RGBCube/uutils-coreutils
1
Fork 0
mirror of https://github.com/RGBCube/uutils-coreutils synced 2025-08-01 05:27:45 +00:00
Code Issues Activity

wc: unix input redirect

Browse source
This commit is contained in:
zhitkoff 2023-12-01 16:20:25 -05:00 • committed by Yury Zhytkou
parent 054ca4a6b5
commit 253926f2e2
1 changed files with 20 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

21
src/uu/wc/src/count_fast.rs
View file

@ -101,7 +101,26 @@ pub(crate) fn count_bytes_fast<T: WordCountable>(handle: &mut T) -> (usize, Opti
// This condition usually occurs for files in pseudo-filesystems like /proc, /sys
// that report `st_size` in the multiples of system page size.
// In such cases - fall back on full read
if (stat.st_mode as libc::mode_t & S_IFREG) != 0 && stat.st_size > 0 {
//
// And finally a special case of input redirection in *nix shell:
// `( wc -c ; wc -c ) < file` should return
// ```
// size_of_file
// 0
// ```
// Similarly
// `( head -c1 ; wc -c ) < file` should return
// ```
// first_byte_of_file
// size_of_file - 1
// ```
// Since the input stream from file is treated as continuous across both commands inside ().
// In cases like this, due to `<` redirect, the `stat.st_mode` would report input as a regular file
// and `stat.st_size` would report the size of file on disk
// and NOT the remaining number of bytes in the input stream. The raw file descriptor
// in this situation would be equal to `0` for STDIN in both invocations.
// Therefore we cannot rely of `st_size` here and should fall back on full read.
if fd > 0 && (stat.st_mode as libc::mode_t & S_IFREG) != 0 && stat.st_size > 0 {
let sys_page_size = unsafe { sysconf(_SC_PAGESIZE) as usize };
if stat.st_size as usize % sys_page_size > 0 {
// regular file or file from /proc, /sys and similar pseudo-filesystems