lib-vt: boilerplate to build a shared object

Author: mitchellh

build.zig

@@ -31,6 +31,7 @@ pub fn build(b: *std.Build) !void {
 
     // All our steps which we'll hook up later. The steps are shown
     // up here just so that they are more self-documenting.
+    const libvt_step = b.step("lib-vt", "Build libghostty-vt");
     const run_step = b.step("run", "Run the app");
     const run_valgrind_step = b.step(
         "run-valgrind",
@@ -86,7 +87,7 @@ pub fn build(b: *std.Build) !void {
         check_step.dependOn(dist.install_step);
     }
 
-    // libghostty
+    // libghostty (internal, big)
     const libghostty_shared = try buildpkg.GhosttyLib.initShared(
         b,
         &deps,
@@ -96,6 +97,15 @@ pub fn build(b: *std.Build) !void {
         &deps,
     );
 
+    // libghostty-vt
+    const libghostty_vt_shared = try buildpkg.GhosttyLibVt.initShared(
+        b,
+        &mod,
+        &deps,
+    );
+    libghostty_vt_shared.install(libvt_step, "libghostty-vt.so");
+    libghostty_vt_shared.installHeader(libvt_step);
+
     // Helpgen
     if (config.emit_helpgen) deps.help_strings.install();
 

include/ghostty-vt.h

@@ -0,0 +1,14 @@
+// libghostty-vt
+
+#ifndef GHOSTTY_VT_H
+#define GHOSTTY_VT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GHOSTTY_VT_H */

src/build/GhosttyLibVt.zig

@@ -0,0 +1,72 @@
+const GhosttyLibVt = @This();
+
+const std = @import("std");
+const RunStep = std.Build.Step.Run;
+const Config = @import("Config.zig");
+const GhosttyZig = @import("GhosttyZig.zig");
+const SharedDeps = @import("SharedDeps.zig");
+const LibtoolStep = @import("LibtoolStep.zig");
+const LipoStep = @import("LipoStep.zig");
+
+/// The step that generates the file.
+step: *std.Build.Step,
+
+/// The final library file
+output: std.Build.LazyPath,
+dsym: ?std.Build.LazyPath,
+
+pub fn initShared(
+    b: *std.Build,
+    zig: *const GhosttyZig,
+    deps: *const SharedDeps,
+) !GhosttyLibVt {
+    const lib = b.addSharedLibrary(.{
+        .name = "ghostty-vt",
+        .root_module = zig.vt,
+    });
+
+    // Get our debug symbols
+    const dsymutil: ?std.Build.LazyPath = dsymutil: {
+        if (!deps.config.target.result.os.tag.isDarwin()) {
+            break :dsymutil null;
+        }
+
+        const dsymutil = RunStep.create(b, "dsymutil");
+        dsymutil.addArgs(&.{"dsymutil"});
+        dsymutil.addFileArg(lib.getEmittedBin());
+        dsymutil.addArgs(&.{"-o"});
+        const output = dsymutil.addOutputFileArg("libghostty-vt.dSYM");
+        break :dsymutil output;
+    };
+
+    return .{
+        .step = &lib.step,
+        .output = lib.getEmittedBin(),
+        .dsym = dsymutil,
+    };
+}
+
+pub fn install(
+    self: *const GhosttyLibVt,
+    step: *std.Build.Step,
+    name: []const u8,
+) void {
+    const b = self.step.owner;
+    const lib_install = b.addInstallLibFile(
+        self.output,
+        name,
+    );
+    step.dependOn(&lib_install.step);
+}
+
+pub fn installHeader(
+    self: *const GhosttyLibVt,
+    step: *std.Build.Step,
+) void {
+    const b = self.step.owner;
+    const header_install = b.addInstallHeaderFile(
+        b.path("include/ghostty-vt.h"),
+        "ghostty-vt.h",
+    );
+    step.dependOn(&header_install.step);
+}

src/build/main.zig

@@ -13,6 +13,7 @@ pub const GhosttyDocs = @import("GhosttyDocs.zig");
 pub const GhosttyExe = @import("GhosttyExe.zig");
 pub const GhosttyFrameData = @import("GhosttyFrameData.zig");
 pub const GhosttyLib = @import("GhosttyLib.zig");
+pub const GhosttyLibVt = @import("GhosttyLibVt.zig");
 pub const GhosttyResources = @import("GhosttyResources.zig");
 pub const GhosttyI18n = @import("GhosttyI18n.zig");
 pub const GhosttyXcodebuild = @import("GhosttyXcodebuild.zig");

src/lib_vt.zig

@@ -65,6 +65,12 @@ pub const EraseLine = terminal.EraseLine;
 pub const TabClear = terminal.TabClear;
 pub const Attribute = terminal.Attribute;
 
+comptime {
+    if (terminal.is_c_lib) {
+        _ = terminal.c_api;
+    }
+}
+
 test {
     _ = terminal;
 }

src/terminal/c_api.zig

@@ -0,0 +1,5 @@
+pub export fn ghostty_hi() void {
+    // Does nothing, but you can see this symbol exists:
+    // nm -D --defined-only zig-out/lib/libghostty-vt.so | rg ' T '
+    // This is temporary as we figure out the API.
+}

src/terminal/main.zig

@@ -62,6 +62,13 @@ pub const Attribute = sgr.Attribute;
 
 pub const isSafePaste = sanitize.isSafePaste;
 
+/// This is set to true when we're building the C library.
+pub const is_c_lib = @import("root") == @import("../lib_vt.zig");
+
+/// This is the C API for this package. Do NOT reference this unless
+/// you want a bunch of symbols exported into your final artifact.
+pub const c_api = @import("c_api.zig");
+
 test {
     @import("std").testing.refAllDecls(@This());