Re: [RFA] Add la_getstr member to language_defn

Thiago Jung Bauermann
2009-02-05T12:21:18Z

El miÃ©, 04-02-2009 a las 17:53 -0700, Tom Tromey escribiÃ³:
> >>>>> "Thiago" == Thiago Jung Bauermann <bauerman@br.ibm.com> writes:
> I read it a little more closely and I'm afraid I have a couple more
> comments. Mostly they are little formatting nits, nothing important.
>
> If you agree with the more substantive comments, then I think this
> patch is ok with the suggested changes -- no need for another review.
> If you don't agree, let's discuss it.
>
> Thiago> +void
> Thiago> +c_get_string (struct value *value, gdb_byte **buffer, int *length,
> Thiago> + const char **charset)
> Thiago> +{
> Thiago> + int err, width;
> Thiago> + unsigned int fetchlimit;
> Thiago> + struct type *type = value_type (value);
>
> I think this should probably use check_typedef. Otherwise it seems
> like we would not extract some strings properly. E.g., consider a
> case like "typedef char *string;" ... what will happen?

Nice catch. Fixed.

> Thiago> + else if (TYPE_CODE (value_type (value)) == TYPE_CODE_PTR)
>
> This should use 'type' instead of calling value_type again.

Fixed.

> Thiago> + if (extract_unsigned_integer (contents + i*width, width) == 0)
>
> Need spaces around the "*".

Fixed.

> Thiago> + /* i is now either the number of non-null characters, or fetchlimit. */
>
> Use "I", not "i" .. a tiny nit for the GNU style, where the value of a
> variable is referred to by uppercasing the name.

Ok. I also uppercased fetchlimit.

> Thiago> + *length = i*width;
>
> Spaces.

Fixed.

> Thiago> + /* If the last character is null, subtract it from length. */
> Thiago> + if (extract_unsigned_integer (*buffer + *length - width, width) == 0)
> Thiago> + *length -= width;
>
> This second line looks like it has too much indentation.

Fixed. I also uppercased length in the comment.

> Also, I suspect this should start "if (*length > 0 &&".
> Otherwise, it seems like it will read memory before *BUFFER when
> *LENGTH==0.

Nice catch again. Fixed.

> Thiago> +error:
>
> Emacs claims that labels are indented one space in the GNU style.
> I didn't see this in the standards manual though.

Ok, changed.

> Thiago> +++ b/gdb/value.h
> [...]
> Thiago> +extern char * type_to_string (struct type *type);
>
> Extra space after the "*".

Fixed.

> thanks for persevering,

:-)

I committed the following. Thanks for the review.
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

2009-02-05 Thiago Jung Bauermann <bauerman@br.ibm.com>

* language.h (language_dfn): Add la_get_string member.
(LA_GET_STRING): New macro.
(default_get_string): New prototype.
* language.c (default_get_string): New function.
(unknown_language_defn, auto_language_defn, local_language_defn): Use
default_get_string for la_get_string.
* c-lang.c (c_get_string): New function.
(c_language_defn, cplus_language_defn, asm_language_defn): Use
c_get_string for la_get_string.
(minimal_language_defn): Likewise
* ada-lang.c (ada_language_defn): Likewise.
* f-lang.c (f_language_defn): Use default_get_string for
la_get_string.
* jv-lang.c (java_language_defn): Likewise.
* m2-lang.c (m2_language_defn): Likewise.
* objc-lang.c (objc_language_defn): Likewise.
* p-lang.c (p_language_defn): Likewise.
* scm-lang.c (scm_language_defn): Likewise.
* typeprint.c (type_to_string): New function.
* value.h (type_to_string): New prototype.
* valprint.c (val_print_string): Factor out code for reading string
from the inferior into its own function. Put 2 spaces after period
in comments.
(read_string): New function.
* valprint.h (read_string): New prototype.

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 656e771..a01d45c 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -1,7 +1,7 @@
/* Ada language support routines for GDB, the GNU debugger. Copyright (C)

- 1992, 1993, 1994, 1997, 1998, 1999, 2000, 2003, 2004, 2005, 2007
- Free Software Foundation, Inc.
+ 1992, 1993, 1994, 1997, 1998, 1999, 2000, 2003, 2004, 2005, 2007, 2008,
+ 2009 Free Software Foundation, Inc.

This file is part of GDB.

@@ -11055,6 +11055,7 @@ const struct language_defn ada_language_defn = {
ada_language_arch_info,
ada_print_array_index,
default_pass_by_reference,
+ c_get_string,
LANG_MAGIC
};

diff --git a/gdb/c-lang.c b/gdb/c-lang.c
index 309a0b0..8b5410f 100644
--- a/gdb/c-lang.c
+++ b/gdb/c-lang.c
@@ -181,6 +181,122 @@ c_printstr (struct ui_file *stream, const gdb_byte *string,
if (force_ellipses || i < length)
fputs_filtered ("...", stream);
}
+
+/* Obtain a C string from the inferior storing it in a newly allocated
+ buffer in BUFFER, which should be freed by the caller. The string is
+ read until a null character is found. If VALUE is an array with known
+ length, the function will not read past the end of the array. LENGTH
+ will contain the size of the string in bytes (not counting the null
+ character).
+
+ Assumes strings are terminated by a null character. The size of a character
+ is determined by the length of the target type of the pointer or array.
+ This means that a null byte present in a multi-byte character will not
+ terminate the string unless the whole character is null.
+
+ CHARSET is always set to the target charset. */
+
+void
+c_get_string (struct value *value, gdb_byte **buffer, int *length,
+ const char **charset)
+{
+ int err, width;
+ unsigned int fetchlimit;
+ struct type *type = check_typedef (value_type (value));
+ struct type *element_type = TYPE_TARGET_TYPE (type);
+
+ if (element_type == NULL)
+ goto error;
+
+ if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+ {
+ /* If we know the size of the array, we can use it as a limit on the
+ number of characters to be fetched. */
+ if (TYPE_NFIELDS (type) == 1
+ && TYPE_CODE (TYPE_FIELD_TYPE (type, 0)) == TYPE_CODE_RANGE)
+ {
+ LONGEST low_bound, high_bound;
+
+ get_discrete_bounds (TYPE_FIELD_TYPE (type, 0),
+ &low_bound, &high_bound);
+ fetchlimit = high_bound - low_bound + 1;
+ }
+ else
+ fetchlimit = UINT_MAX;
+ }
+ else if (TYPE_CODE (type) == TYPE_CODE_PTR)
+ fetchlimit = UINT_MAX;
+ else
+ /* We work only with arrays and pointers. */
+ goto error;
+
+ element_type = check_typedef (element_type);
+ if (TYPE_CODE (element_type) != TYPE_CODE_INT
+ && TYPE_CODE (element_type) != TYPE_CODE_CHAR)
+ /* If the elements are not integers or characters, we don't consider it
+ a string. */
+ goto error;
+
+ width = TYPE_LENGTH (element_type);
+
+ /* If the string lives in GDB's memory intead of the inferior's, then we
+ just need to copy it to BUFFER. Also, since such strings are arrays
+ with known size, FETCHLIMIT will hold the size of the array. */
+ if ((VALUE_LVAL (value) == not_lval
+ || VALUE_LVAL (value) == lval_internalvar)
+ && fetchlimit != UINT_MAX)
+ {
+ int i;
+ const gdb_byte *contents = value_contents (value);
+
+ /* Look for a null character. */
+ for (i = 0; i < fetchlimit; i++)
+ if (extract_unsigned_integer (contents + i * width, width) == 0)
+ break;
+
+ /* I is now either the number of non-null characters, or FETCHLIMIT. */
+ *length = i * width;
+ *buffer = xmalloc (*length);
+ memcpy (*buffer, contents, *length);
+ err = 0;
+ }
+ else
+ {
+ err = read_string (value_as_address (value), -1, width, fetchlimit,
+ buffer, length);
+ if (err)
+ {
+ xfree (buffer);
+ error (_("Error reading string from inferior: %s"),
+ safe_strerror (err));
+ }
+ }
+
+ /* If the last character is null, subtract it from LENGTH. */
+ if (*length > 0
+ && extract_unsigned_integer (*buffer + *length - width, width) == 0)
+ *length -= width;
+
+ *charset = target_charset ();
+
+ return;
+
+ error:
+ {
+ char *type_str;
+
+ type_str = type_to_string (type);
+ if (type_str)
+ {
+ make_cleanup (xfree, type_str);
+ error (_("Trying to read string with inappropriate type `%s'."),
+ type_str);
+ }
+ else
+ error (_("Trying to read string with inappropriate type."));
+ }
+}
+
\f
/* Preprocessing and parsing C and C++ expressions. */

@@ -314,6 +430,7 @@ const struct language_defn c_language_defn =
c_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ c_get_string,
LANG_MAGIC
};

@@ -432,6 +549,7 @@ const struct language_defn cplus_language_defn =
cplus_language_arch_info,
default_print_array_index,
cp_pass_by_reference,
+ c_get_string,
LANG_MAGIC
};

@@ -469,6 +587,7 @@ const struct language_defn asm_language_defn =
c_language_arch_info, /* FIXME: la_language_arch_info. */
default_print_array_index,
default_pass_by_reference,
+ c_get_string,
LANG_MAGIC
};

@@ -511,6 +630,7 @@ const struct language_defn minimal_language_defn =
c_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ c_get_string,
LANG_MAGIC
};

diff --git a/gdb/f-lang.c b/gdb/f-lang.c
index cf4abaa..6359841 100644
--- a/gdb/f-lang.c
+++ b/gdb/f-lang.c
@@ -343,6 +343,7 @@ const struct language_defn f_language_defn =
f_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/jv-lang.c b/gdb/jv-lang.c
index 83fc064..0728866 100644
--- a/gdb/jv-lang.c
+++ b/gdb/jv-lang.c
@@ -1128,6 +1128,7 @@ const struct language_defn java_language_defn =
java_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/language.c b/gdb/language.c
index bdf2ed7..3c37a64 100644
--- a/gdb/language.c
+++ b/gdb/language.c
@@ -1043,6 +1043,13 @@ default_print_array_index (struct value *index_value, struct ui_file *stream,
fprintf_filtered (stream, "] = ");
}

+void
+default_get_string (struct value *value, gdb_byte **buffer, int *length,
+ const char **charset)
+{
+ error (_("Getting a string is unsupported in this language."));
+}
+
/* Define the language that is no language. */

static int
@@ -1165,6 +1172,7 @@ const struct language_defn unknown_language_defn =
unknown_language_arch_info, /* la_language_arch_info. */
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

@@ -1203,6 +1211,7 @@ const struct language_defn auto_language_defn =
unknown_language_arch_info, /* la_language_arch_info. */
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

@@ -1240,6 +1249,7 @@ const struct language_defn local_language_defn =
unknown_language_arch_info, /* la_language_arch_info. */
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};
\f
diff --git a/gdb/language.h b/gdb/language.h
index e7dd01e..85826fd 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -282,6 +282,14 @@ struct language_defn
reference at the language level. */
int (*la_pass_by_reference) (struct type *type);

+ /* Obtain a string from the inferior, storing it in a newly allocated
+ buffer in BUFFER, which should be freed by the caller. LENGTH will
+ hold the size in bytes of the string (only actual characters, excluding
+ an eventual terminating null character). CHARSET will hold the encoding
+ used in the string. */
+ void (*la_get_string) (struct value *value, gdb_byte **buffer, int *length,
+ const char **charset);
+
/* Add fields above this point, so the magic number is always last. */
/* Magic number for compat checking */

@@ -380,6 +388,8 @@ extern enum language set_language (enum language);
force_ellipses,options))
#define LA_EMIT_CHAR(ch, stream, quoter) \
(current_language->la_emitchar(ch, stream, quoter))
+#define LA_GET_STRING(value, buffer, length, encoding) \
+ (current_language->la_get_string(value, buffer, length, encoding))

#define LA_PRINT_ARRAY_INDEX(index_value, stream, optins) \
(current_language->la_print_array_index(index_value, stream, options))
@@ -489,4 +499,10 @@ int default_pass_by_reference (struct type *type);
void default_print_typedef (struct type *type, struct symbol *new_symbol,
struct ui_file *stream);

+void default_get_string (struct value *value, gdb_byte **buffer, int *length,
+ const char **charset);
+
+void c_get_string (struct value *value, gdb_byte **buffer, int *length,
+ const char **charset);
+
#endif /* defined (LANGUAGE_H) */
diff --git a/gdb/m2-lang.c b/gdb/m2-lang.c
index a8dd8ad..9e4bb1b 100644
--- a/gdb/m2-lang.c
+++ b/gdb/m2-lang.c
@@ -394,6 +394,7 @@ const struct language_defn m2_language_defn =
m2_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/objc-lang.c b/gdb/objc-lang.c
index 466221c..a6c74a3 100644
--- a/gdb/objc-lang.c
+++ b/gdb/objc-lang.c
@@ -531,6 +531,7 @@ const struct language_defn objc_language_defn = {
c_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/p-lang.c b/gdb/p-lang.c
index 0e0de2e..4ba6136 100644
--- a/gdb/p-lang.c
+++ b/gdb/p-lang.c
@@ -433,6 +433,7 @@ const struct language_defn pascal_language_defn =
pascal_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/scm-lang.c b/gdb/scm-lang.c
index b604e40..345befd 100644
--- a/gdb/scm-lang.c
+++ b/gdb/scm-lang.c
@@ -273,6 +273,7 @@ const struct language_defn scm_language_defn =
c_language_arch_info,
default_print_array_index,
default_pass_by_reference,
+ default_get_string,
LANG_MAGIC
};

diff --git a/gdb/typeprint.c b/gdb/typeprint.c
index 678aaa1..1f824fa 100644
--- a/gdb/typeprint.c
+++ b/gdb/typeprint.c
@@ -33,6 +33,7 @@
#include "cp-abi.h"
#include "typeprint.h"
#include "gdb_string.h"
+#include "exceptions.h"
#include "valprint.h"
#include <errno.h>

@@ -78,6 +79,34 @@ type_print (struct type *type, char *varstring, struct ui_file *stream,
LA_PRINT_TYPE (type, varstring, stream, show, 0);
}

+/* Print TYPE to a string, returning it. The caller is responsible for
+ freeing the string. */
+
+char *
+type_to_string (struct type *type)
+{
+ char *s = NULL;
+ long dummy;
+ struct ui_file *stb;
+ struct cleanup *old_chain;
+ volatile struct gdb_exception except;
+
+ stb = mem_fileopen ();
+ old_chain = make_cleanup_ui_file_delete (stb);
+
+ TRY_CATCH (except, RETURN_MASK_ALL)
+ {
+ type_print (type, "", stb, -1);
+ s = ui_file_xstrdup (stb, &dummy);
+ }
+ if (except.reason < 0)
+ s = NULL;
+
+ do_cleanups (old_chain);
+
+ return s;
+}
+
/* Print type of EXP, or last thing in value history if EXP == NULL.
show is passed to type_print. */

diff --git a/gdb/valprint.c b/gdb/valprint.c
index b61da54..d13dc4c 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -1177,43 +1177,44 @@ partial_memory_read (CORE_ADDR memaddr, gdb_byte *myaddr, int len, int *errnoptr
return (nread);
}

-/* Print a string from the inferior, starting at ADDR and printing up to LEN
- characters, of WIDTH bytes a piece, to STREAM. If LEN is -1, printing
- stops at the first null byte, otherwise printing proceeds (including null
- bytes) until either print_max or LEN characters have been printed,
- whichever is smaller. */
-
-/* FIXME: Use target_read_string. */
+/* Read a string from the inferior, at ADDR, with LEN characters of WIDTH bytes
+ each. Fetch at most FETCHLIMIT characters. BUFFER will be set to a newly
+ allocated buffer containing the string, which the caller is responsible to
+ free, and BYTES_READ will be set to the number of bytes read. Returns 0 on
+ success, or errno on failure.
+
+ If LEN > 0, reads exactly LEN characters (including eventual NULs in
+ the middle or end of the string). If LEN is -1, stops at the first
+ null character (not necessarily the first null byte) up to a maximum
+ of FETCHLIMIT characters. Set FETCHLIMIT to UINT_MAX to read as many
+ characters as possible from the string.
+
+ Unless an exception is thrown, BUFFER will always be allocated, even on
+ failure. In this case, some characters might have been read before the
+ failure happened. Check BYTES_READ to recognize this situation.
+
+ Note: There was a FIXME asking to make this code use target_read_string,
+ but this function is more general (can read past null characters, up to
+ given LEN). Besides, it is used much more often than target_read_string
+ so it is more tested. Perhaps callers of target_read_string should use
+ this function instead? */

int
-val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
- const struct value_print_options *options)
+read_string (CORE_ADDR addr, int len, int width, unsigned int fetchlimit,
+ gdb_byte **buffer, int *bytes_read)
{
- int force_ellipsis = 0; /* Force ellipsis to be printed if nonzero. */
- int errcode; /* Errno returned from bad reads. */
- unsigned int fetchlimit; /* Maximum number of chars to print. */
- unsigned int nfetch; /* Chars to fetch / chars fetched. */
- unsigned int chunksize; /* Size of each fetch, in chars. */
- gdb_byte *buffer = NULL; /* Dynamically growable fetch buffer. */
- gdb_byte *bufptr; /* Pointer to next available byte in buffer. */
- gdb_byte *limit; /* First location past end of fetch buffer. */
- struct cleanup *old_chain = NULL; /* Top of the old cleanup chain. */
- int found_nul; /* Non-zero if we found the nul char */
-
- /* First we need to figure out the limit on the number of characters we are
- going to attempt to fetch and print. This is actually pretty simple. If
- LEN >= zero, then the limit is the minimum of LEN and print_max. If
- LEN is -1, then the limit is print_max. This is true regardless of
- whether print_max is zero, UINT_MAX (unlimited), or something in between,
- because finding the null byte (or available memory) is what actually
- limits the fetch. */
-
- fetchlimit = (len == -1 ? options->print_max : min (len, options->print_max));
-
- /* Now decide how large of chunks to try to read in one operation. This
+ int found_nul; /* Non-zero if we found the nul char. */
+ int errcode; /* Errno returned from bad reads. */
+ unsigned int nfetch; /* Chars to fetch / chars fetched. */
+ unsigned int chunksize; /* Size of each fetch, in chars. */
+ gdb_byte *bufptr; /* Pointer to next available byte in buffer. */
+ gdb_byte *limit; /* First location past end of fetch buffer. */
+ struct cleanup *old_chain = NULL; /* Top of the old cleanup chain. */
+
+ /* Decide how large of chunks to try to read in one operation. This
is also pretty simple. If LEN >= zero, then we want fetchlimit chars,
so we might as well read them all in one operation. If LEN is -1, we
- are looking for a null terminator to end the fetching, so we might as
+ are looking for a NUL terminator to end the fetching, so we might as
well read in blocks that are large enough to be efficient, but not so
large as to be slow if fetchlimit happens to be large. So we choose the
minimum of 8 and fetchlimit. We used to use 200 instead of 8 but
@@ -1221,17 +1222,17 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,

chunksize = (len == -1 ? min (8, fetchlimit) : fetchlimit);

- /* Loop until we either have all the characters to print, or we encounter
- some error, such as bumping into the end of the address space. */
+ /* Loop until we either have all the characters, or we encounter
+ some error, such as bumping into the end of the address space. */

found_nul = 0;
old_chain = make_cleanup (null_cleanup, 0);

if (len > 0)
{
- buffer = (gdb_byte *) xmalloc (len * width);
- bufptr = buffer;
- old_chain = make_cleanup (xfree, buffer);
+ *buffer = (gdb_byte *) xmalloc (len * width);
+ bufptr = *buffer;
+ old_chain = make_cleanup (xfree, *buffer);

nfetch = partial_memory_read (addr, bufptr, len * width, &errcode)
/ width;
@@ -1241,32 +1242,36 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
else if (len == -1)
{
unsigned long bufsize = 0;
+
+ *buffer = NULL;
+
do
{
QUIT;
nfetch = min (chunksize, fetchlimit - bufsize);

- if (buffer == NULL)
- buffer = (gdb_byte *) xmalloc (nfetch * width);
+ if (*buffer == NULL)
+ *buffer = (gdb_byte *) xmalloc (nfetch * width);
else
{
discard_cleanups (old_chain);
- buffer = (gdb_byte *) xrealloc (buffer, (nfetch + bufsize) * width);
+ *buffer = (gdb_byte *) xrealloc (*buffer,
+ (nfetch + bufsize) * width);
}

- old_chain = make_cleanup (xfree, buffer);
- bufptr = buffer + bufsize * width;
+ old_chain = make_cleanup (xfree, *buffer);
+ bufptr = *buffer + bufsize * width;
bufsize += nfetch;

- /* Read as much as we can. */
+ /* Read as much as we can. */
nfetch = partial_memory_read (addr, bufptr, nfetch * width, &errcode)
- / width;
+ / width;

- /* Scan this chunk for the null byte that terminates the string
+ /* Scan this chunk for the null character that terminates the string
to print. If found, we don't need to fetch any more. Note
that bufptr is explicitly left pointing at the next character
- after the null byte, or at the next character after the end of
- the buffer. */
+ after the null character, or at the next character after the end
+ of the buffer. */

limit = bufptr + nfetch * width;
while (bufptr < limit)
@@ -1279,7 +1284,7 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
if (c == 0)
{
/* We don't care about any error which happened after
- the NULL terminator. */
+ the NUL terminator. */
errcode = 0;
found_nul = 1;
break;
@@ -1287,26 +1292,71 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
}
}
while (errcode == 0 /* no error */
- && bufptr - buffer < fetchlimit * width /* no overrun */
- && !found_nul); /* haven't found nul yet */
+ && bufptr - *buffer < fetchlimit * width /* no overrun */
+ && !found_nul); /* haven't found NUL yet */
}
else
- { /* length of string is really 0! */
- buffer = bufptr = NULL;
+ { /* Length of string is really 0! */
+ /* We always allocate *buffer. */
+ *buffer = bufptr = xmalloc (1);
errcode = 0;
}

/* bufptr and addr now point immediately beyond the last byte which we
consider part of the string (including a '\0' which ends the string). */
+ *bytes_read = bufptr - *buffer;
+
+ QUIT;
+
+ discard_cleanups (old_chain);
+
+ return errcode;
+}
+
+/* Print a string from the inferior, starting at ADDR and printing up to LEN
+ characters, of WIDTH bytes a piece, to STREAM. If LEN is -1, printing
+ stops at the first null byte, otherwise printing proceeds (including null
+ bytes) until either print_max or LEN characters have been printed,
+ whichever is smaller. */
+
+int
+val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
+ const struct value_print_options *options)
+{
+ int force_ellipsis = 0; /* Force ellipsis to be printed if nonzero. */
+ int errcode; /* Errno returned from bad reads. */
+ int found_nul; /* Non-zero if we found the nul char */
+ unsigned int fetchlimit; /* Maximum number of chars to print. */
+ int bytes_read;
+ gdb_byte *buffer = NULL; /* Dynamically growable fetch buffer. */
+ struct cleanup *old_chain = NULL; /* Top of the old cleanup chain. */
+
+ /* First we need to figure out the limit on the number of characters we are
+ going to attempt to fetch and print. This is actually pretty simple. If
+ LEN >= zero, then the limit is the minimum of LEN and print_max. If
+ LEN is -1, then the limit is print_max. This is true regardless of
+ whether print_max is zero, UINT_MAX (unlimited), or something in between,
+ because finding the null byte (or available memory) is what actually
+ limits the fetch. */
+
+ fetchlimit = (len == -1 ? options->print_max : min (len, options->print_max));
+
+ errcode = read_string (addr, len, width, fetchlimit, &buffer, &bytes_read);
+ old_chain = make_cleanup (xfree, buffer);
+
+ addr += bytes_read;

/* We now have either successfully filled the buffer to fetchlimit, or
- terminated early due to an error or finding a null char when LEN is -1. */
+ terminated early due to an error or finding a null char when LEN is -1. */
+
+ /* Determine found_nul by looking at the last character read. */
+ found_nul = extract_unsigned_integer (buffer + bytes_read - width, width) == 0;

if (len == -1 && !found_nul)
{
gdb_byte *peekbuf;

- /* We didn't find a null terminator we were looking for. Attempt
+ /* We didn't find a NUL terminator we were looking for. Attempt
to peek at the next character. If not successful, or it is not
a null byte, then force ellipsis to be printed. */

@@ -1316,26 +1366,24 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
&& extract_unsigned_integer (peekbuf, width) != 0)
force_ellipsis = 1;
}
- else if ((len >= 0 && errcode != 0) || (len > (bufptr - buffer) / width))
+ else if ((len >= 0 && errcode != 0) || (len > bytes_read / width))
{
/* Getting an error when we have a requested length, or fetching less
than the number of characters actually requested, always make us
- print ellipsis. */
+ print ellipsis. */
force_ellipsis = 1;
}

- QUIT;
-
/* If we get an error before fetching anything, don't print a string.
But if we fetch something and then get an error, print the string
and then the error message. */
- if (errcode == 0 || bufptr > buffer)
+ if (errcode == 0 || bytes_read > 0)
{
if (options->addressprint)
{
fputs_filtered (" ", stream);
}
- LA_PRINT_STRING (stream, buffer, (bufptr - buffer) / width, width, force_ellipsis, options);
+ LA_PRINT_STRING (stream, buffer, bytes_read / width, width, force_ellipsis, options);
}

if (errcode != 0)
@@ -1353,9 +1401,11 @@ val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream,
fprintf_filtered (stream, ": %s>", safe_strerror (errcode));
}
}
+
gdb_flush (stream);
do_cleanups (old_chain);
- return ((bufptr - buffer) / width);
+
+ return (bytes_read / width);
}
\f

diff --git a/gdb/valprint.h b/gdb/valprint.h
index 6e85bb4..8b65af6 100644
--- a/gdb/valprint.h
+++ b/gdb/valprint.h
@@ -136,4 +136,7 @@ extern void print_hex_chars (struct ui_file *, const gdb_byte *,

extern void print_char_chars (struct ui_file *, const gdb_byte *,
unsigned int, enum bfd_endian);
+
+int read_string (CORE_ADDR addr, int len, int width, unsigned int fetchlimit,
+ gdb_byte **buffer, int *bytes_read);
#endif
diff --git a/gdb/value.h b/gdb/value.h
index 724aa5a..9a11190 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -524,6 +524,8 @@ extern void modify_field (gdb_byte *addr, LONGEST fieldval, int bitpos,
extern void type_print (struct type *type, char *varstring,
struct ui_file *stream, int show);

+extern char *type_to_string (struct type *type);
+
extern gdb_byte *baseclass_addr (struct type *type, int index,
gdb_byte *valaddr,
struct value **valuep, int *errp);