bug#80855: gzip-1.14.52-05ea on Alpine Linux

[Paul Eggert]

Thanks, I hope I fixed that one by installing the attached.
From 7de030e24744aa848bea0a5ed7d66a1413d8e9f7 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Sat, 18 Apr 2026 13:40:10 -0700
Subject: [PATCH] gzip: fix diagnostic after failed write
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* gzip.c (main, finish_out): Check ferror after fflush.
That way, if the fflush fails we get a more-precise errno.
If ferror fails, just report EIO regardless of actual error.
(create_outfile): Do not assume a successful sigprocmask
leaves errno alone, when issuing a diagnostic after a failed
write.  This fixes an unlikely bug I introduced in commit
a979d9c4db0adbf341eb329abaf3560aa12f10fd dated 2006-12-07.
* util.c (write_err): New function, with most of the old
write_error’s implementation.
(write_error): Use it.
---
 gzip.c |  8 +++++++-
 gzip.h |  1 +
 util.c | 13 ++++++++++---
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/gzip.c b/gzip.c
index b571c42..ec60ad0 100644
--- a/gzip.c
+++ b/gzip.c
@@ -636,6 +636,8 @@ int main (int argc, char **argv)
           do_list (-1);
         if (fflush (stdout) != 0)
           write_error ();
+        if (ferror (stdout))
+          write_err (EIO);
       }
     if (to_stdout
         && ((synchronous
@@ -1104,7 +1106,7 @@ create_outfile ()
           break;
 
         default:
-          write_error ();
+          write_err (open_errno);
         }
     }
 
@@ -2030,6 +2032,10 @@ do_exit (int exitcode)
 static void
 finish_out ()
 {
+  if (fflush (stdout) < 0)
+    write_error ();
+  if (ferror (stdout))
+    write_err (EIO);
   if (fclose (stdout) != 0)
     write_error ();
   do_exit (OK);
diff --git a/gzip.h b/gzip.h
index bb87fee..326caef 100644
--- a/gzip.h
+++ b/gzip.h
@@ -319,6 +319,7 @@ _Noreturn extern void gzip_error (char const *m);
 _Noreturn extern void xalloc_die (void);
 extern void warning       (char const *m);
 _Noreturn extern void read_error (void);
+_Noreturn extern void write_err (int err);
 _Noreturn extern void write_error (void);
 extern void display_ratio (off_t num, off_t den, FILE *file);
 
diff --git a/util.c b/util.c
index 9d89f8d..fc521dc 100644
--- a/util.c
+++ b/util.c
@@ -388,14 +388,21 @@ void read_error()
     abort_gzip();
 }
 
-void write_error()
+void
+write_err (int err)
 {
-  int exitcode = errno == EPIPE ? WARNING : ERROR;
+  int exitcode = err == EPIPE ? WARNING : ERROR;
   if (! (exitcode == WARNING && quiet))
-    fprintf (stderr, "\n%s: %s: %s\n", program_name, ofname, strerror (errno));
+    fprintf (stderr, "\n%s: %s: %s\n", program_name, ofname, strerror (err));
   finish_up_gzip (exitcode);
 }
 
+void
+write_error ()
+{
+  write_err (errno);
+}
+
 /* ========================================================================
  * Display compression ratio on the given stream on 6 characters.
  */
-- 
2.51.0