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[Bug python/11417] New: lazy string of zero length requires a valid pointer
- From: "zilla at kayari dot org" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: 22 Mar 2010 15:29:48 -0000
- Subject: [Bug python/11417] New: lazy string of zero length requires a valid pointer
- Reply-to: sourceware-bugzilla at sourceware dot org
I don't know if this behaviour is intentional, but it used to work when I was
using gdb.Value.string and fails with gdb.Value.lazy_string
I have a pretty printer for a string-like C++ class holding a char pointer and a
length. The pointer can be NULL, in which case the length will be 0.
struct Str {
Str(const char* s = 0) : str(s), len(s ? strlen(s) : 0) { }
const char* str;
int len;
};
Previously my pretty printer looked like:
class StrPrinter:
"Print a Str"
def __init__ (self, val):
self.val = val
def to_string (self):
return '"' + self.val['str'].string('', 'ignore', self.val['len']) + '"'
If the pointer was null this printed ""
(gdb) p/r null
$5 = {str = 0x0, len = 0}
(gdb) p null
$6 = ""
(this despite the docs for Value.string saying "The string is assumed to be
terminated by a zero of the appropriate width.")
I changed the printer to:
class Str2Printer:
"Print a Str2"
def __init__ (self, val):
self.val = val
def to_string (self):
return self.val['str'].lazy_string('', self.val['len'])
I like that I don't need to add double-quotes now, but it seems I now need to
handle NULL explicitly because lazy string doesn't like NULL even when the
length is zero:
(gdb) p/r null2
$2 = {str = 0x0, len = 0}
(gdb) p null2
$3 = Traceback (most recent call last):
File "/home/wakelj/src/tests/pretty/str-gdb.py", line 23, in to_string
return self.val['str'].lazy_string('', self.val['len'])
MemoryError: Cannot create a lazy string from a GDB-side string.
Are these differences between Value.string and Value.lazy_string intentional?
--
Summary: lazy string of zero length requires a valid pointer
Product: gdb
Version: 7.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: python
AssignedTo: unassigned at sourceware dot org
ReportedBy: zilla at kayari dot org
CC: gdb-prs at sourceware dot org
http://sourceware.org/bugzilla/show_bug.cgi?id=11417
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