Re: Automatically replace shared library extensions on Symbian

[Pedro Alves <pedro at codesourcery dot com>]

On Monday 08 March 2010 04:54:15, Joel Brobecker wrote:

> > +# If non-empty, this is a file extension that will be opened in place
> > +# of the file extension reported by the shared library list.
> > +v:const char *:solib_symbols_extension:::::::pstring (gdbarch->solib_symbols_extension)
> 
> Would you mind expanding the commend above to explain that Symbian OS
> is one example where this can be useful, and why? Basically, the current
> description is a bit short, and I also found the paragraph describing
> what happens on Symbian to be very interesting and useful...

I sure don't.

> Another option for preserving the description of what happens on Symbian OS
> is to provide it at the location where you call set_solib_symbols_extension,
> but it might be more difficult for someone working on a different architecture
> having the same problem and looking for the gdbarch method that would allow
> him to solve his problem?

How about this?  I extended the comment a bit in gdbarch.sh, avoiding
too much target speficic info there, and described better the symbian
specific case at the callback's call site.  

 +# If non-empty, this is a file extension that will be opened in place
 +# of the file extension reported by the shared library list.
 +#
 +# This is most useful for toolchains that use a post-linker tool,
 +# where the names of the files ran on the target differ in extension
 +# compared to the names of the files GDB should load for debug info.
 +v:const char *:solib_symbols_extension:::::::pstring (gdbarch->solib_symbols_extension)

 +  /* On this target, the toolchain outputs ELF files, with `sym' for
 +     filename extension (e.g., `FOO.sym'); these are post-linker
 +     processed into PE-ish DLLs (e.g., `FOO.dll'), and its these that
 +     are actually copied to and ran on the target.  Naturally, when
 +     listing shared libraries, Symbian stubs report the DLL filenames.
 +     Setting this makes it so that GDB automatically looks for the
 +     corresponding ELF files on the host's filesystem.  */
 +  set_gdbarch_solib_symbols_extension (gdbarch, "sym");

I think the mention of the post-linker in gdbarch.sh should
be enough to ring a bell to someone looking for something
like this.

-- 
Pedro Alves

2010-03-08  Daniel Jacobowitz  <dan@codesourcery.com>
	    Pedro Alves  <pedro@codesourcery.com>

	gdb/
	* solib.c (solib_find): Replace extension if
	solib_symbols_extension set in the target gdbarch.
	* arm-symbian-tdep.c (arm_symbian_init_abi): Set
	solib_symbols_extension to "sym".
	* gdbarch.sh (solib_symbols_extension): New variable.
	(pstring): New function.
	* gdbarch.h, gdbarch.c: Regenerate.

---
 gdb/arm-symbian-tdep.c |    9 +++++++++
 gdb/gdbarch.c          |   29 +++++++++++++++++++++++++++++
 gdb/gdbarch.h          |   10 ++++++++++
 gdb/gdbarch.sh         |   16 ++++++++++++++++
 gdb/solib.c            |   24 ++++++++++++++++++++++++
 5 files changed, 88 insertions(+)

Index: src/gdb/solib.c
===================================================================
--- src.orig/gdb/solib.c	2010-03-05 19:24:51.000000000 +0000
+++ src/gdb/solib.c	2010-03-08 11:14:56.000000000 +0000
@@ -150,6 +150,30 @@ solib_find (char *in_pathname, int *fd)
   int found_file = -1;
   char *temp_pathname = NULL;
   int gdb_sysroot_is_empty;
+  const char *solib_symbols_extension
+    = gdbarch_solib_symbols_extension (target_gdbarch);
+
+  /* If solib_symbols_extension is set, replace the file's
+     extension.  */
+  if (solib_symbols_extension)
+    {
+      char *p = in_pathname + strlen (in_pathname);
+      while (p > in_pathname && *p != '.')
+	p--;
+
+      if (*p == '.')
+	{
+	  char *new_pathname;
+
+	  new_pathname = alloca (p - in_pathname + 1
+				 + strlen (solib_symbols_extension) + 1);
+	  memcpy (new_pathname, in_pathname, p - in_pathname + 1);
+	  strcpy (new_pathname + (p - in_pathname) + 1,
+		  solib_symbols_extension);
+
+	  in_pathname = new_pathname;
+	}
+    }
 
   gdb_sysroot_is_empty = (gdb_sysroot == NULL || *gdb_sysroot == 0);
 
Index: src/gdb/arm-symbian-tdep.c
===================================================================
--- src.orig/gdb/arm-symbian-tdep.c	2010-03-05 19:24:51.000000000 +0000
+++ src/gdb/arm-symbian-tdep.c	2010-03-08 11:43:17.000000000 +0000
@@ -69,6 +69,15 @@ arm_symbian_init_abi (struct gdbarch_inf
   /* Shared library handling.  */
   set_gdbarch_skip_trampoline_code (gdbarch, arm_symbian_skip_trampoline_code);
 
+  /* On this target, the toolchain outputs ELF files, with `sym' for
+     filename extension (e.g., `FOO.sym'); these are post-linker
+     processed into PE-ish DLLs (e.g., `FOO.dll'), and its these that
+     are actually copied to and ran on the target.  Naturally, when
+     listing shared libraries, Symbian stubs report the DLL filenames.
+     Setting this makes it so that GDB automatically looks for the
+     corresponding ELF files on the host's filesystem.  */
+  set_gdbarch_solib_symbols_extension (gdbarch, "sym");
+
   set_solib_ops (gdbarch, &solib_target_so_ops);
 }
 
Index: src/gdb/gdbarch.sh
===================================================================
--- src.orig/gdb/gdbarch.sh	2010-03-08 00:55:44.000000000 +0000
+++ src/gdb/gdbarch.sh	2010-03-08 11:46:24.000000000 +0000
@@ -774,6 +774,14 @@ v:const char *:qsupported:::0:0::0:gdbar
 f:const char *:auto_charset:void::default_auto_charset:default_auto_charset::0
 # Return the "auto" target wide charset.
 f:const char *:auto_wide_charset:void::default_auto_wide_charset:default_auto_wide_charset::0
+
+# If non-empty, this is a file extension that will be opened in place
+# of the file extension reported by the shared library list.
+#
+# This is most useful for toolchains that use a post-linker tool,
+# where the names of the files ran on the target differ in extension
+# compared to the names of the files GDB should load for debug info.
+v:const char *:solib_symbols_extension:::::::pstring (gdbarch->solib_symbols_extension)
 EOF
 }
 
@@ -1245,6 +1253,14 @@ pformat (const struct floatformat **form
     return format[0]->name;
 }
 
+static const char *
+pstring (const char *string)
+{
+  if (string == NULL)
+    return "(null)";
+  return string;
+}
+
 EOF
 
 # gdbarch open the gdbarch object
Index: src/gdb/gdbarch.c
===================================================================
--- src.orig/gdb/gdbarch.c	2010-03-08 00:55:44.000000000 +0000
+++ src/gdb/gdbarch.c	2010-03-08 11:47:03.000000000 +0000
@@ -77,6 +77,14 @@ pformat (const struct floatformat **form
     return format[0]->name;
 }
 
+static const char *
+pstring (const char *string)
+{
+  if (string == NULL)
+    return "(null)";
+  return string;
+}
+
 
 /* Maintain the struct gdbarch object */
 
@@ -255,6 +263,7 @@ struct gdbarch
   const char * qsupported;
   gdbarch_auto_charset_ftype *auto_charset;
   gdbarch_auto_wide_charset_ftype *auto_wide_charset;
+  const char * solib_symbols_extension;
 };
 
 
@@ -401,6 +410,7 @@ struct gdbarch startup_gdbarch =
   0,  /* qsupported */
   default_auto_charset,  /* auto_charset */
   default_auto_wide_charset,  /* auto_wide_charset */
+  0,  /* solib_symbols_extension */
   /* startup_gdbarch() */
 };
 
@@ -1148,6 +1158,9 @@ gdbarch_dump (struct gdbarch *gdbarch, s
                       "gdbarch_dump: sofun_address_maybe_missing = %s\n",
                       plongest (gdbarch->sofun_address_maybe_missing));
   fprintf_unfiltered (file,
+                      "gdbarch_dump: solib_symbols_extension = %s\n",
+                      pstring (gdbarch->solib_symbols_extension));
+  fprintf_unfiltered (file,
                       "gdbarch_dump: sp_regnum = %s\n",
                       plongest (gdbarch->sp_regnum));
   fprintf_unfiltered (file,
@@ -3647,6 +3660,22 @@ set_gdbarch_auto_wide_charset (struct gd
   gdbarch->auto_wide_charset = auto_wide_charset;
 }
 
+const char *
+gdbarch_solib_symbols_extension (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_solib_symbols_extension called\n");
+  return gdbarch->solib_symbols_extension;
+}
+
+void
+set_gdbarch_solib_symbols_extension (struct gdbarch *gdbarch,
+                                     const char * solib_symbols_extension)
+{
+  gdbarch->solib_symbols_extension = solib_symbols_extension;
+}
+
 
 /* Keep a registry of per-architecture data-pointers required by GDB
    modules. */
Index: src/gdb/gdbarch.h
===================================================================
--- src.orig/gdb/gdbarch.h	2010-03-08 00:55:44.000000000 +0000
+++ src/gdb/gdbarch.h	2010-03-08 11:46:59.000000000 +0000
@@ -940,6 +940,16 @@ typedef const char * (gdbarch_auto_wide_
 extern const char * gdbarch_auto_wide_charset (struct gdbarch *gdbarch);
 extern void set_gdbarch_auto_wide_charset (struct gdbarch *gdbarch, gdbarch_auto_wide_charset_ftype *auto_wide_charset);
 
+/* If non-empty, this is a file extension that will be opened in place
+   of the file extension reported by the shared library list.
+  
+   This is most useful for toolchains that use a post-linker tool,
+   where the names of the files ran on the target differ in extension
+   compared to the names of the files GDB should load for debug info. */
+
+extern const char * gdbarch_solib_symbols_extension (struct gdbarch *gdbarch);
+extern void set_gdbarch_solib_symbols_extension (struct gdbarch *gdbarch, const char * solib_symbols_extension);
+
 /* Definition for an unknown syscall, used basically in error-cases.  */
 #define UNKNOWN_SYSCALL (-1)