maint: avoid new coverity warnings

* src/sync.c (sync_arg): Initialise variable to avoid
unitialized access if assert is disabled.
* src/head.c (elide_tail_bytes_file): Support this function
with ---presume-input-pipe and larger files,
which regressed with commit v8.23-47-g2662702.
(elide_tail_lines_file): Likewise.
* src/dd.c (dd_copy): Explicitly don't try to ftruncate()
upon failure to lseek() (the existing check against
st_size was already protecting that).
* src/factor.c (factor_using_squfof): Assert (only when
linting due to performance) to avoid the implication of
divide by zero.
* src/od.c (read_block): Remove dead code.
* src/tac.c (tac_seekable): Likewise.
* src/ls.c (gobble_file): Likewise.

1 files changed, 0 insertions, 5 deletions

diff --git a/src/tac.c b/src/tac.c
index 2d73c6e78..57e7e761d 100644
--- a/src/tac.c
+++ b/src/tac.c
@@ -321,8 +321,6 @@ tac_seekable (int input_fd, const char *file, off_t file_pos)
                  'G_buffer_size'. */
               char *newbuffer;
               size_t offset = sentinel_length ? sentinel_length : 1;
-              ptrdiff_t match_start_offset = match_start - G_buffer;
-              ptrdiff_t past_end_offset = past_end - G_buffer;
               size_t old_G_buffer_size = G_buffer_size;
 
               read_size *= 2;
@@ -331,9 +329,6 @@ tac_seekable (int input_fd, const char *file, off_t file_pos)
                 xalloc_die ();
               newbuffer = xrealloc (G_buffer - offset, G_buffer_size);
               newbuffer += offset;
-              /* Adjust the pointers for the new buffer location.  */
-              match_start = newbuffer + match_start_offset;
-              past_end = newbuffer + past_end_offset;
               G_buffer = newbuffer;
             }