From 695cb04af5218cd7b42c7eaaefc186472b99a995 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Fri, 9 Jun 2023 17:40:53 +0200
Subject: [PATCH] gpg: Print status line and proper diagnostics for write
 errors.

* common/iobuf.c (file_filter): Improve diagnostics.
* g10/build-packet.c (do_plaintext): Make sure to cache all error
cases.
--

GnuPG-bug-id: 6528
---
 common/iobuf.c     |  9 ++++++---
 g10/build-packet.c | 14 +++++++++++---
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/common/iobuf.c b/common/iobuf.c
index 825b97704..dee3b46b1 100644
--- a/common/iobuf.c
+++ b/common/iobuf.c
@@ -503,7 +503,8 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
 	      if (ec != ERROR_BROKEN_PIPE)
 		{
 		  rc = gpg_error_from_errno (ec);
-		  log_error ("%s: read error: ec=%d\n", a->fname, ec);
+		  log_error ("%s: read error: %s (ec=%d)\n",
+                             a->fname, gpg_strerror (rc), ec);
 		}
 	    }
 	  else if (!nread)
@@ -573,7 +574,8 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
 		{
 		  int ec = (int) GetLastError ();
 		  rc = gpg_error_from_errno (ec);
-		  log_error ("%s: write error: ec=%d\n", a->fname, ec);
+		  log_error ("%s: write error: %s (ec=%d)\n",
+                             a->fname, gpg_strerror (rc), ec);
 		  break;
 		}
 	      p += n;
@@ -632,7 +634,8 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
           if (ec != ERROR_BROKEN_PIPE)
             {
               rc = gpg_error_from_errno (ec);
-              log_error ("%s: read error: ec=%d\n", a->fname, ec);
+              log_error ("%s: read error: %s (ec=%d)\n",
+                         a->fname, gpg_strerror (rc), ec);
             }
           a->npeeked = 0;
         }
diff --git a/g10/build-packet.c b/g10/build-packet.c
index 192dfaef5..67d4a6eef 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -991,12 +991,20 @@ do_plaintext( IOBUF out, int ctb, PKT_plaintext *pt )
         if (nbytes == (size_t)(-1)
             && (iobuf_error (out) || iobuf_error (pt->buf)))
             return iobuf_error (out)? iobuf_error (out):iobuf_error (pt->buf);
+        /* Always get the error to catch write errors because
+         * iobuf_copy does not reliable return (-1) in that case.  */
+        rc = iobuf_error (out);
         if(ctb_new_format_p (ctb) && !pt->len)
           /* Turn off partial body length mode.  */
           iobuf_set_partial_body_length_mode (out, 0);
-        if( pt->len && nbytes != pt->len )
-          log_error("do_plaintext(): wrote %lu bytes but expected %lu bytes\n",
-                    (ulong)nbytes, (ulong)pt->len );
+        if (pt->len && nbytes != pt->len)
+          {
+            log_error ("do_plaintext(): wrote %lu bytes"
+                       " but expected %lu bytes\n",
+                       (ulong)nbytes, (ulong)pt->len );
+            if (!rc) /* Just in case no error was set  */
+              rc = gpg_error (GPG_ERR_EIO);
+          }
       }
 
     return rc;