* src/fold.c (adjust_column): Ensure BS goes back
1 column after a TAB.
* tests/fold/fold-characters.sh: Add test cases.
* NEWS: Mention the bug fix.
---
NEWS | 5 +++--
src/fold.c | 6 +++++-
tests/fold/fold-characters.sh | 18 ++++++++++++++++++
3 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/NEWS b/NEWS
index a5e6ba57a..2460c14e6 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,9 @@ GNU coreutils NEWS -*-
outline -*-
[bug introduced in coreutils-9.11]
'fold' no longer prematurely wraps lines with a wide character towards
- the start of a line, followed by multiple backspaces.
- [bug introduced in coreutils-9.8]
+ the start of a line, followed by multiple backspaces. Also backspaces
+ after a tab character are accounted for correctly.
+ [bugs introduced in coreutils-9.8]
'realpath' without -s, or 'readlink' with -e,-f,-m no longer
loop infinitely when resolving a symbolic link which
diff --git a/src/fold.c b/src/fold.c
index 2d725c3d5..170cdb752 100644
--- a/src/fold.c
+++ b/src/fold.c
@@ -121,7 +121,11 @@ adjust_column (size_t column, mcel_t g)
else if (g.ch == '\r')
column = 0;
else if (g.ch == '\t')
- column += TAB_WIDTH - column % TAB_WIDTH;
+ {
+ /* A backspace after a tab moves back one column. */
+ last_character_width = 1;
+ column += TAB_WIDTH - column % TAB_WIDTH;
+ }
else
{
if (counting_mode == COUNT_CHARACTERS)
diff --git a/tests/fold/fold-characters.sh b/tests/fold/fold-characters.sh
index cfdee2b3e..a6a083c53 100755
--- a/tests/fold/fold-characters.sh
+++ b/tests/fold/fold-characters.sh
@@ -97,4 +97,22 @@ test $(env printf '\xC3' | fold | wc -c) = 1 || fail=1
# causing premature line wrapping.
test $(env printf 'A\uB250\b\bB\n' | fold -w80 | wc -l) = 1 || fail=1
+# A backspace after an initial tab must move back one column.
+env printf '\t\bX\n' > exp5 || framework_failure_
+fold -w8 exp5 > out5 || fail=1
+compare exp5 out5 || fail=1
+fold --characters -w8 exp5 > out5 || fail=1
+compare exp5 out5 || fail=1
+
+# A tab must reset the saved width after a wide character.
+env printf '\uB250\t\bXX\n' > input6 || framework_failure_
+env printf '\uB250\t\bX\nX\n' > exp6 || framework_failure_
+fold -w8 input6 > out6 || fail=1
+compare exp6 out6 || fail=1
+
+# Likewise after a zero width combining character.
+env printf 'a\u0301\t\bX\n' > exp7 || framework_failure_
+fold -w8 exp7 > out7 || fail=1
+compare exp7 out7 || fail=1
+
Exit $fail
--
2.55.0
