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[PATCH v2 23/36] Guile extension language: scm-lazy-string.c


This patch adds lazy-string support.
Testcases are in other files.

2014-01-20  Doug Evans  <xdje42@gmail.com>

	* guile/scm-lazy-string.c: New file.

diff --git a/gdb/guile/scm-lazy-string.c b/gdb/guile/scm-lazy-string.c
new file mode 100644
index 0000000..e965d01
--- /dev/null
+++ b/gdb/guile/scm-lazy-string.c
@@ -0,0 +1,373 @@
+/* Scheme interface to lazy strings.
+
+   Copyright (C) 2010-2014 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* See README file in this directory for implementation notes, coding
+   conventions, et.al.  */
+
+#include "defs.h"
+#include "charset.h"
+#include "value.h"
+#include "exceptions.h"
+#include "valprint.h"
+#include "language.h"
+#include "gdb_assert.h"
+#include "guile-internal.h"
+
+/* The <gdb:lazy-string> smob.  */
+
+typedef struct
+{
+  /* This always appears first.  */
+  gdb_smob base;
+
+  /*  Holds the address of the lazy string.  */
+  CORE_ADDR address;
+
+  /*  Holds the encoding that will be applied to the string when the string
+      is printed by GDB.  If the encoding is set to NULL then GDB will select
+      the most appropriate encoding when the sting is printed.
+      Space for this is malloc'd and will be freed when the object is
+      freed.  */
+  char *encoding;
+
+  /* Holds the length of the string in characters.  If the length is -1,
+     then the string will be fetched and encoded up to the first null of
+     appropriate width.  */
+  int length;
+
+  /*  This attribute holds the type that is represented by the lazy
+      string's type.  */
+  struct type *type;
+} lazy_string_smob;
+
+static const char lazy_string_smob_name[] = "gdb:lazy-string";
+
+/* The tag Guile knows the lazy string smob by.  */
+static scm_t_bits lazy_string_smob_tag;
+
+/* Administrivia for lazy string smobs.  */
+
+/* The smob "mark" function for <gdb:lazy-string>.  */
+
+static SCM
+lsscm_mark_lazy_string_smob (SCM self)
+{
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (self);
+
+  /* Do this last.  */
+  return gdbscm_mark_gsmob (&ls_smob->base);
+}
+
+/* The smob "free" function for <gdb:lazy-string>.  */
+
+static size_t
+lsscm_free_lazy_string_smob (SCM self)
+{
+  lazy_string_smob *v_smob = (lazy_string_smob *) SCM_SMOB_DATA (self);
+
+  xfree (v_smob->encoding);
+
+  return 0;
+}
+
+/* The smob "print" function for <gdb:lazy-string>.  */
+
+static int
+lsscm_print_lazy_string_smob (SCM self, SCM port, scm_print_state *pstate)
+{
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (self);
+
+  gdbscm_printf (port, "#<%s", lazy_string_smob_name);
+  gdbscm_printf (port, " @%s", hex_string (ls_smob->address));
+  if (ls_smob->length >= 0)
+    gdbscm_printf (port, " length %d", ls_smob->length);
+  if (ls_smob->encoding != NULL)
+    gdbscm_printf (port, " encoding %s", ls_smob->encoding);
+  scm_puts (">", port);
+
+  scm_remember_upto_here_1 (self);
+
+  /* Non-zero means success.  */
+  return 1;
+}
+
+/* Low level routine to create a <gdb:lazy-string> object.
+   The caller must verify !(address == 0 && length != 0).  */
+
+static SCM
+lsscm_make_lazy_string_smob (CORE_ADDR address, int length,
+			     const char *encoding, struct type *type)
+{
+  lazy_string_smob *ls_smob = (lazy_string_smob *)
+    scm_gc_malloc (sizeof (lazy_string_smob), lazy_string_smob_name);
+  SCM ls_scm;
+
+  /* Caller must verify this.  */
+  gdb_assert (!(address == 0 && length != 0));
+  gdb_assert (type != NULL);
+
+  ls_smob->address = address;
+  /* Coerce all values < 0 to -1.  */
+  ls_smob->length = length < 0 ? -1 : length;
+  if (encoding == NULL || strcmp (encoding, "") == 0)
+    ls_smob->encoding = NULL;
+  else
+    ls_smob->encoding = xstrdup (encoding);
+  ls_smob->type = type;
+
+  ls_scm = scm_new_smob (lazy_string_smob_tag, (scm_t_bits) ls_smob);
+  gdbscm_init_gsmob (&ls_smob->base);
+
+  return ls_scm;
+}
+
+/* Return non-zero if SCM is a <gdb:lazy-string> object.  */
+
+int
+lsscm_is_lazy_string (SCM scm)
+{
+  return SCM_SMOB_PREDICATE (lazy_string_smob_tag, scm);
+}
+
+/* (lazy-string? object) -> boolean */
+
+static SCM
+gdbscm_lazy_string_p (SCM scm)
+{
+  return scm_from_bool (lsscm_is_lazy_string (scm));
+}
+
+/* Main entry point to create a <gdb:lazy-string> object.
+   If there's an error a <gdb:exception> object is returned.  */
+
+SCM
+lsscm_make_lazy_string (CORE_ADDR address, int length,
+			const char *encoding, struct type *type)
+{
+  if (address == 0 && length != 0)
+    {
+      return gdbscm_make_out_of_range_error
+	(NULL, 0, scm_from_int (length),
+	 _("cannot create a lazy string with address 0x0"
+	   " and a non-zero length"));
+    }
+
+  if (type == NULL)
+    {
+      return gdbscm_make_out_of_range_error
+	(NULL, 0, scm_from_int (0), _("a lazy string's type cannot be NULL"));
+    }
+
+  return lsscm_make_lazy_string_smob (address, length, encoding, type);
+}
+
+/* Returns the <gdb:lazy-string> smob in SELF.
+   Throws an exception if SELF is not a <gdb:lazy-string> object.  */
+
+static SCM
+lsscm_get_lazy_string_arg_unsafe (SCM self, int arg_pos, const char *func_name)
+{
+  SCM_ASSERT_TYPE (lsscm_is_lazy_string (self), self, arg_pos, func_name,
+		   lazy_string_smob_name);
+
+  return self;
+}
+
+/* Lazy string methods.  */
+
+/* (lazy-string-address <gdb:lazy-string>) -> address */
+
+static SCM
+gdbscm_lazy_string_address (SCM self)
+{
+  SCM ls_scm = lsscm_get_lazy_string_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (ls_scm);
+
+  return gdbscm_scm_from_ulongest (ls_smob->address);
+}
+
+/* (lazy-string-length <gdb:lazy-string>) -> integer */
+
+static SCM
+gdbscm_lazy_string_length (SCM self)
+{
+  SCM ls_scm = lsscm_get_lazy_string_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (ls_scm);
+
+  return scm_from_int (ls_smob->length);
+}
+
+/* (lazy-string-encoding <gdb:lazy-string>) -> string */
+
+static SCM
+gdbscm_lazy_string_encoding (SCM self)
+{
+  SCM ls_scm = lsscm_get_lazy_string_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (ls_scm);
+
+  /* An encoding can be set to NULL by the user, so check first.
+     If NULL return #f.  */
+  if (ls_smob != NULL)
+    return gdbscm_scm_from_c_string (ls_smob->encoding);
+  return SCM_BOOL_F;
+}
+
+/* (lazy-string-type <gdb:lazy-string>) -> <gdb:type> */
+
+static SCM
+gdbscm_lazy_string_type (SCM self)
+{
+  SCM ls_scm = lsscm_get_lazy_string_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (ls_scm);
+
+  return tyscm_scm_from_type (ls_smob->type);
+}
+
+/* (lazy-string->value <gdb:lazy-string>) -> <gdb:value> */
+
+static SCM
+gdbscm_lazy_string_to_value (SCM self)
+{
+  SCM ls_scm = lsscm_get_lazy_string_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
+  lazy_string_smob *ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (ls_scm);
+  struct value *value = NULL;
+  volatile struct gdb_exception except;
+
+  if (ls_smob->address == 0)
+    {
+      gdbscm_throw (gdbscm_make_out_of_range_error (FUNC_NAME, SCM_ARG1, self,
+				_("cannot create a value from NULL")));
+    }
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      value = value_at_lazy (ls_smob->type, ls_smob->address);
+    }
+  GDBSCM_HANDLE_GDB_EXCEPTION (except);
+
+  return vlscm_scm_from_value (value);
+}
+
+/* A "safe" version of gdbscm_lazy_string_to_value for use by
+   vlscm_convert_typed_value_from_scheme.
+   The result, upon success, is the value of <gdb:lazy-string> STRING.
+   ARG_POS is the argument position of STRING in the original Scheme
+   function call, used in exception text.
+   If there's an error, NULL is returned and a <gdb:exception> object
+   is stored in *except_scmp.
+
+   Note: The result is still "lazy".  The caller must call value_fetch_lazy
+   to actually fetch the value.  */
+
+struct value *
+lsscm_safe_lazy_string_to_value (SCM string, int arg_pos,
+				 const char *func_name, SCM *except_scmp)
+{
+  lazy_string_smob *ls_smob;
+  struct value *value = NULL;
+  volatile struct gdb_exception except;
+
+  gdb_assert (lsscm_is_lazy_string (string));
+
+  ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (string);
+  *except_scmp = SCM_BOOL_F;
+
+  if (ls_smob->address == 0)
+    {
+      *except_scmp
+	= gdbscm_make_out_of_range_error (FUNC_NAME, SCM_ARG1, string,
+					 _("cannot create a value from NULL"));
+      return NULL;
+    }
+
+  TRY_CATCH (except, RETURN_MASK_ALL)
+    {
+      value = value_at_lazy (ls_smob->type, ls_smob->address);
+    }
+  if (except.reason < 0)
+    {
+      *except_scmp = gdbscm_scm_from_gdb_exception (except);
+      return NULL;
+    }
+
+  return value;
+}
+
+/* Print a lazy string to STREAM using val_print_string.
+   STRING must be a <gdb:lazy-string> object.  */
+
+void
+lsscm_val_print_lazy_string (SCM string, struct ui_file *stream,
+			     const struct value_print_options *options)
+{
+  lazy_string_smob *ls_smob;
+
+  gdb_assert (lsscm_is_lazy_string (string));
+
+  ls_smob = (lazy_string_smob *) SCM_SMOB_DATA (string);
+
+  val_print_string (ls_smob->type, ls_smob->encoding,
+		    ls_smob->address, ls_smob->length,
+		    stream, options);
+}
+
+/* Initialize the Scheme lazy-strings code.  */
+
+static const scheme_function lazy_string_functions[] =
+{
+  { "lazy-string?", 1, 0, 0, gdbscm_lazy_string_p,
+    "\
+Return #t if the object is a <gdb:lazy-string> object." },
+
+  { "lazy-string-address", 1, 0, 0, gdbscm_lazy_string_address,
+    "\
+Return the address of the lazy-string." },
+
+  { "lazy-string-length", 1, 0, 0, gdbscm_lazy_string_length,
+    "\
+Return the length of the lazy-string.\n\
+If the length is -1 then the length is determined by the first null\n\
+of appropriate width." },
+
+  { "lazy-string-encoding", 1, 0, 0, gdbscm_lazy_string_encoding,
+    "\
+Return the encoding of the lazy-string." },
+
+  { "lazy-string-type", 1, 0, 0, gdbscm_lazy_string_type,
+    "\
+Return the <gdb:type> of the lazy-string." },
+
+  { "lazy-string->value", 1, 0, 0, gdbscm_lazy_string_to_value,
+    "\
+Return the <gdb:value> representation of the lazy-string." },
+
+  END_FUNCTIONS
+};
+
+void
+gdbscm_initialize_lazy_strings (void)
+{
+  lazy_string_smob_tag = gdbscm_make_smob_type (lazy_string_smob_name,
+						sizeof (lazy_string_smob));
+  scm_set_smob_mark (lazy_string_smob_tag, lsscm_mark_lazy_string_smob);
+  scm_set_smob_free (lazy_string_smob_tag, lsscm_free_lazy_string_smob);
+  scm_set_smob_print (lazy_string_smob_tag, lsscm_print_lazy_string_smob);
+
+  gdbscm_define_functions (lazy_string_functions, 1);
+}


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