From 1abaeece719c99ad9b408257b71c19c62db438cc Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel@labath.sk>
Date: Wed, 10 Jul 2019 17:09:47 +0000
Subject: [PATCH] Options: Reduce code duplication

Summary:
While investigating breakages caused by D63110, I noticed we were
building the short options strings in three places. Some of them used a
leading ':' to detect missing arguments, and some didn't. This was the
indirect cause of D63110. Here, I move the common code into a utility
function.

Also, unify the code which appends the sentinel value at the end of the
option vector, and make it harder for users to pass invalid argc-argv
combos to getopt (another component of D63110) by having the
OptionParser::Parse function take a (Mutable)ArrayRef.

This unification has uncovered that we don't handle missing arguments
while building aliases, However, it's not possible to write an effective
test for this, as right now it is not possible to return an error out of
the alias parsing code (which means we are printing the generic
"failure" message even after this patch).

Reviewers: mgorny, aprantl

Reviewed By: mgorny

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D63770

llvm-svn: 365665
---
 lldb/include/lldb/Host/OptionParser.h    |   8 +-
 lldb/source/Host/common/OptionParser.cpp |   8 +-
 lldb/source/Interpreter/CommandAlias.cpp |   2 +
 lldb/source/Interpreter/Options.cpp      | 102 ++++++++---------------
 4 files changed, 48 insertions(+), 72 deletions(-)

diff --git a/lldb/include/lldb/Host/OptionParser.h b/lldb/include/lldb/Host/OptionParser.h
index ca0594645645..b03eeb74ec4e 100644
--- a/lldb/include/lldb/Host/OptionParser.h
+++ b/lldb/include/lldb/Host/OptionParser.h
@@ -13,6 +13,7 @@
 #include <string>
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/ArrayRef.h"
 
 struct option;
 
@@ -37,8 +38,11 @@ public:
 
   static void EnableError(bool error);
 
-  static int Parse(int argc, char *const argv[], llvm::StringRef optstring,
-                   const Option *longopts, int *longindex);
+  /// Argv must be an argument vector "as passed to main", i.e. terminated with
+  /// a nullptr.
+  static int Parse(llvm::MutableArrayRef<char *> argv,
+                   llvm::StringRef optstring, const Option *longopts,
+                   int *longindex);
 
   static char *GetOptionArgument();
   static int GetOptionIndex();
diff --git a/lldb/source/Host/common/OptionParser.cpp b/lldb/source/Host/common/OptionParser.cpp
index 92ff6f63d951..1e76f9b8f9f1 100644
--- a/lldb/source/Host/common/OptionParser.cpp
+++ b/lldb/source/Host/common/OptionParser.cpp
@@ -27,8 +27,9 @@ void OptionParser::Prepare(std::unique_lock<std::mutex> &lock) {
 
 void OptionParser::EnableError(bool error) { opterr = error ? 1 : 0; }
 
-int OptionParser::Parse(int argc, char *const argv[], llvm::StringRef optstring,
-                        const Option *longopts, int *longindex) {
+int OptionParser::Parse(llvm::MutableArrayRef<char *> argv,
+                        llvm::StringRef optstring, const Option *longopts,
+                        int *longindex) {
   std::vector<option> opts;
   while (longopts->definition != nullptr) {
     option opt;
@@ -41,7 +42,8 @@ int OptionParser::Parse(int argc, char *const argv[], llvm::StringRef optstring,
   }
   opts.push_back(option());
   std::string opt_cstr = optstring;
-  return getopt_long_only(argc, argv, opt_cstr.c_str(), &opts[0], longindex);
+  return getopt_long_only(argv.size() - 1, argv.data(), opt_cstr.c_str(),
+                          &opts[0], longindex);
 }
 
 char *OptionParser::GetOptionArgument() { return optarg; }
diff --git a/lldb/source/Interpreter/CommandAlias.cpp b/lldb/source/Interpreter/CommandAlias.cpp
index 7d159a3baa07..8c40574ee50e 100644
--- a/lldb/source/Interpreter/CommandAlias.cpp
+++ b/lldb/source/Interpreter/CommandAlias.cpp
@@ -30,6 +30,8 @@ static bool ProcessAliasOptionsArgs(lldb::CommandObjectSP &cmd_obj_sp,
 
   Args args(options_args);
   std::string options_string(options_args);
+  // TODO: Find a way to propagate errors in this CommandReturnObject up the
+  // stack.
   CommandReturnObject result;
   // Check to see if the command being aliased can take any command options.
   Options *options = cmd_obj_sp->GetOptions();
diff --git a/lldb/source/Interpreter/Options.cpp b/lldb/source/Interpreter/Options.cpp
index e015ee4c5756..ba15c020f2da 100644
--- a/lldb/source/Interpreter/Options.cpp
+++ b/lldb/source/Interpreter/Options.cpp
@@ -930,6 +930,7 @@ static std::vector<char *> GetArgvForParsing(const Args &args) {
   result.push_back(const_cast<char *>("<FAKE-ARG0>"));
   for (const Args::ArgEntry &entry : args)
     result.push_back(const_cast<char *>(entry.c_str()));
+  result.push_back(nullptr);
   return result;
 }
 
@@ -972,19 +973,15 @@ static size_t FindArgumentIndexForOption(const Args &args,
   return size_t(-1);
 }
 
-llvm::Expected<Args> Options::ParseAlias(const Args &args,
-                                         OptionArgVector *option_arg_vector,
-                                         std::string &input_line) {
-  StreamString sstr;
-  int i;
-  Option *long_options = GetLongOptions();
+static std::string BuildShortOptions(const Option *long_options) {
+  std::string storage;
+  llvm::raw_string_ostream sstr(storage);
 
-  if (long_options == nullptr) {
-    return llvm::make_error<llvm::StringError>("Invalid long options",
-                                               llvm::inconvertibleErrorCode());
-  }
+  // Leading : tells getopt to return a : for a missing option argument AND to
+  // suppress error messages.
+  sstr << ":";
 
-  for (i = 0; long_options[i].definition != nullptr; ++i) {
+  for (size_t i = 0; long_options[i].definition != nullptr; ++i) {
     if (long_options[i].flag == nullptr) {
       sstr << (char)long_options[i].val;
       switch (long_options[i].definition->option_has_arg) {
@@ -1000,6 +997,20 @@ llvm::Expected<Args> Options::ParseAlias(const Args &args,
       }
     }
   }
+  return std::move(sstr.str());
+}
+
+llvm::Expected<Args> Options::ParseAlias(const Args &args,
+                                         OptionArgVector *option_arg_vector,
+                                         std::string &input_line) {
+  Option *long_options = GetLongOptions();
+
+  if (long_options == nullptr) {
+    return llvm::make_error<llvm::StringError>("Invalid long options",
+                                               llvm::inconvertibleErrorCode());
+  }
+
+  std::string short_options = BuildShortOptions(long_options);
 
   Args args_copy = args;
   std::vector<char *> argv = GetArgvForParsing(args);
@@ -1009,8 +1020,13 @@ llvm::Expected<Args> Options::ParseAlias(const Args &args,
   int val;
   while (true) {
     int long_options_index = -1;
-    val = OptionParser::Parse(argv.size(), &*argv.begin(), sstr.GetString(),
-                              long_options, &long_options_index);
+    val = OptionParser::Parse(argv, short_options, long_options,
+                              &long_options_index);
+
+    if (val == ':') {
+      return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                     "last option requires an argument");
+    }
 
     if (val == -1)
       break;
@@ -1116,33 +1132,13 @@ llvm::Expected<Args> Options::ParseAlias(const Args &args,
 OptionElementVector Options::ParseForCompletion(const Args &args,
                                                 uint32_t cursor_index) {
   OptionElementVector option_element_vector;
-  StreamString sstr;
   Option *long_options = GetLongOptions();
   option_element_vector.clear();
 
   if (long_options == nullptr)
     return option_element_vector;
 
-  // Leading : tells getopt to return a : for a missing option argument AND to
-  // suppress error messages.
-
-  sstr << ":";
-  for (int i = 0; long_options[i].definition != nullptr; ++i) {
-    if (long_options[i].flag == nullptr) {
-      sstr << (char)long_options[i].val;
-      switch (long_options[i].definition->option_has_arg) {
-      default:
-      case OptionParser::eNoArgument:
-        break;
-      case OptionParser::eRequiredArgument:
-        sstr << ":";
-        break;
-      case OptionParser::eOptionalArgument:
-        sstr << "::";
-        break;
-      }
-    }
-  }
+  std::string short_options = BuildShortOptions(long_options);
 
   std::unique_lock<std::mutex> lock;
   OptionParser::Prepare(lock);
@@ -1153,10 +1149,6 @@ OptionElementVector Options::ParseForCompletion(const Args &args,
 
   std::vector<char *> dummy_vec = GetArgvForParsing(args);
 
-  // I stick an element on the end of the input, because if the last element
-  // is option that requires an argument, getopt_long_only will freak out.
-  dummy_vec.push_back(const_cast<char *>("<FAKE-VALUE>"));
-
   bool failed_once = false;
   uint32_t dash_dash_pos = -1;
 
@@ -1164,8 +1156,8 @@ OptionElementVector Options::ParseForCompletion(const Args &args,
     bool missing_argument = false;
     int long_options_index = -1;
 
-    val = OptionParser::Parse(dummy_vec.size(), &dummy_vec[0], sstr.GetString(),
-                              long_options, &long_options_index);
+    val = OptionParser::Parse(dummy_vec, short_options, long_options,
+                              &long_options_index);
 
     if (val == -1) {
       // When we're completing a "--" which is the last option on line,
@@ -1328,7 +1320,6 @@ llvm::Expected<Args> Options::Parse(const Args &args,
                                     ExecutionContext *execution_context,
                                     lldb::PlatformSP platform_sp,
                                     bool require_validation) {
-  StreamString sstr;
   Status error;
   Option *long_options = GetLongOptions();
   if (long_options == nullptr) {
@@ -1336,38 +1327,15 @@ llvm::Expected<Args> Options::Parse(const Args &args,
                                                llvm::inconvertibleErrorCode());
   }
 
-  // Leading : tells getopt to return a : for a missing option argument AND to
-  // suppress error messages.
-  sstr << ":";
-  for (int i = 0; long_options[i].definition != nullptr; ++i) {
-    if (long_options[i].flag == nullptr) {
-      if (isprint8(long_options[i].val)) {
-        sstr << (char)long_options[i].val;
-        switch (long_options[i].definition->option_has_arg) {
-        default:
-        case OptionParser::eNoArgument:
-          break;
-        case OptionParser::eRequiredArgument:
-          sstr << ':';
-          break;
-        case OptionParser::eOptionalArgument:
-          sstr << "::";
-          break;
-        }
-      }
-    }
-  }
+  std::string short_options = BuildShortOptions(long_options);
   std::vector<char *> argv = GetArgvForParsing(args);
-  // If the last option requires an argument but doesn't have one,
-  // some implementations of getopt_long will still try to read it.
-  argv.push_back(nullptr);
   std::unique_lock<std::mutex> lock;
   OptionParser::Prepare(lock);
   int val;
   while (true) {
     int long_options_index = -1;
-    val = OptionParser::Parse(argv.size() - 1, &*argv.begin(), sstr.GetString(),
-                              long_options, &long_options_index);
+    val = OptionParser::Parse(argv, short_options, long_options,
+                              &long_options_index);
 
     if (val == ':') {
       error.SetErrorStringWithFormat("last option requires an argument");