2018-02-10 07:44:59 +08:00
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/* Path manipulation routines for GDB and gdbserver.
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Copyright (C) 1986-2018 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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#ifndef PATHSTUFF_H
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#define PATHSTUFF_H
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/* Path utilities. */
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/* Return the real path of FILENAME, expanding all the symbolic links.
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Contrary to "gdb_abspath", this function does not use
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CURRENT_DIRECTORY for path expansion. Instead, it relies on the
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current working directory (CWD) of GDB or gdbserver. */
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extern gdb::unique_xmalloc_ptr<char> gdb_realpath (const char *filename);
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/* Return a copy of FILENAME, with its directory prefix canonicalized
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by gdb_realpath. */
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extern gdb::unique_xmalloc_ptr<char>
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gdb_realpath_keepfile (const char *filename);
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/* Return PATH in absolute form, performing tilde-expansion if necessary.
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PATH cannot be NULL or the empty string.
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This does not resolve symlinks however, use gdb_realpath for that.
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Contrary to "gdb_realpath", this function uses CURRENT_DIRECTORY
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for the path expansion. This may lead to scenarios the current
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working directory (CWD) is different than CURRENT_DIRECTORY. */
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extern gdb::unique_xmalloc_ptr<char> gdb_abspath (const char *path);
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Make gdbserver work with filename-only binaries
Simon mentioned on IRC that, after the startup-with-shell feature has
been implemented on gdbserver, it is not possible to specify a
filename-only binary, like:
$ gdbserver :1234 a.out
/bin/bash: line 0: exec: a.out: not found
During startup program exited with code 127.
Exiting
This happens on systems where the current directory "." is not listed
in the PATH environment variable. Although including "." in the PATH
variable is a possible workaround, this can be considered a regression
because before startup-with-shell it was possible to use only the
filename (due to reason that gdbserver used "exec*" directly).
The idea of the patch is to verify if the program path provided by the
user (or by the remote protocol) contains a directory separator
character. If it doesn't, it means we're dealing with a filename-only
binary, so we call "gdb_abspath" to properly expand it and transform
it into a full path. Otherwise, we leave the program path untouched.
This mimicks the behaviour seen on GDB (look at "openp" and
"attach_inferior", for example).
I am also submitting a testcase which exercises the scenario described
above. This test requires gdbserver to be executed in a different CWD
than the original, so I also created a helper function, "with_cwd" (on
testsuite/lib/gdb.exp), which takes care of cd'ing into and out of the
specified dir.
Built and regtested on BuildBot, without regressions.
gdb/ChangeLog:
2018-02-28 Sergio Durigan Junior <sergiodj@redhat.com>
Simon Marchi <simon.marchi@polymtl.ca>
* common/common-utils.c: Include "sys/stat.h".
(is_regular_file): Move here from "source.c"; change return
type to "bool".
* common/common-utils.h (is_regular_file): New prototype.
* common/pathstuff.c (contains_dir_separator): New function.
* common/pathstuff.h (contains_dir_separator): New prototype.
* source.c: Don't include "sys/stat.h".
(is_regular_file): Move to "common/common-utils.c".
gdb/gdbserver/ChangeLog:
2018-02-28 Sergio Durigan Junior <sergiodj@redhat.com>
* server.c: Include "filenames.h" and "pathstuff.h".
(program_name): Delete variable.
(program_path): New anonymous class.
(get_exec_wrapper): Use "program_path" instead of
"program_name".
(handle_v_run): Likewise.
(captured_main): Likewise.
(process_serial_event): Likewise.
gdb/testsuite/ChangeLog:
2018-02-28 Sergio Durigan Junior <sergiodj@redhat.com>
* gdb.server/abspath.exp: New file.
* lib/gdb.exp (with_cwd): New procedure.
2018-02-10 07:54:41 +08:00
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/* Return whether PATH contains a directory separator character. */
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extern bool contains_dir_separator (const char *path);
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Add DWARF index cache
New in v3:
- Remove things related to the dwarf-5 format.
- Fix compilation on mingw (scoped_mmap.c).
GDB can generate indexes for DWARF debug information, which, when
integrated in the original binary, can speed up loading object files.
This can be done using the gdb-add-index script or directly by the
linker itself. However, not many people know about this. And even
among those who do, because it requires additional steps, I don't know a
lot of people who actually go through that trouble.
To help make using the DWARF index more transparent, this patch
introduces a DWARF index cache. When enabled, loading an index-less
binary in GDB will automatically save an index file in ~/.cache/gdb.
When loading that same object file again, the index file will be looked
up and used to load the DWARF index. You therefore get the benefit of
the DWARF index without having to do additional manual steps or
modifying your build system. When an index section is already present
in the file, GDB will prefer that one over looking up the cache.
When doing my edit-compile-debug cycle, I often debug multiple times the
same build, so the cache helps reducing the load time of the debug
sessions after the first one.
- The saved index file is exactly the same as the output of the "save
gdb-index" command. It is therefore the exact same content that would
be found in the .gdb_index or .debug_names section. We just leave it
as a standalone file instead of merging it in the binary.
- The cache is just a directory with files named after the object
file's build-id. It is not possible to save/load the index for an
object file without build-id in the cache.
- The cache uses the gdb index format. The problem with the dwarf-5
format is that we can generate an addendum to the .debug_str section
that you're supposed to integrate to the original binary. This
complicates a little bit loading the data from the cached index files,
so I would leave this for later.
- The size taken up by ~/.cache/gdb is not limited. I was thinking we
could add configurable limit (like ccache does), but that would come
after. Also, maybe a command to flush the cache.
- The cache is disabled by default. I think once it's been out there
and tested for a while, it could be turned on by default, so that
everybody can enjoy it.
- The code was made to follow the XDG specification: if the
XDG_CACHE_HOME environment variable, it is used, otherwise it falls
back to ~/.cache/gdb. It is possible to change it using "set
index-cache directory". On other OSes than GNU/Linux, ~/.cache may
not be the best place to put such data. On macOS it should probably
default to ~/Library/Caches/... On Windows, %LocalAppData%/... I
don't intend to do this part, but further patches are welcome.
- I think that we need to be careful that multiple instances of GDB
don't interfere with each other (not far fetched at all if you run GDB
in some automated script) and the cache is always coherent (either the
file is not found, or it is found and entirely valid). Writing the
file directly to its final location seems like a recipe for failure.
One GDB could read a file in the index while it is being written by
another GDB. To mitigate this, I made write_psymtabs_to_index write
to temporary files and rename them once it's done. Two GDB instances
writing the index for the same file should not step on each other's
toes (the last file to be renamed will stay). A GDB looking up a file
will only see a complete file or no file. Also, if GDB crashes while
generating the index file, it will leave a work-in-progress file, but
it won't be picked up by other instances looking up in the cache.
gdb/ChangeLog:
* common/pathstuff.h (get_standard_cache_dir): New.
* common/pathstuff.c (get_standard_cache_dir): New.
* build-id.h (build_id_to_string): New.
* dwarf-index-common.h (INDEX4_SUFFIX, INDEX5_SUFFIX,
DEBUG_STR_SUFFIX): Move to here.
* dwarf-index-write.c (INDEX4_SUFFIX, INDEX5_SUFFIX,
DEBUG_STR_SUFFIX): Move from there.
(write_psymtabs_to_index): Make non-static, add basename
parameter. Write to temporary files, rename when done.
(save_gdb_index_command): Adjust call to
write_psymtabs_to_index.
* dwarf2read.h (dwarf2_per_objfile) <index_cache_res>: New
field.
* dwarf2read.c (dwz_file) <index_cache_res>: New field.
(get_gdb_index_contents_from_cache): New.
(get_gdb_index_contents_from_cache_dwz): New.
(dwarf2_initialize_objfile): Read index from cache.
(dwarf2_build_psymtabs): Save to index.
* dwarf-index-cache.h: New file.
* dwarf-index-cache.c: New file.
* dwarf-index-write.h: New file.
gdb/testsuite/ChangeLog:
* boards/index-cache-gdb.exp: New file.
* gdb.dwarf2/index-cache.exp: New file.
* gdb.dwarf2/index-cache.c: New file.
* gdb.base/maint.exp: Check if we are using the index cache.
2018-08-08 06:14:20 +08:00
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/* Get the usual user cache directory for the current platform.
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On Linux, it follows the XDG Base Directory specification: use
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$XDG_CACHE_HOME/gdb if the XDG_CACHE_HOME environment variable is defined,
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otherwise $HOME/.cache. The return value is absolute and tilde-expanded.
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Return an empty string if neither XDG_CACHE_HOME or HOME are defined. */
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extern std::string get_standard_cache_dir ();
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2018-02-10 07:44:59 +08:00
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#endif /* PATHSTUFF_H */
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