MemoryRegion: Print "don't know" permission values as such

Summary:
The permissions in a memory region have ternary states (yes, no, don't
know), but the memory region command only prints in binary, treating
"don't know" as "yes", which is particularly confusing as for instance
the unwinder will treat an unknown value as "no".

This patch makes is so that we distinguish all three states when
printing the values, using "?" to indicate the lack of information. It
is implemented via a special argument to the format provider for the
OptionalBool enumeration.

Reviewers: clayborg, jingham

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D69106

4 files changed, 33 insertions, 25 deletions

diff --git a/lldb/include/lldb/Target/MemoryRegionInfo.h b/lldb/include/lldb/Target/MemoryRegionInfo.h
index c6c4e080f8d..07e50188843 100644
--- a/lldb/include/lldb/Target/MemoryRegionInfo.h
+++ b/lldb/include/lldb/Target/MemoryRegionInfo.h
@@ -133,21 +133,13 @@ public:
 
 namespace llvm {
 template <>
+/// If Options is empty, prints a textual representation of the value. If
+/// Options is a single character, it uses that character for the "yes" value,
+/// while "no" is printed as "-", and "don't know" as "?". This can be used to
+/// print the permissions in the traditional "rwx" form.
 struct format_provider<lldb_private::MemoryRegionInfo::OptionalBool> {
   static void format(const lldb_private::MemoryRegionInfo::OptionalBool &B,
-                     raw_ostream &OS, StringRef Options) {
-    switch(B) {
-    case lldb_private::MemoryRegionInfo::eNo:
-      OS << "no";
-      return;
-    case lldb_private::MemoryRegionInfo::eYes:
-      OS << "yes";
-      return;
-    case lldb_private::MemoryRegionInfo::eDontKnow:
-      OS << "don't know";
-      return;
-    }
-  }
+                     raw_ostream &OS, StringRef Options);
 };
 }
 
diff --git a/lldb/source/Commands/CommandObjectMemory.cpp b/lldb/source/Commands/CommandObjectMemory.cpp
index 679a7b6a998..a20290f94bf 100644
--- a/lldb/source/Commands/CommandObjectMemory.cpp
+++ b/lldb/source/Commands/CommandObjectMemory.cpp
@@ -1730,15 +1730,12 @@ protected:
               section_name = section_sp->GetName();
             }
           }
-          result.AppendMessageWithFormat(
-              "[0x%16.16" PRIx64 "-0x%16.16" PRIx64 ") %c%c%c%s%s%s%s\n",
+          result.AppendMessageWithFormatv(
+              "[{0:x16}-{1:x16}) {2:r}{3:w}{4:x}{5}{6}{7}{8}\n",
               range_info.GetRange().GetRangeBase(),
-              range_info.GetRange().GetRangeEnd(),
-              range_info.GetReadable() ? 'r' : '-',
-              range_info.GetWritable() ? 'w' : '-',
-              range_info.GetExecutable() ? 'x' : '-', name ? " " : "",
-              name.AsCString(""), section_name ? " " : "",
-              section_name.AsCString(""));
+              range_info.GetRange().GetRangeEnd(), range_info.GetReadable(),
+              range_info.GetWritable(), range_info.GetExecutable(),
+              name ? " " : "", name, section_name ? " " : "", section_name);
           m_prev_end_addr = range_info.GetRange().GetRangeEnd();
           result.SetStatus(eReturnStatusSuccessFinishResult);
         } else {
diff --git a/lldb/source/Target/MemoryRegionInfo.cpp b/lldb/source/Target/MemoryRegionInfo.cpp
index 1feb84bffc5..2c31563786a 100644
--- a/lldb/source/Target/MemoryRegionInfo.cpp
+++ b/lldb/source/Target/MemoryRegionInfo.cpp
@@ -8,13 +8,33 @@
 
 #include "lldb/Target/MemoryRegionInfo.h"
 
+using namespace lldb_private;
+
 llvm::raw_ostream &lldb_private::operator<<(llvm::raw_ostream &OS,
                                             const MemoryRegionInfo &Info) {
-  return OS << llvm::formatv("MemoryRegionInfo([{0}, {1}), {2}, {3}, {4}, {5}, "
-                             "`{6}`, {7}, {8})",
+  return OS << llvm::formatv("MemoryRegionInfo([{0}, {1}), {2:r}{3:w}{4:x}, "
+                             "{5}, `{6}`, {7}, {8})",
                              Info.GetRange().GetRangeBase(),
                              Info.GetRange().GetRangeEnd(), Info.GetReadable(),
                              Info.GetWritable(), Info.GetExecutable(),
                              Info.GetMapped(), Info.GetName(), Info.GetFlash(),
                              Info.GetBlocksize());
 }
+
+void llvm::format_provider<MemoryRegionInfo::OptionalBool>::format(
+    const MemoryRegionInfo::OptionalBool &B, raw_ostream &OS,
+    StringRef Options) {
+  assert(Options.size() <= 1);
+  bool Empty = Options.empty();
+  switch (B) {
+  case lldb_private::MemoryRegionInfo::eNo:
+    OS << (Empty ? "no" : "-");
+    return;
+  case lldb_private::MemoryRegionInfo::eYes:
+    OS << (Empty ? "yes" : Options);
+    return;
+  case lldb_private::MemoryRegionInfo::eDontKnow:
+    OS << (Empty ? "don't know" : "?");
+    return;
+  }
+}
diff --git a/lldb/test/Shell/Minidump/memory-region-from-module.yaml b/lldb/test/Shell/Minidump/memory-region-from-module.yaml
index 0c405e8f6c2..fb6c4a40a69 100644
--- a/lldb/test/Shell/Minidump/memory-region-from-module.yaml
+++ b/lldb/test/Shell/Minidump/memory-region-from-module.yaml
@@ -19,8 +19,7 @@
 # ALL: [0x0000000000000000-0x0000000000004000) ---
 # ALL-LABEL: (lldb) memory region 0x4000
 # CHECK1: [0x0000000000004000-0x00000000000040b0) r-x {{.*}}memory-region-from-module.exe PT_LOAD[0]
-# TODO: This output does not give any indication that the region is only "potentially" writable.
-# CHECK2: [0x0000000000004000-0x0000000000004010) rwx
+# CHECK2: [0x0000000000004000-0x0000000000004010) r??
 # ALL-LABEL: (lldb) memory region 0x5000
 # ALL: [0x0000000000005000-0x000000000000505c) rw- {{.*}}memory-region-from-module.exe PT_LOAD[1]
 # ALL-LABEL: (lldb) memory region 0x6000