simpler impl of docker.amInside()

src/docker.zig

@@ -1,19 +1,5 @@
-const std = @import("std");
+const extras = @import("extras");
 
-const strings = @import("./strings.zig");
-
-pub fn amInside(alloc: std.mem.Allocator) !bool {
-    const max = std.math.maxInt(usize);
-    const c = try std.fs.cwd().readFileAlloc(alloc, "/proc/1/cgroup", max);
-    var it = std.mem.split(u8, c, "\n");
-    while (it.next()) |item| {
-        const line = try strings.splitAlloc(alloc, item, ":");
-        if (line.len < 3) {
-            continue;
-        }
-        if (!strings.list.contains(&.{ "/", "/init.scope" }, line[2])) {
-            return true;
-        }
-    }
-    return false;
+pub fn amInside() !bool {
+    return try extras.doesFileExist(null, "/.dockerenv");
 }

src/main.zig

@@ -38,7 +38,7 @@ pub fn main() !void {
                 try w.print(".{s}", .{h[0..9]});
             }
         }
-        if (docker.amInside(alloc) catch false) try w.writeAll(".docker");
+        if (docker.amInside() catch false) try w.writeAll(".docker");
         try w.print(".zig{}", .{builtin.zig_version});
         version = sbuilder.toOwnedSlice();
     }