[binutils-gdb] gdb/corelow.c: do not try to reopen a file if open failed once

[Lancelot SIX]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ea70f941f9b2ccb0bbcda62496426e060da946a7

commit ea70f941f9b2ccb0bbcda62496426e060da946a7
Author: Lancelot SIX <lancelot.six@amd.com>
Date:   Wed May 31 15:04:55 2023 +0100

    gdb/corelow.c: do not try to reopen a file if open failed once
    
    In the current implementation, core_target::build_file_mappings will try
    to locate and open files which were mapped in the process for which the
    core dump was produced.  If the file cannot be found or cannot be
    opened, GDB will re-try to open it once for each time it was mapped in
    the process's address space.
    
    This patch makes it so GDB recognizes that it has already failed to open
    a given file once and does not re-try the process for each mapping.
    
    Reviewed-By: John Baldwin <jhb@FreeBSD.org>
    Approved-By: Andrew Burgess <aburgess@redhat.com>

Diff:
---
 gdb/corelow.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/gdb/corelow.c b/gdb/corelow.c
index 0b51428f77c..0a7ff56848a 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -233,6 +233,16 @@ core_target::build_file_mappings ()
 	   weed out non-file-backed mappings.  */
 	gdb_assert (filename != nullptr);
 
+	if (unavailable_paths.find (filename) != unavailable_paths.end ())
+	  {
+	    /* We have already seen some mapping for FILENAME but failed to
+	       find/open the file.  There is no point in trying the same
+	       thing again so just record that the range [start, end) is
+	       unavailable.  */
+	    m_core_unavailable_mappings.emplace_back (start, end - start);
+	    return;
+	  }
+
 	struct bfd *bfd = bfd_map[filename];
 	if (bfd == nullptr)
 	  {
@@ -250,11 +260,10 @@ core_target::build_file_mappings ()
 	    if (expanded_fname == nullptr)
 	      {
 		m_core_unavailable_mappings.emplace_back (start, end - start);
-		/* Print just one warning per path.  */
-		if (unavailable_paths.insert (filename).second)
-		  warning (_("Can't open file %s during file-backed mapping "
-			     "note processing"),
-			   filename);
+		unavailable_paths.insert (filename);
+		warning (_("Can't open file %s during file-backed mapping "
+			   "note processing"),
+			 filename);
 		return;
 	      }
 
@@ -263,10 +272,10 @@ core_target::build_file_mappings ()
 	    if (bfd == nullptr || !bfd_check_format (bfd, bfd_object))
 	      {
 		m_core_unavailable_mappings.emplace_back (start, end - start);
-		if (unavailable_paths.insert (filename).second)
-		  warning (_("Can't open file %s which was expanded to %s "
-			     "during file-backed mapping note processing"),
-			   filename, expanded_fname.get ());
+		unavailable_paths.insert (filename);
+		warning (_("Can't open file %s which was expanded to %s "
+			   "during file-backed mapping note processing"),
+			 filename, expanded_fname.get ());
 
 		if (bfd != nullptr)
 		  bfd_close (bfd);