Patchwork [1/2] Look for separate debug files in debug directories under a sysroot.

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Submitter John Baldwin
Date Jan. 23, 2019, 1:03 a.m.
Message ID <efae43ea34de8dfb49dca937f8d0e65cbcde4d5d.1548205042.git.jhb@FreeBSD.org>
Download mbox | patch
Permalink /patch/31174/
State New
Headers show

Comments

John Baldwin - Jan. 23, 2019, 1:03 a.m.
When an object file is present in a system root, GDB currently looks
for separate debug files under the global debugfile directories.  For
example, if the sysroot is set to "/myroot" and hte global debugfile
directory is set to "/usr/lib/debug", GDB will look for a separate
debug file for "/myroot/lib/libc.so.7" in the following paths:

  /myroot/lib/libc.so.7.debug
  /myroot/lib/.debug/libc.so.7.debug
  /usr/lib/debug//myroot/lib/libc.so.7.debug
  /usr/lib/debug/lib/libc.so.7.debug

However, some system roots include a full system installation
including a nested global debugfile directory under the sysroot.  This
patch adds an additional check to support such systems.  In the
example above the additional path searched is:

  /myroot/usr/lib/debug/lib/libc.so.7.debug

To try to preserve existing behavior as much as possible, this new
path is searched last for each global debugfile directory.

gdb/ChangeLog:

	* symfile.c (find_separate_debug_file): Look for separate debug
	files in debug directories under the sysroot.
---
 gdb/ChangeLog |  5 +++++
 gdb/symfile.c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+)
Simon Marchi - Jan. 26, 2019, 5:16 a.m.
On 2019-01-22 20:03, John Baldwin wrote:
> When an object file is present in a system root, GDB currently looks
> for separate debug files under the global debugfile directories.  For
> example, if the sysroot is set to "/myroot" and hte global debugfile
> directory is set to "/usr/lib/debug", GDB will look for a separate
> debug file for "/myroot/lib/libc.so.7" in the following paths:
> 
>   /myroot/lib/libc.so.7.debug
>   /myroot/lib/.debug/libc.so.7.debug
>   /usr/lib/debug//myroot/lib/libc.so.7.debug
>   /usr/lib/debug/lib/libc.so.7.debug
> 
> However, some system roots include a full system installation
> including a nested global debugfile directory under the sysroot.  This
> patch adds an additional check to support such systems.  In the
> example above the additional path searched is:
> 
>   /myroot/usr/lib/debug/lib/libc.so.7.debug
> 
> To try to preserve existing behavior as much as possible, this new
> path is searched last for each global debugfile directory.

I played with this a bit using a Raspbian sysroot.  I think the behavior 
you propose makes sense, perhaps more than the current behavior (I would 
be curious to see a real-word case for that one).  But anyway, keeping 
the old behavior and adding a new one is fine.  It's rather cheap to 
check many possible locations, and since there's a crc check, there's 
very little chance of loading a wrong separate debug file.

As discussed on IRC, we should probably add the same behavior for 
build-id-based separate debug files.

> diff --git a/gdb/symfile.c b/gdb/symfile.c
> index 7f800add8c..c6d2c7c537 100644
> --- a/gdb/symfile.c
> +++ b/gdb/symfile.c
> @@ -1465,6 +1465,25 @@ find_separate_debug_file (const char *dir,
>  	  if (separate_debug_file_exists (debugfile, crc32, objfile))
>  	    return debugfile;
>  	}
> +
> +      /* If the file is in the sysroot, try using its base path in the
> +	 sysroot's global debugfile directory.  */
> +      if (canon_dir != NULL
> +	  && filename_ncmp (canon_dir, gdb_sysroot,
> +			    strlen (gdb_sysroot)) == 0
> +	  && IS_DIR_SEPARATOR (canon_dir[strlen (gdb_sysroot)]))
> +	{

Is there any reason to duplicate the if above?  It looks to be the same 
as the previous check, so the new code could go in the existing if.

> +	  debugfile = target_prefix ? "target:" : "";
> +	  debugfile += gdb_sysroot;
> +	  debugfile += debugdir.get ();
> +	  debugfile += (canon_dir + strlen (gdb_sysroot));
> +	  debugfile += "/";
> +	  debugfile += debuglink;
> +
> +	  if (separate_debug_file_exists (debugfile, crc32, objfile))
> +	    return debugfile;
> +	}
> +

Simon

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 938fa83ca8..a401cfc784 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@ 
+2019-01-22  John Baldwin  <jhb@FreeBSD.org>
+
+	* symfile.c (find_separate_debug_file): Look for separate debug
+	files in debug directories under the sysroot.
+
 2019-01-22  John Baldwin  <jhb@FreeBSD.org>
 
 	* ppc-fbsd-tdep.c (ppcfbsd_get_thread_local_address): New.
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 7f800add8c..c6d2c7c537 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1465,6 +1465,25 @@  find_separate_debug_file (const char *dir,
 	  if (separate_debug_file_exists (debugfile, crc32, objfile))
 	    return debugfile;
 	}
+
+      /* If the file is in the sysroot, try using its base path in the
+	 sysroot's global debugfile directory.  */
+      if (canon_dir != NULL
+	  && filename_ncmp (canon_dir, gdb_sysroot,
+			    strlen (gdb_sysroot)) == 0
+	  && IS_DIR_SEPARATOR (canon_dir[strlen (gdb_sysroot)]))
+	{
+	  debugfile = target_prefix ? "target:" : "";
+	  debugfile += gdb_sysroot;
+	  debugfile += debugdir.get ();
+	  debugfile += (canon_dir + strlen (gdb_sysroot));
+	  debugfile += "/";
+	  debugfile += debuglink;
+
+	  if (separate_debug_file_exists (debugfile, crc32, objfile))
+	    return debugfile;
+	}
+
     }
 
   return std::string ();