[lldb] Change the two remaining SInt64 settings in Target to uint (#105460)

TargetProperties.td had a few settings listed as signed integral values,
but the Target.cpp methods reading those values were reading them as
unsigned. e.g. target.max-memory-read-size, some accesses of
target.max-children-count, still today, previously
target.max-string-summary-length.

After Jonas' change to use templates to read these values in
https://reviews.llvm.org/D149774, when the code tried to fetch these
values, we'd eventually end up calling OptionValue::GetAsUInt64 which
checks that the value is actually a UInt64 before returning it; finding
that it was an SInt64, it would drop the user setting and return the
default value. This manifested as a bug that target.max-memory-read-size
is never used for memory read.

target.max-children-count is less straightforward, where one read of
that setting was fetching it as an int64_t, the other as a uint64_t.

I suspect all of these settings were originally marked as SInt64 so a
user could do -1 for "infinite", getting it static_cast to a UINT64_MAX
value along the way. I can't find any documentation for this behavior,
but it seems like something Greg would have done. We've partially lost
that behavior already via
#72233 for
target.max-string-summary-length, and this further removes it.

We're still fetching UInt64's and returning them as uint32_t's but I'm
not overly pressed about someone setting a count/size limit over 4GB.

I added a simple API test for the memory read setting limit.

Author: jasonmolenda

lldb/source/Target/Target.cpp

@@ -4609,7 +4609,7 @@ uint32_t TargetProperties::GetMaxZeroPaddingInFloatFormat() const {
 
 uint32_t TargetProperties::GetMaximumNumberOfChildrenToDisplay() const {
   const uint32_t idx = ePropertyMaxChildrenCount;
-  return GetPropertyAtIndexAs<int64_t>(
+  return GetPropertyAtIndexAs<uint64_t>(
       idx, g_target_properties[idx].default_uint_value);
 }
 

lldb/source/Target/TargetProperties.td

@@ -92,7 +92,7 @@ let Definition = "target" in {
   def MaxZeroPaddingInFloatFormat: Property<"max-zero-padding-in-float-format", "UInt64">,
     DefaultUnsignedValue<6>,
     Desc<"The maximum number of zeroes to insert when displaying a very small float before falling back to scientific notation.">;
-  def MaxChildrenCount: Property<"max-children-count", "SInt64">,
+  def MaxChildrenCount: Property<"max-children-count", "UInt64">,
     DefaultUnsignedValue<256>,
     Desc<"Maximum number of children to expand in any level of depth.">;
   def MaxChildrenDepth: Property<"max-children-depth", "UInt64">,
@@ -101,7 +101,7 @@ let Definition = "target" in {
   def MaxSummaryLength: Property<"max-string-summary-length", "UInt64">,
     DefaultUnsignedValue<1024>,
     Desc<"Maximum number of characters to show when using %s in summary strings.">;
-  def MaxMemReadSize: Property<"max-memory-read-size", "SInt64">,
+  def MaxMemReadSize: Property<"max-memory-read-size", "UInt64">,
     DefaultUnsignedValue<1024>,
     Desc<"Maximum number of bytes that 'memory read' will fetch before --force must be specified.">;
   def BreakpointUseAvoidList: Property<"breakpoints-use-platform-avoid-list", "Boolean">,

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/forward_list/TestDataFormatterGenericForwardList.py

@@ -2,7 +2,6 @@
 Test lldb data formatter subsystem.
 """
 
-
 import lldb
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
@@ -51,7 +50,7 @@ def do_test(self, stdlib_type):
         self.expect(
             "settings show target.max-children-count",
             matching=True,
-            substrs=["target.max-children-count (int) = 256"],
+            substrs=["target.max-children-count (unsigned) = 256"],
         )
 
         self.expect(
@@ -132,7 +131,7 @@ def do_test_ptr_and_ref(self, stdlib_type):
         self.expect(
             "settings show target.max-children-count",
             matching=True,
-            substrs=["target.max-children-count (int) = 256"],
+            substrs=["target.max-children-count (unsigned) = 256"],
         )
 
         self.expect(

lldb/test/API/functionalities/memory/big-read/Makefile

@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+
+include Makefile.rules

lldb/test/API/functionalities/memory/big-read/TestMemoryReadMaximumSize.py

@@ -0,0 +1,31 @@
+"""
+Test the maximum memory read setting.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestMemoryReadMaximumSize(TestBase):
+    def test_memory_read_max_setting(self):
+        """Test the target.max-memory-read-size setting."""
+        self.build()
+        (
+            self.target,
+            self.process,
+            self.thread,
+            self.bp,
+        ) = lldbutil.run_to_source_breakpoint(
+            self, "breakpoint here", lldb.SBFileSpec("main.c")
+        )
+        self.assertTrue(self.bp.IsValid())
+
+        self.expect(
+            "mem rea -f x -s 4 -c 2048 `&c`",
+            error=True,
+            substrs=["Normally, 'memory read' will not read over 1024 bytes of data"],
+        )
+        self.runCmd("settings set target.max-memory-read-size `2048 * sizeof(int)`")
+        self.expect("mem rea -f x -s 4 -c 2048 `&c`", substrs=["feed"])

lldb/test/API/functionalities/memory/big-read/main.c

@@ -0,0 +1,9 @@
+#include <string.h>
+int main() {
+  int c[2048];
+  memset(c, 0, 2048 * sizeof(int));
+
+  c[2047] = 0xfeed;
+
+  return c[2047]; // breakpoint here
+}