ls: fix alignment when month names have varying widths

Reported by Samuel Thibault and Stéphane Raimbault, as the glibc fr_FR
locale has recently changed to use the official but variable width
abbreviated month names. Other glibc locales also have variable widths.
http://sourceware.org/ml/libc-locales/2008-q1/msg00035.html
http://sourceware.org/bugzilla/show_bug.cgi?id=9859
* NEWS: Mention the fix
* gl/lib/mbsalign.c: A new module to align and truncate a
string in a specified number of screen cells, while handling
multi-byte characters appropriately.
* gl/lib/mbsalign.h: Ditto
* gl/modules/mbsalign: Ditto
* bootstrap.conf: Reference the new module
* src/ls.c (abmon_init): New function, precompute the abbreviated
months aligned left in a minimum width column <= 5 screen cells.
(align_nstrftime): New function, replace the first %b in the
format specification to strftime with the precomputed month string.
Note using the cached month strings speeds up `ls -lU` by around 17%
on glibc-2.7-2 on linux at least.  Also if we implement this function
using heap storage rather than automatic storage, and use snprintf
instead of strcpy, ls will slow down by 2% and 1% respectively
(i.e. a net gain of 14% rather than 17%).
* tests/ls/abmon-align: A new test to test ls alignment for
various formats and locales
* tests/Makefile.am: Reference the new test

2 files changed, 52 insertions, 0 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 2e2a5f06f..07f34ec45 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -331,6 +331,7 @@ TESTS =						\
   ln/misc					\
   ln/sf-1					\
   ln/target-1					\
+  ls/abmon-align				\
   ls/color-clear-to-eol				\
   ls/color-dtype-dir				\
   ls/dangle					\
diff --git a/tests/ls/abmon-align b/tests/ls/abmon-align
new file mode 100755
index 000000000..73b51e8a2
--- /dev/null
+++ b/tests/ls/abmon-align
@@ -0,0 +1,51 @@
+#!/bin/sh
+# Ensure ls output is aligned when using abbreviated months from the locale
+
+# Copyright (C) 2009 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  ls --version
+fi
+
+. $srcdir/test-lib.sh
+
+for mon in $(seq -w 12); do
+    touch -d"+$mon month" $mon.ts || framework_failure
+done
+
+fail=0
+
+# Note some of the following locales may be missing but if so
+# we should fail back to the C locale which should be aligned
+
+for format in "%b" "[%b" "%b]" "[%b]"; do
+  for LOC in C gv_GB ga_IE fi_FI.utf8 zh_CN ar_SY $LOCALE_FR_UTF8; do
+    n_widths=$(
+      LC_ALL=$LOC TIME_STYLE=+"$format" ls -lgG *.ts |
+      LC_ALL=C sed '1d; s/.\{15\}\(.*\) ...ts$/\1/; s/ /./g' |
+      while read mon; do echo "$mon" | LC_ALL=$LOC wc -L; done |
+      uniq | wc -l
+    )
+    test "$n_widths" = "1" || { fail=1; break 2; }
+  done
+done
+if test "$fail" = "1"; then
+   echo "misalignment detected in $LOC locale:"
+   LC_ALL=$LOC TIME_STYLE=+%b ls -lgG *.ts
+fi
+
+Exit $fail