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Merge pull request #7925 from alexs-sh/shred-minor-updates

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shred: minor improvements and tests
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Daniel Hofstetter 2025-05-21 17:11:29 +02:00 • committed by GitHub
commit 10b2a24a73
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1 changed files with 11 additions and 6 deletions
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17
src/uu/shred/src/shred.rs
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@ -49,11 +49,11 @@ const NAME_CHARSET: &[u8] = b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMN
const PATTERN_LENGTH: usize = 3; const PATTERN_LENGTH: usize = 3;
const PATTERN_BUFFER_SIZE: usize = BLOCK_SIZE + PATTERN_LENGTH - 1; const PATTERN_BUFFER_SIZE: usize = BLOCK_SIZE + PATTERN_LENGTH - 1;
/// Optimal block size for the filesystem. This constant is used for data size alignment, /// Optimal block size for the filesystem. This constant is used for data size alignment, similar
/// similar to the behavior of GNU shred. Usually, optimal block size is a 4K block, which is why /// to the behavior of GNU shred. Usually, optimal block size is a 4K block (2^12), which is why
/// it's defined as a constant. However, it's possible to get the actual size at runtime using, for /// it's defined as a constant. However, it's possible to get the actual size at runtime using, for
/// example, `std::os::unix::fs::MetadataExt::blksize()`. /// example, `std::os::unix::fs::MetadataExt::blksize()`.
const OPTIMAL_IO_BLOCK_SIZE: usize = 4096; const OPTIMAL_IO_BLOCK_SIZE: usize = 1 << 12;
/// Patterns that appear in order for the passes /// Patterns that appear in order for the passes
/// ///
@ -514,12 +514,17 @@ fn wipe_file(
} }
fn split_on_blocks(file_size: u64, exact: bool) -> (u64, u64) { fn split_on_blocks(file_size: u64, exact: bool) -> (u64, u64) {
// OPTIMAL_IO_BLOCK_SIZE must not exceed BLOCK_SIZE. Violating this may cause overflows due
// to alignment or performance issues.This kind of misconfiguration is
// highly unlikely but would indicate a serious error.
const _: () = assert!(OPTIMAL_IO_BLOCK_SIZE <= BLOCK_SIZE);
let file_size = if exact { let file_size = if exact {
file_size file_size
} else { } else {
// The main idea here is to align the file size to the OPTIMAL_IO_BLOCK_SIZE, and then split it into // The main idea here is to align the file size to the OPTIMAL_IO_BLOCK_SIZE, and then
// BLOCK_SIZE + remaining bytes. Since the input data is already aligned to N * OPTIMAL_IO_BLOCK_SIZE, // split it into BLOCK_SIZE + remaining bytes. Since the input data is already aligned to N
// the output file size will also be aligned and correct. // * OPTIMAL_IO_BLOCK_SIZE, the output file size will also be aligned and correct.
file_size.div_ceil(OPTIMAL_IO_BLOCK_SIZE as u64) * OPTIMAL_IO_BLOCK_SIZE as u64 file_size.div_ceil(OPTIMAL_IO_BLOCK_SIZE as u64) * OPTIMAL_IO_BLOCK_SIZE as u64
}; };
(file_size / BLOCK_SIZE as u64, file_size % BLOCK_SIZE as u64) (file_size / BLOCK_SIZE as u64, file_size % BLOCK_SIZE as u64)