464 lines
13 KiB
C
464 lines
13 KiB
C
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/* Caching of GDB/DWARF index files.
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Copyright (C) 1994-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "dwarf-index-cache.h"
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#include "build-id.h"
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#include "cli/cli-cmds.h"
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#include "command.h"
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#include "common/scoped_mmap.h"
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#include "common/pathstuff.h"
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#include "dwarf-index-write.h"
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#include "dwarf2read.h"
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#include "objfiles.h"
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#include "selftest.h"
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#include <string>
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#include <stdlib.h>
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/* When set to 1, show debug messages about the index cache. */
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static int debug_index_cache = 0;
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/* The index cache directory, used for "set/show index-cache directory". */
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static char *index_cache_directory = NULL;
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/* See dwarf-index.cache.h. */
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index_cache global_index_cache;
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/* set/show index-cache commands. */
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static cmd_list_element *set_index_cache_prefix_list;
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static cmd_list_element *show_index_cache_prefix_list;
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/* A cheap (as in low-quality) recursive mkdir. Try to create all the parents
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directories up to DIR and DIR itself. Stop if we hit an error along the way.
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There is no attempt to remove created directories in case of failure. */
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static void
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mkdir_recursive (const char *dir)
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{
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gdb::unique_xmalloc_ptr<char> holder (xstrdup (dir));
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char * const start = holder.get ();
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char *component_start = start;
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char *component_end = start;
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while (1)
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{
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/* Find the beginning of the next component. */
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while (*component_start == '/')
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component_start++;
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/* Are we done? */
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if (*component_start == '\0')
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return;
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/* Find the slash or null-terminator after this component. */
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component_end = component_start;
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while (*component_end != '/' && *component_end != '\0')
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component_end++;
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/* Temporarily replace the slash with a null terminator, so we can create
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the directory up to this component. */
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char saved_char = *component_end;
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*component_end = '\0';
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/* If we get EEXIST and the existing path is a directory, then we're
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happy. If it exists, but it's a regular file and this is not the last
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component, we'll fail at the next component. If this is the last
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component, the caller will fail with ENOTDIR when trying to
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open/create a file under that path. */
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if (mkdir (start, 0700) != 0)
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if (errno != EEXIST)
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return;
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/* Restore the overwritten char. */
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*component_end = saved_char;
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component_start = component_end;
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}
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}
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/* Default destructor of index_cache_resource. */
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index_cache_resource::~index_cache_resource () = default;
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/* See dwarf-index-cache.h. */
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void
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index_cache::set_directory (std::string dir)
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{
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gdb_assert (!dir.empty ());
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m_dir = std::move (dir);
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if (debug_index_cache)
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printf_unfiltered ("index cache: now using directory %s\n", m_dir.c_str ());
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}
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/* See dwarf-index-cache.h. */
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void
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index_cache::enable ()
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: enabling (%s)\n", m_dir.c_str ());
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m_enabled = true;
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}
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/* See dwarf-index-cache.h. */
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void
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index_cache::disable ()
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: disabling\n");
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m_enabled = false;
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}
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/* See dwarf-index-cache.h. */
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void
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index_cache::store (struct dwarf2_per_objfile *dwarf2_per_objfile)
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{
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objfile *obj = dwarf2_per_objfile->objfile;
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if (!enabled ())
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return;
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const bfd_build_id *build_id = build_id_bfd_get (obj->obfd);
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if (build_id == nullptr)
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: objfile %s has no build id\n",
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objfile_name (obj));
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return;
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}
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if (m_dir.empty ())
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{
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warning (_("The index cache directory name is empty, skipping store."));
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return;
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}
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std::string build_id_str = build_id_to_string (build_id);
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TRY
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{
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/* Try to create the containing directory. */
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mkdir_recursive (m_dir.c_str ());
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if (debug_index_cache)
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printf_unfiltered ("index cache: writing index cache for objfile %s\n",
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objfile_name (obj));
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/* Write the index itself to the directory, using the build id as the
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filename. */
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write_psymtabs_to_index (dwarf2_per_objfile, m_dir.c_str (),
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build_id_str.c_str (), dw_index_kind::GDB_INDEX);
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}
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CATCH (except, RETURN_MASK_ERROR)
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: couldn't store index cache for objfile "
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"%s: %s", objfile_name (obj), except.message);
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}
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END_CATCH
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}
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#if HAVE_SYS_MMAN_H
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/* Hold the resources for an mmapped index file. */
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struct index_cache_resource_mmap final : public index_cache_resource
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{
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/* Try to mmap FILENAME. Throw an exception on failure, including if the
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file doesn't exist. */
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index_cache_resource_mmap (const char *filename)
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: mapping (mmap_file (filename))
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{}
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scoped_mmap mapping;
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};
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/* See dwarf-index-cache.h. */
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gdb::array_view<const gdb_byte>
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index_cache::lookup_gdb_index (const bfd_build_id *build_id,
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std::unique_ptr<index_cache_resource> *resource)
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{
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if (!enabled ())
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return {};
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if (m_dir.empty ())
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{
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warning (_("The index cache directory name is empty, skipping cache "
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"lookup."));
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return {};
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}
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/* Compute where we would expect a gdb index file for this build id to be. */
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std::string filename = make_index_filename (build_id, INDEX4_SUFFIX);
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TRY
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: trying to read %s\n",
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filename.c_str ());
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/* Try to map that file. */
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index_cache_resource_mmap *mmap_resource
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= new index_cache_resource_mmap (filename.c_str ());
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/* Yay, it worked! Hand the resource to the caller. */
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resource->reset (mmap_resource);
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return gdb::array_view<const gdb_byte>
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((const gdb_byte *) mmap_resource->mapping.get (),
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mmap_resource->mapping.size ());
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}
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CATCH (except, RETURN_MASK_ERROR)
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{
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if (debug_index_cache)
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printf_unfiltered ("index cache: couldn't read %s: %s\n",
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filename.c_str (), except.message);
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}
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END_CATCH
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return {};
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}
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#else /* !HAVE_SYS_MMAN_H */
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/* See dwarf-index-cache.h. This is a no-op on unsupported systems. */
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gdb::array_view<const gdb_byte>
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index_cache::lookup_gdb_index (const bfd_build_id *build_id,
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std::unique_ptr<index_cache_resource> *resource)
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{
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return {};
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}
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#endif
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/* See dwarf-index-cache.h. */
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std::string
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index_cache::make_index_filename (const bfd_build_id *build_id,
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const char *suffix) const
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{
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std::string build_id_str = build_id_to_string (build_id);
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return m_dir + SLASH_STRING + build_id_str + suffix;
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}
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/* "set index-cache" handler. */
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static void
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set_index_cache_command (const char *arg, int from_tty)
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{
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printf_unfiltered (_("\
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Missing arguments. See \"help set index-cache\" for help.\n"));
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}
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/* True when we are executing "show index-cache". This is used to improve the
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printout a little bit. */
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static bool in_show_index_cache_command = false;
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/* "show index-cache" handler. */
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static void
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show_index_cache_command (const char *arg, int from_tty)
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{
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/* Note that we are executing "show index-cache". */
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auto restore_flag = make_scoped_restore (&in_show_index_cache_command, true);
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/* Call all "show index-cache" subcommands. */
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cmd_show_list (show_index_cache_prefix_list, from_tty, "");
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printf_unfiltered ("\n");
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printf_unfiltered
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(_("The index cache is currently %s.\n"),
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global_index_cache.enabled () ? _("enabled") : _("disabled"));
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}
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/* "set index-cache on" handler. */
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static void
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set_index_cache_on_command (const char *arg, int from_tty)
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{
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global_index_cache.enable ();
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}
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/* "set index-cache off" handler. */
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static void
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set_index_cache_off_command (const char *arg, int from_tty)
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{
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global_index_cache.disable ();
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}
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/* "set index-cache directory" handler. */
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static void
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set_index_cache_directory_command (const char *arg, int from_tty,
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cmd_list_element *element)
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{
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/* Make sure the index cache directory is absolute and tilde-expanded. */
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gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (index_cache_directory));
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xfree (index_cache_directory);
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index_cache_directory = abs.release ();
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global_index_cache.set_directory (index_cache_directory);
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}
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/* "show index-cache stats" handler. */
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static void
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show_index_cache_stats_command (const char *arg, int from_tty)
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{
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const char *indent = "";
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/* If this command is invoked through "show index-cache", make the display a
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bit nicer. */
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if (in_show_index_cache_command)
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{
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indent = " ";
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printf_unfiltered ("\n");
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}
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printf_unfiltered (_("%s Cache hits (this session): %u\n"),
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indent, global_index_cache.n_hits ());
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printf_unfiltered (_("%sCache misses (this session): %u\n"),
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indent, global_index_cache.n_misses ());
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}
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#if GDB_SELF_TEST && defined (HAVE_MKDTEMP)
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namespace selftests
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{
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/* Try to create DIR using mkdir_recursive and make sure it exists. */
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static bool
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create_dir_and_check (const char *dir)
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{
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mkdir_recursive (dir);
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struct stat st;
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if (stat (dir, &st) != 0)
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perror_with_name ("stat");
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return (st.st_mode & S_IFDIR) != 0;
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}
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/* Test mkdir_recursive. */
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static void
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test_mkdir_recursive ()
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{
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char base[] = "/tmp/gdb-selftests-XXXXXX";
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if (mkdtemp (base) == NULL)
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perror_with_name ("mkdtemp");
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/* Try not to leave leftover directories. */
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struct cleanup_dirs {
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cleanup_dirs (const char *base)
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: m_base (base)
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{}
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~cleanup_dirs () {
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rmdir (string_printf ("%s/a/b/c/d/e", m_base).c_str ());
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rmdir (string_printf ("%s/a/b/c/d", m_base).c_str ());
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rmdir (string_printf ("%s/a/b/c", m_base).c_str ());
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rmdir (string_printf ("%s/a/b", m_base).c_str ());
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rmdir (string_printf ("%s/a", m_base).c_str ());
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rmdir (m_base);
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}
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private:
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const char *m_base;
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} cleanup_dirs (base);
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std::string dir = string_printf ("%s/a/b", base);
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SELF_CHECK (create_dir_and_check (dir.c_str ()));
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dir = string_printf ("%s/a/b/c//d/e/", base);
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SELF_CHECK (create_dir_and_check (dir.c_str ()));
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}
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}
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#endif /* GDB_SELF_TEST && defined (HAVE_MKDTEMP) */
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void
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_initialize_index_cache ()
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{
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/* Set the default index cache directory. */
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std::string cache_dir = get_standard_cache_dir ();
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if (!cache_dir.empty ())
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{
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index_cache_directory = xstrdup (cache_dir.c_str ());
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global_index_cache.set_directory (std::move (cache_dir));
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}
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else
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warning (_("Couldn't determine a path for the index cache directory."));
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/* set index-cache */
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add_prefix_cmd ("index-cache", class_files, set_index_cache_command,
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_("Set index-cache options"), &set_index_cache_prefix_list,
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"set index-cache ", false, &setlist);
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/* show index-cache */
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add_prefix_cmd ("index-cache", class_files, show_index_cache_command,
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_("Show index-cache options"), &show_index_cache_prefix_list,
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"show index-cache ", false, &showlist);
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/* set index-cache on */
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add_cmd ("on", class_files, set_index_cache_on_command,
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_("Enable the index cache."), &set_index_cache_prefix_list);
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/* set index-cache off */
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add_cmd ("off", class_files, set_index_cache_off_command,
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_("Disable the index cache."), &set_index_cache_prefix_list);
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/* set index-cache directory */
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add_setshow_filename_cmd ("directory", class_files, &index_cache_directory,
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_("Set the directory of the index cache."),
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_("Show the directory of the index cache."),
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NULL,
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set_index_cache_directory_command, NULL,
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&set_index_cache_prefix_list,
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&show_index_cache_prefix_list);
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/* show index-cache stats */
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add_cmd ("stats", class_files, show_index_cache_stats_command,
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_("Show some stats about the index cache."),
|
||
|
&show_index_cache_prefix_list);
|
||
|
|
||
|
/* set debug index-cache */
|
||
|
add_setshow_boolean_cmd ("index-cache", class_maintenance,
|
||
|
&debug_index_cache,
|
||
|
_("Set display of index-cache debug messages."),
|
||
|
_("Show display of index-cache debug messages."),
|
||
|
_("\
|
||
|
When non-zero, debugging output for the index cache is displayed."),
|
||
|
NULL, NULL,
|
||
|
&setdebuglist, &showdebuglist);
|
||
|
|
||
|
#if GDB_SELF_TEST && defined (HAVE_MKDTEMP)
|
||
|
selftests::register_test ("mkdir_recursive", selftests::test_mkdir_recursive);
|
||
|
#endif
|
||
|
}
|