[1/4] Remove read_memory_string

Message ID 20200612215356.22145-2-tromey@adacore.com
State New
Headers show
Series
  • Unify string-reading APIs
Related show

Commit Message

Tom Tromey June 12, 2020, 9:53 p.m.
read_memory_string is redundant and only called in a couple of spots.
This patch removes it in favor of target_read_string.

gdb/ChangeLog
2020-06-02  Tom Tromey  <tromey@adacore.com>

	* corefile.c (read_memory_string): Remove.
	* ada-valprint.c (ada_value_print_ptr): Update.
	* ada-lang.h (ada_tag_name): Change return type.
	* ada-lang.c (type_from_tag): Update.
	(ada_tag_name_from_tsd): Change return type.  Use
	target_read_string.
	(ada_tag_name): Likewise.
	* gdbcore.h (read_memory_string): Don't declare.
---
 gdb/ChangeLog      | 11 +++++++++++
 gdb/ada-lang.c     | 34 ++++++++++++++++++++--------------
 gdb/ada-lang.h     |  2 +-
 gdb/ada-valprint.c |  4 ++--
 gdb/corefile.c     | 27 ---------------------------
 gdb/gdbcore.h      |  6 ------
 6 files changed, 34 insertions(+), 50 deletions(-)

-- 
2.21.3

Comments

Simon Marchi June 13, 2020, 2:19 p.m. | #1
On 2020-06-12 5:53 p.m., Tom Tromey wrote:
> @@ -6721,34 +6721,38 @@ ada_get_tsd_from_tag (struct value *tag)

>     The returned value is good until the next call.  May return NULL

>     if we are unable to determine the tag name.  */

>  

> -static char *

> +static gdb::unique_xmalloc_ptr<char>

>  ada_tag_name_from_tsd (struct value *tsd)


The comment above needs to be updated.

>  {

> -  static char name[1024];

>    char *p;

>    struct value *val;

>  

>    val = ada_value_struct_elt (tsd, "expanded_name", 1);

>    if (val == NULL)

>      return NULL;

> -  read_memory_string (value_as_address (val), name, sizeof (name) - 1);

> -  for (p = name; *p != '\0'; p += 1)

> +  gdb::unique_xmalloc_ptr<char> buffer;

> +  int err;

> +  if (target_read_string (value_as_address (val), &buffer, INT_MAX, &err) == 0

> +      || err != 0)

> +    return nullptr;

> +

> +  for (p = (char *) buffer.get (); *p != '\0'; p += 1)


This cast is unnecessary.  I'd also change `p += 1` for p++ or ++p.

The enclosing for loop should use braces, normally.

Simon
Simon Marchi via Gdb-patches June 15, 2020, 12:37 p.m. | #2
On 6/12/20 10:53 PM, Tom Tromey wrote:
> read_memory_string is redundant and only called in a couple of spots.

> This patch removes it in favor of target_read_string.

> 


There's a difference of behavior that is getting lost here -- read_memory_string
throws an error on memory read failure, while target_read_string does not.

Similarly to how we have read_memory throwing, vs target_read_memory not
throwing.  It would make sense to me to reimplement read_memory_string on top
of target_read_string and throw on error, for instance.

Did you go over the call paths, to check whether the behavior change
is desirable?

Thanks,
Pedro Alves

> gdb/ChangeLog

> 2020-06-02  Tom Tromey  <tromey@adacore.com>

> 

> 	* corefile.c (read_memory_string): Remove.

> 	* ada-valprint.c (ada_value_print_ptr): Update.

> 	* ada-lang.h (ada_tag_name): Change return type.

> 	* ada-lang.c (type_from_tag): Update.

> 	(ada_tag_name_from_tsd): Change return type.  Use

> 	target_read_string.

> 	(ada_tag_name): Likewise.

> 	* gdbcore.h (read_memory_string): Don't declare.

> ---

>  gdb/ChangeLog      | 11 +++++++++++

>  gdb/ada-lang.c     | 34 ++++++++++++++++++++--------------

>  gdb/ada-lang.h     |  2 +-

>  gdb/ada-valprint.c |  4 ++--

>  gdb/corefile.c     | 27 ---------------------------

>  gdb/gdbcore.h      |  6 ------

>  6 files changed, 34 insertions(+), 50 deletions(-)

> 

> diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c

> index f7b973f36ee..3245758a1bd 100644

> --- a/gdb/ada-lang.c

> +++ b/gdb/ada-lang.c

> @@ -6567,10 +6567,10 @@ value_tag_from_contents_and_address (struct type *type,

>  static struct type *

>  type_from_tag (struct value *tag)

>  {

> -  const char *type_name = ada_tag_name (tag);

> +  gdb::unique_xmalloc_ptr<char> type_name = ada_tag_name (tag);

>  

>    if (type_name != NULL)

> -    return ada_find_any_type (ada_encode (type_name));

> +    return ada_find_any_type (ada_encode (type_name.get ()));

>    return NULL;

>  }

>  

> @@ -6721,34 +6721,38 @@ ada_get_tsd_from_tag (struct value *tag)

>     The returned value is good until the next call.  May return NULL

>     if we are unable to determine the tag name.  */

>  

> -static char *

> +static gdb::unique_xmalloc_ptr<char>

>  ada_tag_name_from_tsd (struct value *tsd)

>  {

> -  static char name[1024];

>    char *p;

>    struct value *val;

>  

>    val = ada_value_struct_elt (tsd, "expanded_name", 1);

>    if (val == NULL)

>      return NULL;

> -  read_memory_string (value_as_address (val), name, sizeof (name) - 1);

> -  for (p = name; *p != '\0'; p += 1)

> +  gdb::unique_xmalloc_ptr<char> buffer;

> +  int err;

> +  if (target_read_string (value_as_address (val), &buffer, INT_MAX, &err) == 0

> +      || err != 0)

> +    return nullptr;

> +

> +  for (p = (char *) buffer.get (); *p != '\0'; p += 1)

>      if (isalpha (*p))

>        *p = tolower (*p);

> -  return name;

> +

> +  return buffer;

>  }

>  

>  /* The type name of the dynamic type denoted by the 'tag value TAG, as

>     a C string.

>  

>     Return NULL if the TAG is not an Ada tag, or if we were unable to

> -   determine the name of that tag.  The result is good until the next

> -   call.  */

> +   determine the name of that tag.  */

>  

> -const char *

> +gdb::unique_xmalloc_ptr<char>

>  ada_tag_name (struct value *tag)

>  {

> -  char *name = NULL;

> +  gdb::unique_xmalloc_ptr<char> name;

>  

>    if (!ada_is_tag_type (value_type (tag)))

>      return NULL;

> @@ -12104,9 +12108,11 @@ ada_exception_message_1 (void)

>    if (e_msg_len <= 0)

>      return NULL;

>  

> -  gdb::unique_xmalloc_ptr<char> e_msg ((char *) xmalloc (e_msg_len + 1));

> -  read_memory_string (value_address (e_msg_val), e_msg.get (), e_msg_len + 1);

> -  e_msg.get ()[e_msg_len] = '\0';

> +  gdb::unique_xmalloc_ptr<char> e_msg;

> +  int err;

> +  if (target_read_string (value_address (e_msg_val), &e_msg, INT_MAX, &err) == 0

> +      || err != 0)

> +    return nullptr;

>  

>    return e_msg;

>  }

> diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h

> index 5ba00518e6d..9be597942fd 100644

> --- a/gdb/ada-lang.h

> +++ b/gdb/ada-lang.h

> @@ -260,7 +260,7 @@ extern int ada_is_tagged_type (struct type *, int);

>  

>  extern int ada_is_tag_type (struct type *);

>  

> -extern const char *ada_tag_name (struct value *);

> +extern gdb::unique_xmalloc_ptr<char> ada_tag_name (struct value *);

>  

>  extern struct value *ada_tag_value_at_base_address (struct value *obj);

>  

> diff --git a/gdb/ada-valprint.c b/gdb/ada-valprint.c

> index a36e7ca793a..61893d5cad3 100644

> --- a/gdb/ada-valprint.c

> +++ b/gdb/ada-valprint.c

> @@ -754,10 +754,10 @@ ada_value_print_ptr (struct value *val,

>    struct type *type = ada_check_typedef (value_type (val));

>    if (ada_is_tag_type (type))

>      {

> -      const char *name = ada_tag_name (val);

> +      gdb::unique_xmalloc_ptr<char> name = ada_tag_name (val);

>  

>        if (name != NULL)

> -	fprintf_filtered (stream, " (%s)", name);

> +	fprintf_filtered (stream, " (%s)", name.get ());

>      }

>  }

>  

> diff --git a/gdb/corefile.c b/gdb/corefile.c

> index 996e5301b27..fed0e4fe8ad 100644

> --- a/gdb/corefile.c

> +++ b/gdb/corefile.c

> @@ -328,33 +328,6 @@ read_code_unsigned_integer (CORE_ADDR memaddr, int len,

>    return extract_unsigned_integer (buf, len, byte_order);

>  }

>  

> -void

> -read_memory_string (CORE_ADDR memaddr, char *buffer, int max_len)

> -{

> -  char *cp;

> -  int i;

> -  int cnt;

> -

> -  cp = buffer;

> -  while (1)

> -    {

> -      if (cp - buffer >= max_len)

> -	{

> -	  buffer[max_len - 1] = '\0';

> -	  break;

> -	}

> -      cnt = max_len - (cp - buffer);

> -      if (cnt > 8)

> -	cnt = 8;

> -      read_memory (memaddr + (int) (cp - buffer), (gdb_byte *) cp, cnt);

> -      for (i = 0; i < cnt && *cp; i++, cp++)

> -	;			/* null body */

> -

> -      if (i < cnt && !*cp)

> -	break;

> -    }

> -}

> -

>  CORE_ADDR

>  read_memory_typed_address (CORE_ADDR addr, struct type *type)

>  {

> diff --git a/gdb/gdbcore.h b/gdb/gdbcore.h

> index 24db21e462c..58566d58785 100644

> --- a/gdb/gdbcore.h

> +++ b/gdb/gdbcore.h

> @@ -87,12 +87,6 @@ extern ULONGEST read_code_unsigned_integer (CORE_ADDR memaddr,

>  					    int len,

>  					    enum bfd_endian byte_order);

>  

> -/* Read a null-terminated string from the debuggee's memory, given

> -   address, a buffer into which to place the string, and the maximum

> -   available space.  */

> -

> -extern void read_memory_string (CORE_ADDR, char *, int);

> -

>  /* Read the pointer of type TYPE at ADDR, and return the address it

>     represents.  */

>  

>

Patch

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index f7b973f36ee..3245758a1bd 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -6567,10 +6567,10 @@  value_tag_from_contents_and_address (struct type *type,
 static struct type *
 type_from_tag (struct value *tag)
 {
-  const char *type_name = ada_tag_name (tag);
+  gdb::unique_xmalloc_ptr<char> type_name = ada_tag_name (tag);
 
   if (type_name != NULL)
-    return ada_find_any_type (ada_encode (type_name));
+    return ada_find_any_type (ada_encode (type_name.get ()));
   return NULL;
 }
 
@@ -6721,34 +6721,38 @@  ada_get_tsd_from_tag (struct value *tag)
    The returned value is good until the next call.  May return NULL
    if we are unable to determine the tag name.  */
 
-static char *
+static gdb::unique_xmalloc_ptr<char>
 ada_tag_name_from_tsd (struct value *tsd)
 {
-  static char name[1024];
   char *p;
   struct value *val;
 
   val = ada_value_struct_elt (tsd, "expanded_name", 1);
   if (val == NULL)
     return NULL;
-  read_memory_string (value_as_address (val), name, sizeof (name) - 1);
-  for (p = name; *p != '\0'; p += 1)
+  gdb::unique_xmalloc_ptr<char> buffer;
+  int err;
+  if (target_read_string (value_as_address (val), &buffer, INT_MAX, &err) == 0
+      || err != 0)
+    return nullptr;
+
+  for (p = (char *) buffer.get (); *p != '\0'; p += 1)
     if (isalpha (*p))
       *p = tolower (*p);
-  return name;
+
+  return buffer;
 }
 
 /* The type name of the dynamic type denoted by the 'tag value TAG, as
    a C string.
 
    Return NULL if the TAG is not an Ada tag, or if we were unable to
-   determine the name of that tag.  The result is good until the next
-   call.  */
+   determine the name of that tag.  */
 
-const char *
+gdb::unique_xmalloc_ptr<char>
 ada_tag_name (struct value *tag)
 {
-  char *name = NULL;
+  gdb::unique_xmalloc_ptr<char> name;
 
   if (!ada_is_tag_type (value_type (tag)))
     return NULL;
@@ -12104,9 +12108,11 @@  ada_exception_message_1 (void)
   if (e_msg_len <= 0)
     return NULL;
 
-  gdb::unique_xmalloc_ptr<char> e_msg ((char *) xmalloc (e_msg_len + 1));
-  read_memory_string (value_address (e_msg_val), e_msg.get (), e_msg_len + 1);
-  e_msg.get ()[e_msg_len] = '\0';
+  gdb::unique_xmalloc_ptr<char> e_msg;
+  int err;
+  if (target_read_string (value_address (e_msg_val), &e_msg, INT_MAX, &err) == 0
+      || err != 0)
+    return nullptr;
 
   return e_msg;
 }
diff --git a/gdb/ada-lang.h b/gdb/ada-lang.h
index 5ba00518e6d..9be597942fd 100644
--- a/gdb/ada-lang.h
+++ b/gdb/ada-lang.h
@@ -260,7 +260,7 @@  extern int ada_is_tagged_type (struct type *, int);
 
 extern int ada_is_tag_type (struct type *);
 
-extern const char *ada_tag_name (struct value *);
+extern gdb::unique_xmalloc_ptr<char> ada_tag_name (struct value *);
 
 extern struct value *ada_tag_value_at_base_address (struct value *obj);
 
diff --git a/gdb/ada-valprint.c b/gdb/ada-valprint.c
index a36e7ca793a..61893d5cad3 100644
--- a/gdb/ada-valprint.c
+++ b/gdb/ada-valprint.c
@@ -754,10 +754,10 @@  ada_value_print_ptr (struct value *val,
   struct type *type = ada_check_typedef (value_type (val));
   if (ada_is_tag_type (type))
     {
-      const char *name = ada_tag_name (val);
+      gdb::unique_xmalloc_ptr<char> name = ada_tag_name (val);
 
       if (name != NULL)
-	fprintf_filtered (stream, " (%s)", name);
+	fprintf_filtered (stream, " (%s)", name.get ());
     }
 }
 
diff --git a/gdb/corefile.c b/gdb/corefile.c
index 996e5301b27..fed0e4fe8ad 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -328,33 +328,6 @@  read_code_unsigned_integer (CORE_ADDR memaddr, int len,
   return extract_unsigned_integer (buf, len, byte_order);
 }
 
-void
-read_memory_string (CORE_ADDR memaddr, char *buffer, int max_len)
-{
-  char *cp;
-  int i;
-  int cnt;
-
-  cp = buffer;
-  while (1)
-    {
-      if (cp - buffer >= max_len)
-	{
-	  buffer[max_len - 1] = '\0';
-	  break;
-	}
-      cnt = max_len - (cp - buffer);
-      if (cnt > 8)
-	cnt = 8;
-      read_memory (memaddr + (int) (cp - buffer), (gdb_byte *) cp, cnt);
-      for (i = 0; i < cnt && *cp; i++, cp++)
-	;			/* null body */
-
-      if (i < cnt && !*cp)
-	break;
-    }
-}
-
 CORE_ADDR
 read_memory_typed_address (CORE_ADDR addr, struct type *type)
 {
diff --git a/gdb/gdbcore.h b/gdb/gdbcore.h
index 24db21e462c..58566d58785 100644
--- a/gdb/gdbcore.h
+++ b/gdb/gdbcore.h
@@ -87,12 +87,6 @@  extern ULONGEST read_code_unsigned_integer (CORE_ADDR memaddr,
 					    int len,
 					    enum bfd_endian byte_order);
 
-/* Read a null-terminated string from the debuggee's memory, given
-   address, a buffer into which to place the string, and the maximum
-   available space.  */
-
-extern void read_memory_string (CORE_ADDR, char *, int);
-
 /* Read the pointer of type TYPE at ADDR, and return the address it
    represents.  */