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

3 files changed, 20 insertions, 6 deletions

diff --git a/NEWS b/NEWS
index decda0ce4..1c0fef360 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,9 @@ Noteworthy changes in version 2.2.42 (unreleased)
 
   * gpg: Add modes 16 and 30 to --gen-random.
 
+  * gpg: Emit status line and proper diagnostics for write errors.
+    [T6528]
+
   * gpgsm: Support ECC certificates.  [T6253]
 
   * gpgsm: Also announce AES256-CBC in signatures.  [rGaa397fdcdb21]
diff --git a/common/iobuf.c b/common/iobuf.c
index f4766c6a4..4d207d3f8 100644
--- a/common/iobuf.c
+++ b/common/iobuf.c
@@ -483,7 +483,8 @@ 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)
@@ -543,7 +544,8 @@ 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;
@@ -601,7 +603,8 @@ 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 63bfadbe0..5de5114fb 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -761,12 +761,20 @@ 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;