From FEDORA_PATCHES Mon Sep 17 00:00:00 2001

From: Keith Seitz <keiths@redhat.com>

Date: Mon, 27 Jul 2020 16:52:18 -0400

Subject: gdb-rhbz1842691-corefile-mem-access-3of15.patch

;; section_table_xfer_memory: Replace section name with callback predicate

;; Kevin Buettner, RH BZ 1842691

   Author: Kevin Buettner <kevinb@redhat.com>

   Date:   Wed Mar 4 17:42:41 2020 -0700

    section_table_xfer_memory: Replace section name with callback predicate

    This patch is motivated by the need to be able to select sections

    that section_table_xfer_memory_partial should consider for memory

    transfers.  I'll use this facility in the next patch in this series.

    section_table_xfer_memory_partial() can currently be passed a section

    name which may be used to make name-based selections.  This is similar

    to what I want to do, except that I want to be able to consider

    section flags instead of the name.

    I'm replacing the section name parameter with a predicate that,

    when passed a pointer to a target_section struct, will return

    true if that section should be further considered, or false which

    indicates that it shouldn't.

    I've converted the one existing use where a non-NULL section

    name is passed to section_table_xfer_memory_partial().   Instead

    of passing the section name, it now looks like this:

    	  auto match_cb = [=] (const struct target_section *s)

    	    {

    	      return (strcmp (section_name, s->the_bfd_section->name) == 0);

    	    };

    	  return section_table_xfer_memory_partial (readbuf, writebuf,

    						    memaddr, len, xfered_len,

    						    table->sections,

    						    table->sections_end,

    						    match_cb);

    The other callers all passed NULL; they've been simplified somewhat

    in that they no longer need to pass NULL.

    gdb/ChangeLog:

    	* exec.h (section_table_xfer_memory): Revise declaration,

    	replacing section name parameter with an optional callback

    	predicate.

    	* exec.c (section_table_xfer_memory): Likewise.

    	* bfd-target.c, exec.c, target.c, corelow.c: Adjust all callers

    	of section_table_xfer_memory.

diff --git a/gdb/bfd-target.c b/gdb/bfd-target.c

--- a/gdb/bfd-target.c

+++ b/gdb/bfd-target.c

@@ -77,8 +77,7 @@ target_bfd::xfer_partial (target_object object,

 	return section_table_xfer_memory_partial (readbuf, writebuf,

 						  offset, len, xfered_len,

 						  m_table.sections,

-						  m_table.sections_end,

-						  NULL);

+						  m_table.sections_end);

       }

     default:

       return TARGET_XFER_E_IO;

diff --git a/gdb/corelow.c b/gdb/corelow.c

--- a/gdb/corelow.c

+++ b/gdb/corelow.c

@@ -758,8 +758,7 @@ core_target::xfer_partial (enum target_object object, const char *annex,

 	      (readbuf, writebuf,

 	       offset, len, xfered_len,

 	       m_core_section_table.sections,

-	       m_core_section_table.sections_end,

-	       NULL));

+	       m_core_section_table.sections_end));

     case TARGET_OBJECT_AUXV:

       if (readbuf)

diff --git a/gdb/exec.c b/gdb/exec.c

--- a/gdb/exec.c

+++ b/gdb/exec.c

@@ -792,7 +792,8 @@ section_table_xfer_memory_partial (gdb_byte *readbuf, const gdb_byte *writebuf,

 				   ULONGEST *xfered_len,

 				   struct target_section *sections,

 				   struct target_section *sections_end,

-				   const char *section_name)

+				   gdb::function_view

+				     (const struct target_section *)> match_cb)

 {

   int res;

   struct target_section *p;

@@ -808,7 +809,7 @@ section_table_xfer_memory_partial (gdb_byte *readbuf, const gdb_byte *writebuf,

       struct bfd_section *asect = p->the_bfd_section;

       bfd *abfd = asect->owner;

-      if (section_name && strcmp (section_name, asect->name) != 0)

+      if (match_cb != nullptr && !match_cb (p))

 	continue;		/* not the section we need.  */

       if (memaddr >= p->addr)

         {

@@ -881,8 +882,7 @@ exec_target::xfer_partial (enum target_object object,

     return section_table_xfer_memory_partial (readbuf, writebuf,

 					      offset, len, xfered_len,

 					      table->sections,

-					      table->sections_end,

-					      NULL);

+					      table->sections_end);

   else

     return TARGET_XFER_E_IO;

 }

diff --git a/gdb/exec.h b/gdb/exec.h

--- a/gdb/exec.h

+++ b/gdb/exec.h

@@ -58,8 +58,13 @@ extern enum target_xfer_status

    Request to transfer up to LEN 8-bit bytes of the target sections

    defined by SECTIONS and SECTIONS_END.  The OFFSET specifies the

    starting address.

-   If SECTION_NAME is not NULL, only access sections with that same

-   name.

+

+   The MATCH_CB predicate is optional; when provided it will be called

+   for each section under consideration.  When MATCH_CB evaluates as

+   true, the section remains under consideration; a false result

+   removes it from consideration for performing the memory transfers

+   noted above.  See memory_xfer_partial_1() in target.c for an

+   example.

    Return the number of bytes actually transfered, or zero when no

    data is available for the requested range.

@@ -76,7 +81,9 @@ extern enum target_xfer_status

 				     ULONGEST, ULONGEST, ULONGEST *,

 				     struct target_section *,

 				     struct target_section *,

-				     const char *);

+				     gdb::function_view

+				       (const struct target_section *)> match_cb

+				         = nullptr);

 /* Read from mappable read-only sections of BFD executable files.

    Similar to exec_read_partial_read_only, but return

diff --git a/gdb/target.c b/gdb/target.c

--- a/gdb/target.c

+++ b/gdb/target.c

@@ -1022,11 +1022,17 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,

 	  const char *section_name = section->the_bfd_section->name;

 	  memaddr = overlay_mapped_address (memaddr, section);

+

+	  auto match_cb = [=] (const struct target_section *s)

+	    {

+	      return (strcmp (section_name, s->the_bfd_section->name) == 0);

+	    };

+

 	  return section_table_xfer_memory_partial (readbuf, writebuf,

 						    memaddr, len, xfered_len,

 						    table->sections,

 						    table->sections_end,

-						    section_name);

+						    match_cb);

 	}

     }

@@ -1044,8 +1050,7 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,

 	  return section_table_xfer_memory_partial (readbuf, writebuf,

 						    memaddr, len, xfered_len,

 						    table->sections,

-						    table->sections_end,

-						    NULL);

+						    table->sections_end);

 	}

     }