Open directories of files

You can pass files / dirs as arguments an they will be opened. The
directories will be searched for text files (as identified by libmagic)
and those text files will be displayed too.

build.zig

@@ -7,6 +7,7 @@ pub fn build(b: *Builder) void {
     exe.setBuildMode(mode);
     exe.linkSystemLibrary("SDL2");
     exe.linkSystemLibrary("SDL2_TTF");
+    exe.linkSystemLibrary("magic");
     exe.linkSystemLibrary("c");
 
     b.default_step.dependOn(&exe.step);

src/main.zig

@@ -5,6 +5,10 @@ const c = @cImport({
     @cInclude("SDL_ttf.h");
 });
 
+const m = @cImport({
+    @cInclude("magic.h");
+});
+
 const assert = @import("std").debug.assert;
 
 const DrawnText = struct {
@@ -21,14 +25,24 @@ const FileDocMap = struct {
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer {
-        if(gpa.deinit()) {
+        if (gpa.deinit()) {
             std.debug.print("Allocator leak\n", .{});
         }
     }
 
+    var magic = m.magic_open(m.MAGIC_MIME | m.MAGIC_CHECK);
+    const load_result = m.magic_load(magic, null);
+    if (load_result != 0) {
+        std.debug.print("Unable to initialize magic: {d}", .{load_result});
+        return error.MagicInitializationFailed;
+    }
+
     const allocator = gpa.allocator();
 
-    const window_width = 300;
+    const args = try std.process.argsAlloc(allocator);
+    defer std.process.argsFree(allocator, args);
+
+    const window_width = 700;
     const window_height = 500;
     const column_width = 100;
 
@@ -67,12 +81,7 @@ pub fn main() !void {
     }
     defer c.TTF_Quit();
 
-    const text_color: c.SDL_Color = c.SDL_Color {
+    const text_color: c.SDL_Color = c.SDL_Color{ .r = 0, .g = 0, .b = 0, .a = 255 };
-        .r = 0,
-        .g = 0,
-        .b = 0,
-        .a = 255
-    };
 
     // TODO: can we embed this file?
     const font: ?*c.TTF_Font = c.TTF_OpenFont("FreeSans.ttf", 12);
@@ -84,8 +93,47 @@ pub fn main() !void {
 
     var file_paths = std.ArrayList([]const u8).init(allocator);
     defer file_paths.deinit();
-    try file_paths.append("src/main.zig");
+    defer {
-    try file_paths.append("GapProbeScan.cs");
+        for (file_paths.items) |item| {
+            allocator.free(item);
+        }
+    }
+
+    var args_i: usize = 1;
+    while (args_i < args.len) : (args_i += 1) {
+        const arg = args[args_i];
+        if (std.fs.cwd().openIterableDir(arg, .{})) |iter_dir| {
+            std.debug.print("searching dir for files: '{s}'\n", .{arg});
+
+            var iter = iter_dir.iterate();
+            while (try iter.next()) |entry| {
+                if (entry.kind == .File) {
+                    const entry_path = try std.fmt.allocPrint(allocator, "{s}{c}{s}\x00", .{
+                        arg,
+                        std.fs.path.sep,
+                        entry.name,
+                    });
+                    const magic_result = m.magic_file(magic, @ptrCast([*c]const u8, entry_path));
+                    std.debug.print("'{s}': {s}\n", .{ entry.name, magic_result });
+                    if (std.mem.eql(u8, magic_result[0..5], "text/")) {
+                        try file_paths.append(entry_path[0..(entry_path.len - 1)]);
+                    } else {
+                        allocator.free(entry_path);
+                    }
+                }
+            }
+        } else |_| {
+            if (std.fs.cwd().openFile(arg, .{})) |file| {
+                file.close();
+                std.debug.print("Will do docmap for: '{s}'\n", .{arg});
+                var path = try allocator.alloc(u8, arg.len);
+                std.mem.copy(u8, path, arg);
+                try file_paths.append(path);
+            } else |_| {
+                std.debug.print("Arg not file: '{s}'\n", .{arg});
+            }
+        }
+    }
 
     var file_docmaps = std.ArrayList(FileDocMap).init(allocator);
     defer file_docmaps.deinit();
@@ -103,14 +151,15 @@ pub fn main() !void {
             return error.CreateTextureFailed;
         }
 
-        var rect = c.SDL_Rect {
+        var rect = c.SDL_Rect{
             .x = 0,
             .y = 0,
             .w = surface.*.w,
             .h = surface.*.h,
         };
 
-        const file = try std.fs.cwd().openFile(path, .{ });
+        std.debug.print("open file: {s}\n", .{path});
+        const file = try std.fs.cwd().openFile(path, .{});
         defer file.close();
 
         const stat = try file.stat();
@@ -125,8 +174,8 @@ pub fn main() !void {
             return error.FileReadError;
         }
 
-        var docmap = FileDocMap {
+        var docmap = FileDocMap{
-            .title_text = DrawnText {
+            .title_text = DrawnText{
                 .surface = surface,
                 .texture = texture,
                 .rect = rect,
@@ -191,7 +240,7 @@ pub fn main() !void {
         for (file_docmaps.items) |docmap| {
             i = 0;
 
-            var rect = c.SDL_Rect {
+            var rect = c.SDL_Rect{
                 .x = x,
                 .y = y,
                 .w = docmap.title_text.surface.*.w,