Fix/cmp n flag bug #111

kernelpoetlaureate · 2025-12-06T08:09:22Z

cmp: fix -n flag incorrectly enabling verbose output

Bug: When using cmp -n NUM without -l, the program would incorrectly continue comparing after finding the first difference, printing multiple 'differ' lines instead of just one.

Root Cause: The bug was in line 144: if (opt) checked if ANY option was set (including -n), causing it to continue. It should only continue for -l (verbose) mode: if (opt & CMP_OPT_l).

Test Case:

echo -n AAAAA > file1
echo -n BBBBB > file2
# Before: cmp -n 3 file1 file2 → 3 lines of output
# After:  cmp -n 3 file1 file2 → 1 line of output
# Both:   cmp -l -n 3 file1 file2 → 3 lines (correct)

When getopt32() has complementary options it's possible to specify the minimum and maximum number of arguments allowed. Checking these values was inconsistent: - '?' correctly checked that it was followed by a digit but set the otherwise unused spec_flgs variable on error. - '=' failed to check that it was followed by a digit. function old new delta vgetopt32 1307 1319 +12 Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Fix bug introduced in busybox 1.37.0 that broke kernel builds. Fixes commit e2287f9 (od: for !DESKTOP, match output more closely to GNU coreutils 9.1, implement -s) function old new delta rewrite 967 976 +9 Signed-off-by: Natanael Copa <ncopa@alpinelinux.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Using cut with the delimiter flag ("-d") with the "-s" flag to only output lines containing the delimiter will print blank lines. This is deviant behavior from cut provided by GNU Coreutils. Blank lines should be omitted if "-s" is used with "-d". This change introduces a somewhat naiive, yet efficient solution, where line length is checked before looping though bytes. If line length is zero and the "-s" flag is used, the code will jump to parsing the next line to avoid printing a newline character. function old new delta cut_main 1196 1185 -11 Signed-off-by: Colin McAllister <colinmca242@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Commit 0068ce2 (cut: add toybox-compatible options -O OUTSEP, -D, -F LIST) added detection of reversed ranges. Further improvements are possible. - The test for reversed ranges compared the start after it had been decremented with the end before decrement. It thus missed ranges of the form 2-1. - Zero isn't a valid start value for a range. (Nor is it a valid end value, but that's caught by the test for a reversed range.) - The code if (!*ltok) e = INT_MAX; duplicates a check that's already been made. - Display the actual range in the error message to make it easier to find which range was at fault. function old new delta .rodata 100273 100287 +14 cut_main 1239 1237 -2 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 14/-2) Total: 12 bytes Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

This imporves readability Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1218 1228 +10 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1228 1201 -27 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta packed_usage 34897 34849 -48 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1204 1261 +57 static.cut_longopts - 20 +20 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 1/0 up/down: 77/0) Total: 77 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1261 1353 +92 packed_usage 34925 34901 -24 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 92/-24) Total: 68 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta packed_usage 34901 34934 +33 cut_main 1353 1339 -14 .rodata 105724 105685 -39 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/2 up/down: 33/-53) Total: -20 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1339 1348 +9 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1344 1339 -5 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1339 1391 +52 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1391 1410 +19 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta .rodata 105685 105659 -26 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

…ariable function old new delta cut_main 1410 1404 -6 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

We don't need to mimic GNU cut error messages. $ cut -d@ -b3 cut: -d DELIM makes sense only with -f or -F $ cut -s -b3 cut: -s makes sense only with -f or -F function old new delta static._op_on_field 31 32 +1 .rodata 105659 105598 -61 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 1/-61) Total: -60 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

$ cut -s -b3 cut: -s requires -f or -F $ cut -d@ -b3 cut: -d DELIM requires -f or -F function old new delta static.requires_f - 19 +19 static._op_on_field 32 - -32 ------------------------------------------------------------------------------ (add/remove: 1/1 grow/shrink: 0/0 up/down: 19/-32) Total: -13 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta cut_main 1404 1388 -16 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta done_word 790 766 -24 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

For some reason, it was only happening in interactive use function old new delta initialize_context 39 54 +15 parse_stream 3077 3063 -14 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 15/-14) Total: 1 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta done_word 766 777 +11 static.reserved_match 16 12 -4 reserved_list 240 168 -72 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/2 up/down: 11/-76) Total: -65 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta parse_stream 3063 3075 +12 done_word 777 784 +7 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 19/0) Total: 19 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta write2pipe - 133 +133 .rodata 105992 106009 +17 readtoken1 3101 3111 +10 cmdtxt 631 641 +10 nodesize 27 28 +1 redirect 961 916 -45 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 4/1 up/down: 171/-45) Total: 126 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

…quence attacks This fixes CVE-2025-46394 (terminal escape sequence injection) Original credit: Ian.Norton at entrust.com function old new delta header_list 9 15 +6 header_verbose_list 239 244 +5 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 11/0) Total: 11 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Currently vi in Busybox doesn't support filtering text through an external command with ':1,2!cmd'. Instead it behaves as if no range had been supplied and displays the output of the command. Issue a warning and do nothing in such cases. function old new delta colon 3993 4010 +17 Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Remove the puts(cterm) call that was likely leftover debugging code. The controlling terminal name is already properly displayed via the 'Controlling term:' label, so the raw terminal name output was redundant and could cause issues when cterm is NULL. Also add proper cleanup for the allocated cterm string. function old new delta ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0) Total: 0 bytes Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Specifying a PID of 0 for the -p option of chrt would previously result in a "number 0... not in range" error. Now, it means instead that the calling process (i.e. chrt itself) should be operated on; this is to be consistent with the behavior of util-linux's version of chrt. function old new delta chrt_main 462 474 +12 Signed-off-by: Zuo An <zuoan.penguin@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

busybox cp refuses to overwrite another symlink to a directory due to an incorrect stat() call that should be lstat(). When using -T, we want to consider the target argument directly without resolving symlinks. function old new delta cp_main 496 514 +18 Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

…on ppc64le Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta update_local_clock 872 951 +79 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta busybox_main 695 734 +39 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

The first login entry is ignored if a log file contains more than one entry. To fix it, do not break the while loop if the offset is zero. Signed-off-by: Dmitry Klochkov <dmitry.klochkov@bell-sw.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

'\W' in PS1 returned an empty string for the root directory. bash displays '/' in similar circumstances. Avoid returning an empty string for the directory. function old new delta parse_and_put_prompt 873 883 +10 Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Since commit 551bfdb (ls: implement -q, fix -w0, reduce startup time) the '--color' option behaves as though the default argument 'always' had been specified. This is due to an explicit short option for '--color' being given, but without specifying that an argument is expected. function old new delta .rodata 106027 106029 +2 Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

When running `pgrep -x example` against a process `/bin/example --arg`, BusyBox fails to match, while GNU pgrep succeeds. The reason is that the comparison is done only against the full argv[0] rather than comm. This patch changes pgrep -x to also try /proc/[pid]/comm for exact matching. function old new delta pgrep_main 681 670 -11 Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta xatoull_range_sfx - 49 +49 dd_main 1607 1640 +33 bb_banner 47 46 -1 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 1/1 up/down: 82/-1) Total: 81 bytes Signed-off-by: Sertonix <sertonix@posteo.net> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Fixes missing [-s] option in trivial usage section of `eject --help` function old new delta packed_usage 35125 35127 +2 Signed-off-by: Nir Lichtman <nir@lichtman.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta .rodata 106388 106438 +50 tls_xread_record 650 681 +31 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 81/0) Total: 81 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

function old new delta packed_usage 35768 35802 +34 xxd_main 1447 1449 +2 .rodata 106438 106439 +1 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 3/0 up/down: 37/0) Total: 37 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

When using 'cmp -n NUM' without '-l', the program would incorrectly continue comparing after finding the first difference, printing multiple 'differ' lines instead of just one. The bug was in line 144: 'if (opt)' checked if ANY option was set (including -n), causing it to continue. It should only continue for -l (verbose) mode: 'if (opt & CMP_OPT_l)'. This was correct when originally written (only -l and -s existed), but became a bug when -n was added later. Test case: echo -n AAAAA > file1 echo -n BBBBB > file2 Before: cmp -n 3 file1 file2 -> 3 lines of output After: cmp -n 3 file1 file2 -> 1 line of output Both: cmp -l -n 3 file1 file2 -> 3 lines (correct) v2: Removed stale comment as suggested by Harald van Dijk. Signed-off-by: Giorgi Tchankvetadze <giorgitchankvetadze1997@gmail.com>

Stop wasting CPU when skip values exceed file size. Performance improvement: 5500x faster for large skips.

robang74 · 2026-01-19T19:44:09Z

This repository is rarely updated as you can see by 100+ commits into your PR, sent the patch to: busybox@busybox.net

By the way, I am using my git-function project to keep update my fork of busybox:

+:git-shell:master:busybox> lsrmt
busybox.net git://busybox.net/busybox.git (fetch)
busybox.net git://busybox.net/busybox.git (push)
origin https://github.com/robang74/busybox.git (fetch)
origin https://github.com/robang74/busybox.git (push)

While git-functions project stays here:

https://github.com/robang74/git-functions (*)

I will appreciate testers and contributors to the (*) gitshell project. I am very satisfied by using it.

rmyorston and others added 30 commits December 9, 2024 02:16

cut: simplify OPT_ names, eliminate one variable

73e9d25

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: localize 'spos' variable, convert !NUMVAR to NUMVAR == 0

ad12ab4

This imporves readability Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: allocate "printed" only if OPT_CHAR or OPT_BYTE

478ac90

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: "orig_line" is redundant, remove it

808155e

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: rename some variables to hopefully better names

1220b15

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: rename "cut_lists" to "cut_list"

55fc6a1

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: with -F, do not regcomp() pattern for every file

470f009

function old new delta cut_main 1218 1228 +10 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: fix "echo 1.2 | cut -d. -f1,3" (print "1", not "1.")

103139d

function old new delta cut_main 1228 1201 -27 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: comment out code which seems to be not needed

38a3c0a

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: with -F disabled in .config, don't show it in --help

b402b13

function old new delta packed_usage 34897 34849 -48 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: prevent infinite loop if -F REGEX matches empty delimiter

9adafbc

function old new delta cut_main 1339 1348 +9 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: fix handling of -d ''

96a230f

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: tweak comments

ed65616

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: whitespace fixes

f4f8dc6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: "it's legal to pass an empty list" seems to be untrue

7624077

function old new delta cut_main 1344 1339 -5 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: simplify getopt32 code

d48400d

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: fix -F n-m to match toybox

b25ea3f

function old new delta cut_main 1339 1391 +52 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: disallow -f '' and -f '-'

e8622f0

function old new delta cut_main 1391 1410 +19 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: we can't get empty cut_list[], remove the check for that

ba9651b

function old new delta .rodata 105685 105659 -26 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: terminate cut_list[] so that we don't need "size of the array" v…

0bd84c9

…ariable function old new delta cut_main 1410 1404 -6 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

cut: remove unnecessary initialization of regmatch_t

dd40b40

function old new delta cut_main 1404 1388 -16 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Denys Vlasenko added 24 commits August 17, 2025 17:59

hush: make "function" keyword support optional

2ccb891

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

hush: disentangle keyword detection, no logic changes

2bdec03

function old new delta done_word 790 766 -24 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

hush: changes to comments and whitespace, no code changes

3681b5f

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

ash: change procargs() to match recent dash change

381a40a

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

nsenter,unshare: don't use xvfork_parent_waits_and_exits(), it SEGVs …

3621595

…on ppc64le Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

ntpd: set tmx.maxerror properly - avoid STA_UNSYNC

3ff3cb4

function old new delta update_local_clock 872 951 +79 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

busybox: optional --version support

b99a529

function old new delta busybox_main 695 734 +39 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

eject: fix missing -s option in trivial usage

8d7ae80

Fixes missing [-s] option in trivial usage section of `eject --help` function old new delta packed_usage 35125 35127 +2 Signed-off-by: Nir Lichtman <nir@lichtman.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

kernelpoetlaureate force-pushed the fix/cmp-n-flag-bug branch 2 times, most recently from a0a6340 to 8e2db66 Compare December 6, 2025 08:21

kernelpoetlaureate force-pushed the fix/cmp-n-flag-bug branch from 8e2db66 to ae3cb10 Compare December 6, 2025 09:02

cmp: add EOF check in skip loop

e78e8bc

Stop wasting CPU when skip values exceed file size. Performance improvement: 5500x faster for large skips.

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Fix/cmp n flag bug #111

Fix/cmp n flag bug #111

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kernelpoetlaureate commented Dec 6, 2025

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robang74 commented Jan 19, 2026 •

edited

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Fix/cmp n flag bug #111

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kernelpoetlaureate commented Dec 6, 2025

cmp: fix -n flag incorrectly enabling verbose output

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robang74 commented Jan 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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robang74 commented Jan 19, 2026 •

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