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gdb: use bfd_get_section_contents to read section contents in is_linked_with_cygwin_dll

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The function is_linked_with_cygwin_dll currently uses
gdb_bfd_map_section to get some section contents.  This is not ideal
because that memory, which is only used in this function, can't be
released.  Instead, it was suggested to use
bfd_get_full_section_contents.

However, bfd_get_full_section_contents returns a newly allocated buffer,
which is not very practical to use with C++ automatic memory management
constructs.  I decided to make gdb_bfd_get_full_section_contents, a
small alternative to bfd_get_full_section_contents.  It is a small
wrapper around bfd_get_section_contents which returns the full contents
of the section in a gdb::byte_vector.

gdb_bfd_get_full_section_contents could be used at many places that
already allocate a vector of the size of the section and then call
bfd_get_section_contents.  I think these call sites can be updated over
time.

gdb/ChangeLog:

	* gdb_bfd.h: Include gdbsupport/byte-vector.h.
	(gdb_bfd_get_full_section_contents): New declaration.
	* gdb_bfd.c (gdb_bfd_get_full_section_contents): New function.
	* windows-tdep.c (is_linked_with_cygwin_dll): Use
	gdb_bfd_get_full_section_contents.
This commit is contained in:
Simon Marchi 2020-04-02 15:49:06 -04:00
parent e2ff18a0a5
commit e0fc5c3fcb
4 changed files with 36 additions and 8 deletions
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8
gdb/ChangeLog
View File

@ -1,3 +1,11 @@
2020-04-02 Simon Marchi <simon.marchi@polymtl.ca>
* gdb_bfd.h: Include gdbsupport/byte-vector.h.
(gdb_bfd_get_full_section_contents): New declaration.
* gdb_bfd.c (gdb_bfd_get_full_section_contents): New function.
* windows-tdep.c (is_linked_with_cygwin_dll): Use
gdb_bfd_get_full_section_contents.
2020-04-02 Simon Marchi <simon.marchi@polymtl.ca>
* exec.c (build_section_table): Replace internal_error with

14
gdb/gdb_bfd.c
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@ -926,7 +926,19 @@ gdb_bfd_requires_relocations (bfd *abfd)
return gdata->needs_relocations;
}
/* See gdb_bfd.h. */
bool
gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
gdb::byte_vector *contents)
{
bfd_size_type section_size = bfd_section_size (section);
contents->resize (section_size);
return bfd_get_section_contents (abfd, section, contents->data (), 0,
section_size);
}
/* A callback for htab_traverse that prints a single BFD. */

9
gdb/gdb_bfd.h
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@ -21,6 +21,7 @@
#define GDB_BFD_H
#include "registry.h"
#include "gdbsupport/byte-vector.h"
#include "gdbsupport/gdb_ref_ptr.h"
DECLARE_REGISTRY (bfd);
@ -181,4 +182,12 @@ int gdb_bfd_count_sections (bfd *abfd);
int gdb_bfd_requires_relocations (bfd *abfd);
/* Alternative to bfd_get_full_section_contents that returns the section
contents in *CONTENTS, instead of an allocated buffer.
Return true on success, false otherwise. */
bool gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
gdb::byte_vector *contents);
#endif /* GDB_BFD_H */

13
gdb/windows-tdep.c
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@ -935,18 +935,17 @@ is_linked_with_cygwin_dll (bfd *abfd)
bfd_vma idata_addr
= pe_data (abfd)->pe_opthdr.DataDirectory[PE_IMPORT_TABLE].VirtualAddress;
/* Map the section's data. */
bfd_size_type idata_size;
const gdb_byte *const idata_contents
= gdb_bfd_map_section (idata_section, &idata_size);
if (idata_contents == nullptr)
/* Get the section's data. */
gdb::byte_vector idata_contents;
if (!gdb_bfd_get_full_section_contents (abfd, idata_section, &idata_contents))
{
warning (_("Failed to get content of .idata section."));
return false;
}
const gdb_byte *iter = idata_contents;
const gdb_byte *end = idata_contents + idata_size;
size_t idata_size = idata_contents.size ();
const gdb_byte *iter = idata_contents.data ();
const gdb_byte *end = idata_contents.data () + idata_size;
const pe_import_directory_entry null_dir_entry = { 0 };
/* Iterate through all directory entries. */