Add support for response files to the CommandLine library.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50355 91177308-0d34-0410-b5e6-96231b3b80d8

docs/CommandLine.html

@@ -52,6 +52,7 @@
                                    specified</a></li>
         <li><a href="#formatting">Controlling other formatting options</a></li>
         <li><a href="#misc">Miscellaneous option modifiers</a></li>
+        <li><a href="#response">Response files</a></li>
         </ul></li>
 
       <li><a href="#toplevel">Top-Level Classes and Functions</a>
@@ -1442,6 +1443,29 @@ only makes sense with a <a href="#cl::list">cl::list</a> option.</li>
 
 </div>
 
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+  <a name="response">Response files</a>
+</div>
+
+<div class="doc_text">
+
+<p>Some systems, such as certain variants of Microsoft Windows and
+some older Unices have a relatively low limit on command-line
+length. It is therefore customary to use the so-called 'response
+files' to circumvent this restriction. These files are mentioned on
+the command-line (using the "@file") syntax. The program reads these
+files and inserts the contents into argv, thereby working around the
+command-line length limits. Response files are enabled by an optional
+fourth argument to
+<a href="#cl::ParseEnvironmentOptions"><tt>cl::ParseEnvironmentOptions</tt></a>
+and
+<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
+</p>
+
+</div>
+
+
 <!-- ======================================================================= -->
 <div class="doc_subsection">
   <a name="toplevel">Top-Level Classes and Functions</a>
@@ -1475,7 +1499,8 @@ available.</p>
 <p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
 (<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
 which holds <a href="#description">additional extra text</a> to emit when the
-<tt>--help</tt> option is invoked.</p>
+<tt>--help</tt> option is invoked, and a fourth boolean parameter that enables
+<a href="#response">response files</a>.</p>
 
 </div>
 
@@ -1497,11 +1522,13 @@ like <a
 href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
 does.</p>
 
-<p>It takes three parameters: the name of the program (since <tt>argv</tt> may
+<p>It takes four parameters: the name of the program (since <tt>argv</tt> may
 not be available, it can't just look in <tt>argv[0]</tt>), the name of the
-environment variable to examine, and the optional
+environment variable to examine, the optional
 <a href="#description">additional extra text</a> to emit when the
-<tt>--help</tt> option is invoked.</p>
+<tt>--help</tt> option is invoked, and the boolean
+switch that controls whether <a href="#response">reponse files</a>
+should be read.</p>
 
 <p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
 variable's value up into words and then process them using

include/llvm/Support/CommandLine.h

@@ -41,14 +41,16 @@ namespace cl {
 // ParseCommandLineOptions - Command line option processing entry point.
 //
 void ParseCommandLineOptions(int argc, char **argv,
-                             const char *Overview = 0);
+                             const char *Overview = 0,
+                             bool ReadResponseFiles = false);
 
 //===----------------------------------------------------------------------===//
 // ParseEnvironmentOptions - Environment variable option processing alternate
 //                           entry point.
 //
 void ParseEnvironmentOptions(const char *progName, const char *envvar,
-                             const char *Overview = 0);
+                             const char *Overview = 0,
+                             bool ReadResponseFiles = false);
 
 ///===---------------------------------------------------------------------===//
 /// SetVersionPrinter - Override the default (LLVM specific) version printer

lib/Support/CommandLine.cpp

@@ -17,7 +17,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Config/config.h"
+#include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Streams.h"
 #include "llvm/System/Path.h"
@@ -309,7 +311,7 @@ static void ParseCStringVector(std::vector<char *> &output,
 /// an environment variable (whose name is given in ENVVAR).
 ///
 void cl::ParseEnvironmentOptions(const char *progName, const char *envVar,
-                                 const char *Overview) {
+                                 const char *Overview, bool ReadResponseFiles) {
   // Check args.
   assert(progName && "Program name not specified");
   assert(envVar && "Environment variable name missing");
@@ -328,7 +330,7 @@ void cl::ParseEnvironmentOptions(const char *progName, const char *envVar,
   // and hand it off to ParseCommandLineOptions().
   ParseCStringVector(newArgv, envValue);
   int newArgc = newArgv.size();
-  ParseCommandLineOptions(newArgc, &newArgv[0], Overview);
+  ParseCommandLineOptions(newArgc, &newArgv[0], Overview, ReadResponseFiles);
 
   // Free all the strdup()ed strings.
   for (std::vector<char*>::iterator i = newArgv.begin(), e = newArgv.end();
@@ -336,8 +338,44 @@ void cl::ParseEnvironmentOptions(const char *progName, const char *envVar,
     free (*i);
 }
 
+
+/// ExpandResponseFiles - Copy the contents of argv into newArgv,
+/// substituting the contents of the response files for the arguments
+/// of type @file.
+static void ExpandResponseFiles(int argc, char** argv,
+                                std::vector<char*>& newArgv) {
+  for (int i = 1; i != argc; ++i) {
+    char* arg = argv[i];
+
+    if (arg[0] == '@') {
+
+      sys::PathWithStatus respFile(++arg);
+
+      // Check that the response file is not empty (mmap'ing empty
+      // files can be problematic).
+      const sys::FileStatus *FileStat = respFile.getFileStatus();
+      if (!FileStat)
+        continue;
+      if (FileStat->getSize() == 0)
+        continue;
+
+      // Mmap the response file into memory.
+      OwningPtr<MemoryBuffer>
+        respFilePtr(MemoryBuffer::getFile(respFile.c_str()));
+
+      if (respFilePtr == 0)
+        continue;
+
+      ParseCStringVector(newArgv, respFilePtr->getBufferStart());
+    }
+    else {
+      newArgv.push_back(strdup(arg));
+    }
+  }
+}
+
 void cl::ParseCommandLineOptions(int argc, char **argv,
-                                 const char *Overview) {
+                                 const char *Overview, bool ReadResponseFiles) {
   // Process all registered options.
   std::vector<Option*> PositionalOpts;
   std::vector<Option*> SinkOpts;
@@ -346,6 +384,16 @@ void cl::ParseCommandLineOptions(int argc, char **argv,
 
   assert((!Opts.empty() || !PositionalOpts.empty()) &&
          "No options specified!");
+
+  // Expand response files.
+  std::vector<char*> newArgv;
+  if (ReadResponseFiles) {
+    newArgv.push_back(strdup(argv[0]));
+    ExpandResponseFiles(argc, argv, newArgv);
+    argv = &newArgv[0];
+    argc = newArgv.size();
+  }
+
   sys::Path progname(argv[0]);
 
   // Copy the program name into ProgName, making sure not to overflow it.
@@ -664,6 +712,14 @@ void cl::ParseCommandLineOptions(int argc, char **argv,
   PositionalOpts.clear();
   MoreHelp->clear();
 
+  // Free the memory allocated by ExpandResponseFiles.
+  if (ReadResponseFiles) {
+    // Free all the strdup()ed strings.
+    for (std::vector<char*>::iterator i = newArgv.begin(), e = newArgv.end();
+         i != e; ++i)
+      free (*i);
+  }
+
   // If we had an error processing our arguments, don't let the program execute
   if (ErrorParsing) exit(1);
 }