grep/proc-lseek-glitch.patch

Index: grep-2.27/src/grep.c
===================================================================
--- grep-2.27.orig/src/grep.c
+++ grep-2.27/src/grep.c
@@ -1758,29 +1758,17 @@ drain_input (int fd, struct stat const *
 static void
 finalize_input (int fd, struct stat const *st, bool ineof)
 {
-  if (fd != STDIN_FILENO)
-    return;
-
-  if (outleft)
-    {
-      if (ineof)
-        return;
-      if (seek_failed)
-        {
-          if (drain_input (fd, st))
-            return;
-        }
-      else if (0 <= lseek (fd, 0, SEEK_END))
-        return;
-    }
-  else
-    {
-      if (seek_failed || bufoffset == after_last_match
-          || 0 <= lseek (fd, after_last_match, SEEK_SET))
-        return;
-    }
-
-  suppressible_error (errno);
+  if (fd == STDIN_FILENO
+      && (outleft
+          ? (!ineof
+             && (seek_failed
+                 || (lseek (fd, 0, SEEK_END) < 0
+                     /* Linux proc file system has EINVAL (Bug#25180).  */
+                     && errno != EINVAL))
+             && ! drain_input (fd, st))
+          : (bufoffset != after_last_match && !seek_failed
+             && lseek (fd, after_last_match, SEEK_SET) < 0)))
+    suppressible_error (errno);
 }
 
 static bool