macho: save if a symbol is ref'd dynamically

kubkon · Dec 7, 2023 · 1fc19ff · 1fc19ff
1 parent 4f26452
commit 1fc19ff
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Showing 4 changed files with 25 additions and 3 deletions.
diff --git a/src/MachO.zig b/src/MachO.zig
@@ -1005,9 +1005,8 @@ fn resolveSyntheticSymbols(self: *MachO) !void {
         self.mh_execute_header_index = try internal.addSymbol("__mh_execute_header", self);
         const sym = self.getSymbol(self.mh_execute_header_index.?);
         sym.flags.@"export" = true;
+        sym.flags.dyn_ref = true;
         sym.visibility = .global;
-        const nlist = &internal.symtab.items[sym.nlist_idx];
-        nlist.n_desc = macho.REFERENCED_DYNAMICALLY;
     } else if (self.options.dylib) {
         self.mh_dylib_header_index = try internal.addSymbol("__mh_dylib_header", self);
     }

diff --git a/src/MachO/Object.zig b/src/MachO/Object.zig
@@ -763,6 +763,7 @@ pub fn resolveSymbols(self: *Object, macho_file: *MachO) void {
             symbol.file = self.index;
             symbol.flags.weak = nlist.weakDef();
             symbol.flags.weak_ref = false;
+            symbol.flags.dyn_ref = nlist.n_desc & macho.REFERENCED_DYNAMICALLY != 0;
 
             if (nlist.pext() or nlist.weakDef() and nlist.weakRef()) {
                 if (symbol.visibility != .global) {

diff --git a/src/MachO/Symbol.zig b/src/MachO/Symbol.zig
@@ -197,7 +197,9 @@ pub fn setOutputSym(symbol: Symbol, macho_file: *MachO, out: *macho.nlist_64) vo
             out.n_desc |= macho.N_WEAK_DEF;
             macho_file.weak_defines = true;
         }
-        if (nlist.n_desc & macho.REFERENCED_DYNAMICALLY != 0) out.n_desc |= macho.REFERENCED_DYNAMICALLY;
+        if (symbol.flags.dyn_ref) {
+            out.n_desc |= macho.REFERENCED_DYNAMICALLY;
+        }
     } else {
         assert(symbol.visibility == .global);
         out.n_type = macho.N_EXT;
@@ -288,6 +290,9 @@ pub const Flags = packed struct {
     /// Whether this symbol is weakly referenced.
     weak_ref: bool = false,
 
+    /// Whether this symbol is dynamically referenced.
+    dyn_ref: bool = false,
+
     /// Whether this symbol is a thread-local variable.
     tlv: bool = false,
 

diff --git a/test/macho.zig b/test/macho.zig
@@ -36,6 +36,7 @@ pub fn addMachOTests(b: *Build, options: common.Options) *Step {
     macho_step.dependOn(testLayout(b, opts));
     macho_step.dependOn(testLargeBss(b, opts));
     macho_step.dependOn(testLinkOrder(b, opts));
+    macho_step.dependOn(testMhExecuteHeader(b, opts));
     macho_step.dependOn(testNeededFramework(b, opts));
     macho_step.dependOn(testNeededLibrary(b, opts));
     macho_step.dependOn(testNoExportsDylib(b, opts));
@@ -884,6 +885,22 @@ fn testLinkOrder(b: *Build, opts: Options) *Step {
     return test_step;
 }
 
+fn testMhExecuteHeader(b: *Build, opts: Options) *Step {
+    const test_step = b.step("test-macho-mh-execute-header", "");
+
+    const exe = cc(b, opts);
+    exe.addEmptyMain();
+
+    const check = exe.check();
+    check.checkInSymtab();
+    // TODO enhance Mach-O parser
+    // check.checkContains("[referenced dynamically] external __mh_execute_header");
+    check.checkContains("external __mh_execute_header");
+    test_step.dependOn(&check.step);
+
+    return test_step;
+}
+
 fn testNeededFramework(b: *Build, opts: Options) *Step {
     const test_step = b.step("test-macho-needed-framework", "");