zless: improve gzip failure checking

* zless.in: Use --show-preproc-error if available.

2 files changed, 12 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index da3829d..5305e61 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,8 @@ GNU gzip NEWS                                    -*- outline -*-
 
 ** Changes in behavior
 
+  zless now diagnoses gzip failures, if using less 623 or later.
+
   When SIGPIPE is ignored, gzip now exits with status 2 (warning)
   instead of status 1 (error) when writing to a broken pipe.  This is
   more useful with programs like 'less' that treat gzip exit status 2
diff --git a/zless.in b/zless.in
index 7d4d3e4..52767a2 100644
--- a/zless.in
+++ b/zless.in
@@ -64,8 +64,17 @@ less' '[1-9][0-9][0-9][0-9]*)
    use_input_pipe_on_stdin='-';;
 *) use_input_pipe_on_stdin='';;
 esac
+case $less_version in
+less' '623* | \
+less' '62[4-9]* | \
+less' '6[3-9][0-9]* | \
+less' '[7-9][0-9][0-9]* | \
+less' '[1-9][0-9][0-9][0-9]*)
+   show_preproc_error='--show-preproc-error';;
+*) show_preproc_error='';;
+esac
 
 LESSOPEN="|$check_exit_status${use_input_pipe_on_stdin}'gzip' -cdfq -- %s"
 export LESSOPEN
 
-exec less "$@"
+exec less $show_preproc_error "$@"