From f8e14746d2ca72804a4520c059d7bf65ca00c5ac Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 2 Sep 2022 16:32:27 -0500
Subject: [PATCH] Fix --delete bug with short reads
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* gnulib.modules: Add idx.
* src/common.h: Include idx.h.
* src/delete.c (move_archive): Don’t botch short reads.
---
 gnulib.modules |  1 +
 src/common.h   |  1 +
 src/delete.c   | 10 ++++++++--
 3 files changed, 10 insertions(+), 2 deletions(-)

# diff --git a/gnulib.modules b/gnulib.modules
# index 63e8354a..dac77d61 100644
# --- a/gnulib.modules
# +++ b/gnulib.modules
# @@ -54,6 +54,7 @@ gettime
#  gitlog-to-changelog
#  hash
#  human
# +idx
#  inttostr
#  inttypes
#  lchown
--- a/src/common.h
+++ b/src/common.h
@@ -58,6 +58,7 @@
 #include <backupfile.h>
 #include <exclude.h>
 #include <full-write.h>
+#include <idx.h>
 #include <modechange.h>
 #include <quote.h>
 #include <safe-read.h>
--- a/src/delete.c
+++ b/src/delete.c
@@ -55,9 +55,15 @@ move_archive (off_t count)
   off_t position0 = rmtlseek (archive, 0, SEEK_CUR), position = 0;
   if (0 <= position0)
     {
-      off_t increment;
+      /* Pretend the starting position is at the first record
+	 boundary after POSITION0.  This is useful at EOF after
+	 a short read.  */
+      idx_t short_size = position0 % record_size;
+      idx_t start_offset = short_size ? record_size - short_size : 0;
+      off_t increment, move_start;
       if (INT_MULTIPLY_WRAPV (record_size, count, &increment)
-	  || INT_ADD_WRAPV (position0, increment, &position)
+	  || INT_ADD_WRAPV (position0, start_offset, &move_start)
+	  || INT_ADD_WRAPV (move_start, increment, &position)
 	  || position < 0)
 	{
 	  ERROR ((0, EOVERFLOW, "lseek: %s", archive_name_array[0]));