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[lldb] Fix string summary of an empty NSPathStore2 

Summary:
Printing a summary for an empty NSPathStore2 string currently prints random bytes behind the empty string pointer from memory (rdar://55575888).

It seems the reason for this is that the SourceSize parameter in the `ReadStringAndDumpToStreamOptions` - which is supposed to contain the string
length - actually uses the length 0 as a magic value for saying "read as much as possible from the buffer" which is clearly wrong for empty strings.

This patch adds another flag that indicates if we have know the string length or not and makes this behaviour dependent on that (which seemingly
was the original purpose of this magic value).

Reviewers: aprantl, JDevlieghere, shafik

Reviewed By: aprantl

Subscribers: christof, abidh, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D68010
This commit is contained in:
Raphael Isemann 2020-03-19 12:20:18 +01:00
parent 5ce38fcbac
commit 939ca455e7
5 changed files with 33 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lldb/include/lldb/DataFormatters/StringPrinter.h
View File

@ -115,9 +115,15 @@ public:
lldb::ProcessSP GetProcessSP() const { return m_process_sp; }
void SetHasSourceSize(bool e) { m_has_source_size = e; }
bool HasSourceSize() const { return m_has_source_size; }
private:
uint64_t m_location = 0;
lldb::ProcessSP m_process_sp;
/// True iff we know the source size of the string.
bool m_has_source_size = false;
};
class ReadBufferAndDumpToStreamOptions : public DumpToStreamOptions {

22
lldb/source/DataFormatters/StringPrinter.cpp
View File

@ -525,27 +525,33 @@ static bool ReadUTFBufferAndDumpToStream(
if (!options.GetStream())
return false;
uint32_t sourceSize = options.GetSourceSize();
uint32_t sourceSize;
bool needs_zero_terminator = options.GetNeedsZeroTermination();
bool is_truncated = false;
const auto max_size = process_sp->GetTarget().GetMaximumSizeOfStringSummary();
if (!sourceSize) {
if (options.HasSourceSize()) {
sourceSize = options.GetSourceSize();
if (!options.GetIgnoreMaxLength()) {
if (sourceSize > max_size) {
sourceSize = max_size;
is_truncated = true;
}
}
} else {
sourceSize = max_size;
needs_zero_terminator = true;
} else if (!options.GetIgnoreMaxLength()) {
if (sourceSize > max_size) {
sourceSize = max_size;
is_truncated = true;
}
}
const int bufferSPSize = sourceSize * type_width;
lldb::DataBufferSP buffer_sp(new DataBufferHeap(bufferSPSize, 0));
if (!buffer_sp->GetBytes())
// Check if we got bytes. We never get any bytes if we have an empty
// string, but we still continue so that we end up actually printing
// an empty string ("").
if (sourceSize != 0 && !buffer_sp->GetBytes())
return false;
Status error;

7
lldb/source/Plugins/Language/ObjC/NSString.cpp
View File

@ -170,6 +170,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetStream(&stream);
options.SetQuote('"');
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetNeedsZeroTermination(false);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
@ -182,6 +183,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetProcessSP(process_sp);
options.SetStream(&stream);
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetNeedsZeroTermination(false);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
@ -199,6 +201,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetStream(&stream);
options.SetQuote('"');
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
options.SetLanguage(summary_options.GetLanguage());
@ -221,6 +224,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetStream(&stream);
options.SetQuote('"');
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetNeedsZeroTermination(!has_explicit_length);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
@ -241,6 +245,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetStream(&stream);
options.SetQuote('"');
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetNeedsZeroTermination(!has_explicit_length);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
@ -263,6 +268,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetProcessSP(process_sp);
options.SetStream(&stream);
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetNeedsZeroTermination(!has_explicit_length);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
@ -286,6 +292,7 @@ bool lldb_private::formatters::NSStringSummaryProvider(
options.SetProcessSP(process_sp);
options.SetStream(&stream);
options.SetSourceSize(explicit_length);
options.SetHasSourceSize(has_explicit_length);
options.SetIgnoreMaxLength(summary_options.GetCapping() ==
TypeSummaryCapping::eTypeSummaryUncapped);
options.SetLanguage(summary_options.GetLanguage());

6
lldb/test/API/functionalities/data-formatter/data-formatter-objc/nsstring/TestDataFormatterNSString.py
View File

@ -76,8 +76,8 @@ class NSStringDataFormatterTestCase(TestBase):
self.expect('frame variable hebrew', substrs=['לילה טוב'])
def nsstring_data_formatter_commands(self):
self.expect('frame variable str0 str1 str2 str3 str4 str5 str6 str8 str9 str10 str11 label1 label2 processName str12',
substrs=[
self.expect('frame variable empty str0 str1 str2 str3 str4 str5 str6 str8 str9 str10 str11 label1 label2 processName str12',
substrs=['(NSString *) empty = ', ' @""',
# '(NSString *) str0 = ',' @"255"',
'(NSString *) str1 = ', ' @"A rather short ASCII NSString object is here"',
'(NSString *) str2 = ', ' @"A rather short UTF8 NSString object is here"',
@ -104,6 +104,8 @@ class NSStringDataFormatterTestCase(TestBase):
self.expect('expr -d run-target -- path', substrs=['usr/blah/stuff'])
self.expect('frame variable path', substrs=['usr/blah/stuff'])
self.expect('expr -d run-target -- empty_path', substrs=['@""'])
self.expect('frame variable empty_path', substrs=['@""'])
def nsstring_withNULs_commands(self):
"""Check that the NSString formatter supports embedded NULs in the text"""

2
lldb/test/API/functionalities/data-formatter/data-formatter-objc/nsstring/main.m
View File

@ -17,6 +17,7 @@ int main (int argc, const char * argv[])
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSString *empty = @"";
NSString *str0 = [[NSNumber numberWithUnsignedLongLong:0xFF] stringValue];
NSString *str1 = [NSString stringWithCString:"A rather short ASCII NSString object is here" encoding:NSASCIIStringEncoding];
NSString *str2 = [NSString stringWithUTF8String:"A rather short UTF8 NSString object is here"];
@ -69,6 +70,7 @@ int main (int argc, const char * argv[])
NSArray *components = @[@"usr", @"blah", @"stuff"];
NSString *path = [NSString pathWithComponents: components];
NSString *empty_path = [empty stringByDeletingPathExtension];
const unichar someOfTheseAreNUL[] = {'a',' ', 'v','e','r','y',' ',
'm','u','c','h',' ','b','o','r','i','n','g',' ','t','a','s','k',