use an array for 'id' so that we're not returning pointer to a local

src/cmd/fetch.zig

@@ -285,7 +285,7 @@ fn diff_printchange(comptime testt: string, comptime replacement: string, item:
 fn print_dirs(w: std.fs.File.Writer, list: []const zigmod.Module, alloc: std.mem.Allocator) !void {
     for (list) |mod| {
         if (mod.type == .system_lib or mod.type == .framework) continue;
-        if (std.mem.eql(u8, mod.id, "root")) {
+        if (std.mem.eql(u8, &mod.id, &zigmod.Module.ROOT)) {
             try w.writeAll("    pub const _root = \"\";\n");
             continue;
         }
@@ -325,7 +325,7 @@ fn print_pkg_data_to(w: std.fs.File.Writer, notdone: *std.ArrayList(zigmod.Modul
                     mod.short_id(),
                     mod.short_id(),
                 });
-                if (mod.main.len > 0 and !std.mem.eql(u8, mod.id, "root")) {
+                if (mod.main.len > 0 and !std.mem.eql(u8, &mod.id, &zigmod.Module.ROOT)) {
                     try w.print(
                         \\        .import = .{{ "{s}", .{{ .path = dirs._{s} ++ "/{s}" }} }},
                         \\

src/cmd/generate.zig

@@ -284,7 +284,7 @@ fn print_pkg_data_to(w: std.fs.File.Writer, alloc: std.mem.Allocator, cachepath:
                     .hg => @panic("TODO"),
                     .http => @panic("TODO"),
                 }
-                if (mod.main.len > 0 and !std.mem.eql(u8, mod.id, "root")) {
+                if (mod.main.len > 0 and !std.mem.eql(u8, &mod.id, &zigmod.Module.ROOT)) {
                     try w.print("        .name = \"{s}\",\n", .{mod.name});
                     try w.print("        .entry = \"/{}/{s}/{s}\",\n", .{ std.zig.fmtEscapes(fixed_path), try mod.pin(alloc, cachepath), mod.main });
 

src/common.zig

@@ -46,7 +46,7 @@ pub fn collect_deps_deep(cachepath: string, mdir: std.fs.Dir, options: *CollectO
     }
     return zigmod.Module{
         .type = .local,
-        .id = "root",
+        .id = zigmod.Module.ROOT,
         .name = "root",
         .main = m.main,
         .deps = try moduledeps.toOwnedSlice(),
@@ -230,7 +230,7 @@ pub fn get_module_from_dep(d: *zigmod.Dep, cachepath: string, options: *CollectO
         .system_lib, .framework => {
             return zigmod.Module{
                 .type = d.type,
-                .id = try u.do_hash(options.alloc, std.crypto.hash.sha3.Sha3_384, d.path),
+                .id = try u.do_hash(options.alloc, std.crypto.hash.sha3.Shake(96), d.path),
                 .name = d.path,
                 .only_os = d.only_os,
                 .except_os = d.except_os,
@@ -274,7 +274,7 @@ pub fn get_module_from_dep(d: *zigmod.Dep, cachepath: string, options: *CollectO
             dd.for_build = d.for_build;
             const save = dd;
             if (d.type != .local) dd.clean_path = extras.trimPrefix(modpath, cachepath)[1..];
-            if (dd.id.len == 0) dd.id = &u.random_string(48);
+            if (std.mem.eql(u8, &dd.id, &zigmod.Dep.EMPTY)) dd.id = u.random_string(48);
             if (d.name.len > 0) dd.name = d.name;
             if (d.main.len > 0) dd.main = d.main;
             if (d.c_include_dirs.len > 0) dd.c_include_dirs = d.c_include_dirs;
@@ -352,12 +352,11 @@ pub fn parse_lockfile(alloc: std.mem.Allocator, dir: std.fs.Dir) ![]const [4]str
                     .type = std.meta.stringToEnum(zigmod.Dep.Type, iter.next().?).?,
                     .path = iter.next().?,
                     .version = iter.next().?,
-                    .id = "",
+                    .id = zigmod.Dep.EMPTY,
                     .name = "",
                     .main = "",
                     .yaml = null,
                     .deps = &.{},
-                    .parent_id = "",
                 };
                 try list.append([4]string{
                     try asdep.clean_path(alloc),

src/util/dep.zig

@@ -15,7 +15,7 @@ pub const Dep = struct {
 
     type: Type,
     path: string,
-    id: string,
+    id: [48]u8,
     name: string,
     main: string,
     version: string,
@@ -28,7 +28,8 @@ pub const Dep = struct {
     deps: []zigmod.Dep,
     keep: bool = false,
     for_build: bool = false,
-    parent_id: string,
+
+    pub const EMPTY = (" " ** 48).*;
 
     pub const Type = @import("./dep_type.zig").DepType;
 

src/util/funcs.zig

@@ -132,9 +132,9 @@ pub fn validate_hash(alloc: std.mem.Allocator, input: string, file_path: string)
     const data = try file.reader().readAllAlloc(alloc, gb);
     const expected = hash.string;
     const actual = switch (hash.id) {
-        .blake3 => try do_hash(alloc, std.crypto.hash.Blake3, data),
-        .sha256 => try do_hash(alloc, std.crypto.hash.sha2.Sha256, data),
-        .sha512 => try do_hash(alloc, std.crypto.hash.sha2.Sha512, data),
+        .blake3 => &try do_hash(alloc, std.crypto.hash.Blake3, data),
+        .sha256 => &try do_hash(alloc, std.crypto.hash.sha2.Sha256, data),
+        .sha512 => &try do_hash(alloc, std.crypto.hash.sha2.Sha512, data),
     };
     const result = std.mem.startsWith(u8, actual, expected);
     if (!result) {
@@ -143,13 +143,13 @@ pub fn validate_hash(alloc: std.mem.Allocator, input: string, file_path: string)
     return result;
 }
 
-pub fn do_hash(alloc: std.mem.Allocator, comptime algo: type, data: string) !string {
+pub fn do_hash(alloc: std.mem.Allocator, comptime algo: type, data: string) ![algo.digest_length * 2]u8 {
     var h = algo.init(.{});
     var out: [algo.digest_length]u8 = undefined;
     h.update(data);
     h.final(&out);
     const hex = try std.fmt.allocPrint(alloc, "{x}", .{std.fmt.fmtSliceHexLower(out[0..])});
-    return hex;
+    return hex[0 .. algo.digest_length * 2].*;
 }
 
 /// Returns the result of running `git rev-parse HEAD`

src/util/modfile.zig

@@ -15,7 +15,7 @@ const mb = kb * 1024;
 pub const ModFile = struct {
     const Self = @This();
 
-    id: string,
+    id: [48]u8,
     name: string,
     main: string,
     c_include_dirs: []const string,
@@ -52,7 +52,9 @@ pub const ModFile = struct {
     }
 
     pub fn from_mapping(alloc: std.mem.Allocator, mapping: yaml.Mapping) !Self {
-        const id = mapping.get_string("id") orelse "";
+        var id = zigmod.Dep.EMPTY;
+        std.mem.copyForwards(u8, &id, mapping.get_string("id") orelse &u.random_string(48));
+
         const name = mapping.get_string("name") orelse "";
         const main = mapping.get_string("main") orelse "";
 
@@ -61,7 +63,7 @@ pub const ModFile = struct {
         }
 
         return Self{
-            .id = if (id.len == 0) &u.random_string(48) else id,
+            .id = id,
             .name = name,
             .main = main,
             .c_include_dirs = try mapping.get_string_array(alloc, "c_include_dirs"),
@@ -120,10 +122,13 @@ pub const ModFile = struct {
                         }
                     }
 
+                    var id = zigmod.Dep.EMPTY;
+                    std.mem.copyForwards(u8, &id, item.mapping.get_string("id") orelse "");
+
                     try dep_list.append(zigmod.Dep{
                         .type = dep_type,
                         .path = path,
-                        .id = item.mapping.get_string("id") orelse "",
+                        .id = id,
                         .name = name,
                         .main = main,
                         .version = version.?,
@@ -136,7 +141,6 @@ pub const ModFile = struct {
                         .deps = try dep_list_by_name(alloc, item.mapping, &.{"dependencies"}, for_build),
                         .keep = std.mem.eql(u8, "true", item.mapping.get_string("keep") orelse ""),
                         .for_build = for_build,
-                        .parent_id = mapping.get_string("id") orelse "",
                     });
                 }
             }

src/util/module.zig

@@ -13,7 +13,7 @@ const common = @import("./../common.zig");
 
 pub const Module = struct {
     type: zigmod.Dep.Type,
-    id: string,
+    id: [48]u8,
     name: string,
     main: string,
     c_include_dirs: []const string = &.{},
@@ -28,6 +28,8 @@ pub const Module = struct {
     for_build: bool = false,
     min_zig_version: ?std.SemanticVersion,
 
+    pub const ROOT: [48]u8 = ("root" ++ (" " ** 44)).*;
+
     pub fn from(alloc: std.mem.Allocator, dep: zigmod.Dep, cachepath: string, options: *common.CollectOptions) !Module {
         var moddeps = std.ArrayList(Module).init(alloc);
         errdefer moddeps.deinit();
@@ -37,9 +39,13 @@ pub const Module = struct {
                 try moddeps.append(founddep);
             }
         }
+
+        var id = dep.id;
+        if (std.mem.eql(u8, &id, &zigmod.Dep.EMPTY)) id = u.random_string(48);
+
         return Module{
             .type = dep.type,
-            .id = if (dep.id.len > 0) dep.id else &u.random_string(48),
+            .id = id,
             .name = dep.name,
             .main = dep.main,
             .c_include_dirs = dep.c_include_dirs,
@@ -57,7 +63,7 @@ pub const Module = struct {
     }
 
     pub fn eql(self: Module, another: Module) bool {
-        return std.mem.eql(u8, self.id, another.id);
+        return std.mem.eql(u8, &self.id, &another.id);
     }
 
     pub fn get_hash(self: Module, alloc: std.mem.Allocator, cdpath: string) !string {
@@ -131,8 +137,8 @@ pub const Module = struct {
         return false;
     }
 
-    pub fn short_id(self: Module) string {
-        return u.slice(u8, self.id, 0, 12);
+    pub fn short_id(self: *const Module) string {
+        return u.slice(u8, &self.id, 0, @min(12, std.mem.indexOfScalar(u8, &self.id, ' ') orelse self.id.len));
     }
 
     pub fn minZigVersion(self: Module) ?std.SemanticVersion {