Add "merge --input-file-list NAME ..." as a way to exceed CLI limits

README.md

@@ -193,6 +193,8 @@ Usage:
 
 Options:
   --input-files <input-files>                     Input BOM filenames (separate filenames with a space).
+  --input-files-list <input-files-list-files>     One or more text file(s) with input BOM filenames (one per line).
+  --input-files-nul-list <input-files-list-files> One or more text-like file(s) with input BOM filenames (separated by 0x00 characters).
   --output-file <output-file>                     Output BOM filename, will write to stdout if no value provided.
   --input-format <autodetect|json|protobuf|xml>   Specify input file format.
   --output-format <autodetect|json|protobuf|xml>  Specify output file format.
@@ -205,6 +207,24 @@ Options:
 Note: To perform a hierarchical merge all BOMs need the subject of the BOM
 described in the metadata component element.
 
+The `--input-files-list` option can be useful if you have so many filenames to
+merge that your shell interpreter command-line limit is exceeded if you list
+them all as `--input-files`, or if your path names have spaces.
+
+The related `--input-files-nul-list` is intended for lists prepared by commands
+like `find ... -print0` and makes sense on filesystems where carriage-return
+and/or line-feed characters may validly be present in a path name component.
+Note: behavior with multi-byte encodings (Unicode family) where a 0x00 byte
+can be part of a character may be undefined.
+
+If you specify several of these options, the effective file lists will be
+concatenated before the actual merge (first the individual `--input-files`,
+then the contents of `--input-files-list`, and finally the contents of
+`--input-files-nul-list`). If you have a document crafted to describe the
+root of your product hierarchy tree, it is recommended to list it as the
+first of individual `--input-files` (or otherwise on first line among used
+lists).
+
 ### Examples
 
 Merge two XML formatted BOMs:  

src/cyclonedx/Commands/MergeCommand.cs

@@ -22,6 +22,8 @@
 using System.Threading.Tasks;
 using CycloneDX.Models;
 using CycloneDX.Utils;
+using System.IO;
+using System.Collections.Immutable;
 
 namespace CycloneDX.Cli.Commands
 {
@@ -32,6 +34,8 @@ public static void Configure(RootCommand rootCommand)
             Contract.Requires(rootCommand != null);
             var subCommand = new Command("merge", "Merge two or more BOMs");
             subCommand.Add(new Option<List<string>>("--input-files", "Input BOM filenames (separate filenames with a space)."));
+            subCommand.Add(new Option<List<string>>("--input-files-list", "One or more text file(s) with input BOM filenames (one per line)."));
+            subCommand.Add(new Option<List<string>>("--input-files-nul-list", "One or more text-like file(s) with input BOM filenames (separated by 0x00 characters)."));
             subCommand.Add(new Option<string>("--output-file", "Output BOM filename, will write to stdout if no value provided."));
             subCommand.Add(new Option<CycloneDXBomFormat>("--input-format", "Specify input file format."));
             subCommand.Add(new Option<CycloneDXBomFormat>("--output-format", "Specify output file format."));
@@ -61,7 +65,55 @@ public static async Task<int> Merge(MergeCommandOptions options)
                 return (int)ExitCode.ParameterValidationError;
             }
 
-            var inputBoms = await InputBoms(options.InputFiles, options.InputFormat, outputToConsole).ConfigureAwait(false);
+            List<string> InputFiles;
+            if (options.InputFiles != null)
+            {
+                InputFiles = (List<string>)options.InputFiles;
+            }
+            else
+            {
+                InputFiles = new List<string>();
+            }
+
+            Console.WriteLine($"Got " + InputFiles.Count + " individual input file name(s): ['" + string.Join("', '", InputFiles) + "']");
+            if (options.InputFilesList != null)
+            {
+                // For some reason, without an immutable list this claims
+                // modifications of the iterable during iteration and fails:
+                ImmutableList<string> InputFilesList = options.InputFilesList.ToImmutableList();
+                Console.WriteLine($"Got " + InputFilesList.Count + " file(s) with actual input file names: ['" + string.Join("', '", InputFilesList) + "']");
+                foreach (string OneInputFileList in InputFilesList)
+                {
+                    Console.WriteLine($"Adding to input file list from " + OneInputFileList);
+                    string[] lines = File.ReadAllLines(OneInputFileList);
+                    InputFiles.AddRange(lines);
+                    Console.WriteLine($"Got " + lines.Length + " entries from " + OneInputFileList);
+                }
+            }
+
+            if (options.InputFilesNulList != null)
+            {
+                ImmutableList<string> InputFilesNulList = options.InputFilesNulList.ToImmutableList();
+                Console.WriteLine($"Got " + InputFilesNulList.Count + " file(s) with NUL-separated actual input file names: ['" + string.Join("', '", InputFilesNulList) + "']");
+                foreach (string OneInputFileList in InputFilesNulList)
+                {
+                    Console.WriteLine($"Adding to input file list from " + OneInputFileList);
+                    string[] lines = File.ReadAllText(OneInputFileList).Split('\0');
+                    InputFiles.AddRange(lines);
+                    Console.WriteLine($"Got " + lines.Length + " entries from " + OneInputFileList);
+                }
+            }
+
+            // TODO: Consider InputFiles.Distinct().ToList() -
+            //  but that requires C# 3.0 for extension method support,
+            //  and .NET 3.5 to get the LINQ Enumerable class.
+            if (InputFiles.Count == 0)
+            {
+                // Revert to legacy (error-handling) behavior below
+                // in case the parameter was not passed
+                InputFiles = null;
+            }
+            var inputBoms = await InputBoms(InputFiles, options.InputFormat, outputToConsole).ConfigureAwait(false);
 
             Component bomSubject = null;
             if (options.Group != null || options.Name != null || options.Version != null)

src/cyclonedx/Commands/MergeCommandOptions.cs

@@ -21,6 +21,8 @@ namespace CycloneDX.Cli.Commands
     public class MergeCommandOptions
     {
         public IList<string> InputFiles { get; set; }
+        public IList<string> InputFilesList { get; set; }
+        public IList<string> InputFilesNulList { get; set; }
         public string OutputFile { get; set; }
         public CycloneDXBomFormat InputFormat { get; set; }
         public CycloneDXBomFormat OutputFormat { get; set; }
@@ -29,4 +31,4 @@ public class MergeCommandOptions
         public string Name { get; set; }
         public string Version { get; set; }
     }
-}
+}