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Re: [PATCH v2 3/5] Introduce gdb_chdir
On Wednesday, September 20 2017, Pedro Alves wrote:
> On 09/19/2017 05:28 AM, Sergio Durigan Junior wrote:
>> In order to be able to change the inferior's directory before its
>> execution, it is necessary to perform a tilde expansion of the
>> directory provided by the user and then chdir into the resulting dir.
>> This is what gdb_chdir does.
>>
>> Unfortunately it is not possible to use "tilde_expand" from readline
>> because this is common code and gdbserver doesn't use readline. For
>> that reason I decided to go with "glob" and its GNU extension,
>> GLOB_TILDE. With the import of the "glob" module from gnulib, this is
>> a no-brainer.
>>
>> gdb/ChangeLog:
>> yyyy-mm-dd Sergio Durigan Junior <sergiodj@redhat.com>
>>
>> * Makefile.in (SFILES): Add gdb_chdir.c.
>> (HFILES_NO_SRCDIR): Add gdb_chdir.h.
>> (COMMON_OBS): Add gdb_chdir.o.
>> * cli/cli-cmds.c: Include "gdb_chdir.h".
>> (cd_command): Use "gdb_chdir" instead of "tilde_expand
>> plus chdir".
>> * common/gdb_chdir.c: New file.
>> * common/gdb_chdir.h: Likewise.
>>
>> gdb/gdbserver/ChangeLog:
>> yyyy-mm-dd Sergio Durigan Junior <sergiodj@redhat.com>
>>
>> * Makefile.in (SFILES): Add $(srcdir)/common/gdb_chdir.c.
>> (OBS): Add gdb_chdir.o.
>> ---
>> gdb/Makefile.in | 3 ++
>> gdb/cli/cli-cmds.c | 20 +++++-----
>> gdb/common/gdb_chdir.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++
>> gdb/common/gdb_chdir.h | 26 +++++++++++++
>> gdb/gdbserver/Makefile.in | 2 +
>> 5 files changed, 136 insertions(+), 11 deletions(-)
>> create mode 100644 gdb/common/gdb_chdir.c
>> create mode 100644 gdb/common/gdb_chdir.h
>>
>> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
>> index 9dfc117b2f..1f093e6c0f 100644
>> --- a/gdb/Makefile.in
>> +++ b/gdb/Makefile.in
>> @@ -1245,6 +1245,7 @@ SFILES = \
>> common/filestuff.c \
>> common/format.c \
>> common/job-control.c \
>> + common/gdb_chdir.c \
>> common/gdb_vecs.c \
>> common/new-op.c \
>> common/print-utils.c \
>> @@ -1529,6 +1530,7 @@ HFILES_NO_SRCDIR = \
>> common/fileio.h \
>> common/format.h \
>> common/gdb_assert.h \
>> + common/gdb_chdir.h \
>> common/gdb_locale.h \
>> common/gdb_setjmp.h \
>> common/gdb_signals.h \
>> @@ -1734,6 +1736,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
>> frame-unwind.o \
>> gcore.o \
>> gdb_bfd.o \
>> + gdb_chdir.o \
>> gdb-dlfcn.o \
>> gdb_obstack.o \
>> gdb_regex.o \
>> diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
>> index 85d6d21113..653dd56a64 100644
>> --- a/gdb/cli/cli-cmds.c
>> +++ b/gdb/cli/cli-cmds.c
>> @@ -54,6 +54,8 @@
>> #include "tui/tui.h" /* For tui_active et.al. */
>> #endif
>>
>> +#include "gdb_chdir.h"
>> +
>> #include <fcntl.h>
>> #include <algorithm>
>> #include <string>
>> @@ -408,12 +410,7 @@ cd_command (char *dir, int from_tty)
>> repeat might be useful but is more likely to be a mistake. */
>> dont_repeat ();
>>
>> - gdb::unique_xmalloc_ptr<char> dir_holder
>> - (tilde_expand (dir != NULL ? dir : "~"));
>> - dir = dir_holder.get ();
>> -
>> - if (chdir (dir) < 0)
>> - perror_with_name (dir);
>> + gdb_chdir (dir != NULL ? dir : "~");
>>
>> #ifdef HAVE_DOS_BASED_FILE_SYSTEM
>> /* There's too much mess with DOSish names like "d:", "d:.",
>> @@ -436,20 +433,21 @@ cd_command (char *dir, int from_tty)
>> len--;
>> }
>>
>> - dir_holder.reset (savestring (dir, len));
>> - if (IS_ABSOLUTE_PATH (dir_holder.get ()))
>> + std::string newdir = std::string (dir, len);
>> + const char *newdir_str = newdir.c_str ();
>> + if (IS_ABSOLUTE_PATH (newdir_str))
>> {
>> xfree (current_directory);
>> - current_directory = dir_holder.release ();
>> + current_directory = xstrdup (newdir_str);
>
> This introduces one extra deep string dup. One to
> construct the std::string, and another here in this xstrdup.
>
> How about simply, above:
>
> - dir_holder.reset (savestring (dir, len));
> + gdb::unique_xmalloc_ptr<char> dir_holder (savestring (dir, len))
>
>
> But more importantly, isn't there a behavior change here?
> Before, current_directory would be a copy of the the expand
> path, while after the patch, it's a copy of the input string,
> before expansion. Right?
Wow, you're right. I am sorry about letting this slip. I guess I made
so many modifications to this code that in the end I forgot that "dir"
wasn't being updated to hold the expanded path anymore. I will fix
this.
And with your review of patch #4, it is clear that we don't need
a gdb_chdir; we need a gdb_tilde_expand. Therefore I will make the
necessary modifications to export that function instead.
>
>> }
>> else
>> {
>> if (IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1]))
>> - current_directory = concat (current_directory, dir_holder.get (),
>> + current_directory = concat (current_directory, newdir_str,
>> (char *) NULL);
>> else
>> current_directory = concat (current_directory, SLASH_STRING,
>> - dir_holder.get (), (char *) NULL);
>> + newdir_str, (char *) NULL);
>> }
>
>
>> + /* Destroy the object and free M_GLOB. */
>> + ~gdb_glob ()
>> + {
>> + globfree (&m_glob);
>> + }
>> +
>> + /* Return the GL_PATHC component of M_GLOB. */
>> + int
>> + pathc () const
>> + {
>> + return m_glob.gl_pathc;
>> + }
>
> We've been putting type and function name in the
> same line in inline member functions. That's the
> de facto standard in GCC as well, AFAICS.
Done.
>
>> +
>> + /* Return the GL_PATHV component of M_GLOB. */
>> + char **
>> + pathv () const
>> + {
>> + return m_glob.gl_pathv;
>> + }
>
> Ditto.
Done.
>
>> +#ifndef HAVE_GDB_CHDIR_H
>> +#define HAVE_GDB_CHDIR_H
>> +
>> +/* Perform a "chdir" to DIR, doing the proper tilde expansion before. */
>> +extern void gdb_chdir (const char *dir);
>
> Nit, I'd drop "the proper", as it doesn't see to add value.
> I.e., what's proper and what's not proper?
Done.
Thanks,
--
Sergio
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