\n", whence); + return Err(EINVAL); + } + }; + + if new_pos < 0 { + dev_err!(me.dev, "The file offset becomes negative: {}.\n", new_pos); + return Err(EINVAL); + } + + // SAFETY: The file is valid for the duration of this call. + let ret: isize = unsafe { + (*file.as_ptr()).f_pos = new_pos; + new_pos as isize + }; + + Ok(ret) + } + fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, cmd: u32, arg: usize) -> Result { dev_info!(me.dev, "IOCTLing Rust Misc Device Sample\n"); -- 2.50.1