Patchwork [v2] Make ada_decode not use a static buffer

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Submitter Doug Evans via gdb-patches
Date Aug. 28, 2019, 9:24 p.m.
Message ID <20190828212442.204696-1-cbiesinger@google.com>
Download mbox | patch
Permalink /patch/34318/
State New
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Comments

Doug Evans via gdb-patches - Aug. 28, 2019, 9:24 p.m.
[Fixes an issue with the previous version.]

This makes it safer to use in general, and also allows using it on a
background thread in the future.

Inspired by tromey's patch at:
https://github.com/tromey/gdb/commit/1226cbdfa436297a5dec054d94592c45891afa93
(however, implemented in a different way)

gdb/ChangeLog:

2019-08-28  Christian Biesinger  <cbiesinger@google.com>

	* ada-exp.y (write_object_remaining): Update.
	* ada-lang.c (ada_decode): Return a std::string instead of a char*
	and eliminate the static buffer.
	(ada_decode_symbol): Update.
	(ada_la_decode): Update.
	(ada_sniff_from_mangled_name): Update.
	(is_valid_name_for_wild_match): Update.
	(ada_lookup_name_info::matches): Update and simplify.
	(name_matches_regex): Update.
	(ada_add_global_exceptions): Update.
	* ada-lang.h (ada_decode): Update signature.
	* ada-varobj.c (ada_varobj_describe_simple_array_child): Update.
---
 gdb/ada-exp.y    |  2 +-
 gdb/ada-lang.c   | 63 ++++++++++++++++++------------------------------
 gdb/ada-lang.h   |  2 +-
 gdb/ada-varobj.c |  6 ++++-
 4 files changed, 31 insertions(+), 42 deletions(-)
Doug Evans via gdb-patches - Sept. 11, 2019, 3:04 p.m.
ping

On Wed, Aug 28, 2019 at 4:24 PM Christian Biesinger
<cbiesinger@google.com> wrote:
>
> [Fixes an issue with the previous version.]
>
> This makes it safer to use in general, and also allows using it on a
> background thread in the future.
>
> Inspired by tromey's patch at:
> https://github.com/tromey/gdb/commit/1226cbdfa436297a5dec054d94592c45891afa93
> (however, implemented in a different way)
>
> gdb/ChangeLog:
>
> 2019-08-28  Christian Biesinger  <cbiesinger@google.com>
>
>         * ada-exp.y (write_object_remaining): Update.
>         * ada-lang.c (ada_decode): Return a std::string instead of a char*
>         and eliminate the static buffer.
>         (ada_decode_symbol): Update.
>         (ada_la_decode): Update.
>         (ada_sniff_from_mangled_name): Update.
>         (is_valid_name_for_wild_match): Update.
>         (ada_lookup_name_info::matches): Update and simplify.
>         (name_matches_regex): Update.
>         (ada_add_global_exceptions): Update.
>         * ada-lang.h (ada_decode): Update signature.
>         * ada-varobj.c (ada_varobj_describe_simple_array_child): Update.
> ---
>  gdb/ada-exp.y    |  2 +-
>  gdb/ada-lang.c   | 63 ++++++++++++++++++------------------------------
>  gdb/ada-lang.h   |  2 +-
>  gdb/ada-varobj.c |  6 ++++-
>  4 files changed, 31 insertions(+), 42 deletions(-)
>
> diff --git a/gdb/ada-exp.y b/gdb/ada-exp.y
> index c8a7b9c9c7..160e64bc05 100644
> --- a/gdb/ada-exp.y
> +++ b/gdb/ada-exp.y
> @@ -816,7 +816,7 @@ write_object_renaming (struct parser_state *par_state,
>                           renamed_entity_len);
>    ada_lookup_encoded_symbol (name, orig_left_context, VAR_DOMAIN, &sym_info);
>    if (sym_info.symbol == NULL)
> -    error (_("Could not find renamed variable: %s"), ada_decode (name));
> +    error (_("Could not find renamed variable: %s"), ada_decode (name).c_str ());
>    else if (SYMBOL_CLASS (sym_info.symbol) == LOC_TYPEDEF)
>      /* We have a renaming of an old-style renaming symbol.  Don't
>         trust the block information.  */
> diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
> index 609f2d4391..e4e9604294 100644
> --- a/gdb/ada-lang.c
> +++ b/gdb/ada-lang.c
> @@ -1105,22 +1105,16 @@ ada_remove_po_subprogram_suffix (const char *encoded, int *len)
>
>  /* If ENCODED follows the GNAT entity encoding conventions, then return
>     the decoded form of ENCODED.  Otherwise, return "<%s>" where "%s" is
> -   replaced by ENCODED.
> +   replaced by ENCODED.  */
>
> -   The resulting string is valid until the next call of ada_decode.
> -   If the string is unchanged by decoding, the original string pointer
> -   is returned.  */
> -
> -const char *
> +std::string
>  ada_decode (const char *encoded)
>  {
>    int i, j;
>    int len0;
>    const char *p;
> -  char *decoded;
>    int at_start_name;
> -  static char *decoding_buffer = NULL;
> -  static size_t decoding_buffer_size = 0;
> +  std::string decoded;
>
>    /* With function descriptors on PPC64, the value of a symbol named
>       ".FN", if it exists, is the entry point of the function "FN".  */
> @@ -1179,8 +1173,7 @@ ada_decode (const char *encoded)
>
>    /* Make decoded big enough for possible expansion by operator name.  */
>
> -  GROW_VECT (decoding_buffer, decoding_buffer_size, 2 * len0 + 1);
> -  decoded = decoding_buffer;
> +  decoded.resize (2 * len0 + 1, 'X');
>
>    /* Remove trailing __{digit}+ or trailing ${digit}+.  */
>
> @@ -1217,7 +1210,7 @@ ada_decode (const char *encoded)
>                              op_len - 1) == 0)
>                    && !isalnum (encoded[i + op_len]))
>                  {
> -                  strcpy (decoded + j, ada_opname_table[k].decoded);
> +                  strcpy (&decoded.front() + j, ada_opname_table[k].decoded);
>                    at_start_name = 0;
>                    i += op_len;
>                    j += strlen (ada_opname_table[k].decoded);
> @@ -1338,27 +1331,22 @@ ada_decode (const char *encoded)
>            j += 1;
>          }
>      }
> -  decoded[j] = '\000';
> +  decoded.resize (j);
>
>    /* Decoded names should never contain any uppercase character.
>       Double-check this, and abort the decoding if we find one.  */
>
> -  for (i = 0; decoded[i] != '\0'; i += 1)
> +  for (i = 0; i < decoded.length(); ++i)
>      if (isupper (decoded[i]) || decoded[i] == ' ')
>        goto Suppress;
>
> -  if (strcmp (decoded, encoded) == 0)
> -    return encoded;
> -  else
> -    return decoded;
> +  return decoded;
>
>  Suppress:
> -  GROW_VECT (decoding_buffer, decoding_buffer_size, strlen (encoded) + 3);
> -  decoded = decoding_buffer;
>    if (encoded[0] == '<')
> -    strcpy (decoded, encoded);
> +    decoded = encoded;
>    else
> -    xsnprintf (decoded, decoding_buffer_size, "<%s>", encoded);
> +    decoded = '<' + std::string(encoded) + '>';
>    return decoded;
>
>  }
> @@ -1389,13 +1377,13 @@ ada_decode_symbol (const struct general_symbol_info *arg)
>
>    if (!gsymbol->ada_mangled)
>      {
> -      const char *decoded = ada_decode (gsymbol->name);
> +      std::string decoded = ada_decode (gsymbol->name);
>        struct obstack *obstack = gsymbol->language_specific.obstack;
>
>        gsymbol->ada_mangled = 1;
>
>        if (obstack != NULL)
> -       *resultp = obstack_strdup (obstack, decoded);
> +       *resultp = obstack_strdup (obstack, decoded.c_str ());
>        else
>          {
>           /* Sometimes, we can't find a corresponding objfile, in
> @@ -1404,10 +1392,10 @@ ada_decode_symbol (const struct general_symbol_info *arg)
>              significant memory leak (FIXME).  */
>
>            char **slot = (char **) htab_find_slot (decoded_names_store,
> -                                                  decoded, INSERT);
> +                                                  decoded.c_str (), INSERT);
>
>            if (*slot == NULL)
> -            *slot = xstrdup (decoded);
> +            *slot = xstrdup (decoded.c_str ());
>            *resultp = *slot;
>          }
>      }
> @@ -1418,7 +1406,7 @@ ada_decode_symbol (const struct general_symbol_info *arg)
>  static char *
>  ada_la_decode (const char *encoded, int options)
>  {
> -  return xstrdup (ada_decode (encoded));
> +  return xstrdup (ada_decode (encoded).c_str ());
>  }
>
>  /* Implement la_sniff_from_mangled_name for Ada.  */
> @@ -1426,11 +1414,11 @@ ada_la_decode (const char *encoded, int options)
>  static int
>  ada_sniff_from_mangled_name (const char *mangled, char **out)
>  {
> -  const char *demangled = ada_decode (mangled);
> +  std::string demangled = ada_decode (mangled);
>
>    *out = NULL;
>
> -  if (demangled != mangled && demangled != NULL && demangled[0] != '<')
> +  if (demangled != mangled && demangled[0] != '<')
>      {
>        /* Set the gsymbol language to Ada, but still return 0.
>          Two reasons for that:
> @@ -5995,7 +5983,7 @@ is_name_suffix (const char *str)
>  static int
>  is_valid_name_for_wild_match (const char *name0)
>  {
> -  const char *decoded_name = ada_decode (name0);
> +  std::string decoded_name = ada_decode (name0);
>    int i;
>
>    /* If the decoded name starts with an angle bracket, it means that
> @@ -6241,13 +6229,10 @@ ada_lookup_name_info::matches
>           that iff we are doing a verbatim match, the decoded version
>           of the symbol name starts with '<'.  Otherwise, this symbol name
>           is not a suitable completion.  */
> -      const char *sym_name_copy = sym_name;
> -      bool has_angle_bracket;
>
> -      sym_name = ada_decode (sym_name);
> -      has_angle_bracket = (sym_name[0] == '<');
> +      std::string decoded = ada_decode (sym_name);
> +      bool has_angle_bracket = (decoded[0] == '<');
>        match = (has_angle_bracket == m_verbatim_p);
> -      sym_name = sym_name_copy;
>      }
>
>    if (match && !m_verbatim_p)
> @@ -6271,7 +6256,7 @@ ada_lookup_name_info::matches
>        /* Since we are doing wild matching, this means that TEXT
>           may represent an unqualified symbol name.  We therefore must
>           also compare TEXT against the unqualified name of the symbol.  */
> -      sym_name = ada_unqualified_name (ada_decode (sym_name));
> +      sym_name = ada_unqualified_name (ada_decode (sym_name).c_str ());
>
>        if (strncmp (sym_name, text, text_len) == 0)
>         match = true;
> @@ -13496,7 +13481,7 @@ static bool
>  name_matches_regex (const char *name, compiled_regex *preg)
>  {
>    return (preg == NULL
> -         || preg->exec (ada_decode (name), 0, NULL, 0) == 0);
> +         || preg->exec (ada_decode (name).c_str (), 0, NULL, 0) == 0);
>  }
>
>  /* Add all exceptions defined globally whose name name match
> @@ -13529,8 +13514,8 @@ ada_add_global_exceptions (compiled_regex *preg,
>                            lookup_name_info::match_any (),
>                            [&] (const char *search_name)
>                            {
> -                            const char *decoded = ada_decode (search_name);
> -                            return name_matches_regex (decoded, preg);
> +                            std::string decoded = ada_decode (search_name);
> +                            return name_matches_regex (decoded.c_str (), preg);
>                            },
>                            NULL,
>                            VARIABLES_DOMAIN);
> diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h
> index 2fc3f523ca..c7279d5ac3 100644
> --- a/gdb/ada-lang.h
> +++ b/gdb/ada-lang.h
> @@ -227,7 +227,7 @@ extern struct type *ada_get_decoded_type (struct type *type);
>
>  extern const char *ada_decode_symbol (const struct general_symbol_info *);
>
> -extern const char *ada_decode (const char*);
> +extern std::string ada_decode (const char*);
>
>  extern enum language ada_update_initial_language (enum language);
>
> diff --git a/gdb/ada-varobj.c b/gdb/ada-varobj.c
> index a4d553d378..1a5d0ac239 100644
> --- a/gdb/ada-varobj.c
> +++ b/gdb/ada-varobj.c
> @@ -624,6 +624,7 @@ ada_varobj_describe_simple_array_child (struct value *parent_value,
>          of the array index type when such type qualification is
>          needed.  */
>        const char *index_type_name = NULL;
> +      std::string decoded;
>
>        /* If the index type is a range type, find the base type.  */
>        while (TYPE_CODE (index_type) == TYPE_CODE_RANGE)
> @@ -634,7 +635,10 @@ ada_varobj_describe_simple_array_child (struct value *parent_value,
>         {
>           index_type_name = ada_type_name (index_type);
>           if (index_type_name)
> -           index_type_name = ada_decode (index_type_name);
> +           {
> +             decoded = ada_decode (index_type_name);
> +             index_type_name = decoded.c_str ();
> +           }
>         }
>
>        if (index_type_name != NULL)
> --
> 2.23.0.187.g17f5b7556c-goog
>

Patch

diff --git a/gdb/ada-exp.y b/gdb/ada-exp.y
index c8a7b9c9c7..160e64bc05 100644
--- a/gdb/ada-exp.y
+++ b/gdb/ada-exp.y
@@ -816,7 +816,7 @@  write_object_renaming (struct parser_state *par_state,
 			  renamed_entity_len);
   ada_lookup_encoded_symbol (name, orig_left_context, VAR_DOMAIN, &sym_info);
   if (sym_info.symbol == NULL)
-    error (_("Could not find renamed variable: %s"), ada_decode (name));
+    error (_("Could not find renamed variable: %s"), ada_decode (name).c_str ());
   else if (SYMBOL_CLASS (sym_info.symbol) == LOC_TYPEDEF)
     /* We have a renaming of an old-style renaming symbol.  Don't
        trust the block information.  */
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 609f2d4391..e4e9604294 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -1105,22 +1105,16 @@  ada_remove_po_subprogram_suffix (const char *encoded, int *len)
 
 /* If ENCODED follows the GNAT entity encoding conventions, then return
    the decoded form of ENCODED.  Otherwise, return "<%s>" where "%s" is
-   replaced by ENCODED.
+   replaced by ENCODED.  */
 
-   The resulting string is valid until the next call of ada_decode.
-   If the string is unchanged by decoding, the original string pointer
-   is returned.  */
-
-const char *
+std::string
 ada_decode (const char *encoded)
 {
   int i, j;
   int len0;
   const char *p;
-  char *decoded;
   int at_start_name;
-  static char *decoding_buffer = NULL;
-  static size_t decoding_buffer_size = 0;
+  std::string decoded;
 
   /* With function descriptors on PPC64, the value of a symbol named
      ".FN", if it exists, is the entry point of the function "FN".  */
@@ -1179,8 +1173,7 @@  ada_decode (const char *encoded)
 
   /* Make decoded big enough for possible expansion by operator name.  */
 
-  GROW_VECT (decoding_buffer, decoding_buffer_size, 2 * len0 + 1);
-  decoded = decoding_buffer;
+  decoded.resize (2 * len0 + 1, 'X');
 
   /* Remove trailing __{digit}+ or trailing ${digit}+.  */
 
@@ -1217,7 +1210,7 @@  ada_decode (const char *encoded)
                             op_len - 1) == 0)
                   && !isalnum (encoded[i + op_len]))
                 {
-                  strcpy (decoded + j, ada_opname_table[k].decoded);
+                  strcpy (&decoded.front() + j, ada_opname_table[k].decoded);
                   at_start_name = 0;
                   i += op_len;
                   j += strlen (ada_opname_table[k].decoded);
@@ -1338,27 +1331,22 @@  ada_decode (const char *encoded)
           j += 1;
         }
     }
-  decoded[j] = '\000';
+  decoded.resize (j);
 
   /* Decoded names should never contain any uppercase character.
      Double-check this, and abort the decoding if we find one.  */
 
-  for (i = 0; decoded[i] != '\0'; i += 1)
+  for (i = 0; i < decoded.length(); ++i)
     if (isupper (decoded[i]) || decoded[i] == ' ')
       goto Suppress;
 
-  if (strcmp (decoded, encoded) == 0)
-    return encoded;
-  else
-    return decoded;
+  return decoded;
 
 Suppress:
-  GROW_VECT (decoding_buffer, decoding_buffer_size, strlen (encoded) + 3);
-  decoded = decoding_buffer;
   if (encoded[0] == '<')
-    strcpy (decoded, encoded);
+    decoded = encoded;
   else
-    xsnprintf (decoded, decoding_buffer_size, "<%s>", encoded);
+    decoded = '<' + std::string(encoded) + '>';
   return decoded;
 
 }
@@ -1389,13 +1377,13 @@  ada_decode_symbol (const struct general_symbol_info *arg)
 
   if (!gsymbol->ada_mangled)
     {
-      const char *decoded = ada_decode (gsymbol->name);
+      std::string decoded = ada_decode (gsymbol->name);
       struct obstack *obstack = gsymbol->language_specific.obstack;
 
       gsymbol->ada_mangled = 1;
 
       if (obstack != NULL)
-	*resultp = obstack_strdup (obstack, decoded);
+	*resultp = obstack_strdup (obstack, decoded.c_str ());
       else
         {
 	  /* Sometimes, we can't find a corresponding objfile, in
@@ -1404,10 +1392,10 @@  ada_decode_symbol (const struct general_symbol_info *arg)
 	     significant memory leak (FIXME).  */
 
           char **slot = (char **) htab_find_slot (decoded_names_store,
-                                                  decoded, INSERT);
+                                                  decoded.c_str (), INSERT);
 
           if (*slot == NULL)
-            *slot = xstrdup (decoded);
+            *slot = xstrdup (decoded.c_str ());
           *resultp = *slot;
         }
     }
@@ -1418,7 +1406,7 @@  ada_decode_symbol (const struct general_symbol_info *arg)
 static char *
 ada_la_decode (const char *encoded, int options)
 {
-  return xstrdup (ada_decode (encoded));
+  return xstrdup (ada_decode (encoded).c_str ());
 }
 
 /* Implement la_sniff_from_mangled_name for Ada.  */
@@ -1426,11 +1414,11 @@  ada_la_decode (const char *encoded, int options)
 static int
 ada_sniff_from_mangled_name (const char *mangled, char **out)
 {
-  const char *demangled = ada_decode (mangled);
+  std::string demangled = ada_decode (mangled);
 
   *out = NULL;
 
-  if (demangled != mangled && demangled != NULL && demangled[0] != '<')
+  if (demangled != mangled && demangled[0] != '<')
     {
       /* Set the gsymbol language to Ada, but still return 0.
 	 Two reasons for that:
@@ -5995,7 +5983,7 @@  is_name_suffix (const char *str)
 static int
 is_valid_name_for_wild_match (const char *name0)
 {
-  const char *decoded_name = ada_decode (name0);
+  std::string decoded_name = ada_decode (name0);
   int i;
 
   /* If the decoded name starts with an angle bracket, it means that
@@ -6241,13 +6229,10 @@  ada_lookup_name_info::matches
          that iff we are doing a verbatim match, the decoded version
          of the symbol name starts with '<'.  Otherwise, this symbol name
          is not a suitable completion.  */
-      const char *sym_name_copy = sym_name;
-      bool has_angle_bracket;
 
-      sym_name = ada_decode (sym_name);
-      has_angle_bracket = (sym_name[0] == '<');
+      std::string decoded = ada_decode (sym_name);
+      bool has_angle_bracket = (decoded[0] == '<');
       match = (has_angle_bracket == m_verbatim_p);
-      sym_name = sym_name_copy;
     }
 
   if (match && !m_verbatim_p)
@@ -6271,7 +6256,7 @@  ada_lookup_name_info::matches
       /* Since we are doing wild matching, this means that TEXT
          may represent an unqualified symbol name.  We therefore must
          also compare TEXT against the unqualified name of the symbol.  */
-      sym_name = ada_unqualified_name (ada_decode (sym_name));
+      sym_name = ada_unqualified_name (ada_decode (sym_name).c_str ());
 
       if (strncmp (sym_name, text, text_len) == 0)
 	match = true;
@@ -13496,7 +13481,7 @@  static bool
 name_matches_regex (const char *name, compiled_regex *preg)
 {
   return (preg == NULL
-	  || preg->exec (ada_decode (name), 0, NULL, 0) == 0);
+	  || preg->exec (ada_decode (name).c_str (), 0, NULL, 0) == 0);
 }
 
 /* Add all exceptions defined globally whose name name match
@@ -13529,8 +13514,8 @@  ada_add_global_exceptions (compiled_regex *preg,
 			   lookup_name_info::match_any (),
 			   [&] (const char *search_name)
 			   {
-			     const char *decoded = ada_decode (search_name);
-			     return name_matches_regex (decoded, preg);
+			     std::string decoded = ada_decode (search_name);
+			     return name_matches_regex (decoded.c_str (), preg);
 			   },
 			   NULL,
 			   VARIABLES_DOMAIN);
diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h
index 2fc3f523ca..c7279d5ac3 100644
--- a/gdb/ada-lang.h
+++ b/gdb/ada-lang.h
@@ -227,7 +227,7 @@  extern struct type *ada_get_decoded_type (struct type *type);
 
 extern const char *ada_decode_symbol (const struct general_symbol_info *);
 
-extern const char *ada_decode (const char*);
+extern std::string ada_decode (const char*);
 
 extern enum language ada_update_initial_language (enum language);
 
diff --git a/gdb/ada-varobj.c b/gdb/ada-varobj.c
index a4d553d378..1a5d0ac239 100644
--- a/gdb/ada-varobj.c
+++ b/gdb/ada-varobj.c
@@ -624,6 +624,7 @@  ada_varobj_describe_simple_array_child (struct value *parent_value,
 	 of the array index type when such type qualification is
 	 needed.  */
       const char *index_type_name = NULL;
+      std::string decoded;
 
       /* If the index type is a range type, find the base type.  */
       while (TYPE_CODE (index_type) == TYPE_CODE_RANGE)
@@ -634,7 +635,10 @@  ada_varobj_describe_simple_array_child (struct value *parent_value,
 	{
 	  index_type_name = ada_type_name (index_type);
 	  if (index_type_name)
-	    index_type_name = ada_decode (index_type_name);
+	    {
+	      decoded = ada_decode (index_type_name);
+	      index_type_name = decoded.c_str ();
+	    }
 	}
 
       if (index_type_name != NULL)