[PATCH] gdb: move bfd_open_from_target_memory to gdb_bfd

[PATCH] gdb: move bfd_open_from_target_memory to gdb_bfd

[Mihails Strasuns via Gdb-patches]

This function allows to create a BFD handle using an accessible memory
range in a target memory.  It is currently contained in a JIT module but
this functionality may be of wider usefullness - for example, reading
ELF binaries contained within a core dump.

gdb/ChangeLog:
2020-12-07  Mihails Strasuns  <miihails.strasuns@intel.com>

	* jit.c (mem_bfd*, bfd_open_from_target_memory): Removed.
	* gdb_bfd.h (gdb_bfd_open_from_target_memory): New function.
	* gdb_bfd.c (mem_bfd*, gdb_bfd_open_from_target_memory): New functions.
---
 gdb/gdb_bfd.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/gdb_bfd.h |  7 +++++
 gdb/jit.c     | 85 ++-------------------------------------------------
 3 files changed, 94 insertions(+), 83 deletions(-)

diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c
index 58d177cf7df..28dedca2530 100644
--- a/gdb/gdb_bfd.c
+++ b/gdb/gdb_bfd.c
@@ -207,6 +207,91 @@ gdb_bfd_has_target_filename (struct bfd *abfd)
   return is_target_filename (bfd_get_filename (abfd));
 }
 
+/* For `gdb_bfd_open_from_target_memory`.  */
+
+struct target_buffer
+{
+  CORE_ADDR base;
+  ULONGEST size;
+};
+
+/* For `gdb_bfd_open_from_target_memory`.  Opening the file is a no-op.  */
+
+static void *
+mem_bfd_iovec_open (struct bfd *abfd, void *open_closure)
+{
+  return open_closure;
+}
+
+/* For `gdb_bfd_open_from_target_memory`.  Closing the file is just freeing the
+   base/size pair on our side.  */
+
+static int
+mem_bfd_iovec_close (struct bfd *abfd, void *stream)
+{
+  xfree (stream);
+
+  /* Zero means success.  */
+  return 0;
+}
+
+/* For `gdb_bfd_open_from_target_memory`.  For reading the file, we just need to
+   pass through to target_read_memory and fix up the arguments and return
+   values.  */
+
+static file_ptr
+mem_bfd_iovec_pread (struct bfd *abfd, void *stream, void *buf,
+		     file_ptr nbytes, file_ptr offset)
+{
+  int err;
+  struct target_buffer *buffer = (struct target_buffer *) stream;
+
+  /* If this read will read all of the file, limit it to just the rest.  */
+  if (offset + nbytes > buffer->size)
+    nbytes = buffer->size - offset;
+
+  /* If there are no more bytes left, we've reached EOF.  */
+  if (nbytes == 0)
+    return 0;
+
+  err = target_read_memory (buffer->base + offset, (gdb_byte *) buf, nbytes);
+  if (err)
+    return -1;
+
+  return nbytes;
+}
+
+/* For `gdb_bfd_open_from_target_memory`.  For statting the file, we only
+   support the st_size attribute.  */
+
+static int
+mem_bfd_iovec_stat (struct bfd *abfd, void *stream, struct stat *sb)
+{
+  struct target_buffer *buffer = (struct target_buffer*) stream;
+
+  memset (sb, 0, sizeof (struct stat));
+  sb->st_size = buffer->size;
+  return 0;
+}
+
+/* See gdb_bfd.h.  */
+
+gdb_bfd_ref_ptr
+gdb_bfd_open_from_target_memory (CORE_ADDR addr, ULONGEST size,
+				 const char *target,
+				 const char *filename)
+{
+  struct target_buffer *buffer = XNEW (struct target_buffer);
+
+  buffer->base = addr;
+  buffer->size = size;
+  return gdb_bfd_openr_iovec (filename ? filename : "<in-memory>", target,
+			      mem_bfd_iovec_open,
+			      buffer,
+			      mem_bfd_iovec_pread,
+			      mem_bfd_iovec_close,
+			      mem_bfd_iovec_stat);
+}
 
 /* Return the system error number corresponding to ERRNUM.  */
 
diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index 0f450567d50..e622cd88257 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -194,6 +194,13 @@ int gdb_bfd_requires_relocations (bfd *abfd);
 bool gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
 					gdb::byte_vector *contents);
 
+/* Create and initialize a BFD handle from a target in-memory range.  */
+
+gdb_bfd_ref_ptr
+gdb_bfd_open_from_target_memory (CORE_ADDR addr, ULONGEST size,
+				 const char *target,
+				 const char *filename = nullptr);
+
 /* Range adapter for a BFD's sections.
 
    To be used as:
diff --git a/gdb/jit.c b/gdb/jit.c
index b373947a7f9..28594e36fc4 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -73,86 +73,6 @@ show_jit_debug (struct ui_file *file, int from_tty,
   fprintf_filtered (file, _("JIT debugging is %s.\n"), value);
 }
 
-struct target_buffer
-{
-  CORE_ADDR base;
-  ULONGEST size;
-};
-
-/* Opening the file is a no-op.  */
-
-static void *
-mem_bfd_iovec_open (struct bfd *abfd, void *open_closure)
-{
-  return open_closure;
-}
-
-/* Closing the file is just freeing the base/size pair on our side.  */
-
-static int
-mem_bfd_iovec_close (struct bfd *abfd, void *stream)
-{
-  xfree (stream);
-
-  /* Zero means success.  */
-  return 0;
-}
-
-/* For reading the file, we just need to pass through to target_read_memory and
-   fix up the arguments and return values.  */
-
-static file_ptr
-mem_bfd_iovec_pread (struct bfd *abfd, void *stream, void *buf,
-		     file_ptr nbytes, file_ptr offset)
-{
-  int err;
-  struct target_buffer *buffer = (struct target_buffer *) stream;
-
-  /* If this read will read all of the file, limit it to just the rest.  */
-  if (offset + nbytes > buffer->size)
-    nbytes = buffer->size - offset;
-
-  /* If there are no more bytes left, we've reached EOF.  */
-  if (nbytes == 0)
-    return 0;
-
-  err = target_read_memory (buffer->base + offset, (gdb_byte *) buf, nbytes);
-  if (err)
-    return -1;
-
-  return nbytes;
-}
-
-/* For statting the file, we only support the st_size attribute.  */
-
-static int
-mem_bfd_iovec_stat (struct bfd *abfd, void *stream, struct stat *sb)
-{
-  struct target_buffer *buffer = (struct target_buffer*) stream;
-
-  memset (sb, 0, sizeof (struct stat));
-  sb->st_size = buffer->size;
-  return 0;
-}
-
-/* Open a BFD from the target's memory.  */
-
-static gdb_bfd_ref_ptr
-bfd_open_from_target_memory (CORE_ADDR addr, ULONGEST size,
-			     const char *target)
-{
-  struct target_buffer *buffer = XNEW (struct target_buffer);
-
-  buffer->base = addr;
-  buffer->size = size;
-  return gdb_bfd_openr_iovec ("<in-memory>", target,
-			      mem_bfd_iovec_open,
-			      buffer,
-			      mem_bfd_iovec_pread,
-			      mem_bfd_iovec_close,
-			      mem_bfd_iovec_stat);
-}
-
 struct jit_reader
 {
   jit_reader (struct gdb_reader_funcs *f, gdb_dlhandle_up &&h)
@@ -777,9 +697,8 @@ jit_bfd_try_read_symtab (struct jit_code_entry *code_entry,
 			paddress (gdbarch, code_entry->symfile_addr),
 			pulongest (code_entry->symfile_size));
 
-  gdb_bfd_ref_ptr nbfd (bfd_open_from_target_memory (code_entry->symfile_addr,
-						     code_entry->symfile_size,
-						     gnutarget));
+  gdb_bfd_ref_ptr nbfd (gdb_bfd_open_from_target_memory (
+      code_entry->symfile_addr, code_entry->symfile_size, gnutarget));
   if (nbfd == NULL)
     {
       puts_unfiltered (_("Error opening JITed symbol file, ignoring it.\n"));
-- 
2.17.1

Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Christin Eisenschmid, Gary Kershaw
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

Re: [PATCH] gdb: move bfd_open_from_target_memory to gdb_bfd

[Tom Tromey]

>>>>> "Mihails" == Mihails Strasuns via Gdb-patches <gdb-patches@sourceware.org> writes:

Mihails> This function allows to create a BFD handle using an accessible memory
Mihails> range in a target memory.  It is currently contained in a JIT module but
Mihails> this functionality may be of wider usefullness - for example, reading
Mihails> ELF binaries contained within a core dump.

Mihails> gdb/ChangeLog:
Mihails> 2020-12-07  Mihails Strasuns  <miihails.strasuns@intel.com>

Mihails> 	* jit.c (mem_bfd*, bfd_open_from_target_memory): Removed.
Mihails> 	* gdb_bfd.h (gdb_bfd_open_from_target_memory): New function.
Mihails> 	* gdb_bfd.c (mem_bfd*, gdb_bfd_open_from_target_memory): New functions.

Hi.  Thank you for the patch.
It looks good to me.  I found a couple of minor nits, but the patch is
OK with these fixed.

Mihails> +/* Create and initialize a BFD handle from a target in-memory range.  */
Mihails> +
Mihails> +gdb_bfd_ref_ptr
Mihails> +gdb_bfd_open_from_target_memory (CORE_ADDR addr, ULONGEST size,
Mihails> +				 const char *target,
Mihails> +				 const char *filename = nullptr);

In the style style, the return type isn't separated from the function
name in a declaration.

Mihails> +  gdb_bfd_ref_ptr nbfd (gdb_bfd_open_from_target_memory (
Mihails> +      code_entry->symfile_addr, code_entry->symfile_size, gnutarget));

The formatting here looks weird.  Normally breaks would occur before "(".

Tom

RE: [PATCH] gdb: move bfd_open_from_target_memory to gdb_bfd

[Strasuns, Mihails via Gdb-patches]

Amended and pushed as 15cc148fb8.

> -----Original Message-----
> From: Tom Tromey <tom@tromey.com>
> Sent: Wednesday, December 9, 2020 10:31 PM
> To: Mihails Strasuns via Gdb-patches <gdb-patches@sourceware.org>
> Cc: Strasuns, Mihails <mihails.strasuns@intel.com>
> Subject: Re: [PATCH] gdb: move bfd_open_from_target_memory to
> gdb_bfd
> 
> >>>>> "Mihails" == Mihails Strasuns via Gdb-patches <gdb-
> patches@sourceware.org> writes:
> 
> Mihails> This function allows to create a BFD handle using an accessible
> Mihails> memory range in a target memory.  It is currently contained in
> Mihails> a JIT module but this functionality may be of wider usefullness
> Mihails> - for example, reading ELF binaries contained within a core dump.
> 
> Mihails> gdb/ChangeLog:
> Mihails> 2020-12-07  Mihails Strasuns  <miihails.strasuns@intel.com>
> 
> Mihails> 	* jit.c (mem_bfd*, bfd_open_from_target_memory):
> Removed.
> Mihails> 	* gdb_bfd.h (gdb_bfd_open_from_target_memory): New
> function.
> Mihails> 	* gdb_bfd.c (mem_bfd*,
> gdb_bfd_open_from_target_memory): New functions.
> 
> Hi.  Thank you for the patch.
> It looks good to me.  I found a couple of minor nits, but the patch is OK with
> these fixed.
> 
> Mihails> +/* Create and initialize a BFD handle from a target in-memory
> Mihails> +range.  */
> Mihails> +
> Mihails> +gdb_bfd_ref_ptr
> Mihails> +gdb_bfd_open_from_target_memory (CORE_ADDR addr,
> ULONGEST size,
> Mihails> +				 const char *target,
> Mihails> +				 const char *filename = nullptr);
> 
> In the style style, the return type isn't separated from the function name in a
> declaration.
> 
> Mihails> +  gdb_bfd_ref_ptr nbfd (gdb_bfd_open_from_target_memory (
> Mihails> +      code_entry->symfile_addr, code_entry->symfile_size,
> Mihails> + gnutarget));
> 
> The formatting here looks weird.  Normally breaks would occur before "(".
> 
> Tom
Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Christin Eisenschmid, Gary Kershaw
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928