[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/tool/GetFile.cs

+/*
+** 2015 October 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains C# code to download a single file based on a URI.
+*/
+
+using System;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.IO;
+using System.Net;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+///////////////////////////////////////////////////////////////////////////////
+
+#region Assembly Metadata
+[assembly: AssemblyTitle("GetFile Tool")]
+[assembly: AssemblyDescription("Download a single file based on a URI.")]
+[assembly: AssemblyCompany("SQLite Development Team")]
+[assembly: AssemblyProduct("SQLite")]
+[assembly: AssemblyCopyright("Public Domain")]
+[assembly: ComVisible(false)]
+[assembly: Guid("5c4b3728-1693-4a33-a218-8e6973ca15a6")]
+[assembly: AssemblyVersion("1.0.*")]
+
+#if DEBUG
+[assembly: AssemblyConfiguration("Debug")]
+#else
+[assembly: AssemblyConfiguration("Release")]
+#endif
+#endregion
+
+///////////////////////////////////////////////////////////////////////////////
+
+namespace GetFile
+{
+    /// <summary>
+    /// This enumeration is used to represent all the possible exit codes from
+    /// this tool.
+    /// </summary>
+    internal enum ExitCode
+    {
+        /// <summary>
+        /// The file download was a success.
+        /// </summary>
+        Success = 0,
+
+        /// <summary>
+        /// The command line arguments are missing (i.e. null).  Generally,
+        /// this should not happen.
+        /// </summary>
+        MissingArgs = 1,
+
+        /// <summary>
+        /// The wrong number of command line arguments was supplied.
+        /// </summary>
+        WrongNumArgs = 2,
+
+        /// <summary>
+        /// The URI specified on the command line could not be parsed as a
+        /// supported absolute URI.
+        /// </summary>
+        BadUri = 3,
+
+        /// <summary>
+        /// The file name portion of the URI specified on the command line
+        /// could not be extracted from it.
+        /// </summary>
+        BadFileName = 4,
+
+        /// <summary>
+        /// The temporary directory is either invalid (i.e. null) or does not
+        /// represent an available directory.
+        /// </summary>
+        BadTempPath = 5,
+
+        /// <summary>
+        /// An exception was caught in <see cref="Main" />.  Generally, this
+        /// should not happen.
+        /// </summary>
+        Exception = 6,
+
+        /// <summary>
+        /// The file download was canceled.  This tool does not make use of
+        /// the <see cref="WebClient.CancelAsync" /> method; therefore, this
+        /// should not happen.
+        /// </summary>
+        DownloadCanceled = 7,
+
+        /// <summary>
+        /// The file download encountered an error.  Further information about
+        /// this error should be displayed on the console.
+        /// </summary>
+        DownloadError = 8
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+
+    internal static class Program
+    {
+        #region Private Data
+        /// <summary>
+        /// This is used to synchronize multithreaded access to the
+        /// <see cref="previousPercent" /> and <see cref="exitCode"/>
+        /// fields.
+        /// </summary>
+        private static readonly object syncRoot = new object();
+
+        ///////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// This event will be signed when the file download has completed,
+        /// even if the file download itself was canceled or unsuccessful.
+        /// </summary>
+        private static EventWaitHandle doneEvent;
+
+        ///////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// The previous file download completion percentage seen by the
+        /// <see cref="DownloadProgressChanged" /> event handler.  This value
+        /// is never decreased, nor is it ever reset to zero.
+        /// </summary>
+        private static int previousPercent = 0;
+
+        ///////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// This will be the exit code returned by this tool after the file
+        /// download completes, successfully or otherwise.  This value is only
+        /// changed by the <see cref="DownloadFileCompleted" /> event handler.
+        /// </summary>
+        private static ExitCode exitCode = ExitCode.Success;
+        #endregion
+
+        ///////////////////////////////////////////////////////////////////////
+
+        #region Private Support Methods
+        /// <summary>
+        /// This method displays an error message to the console and/or
+        /// displays the command line usage information for this tool.
+        /// </summary>
+        /// <param name="message">
+        /// The error message to display, if any.
+        /// </param>
+        /// <param name="usage">
+        /// Non-zero to display the command line usage information.
+        /// </param>
+        private static void Error(
+            string message,
+            bool usage
+            )
+        {
+            if (message != null)
+                Console.WriteLine(message);
+
+            string fileName = Path.GetFileName(
+                Process.GetCurrentProcess().MainModule.FileName);
+
+            Console.WriteLine(String.Format("usage: {0} <uri>", fileName));
+        }
+
+        ///////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// This method attempts to determine the file name portion of the
+        /// specified URI.
+        /// </summary>
+        /// <param name="uri">
+        /// The URI to process.
+        /// </param>
+        /// <returns>
+        /// The file name portion of the specified URI -OR- null if it cannot
+        /// be determined.
+        /// </returns>
+        private static string GetFileName(
+            Uri uri
+            )
+        {
+            if (uri == null)
+                return null;
+
+            string pathAndQuery = uri.PathAndQuery;
+
+            if (String.IsNullOrEmpty(pathAndQuery))
+                return null;
+
+            int index = pathAndQuery.LastIndexOf('/');
+
+            if ((index < 0) || (index == pathAndQuery.Length))
+                return null;
+
+            return pathAndQuery.Substring(index + 1);
+        }
+        #endregion
+
+        ///////////////////////////////////////////////////////////////////////
+
+        #region Private Event Handlers
+        /// <summary>
+        /// This method is an event handler that is called when the file
+        /// download completion percentage changes.  It will display progress
+        /// on the console.  Special care is taken to make sure that progress
+        /// events are not displayed out-of-order, even if duplicate and/or
+        /// out-of-order events are received.
+        /// </summary>
+        /// <param name="sender">
+        /// The source of the event.
+        /// </param>
+        /// <param name="e">
+        /// Information for the event being processed.
+        /// </param>
+        private static void DownloadProgressChanged(
+            object sender,
+            DownloadProgressChangedEventArgs e
+            )
+        {
+            if (e != null)
+            {
+                int percent = e.ProgressPercentage;
+
+                lock (syncRoot)
+                {
+                    if (percent > previousPercent)
+                    {
+                        Console.Write('.');
+
+                        if ((percent % 10) == 0)
+                            Console.Write(" {0}% ", percent);
+
+                        previousPercent = percent;
+                    }
+                }
+            }
+        }
+
+        ///////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// This method is an event handler that is called when the file
+        /// download has completed, successfully or otherwise.  It will
+        /// display the overall result of the file download on the console,
+        /// including any <see cref="Exception" /> information, if applicable.
+        /// The <see cref="exitCode" /> field is changed by this method to
+        /// indicate the overall result of the file download and the event
+        /// within the <see cref="doneEvent" /> field will be signaled.
+        /// </summary>
+        /// <param name="sender">
+        /// The source of the event.
+        /// </param>
+        /// <param name="e">
+        /// Information for the event being processed.
+        /// </param>
+        private static void DownloadFileCompleted(
+            object sender,
+            AsyncCompletedEventArgs e
+            )
+        {
+            if (e != null)
+            {
+                lock (syncRoot)
+                {
+                    if (previousPercent < 100)
+                        Console.Write(' ');
+                }
+
+                if (e.Cancelled)
+                {
+                    Console.WriteLine("Canceled");
+
+                    lock (syncRoot)
+                    {
+                        exitCode = ExitCode.DownloadCanceled;
+                    }
+                }
+                else
+                {
+                    Exception error = e.Error;
+
+                    if (error != null)
+                    {
+                        Console.WriteLine("Error: {0}", error);
+
+                        lock (syncRoot)
+                        {
+                            exitCode = ExitCode.DownloadError;
+                        }
+                    }
+                    else
+                    {
+                        Console.WriteLine("Done");
+                    }
+                }
+            }
+
+            if (doneEvent != null)
+                doneEvent.Set();
+        }
+        #endregion
+
+        ///////////////////////////////////////////////////////////////////////
+
+        #region Program Entry Point
+        /// <summary>
+        /// This is the entry-point for this tool.  It handles processing the
+        /// command line arguments, setting up the web client, downloading the
+        /// file, and saving it to the file system.
+        /// </summary>
+        /// <param name="args">
+        /// The command line arguments.
+        /// </param>
+        /// <returns>
+        /// Zero upon success; non-zero on failure.  This will be one of the
+        /// values from the <see cref="ExitCode" /> enumeration.
+        /// </returns>
+        private static int Main(
+            string[] args
+            )
+        {
+            //
+            // NOTE: Sanity check the command line arguments.
+            //
+            if (args == null)
+            {
+                Error(null, true);
+                return (int)ExitCode.MissingArgs;
+            }
+
+            if (args.Length != 1)
+            {
+                Error(null, true);
+                return (int)ExitCode.WrongNumArgs;
+            }
+
+            //
+            // NOTE: Attempt to convert the first (and only) command line
+            //       argument to an absolute URI.
+            //
+            Uri uri;
+
+            if (!Uri.TryCreate(args[0], UriKind.Absolute, out uri))
+            {
+                Error("Could not create absolute URI from argument.", false);
+                return (int)ExitCode.BadUri;
+            }
+
+            //
+            // NOTE: Attempt to extract the file name portion of the URI we
+            //       just created.
+            //
+            string fileName = GetFileName(uri);
+
+            if (fileName == null)
+            {
+                Error("Could not extract the file name from the URI.", false);
+                return (int)ExitCode.BadFileName;
+            }
+
+            //
+            // NOTE: Grab the temporary path setup for this process.  If it is
+            //       unavailable, we will not continue.
+            //
+            string directory = Path.GetTempPath();
+
+            if (String.IsNullOrEmpty(directory) ||
+                !Directory.Exists(directory))
+            {
+                Error("Temporary directory is invalid or unavailable.", false);
+                return (int)ExitCode.BadTempPath;
+            }
+
+            try
+            {
+                using (WebClient webClient = new WebClient())
+                {
+                    //
+                    // NOTE: Create the event used to signal completion of the
+                    //       file download.
+                    //
+                    doneEvent = new ManualResetEvent(false);
+
+                    //
+                    // NOTE: Hookup the event handlers we care about on the web
+                    //       client.  These are necessary because the file is
+                    //       downloaded asynchronously.
+                    //
+                    webClient.DownloadProgressChanged +=
+                        new DownloadProgressChangedEventHandler(
+                            DownloadProgressChanged);
+
+                    webClient.DownloadFileCompleted +=
+                        new AsyncCompletedEventHandler(
+                            DownloadFileCompleted);
+
+                    //
+                    // NOTE: Build the fully qualified path and file name,
+                    //       within the temporary directory, where the file to
+                    //       be downloaded will be saved.
+                    //
+                    fileName = Path.Combine(directory, fileName);
+
+                    //
+                    // NOTE: If the file name already exists (in the temporary)
+                    //       directory, delete it.
+                    //
+                    // TODO: Perhaps an error should be raised here instead?
+                    //
+                    if (File.Exists(fileName))
+                        File.Delete(fileName);
+
+                    //
+                    // NOTE: After kicking off the asynchronous file download
+                    //       process, wait [forever] until the "done" event is
+                    //       signaled.
+                    //
+                    Console.WriteLine(
+                        "Downloading \"{0}\" to \"{1}\"...", uri, fileName);
+
+                    webClient.DownloadFileAsync(uri, fileName);
+                    doneEvent.WaitOne();
+                }
+
+                lock (syncRoot)
+                {
+                    return (int)exitCode;
+                }
+            }
+            catch (Exception e)
+            {
+                //
+                // NOTE: An exception was caught.  Report it via the console
+                //       and return failure.
+                //
+                Error(e.ToString(), false);
+                return (int)ExitCode.Exception;
+            }
+        }
+        #endregion
+    }
+}