Fix Get-PnPFile mangling file names containing URL encoding sequences

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed multi-geo compatibility issues with `Get-PnPGeoAdministrator` response handling, `Set-PnPMultiGeoExperience` confirmation prompts, and unsupported-version errors for `Set-PnPMultiGeoCompanyAllowedDataLocation`. [#5401](https://github.com/pnp/powershell/pull/5401)
 - Fixed Power Apps cmdlets to use cloud-specific Power Apps service audiences and endpoints for government clouds. [#5404](https://github.com/pnp/powershell/pull/5404)
 - Fixed `Export-PnPPowerApp`, `Get-PnPPowerPlatformCustomConnector`, `Export-PnPFlow -AsZipPackage`, and `Import-PnPFlow` to use the Power Apps service audience when calling Power Apps and Business Applications endpoints in sovereign clouds. [#5408](https://github.com/pnp/powershell/pull/5408)
+- Fixed `Get-PnPFile` returning the wrong file or a file not found error when the file name contains URL encoding sequences such as `%20` or a `+`. The provided Url is now tried as-is first and only decoded as a fallback, so both literal file names and URLs copied from a browser resolve correctly. [#5010](https://github.com/pnp/powershell/issues/5010) [#1864](https://github.com/pnp/powershell/issues/1864)
 
 ### Removed
 
@@ -30,6 +31,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fabian Hutzli [fabianhutzli]
 - [reusto]
 - Patrick Schneider [pschneid]
+- [svermaak]
 
 ## [3.3.0]
 

src/Commands/Files/GetFile.cs

@@ -72,19 +72,19 @@ protected override void ExecuteCmdlet()
                 // We can't deal with absolute URLs
                 Url = UrlUtility.MakeRelativeUrl(Url);
             }
-
-            // Remove URL decoding from the Url as that will not work. We will encode the + character specifically, because if that is part of the filename, it needs to stay and not be decoded.
-            Url = Utilities.UrlUtilities.UrlDecode(Url.Replace("+", "%2B"));
 
             var webUrl = CurrentWeb.EnsureProperty(w => w.ServerRelativeUrl);
 
-            if (!Url.ToLower().StartsWith(webUrl.ToLower()))
+            // The provided Url can be the literal name of the file or a URL encoded version of it.
+            // Try it as provided first so files with i.e. %20 or + in their actual name resolve,
+            // and only fall back to the decoded form so URLs copied from a browser keep working.
+            // The + character is excluded from decoding as it would otherwise turn into a space.
+            serverRelativeUrl = ToServerRelativeUrl(webUrl, Url);
+            var decodedUrl = Utilities.UrlUtilities.UrlDecode(Url.Replace("+", "%2B"));
+            var decodedServerRelativeUrl = ToServerRelativeUrl(webUrl, decodedUrl);
+            if (!decodedServerRelativeUrl.Equals(serverRelativeUrl, StringComparison.Ordinal) && !FileExists(serverRelativeUrl))
             {
-                serverRelativeUrl = UrlUtility.Combine(webUrl, Url);
-            }
-            else
-            {
-                serverRelativeUrl = Url;
+                serverRelativeUrl = decodedServerRelativeUrl;
             }
 
             switch (ParameterSetName)
@@ -163,6 +163,19 @@ protected override void ExecuteCmdlet()
             }
         }
 
+        private static string ToServerRelativeUrl(string webUrl, string url)
+        {
+            return !url.ToLower().StartsWith(webUrl.ToLower()) ? UrlUtility.Combine(webUrl, url) : url;
+        }
+
+        private bool FileExists(string serverRelativeUrl)
+        {
+            var file = CurrentWeb.GetFileByServerRelativePath(ResourcePath.FromDecodedUrl(serverRelativeUrl));
+            ClientContext.Load(file, f => f.Exists);
+            ClientContext.ExecuteQueryRetry();
+            return file.Exists;
+        }
+
         private static async Task SaveFileToLocal(IFile fileToDownload, string filePath)
         {
             // Start the download