macho: calc number of relocations for each section

kubkon · Jan 2, 2024 · 1c983fb · 1c983fb
1 parent ed4f9ad
commit 1c983fb
Show file tree

Hide file tree

Showing 2 changed files with 48 additions and 13 deletions.
diff --git a/src/MachO/eh_frame.zig b/src/MachO/eh_frame.zig
@@ -352,6 +352,34 @@ pub fn calcSize(macho_file: *MachO) !u32 {
     return offset;
 }
 
+pub fn calcNumRelocs(macho_file: *MachO) u32 {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    var nreloc: u32 = 0;
+
+    for (macho_file.objects.items) |index| {
+        const object = macho_file.getFile(index).?.object;
+        for (object.cies.items) |cie| {
+            if (!cie.alive) continue;
+            if (cie.getPersonality(macho_file)) |_| {
+                nreloc += 1; // personality
+            }
+        }
+
+        for (object.fdes.items) |fde| {
+            if (!fde.alive) continue;
+            nreloc += 1; // CIE ptr
+            nreloc += 1; // function
+            if (fde.getLsdaAtom(macho_file)) |_| {
+                nreloc += 1; // LSDA
+            }
+        }
+    }
+
+    return nreloc;
+}
+
 pub fn write(macho_file: *MachO, buffer: []u8) void {
     const tracy = trace(@src());
     defer tracy.end();

diff --git a/src/MachO/relocatable.zig b/src/MachO/relocatable.zig
@@ -142,41 +142,48 @@ fn calcSectionSizes(macho_file: *MachO) !void {
             atom.value = offset;
             header.size += padding + atom.size;
             header.@"align" = @max(header.@"align", atom.alignment);
+            header.nreloc += @intCast(atom.relocs.len);
         }
     }
 
     if (macho_file.unwind_info_sect_index) |index| {
-        const sect = &macho_file.sections.items(.header)[index];
-        sect.size = calcCompactUnwindSize(macho_file);
-        sect.@"align" = 3;
+        calcCompactUnwindSize(macho_file, index);
     }
 
     if (macho_file.eh_frame_sect_index) |index| {
         const sect = &macho_file.sections.items(.header)[index];
         sect.size = try eh_frame.calcSize(macho_file);
         sect.@"align" = 3;
+        sect.nreloc = eh_frame.calcNumRelocs(macho_file);
     }
 
     // TODO __DWARF sections
-
-    // TODO relocations
-    // they should follow contiguously *after* we lay out contents of each section
-    // *but* they should be before __LINKEDIT sections (symtab, data-in-code)
-
 }
 
-fn calcCompactUnwindSize(macho_file: *MachO) usize {
-    var size: usize = 0;
+fn calcCompactUnwindSize(macho_file: *MachO, sect_index: u8) void {
+    var size: u32 = 0;
+    var nreloc: u32 = 0;
+
     for (macho_file.objects.items) |index| {
         const object = macho_file.getFile(index).?.object;
         for (object.unwind_records.items) |irec| {
             const rec = macho_file.getUnwindRecord(irec);
-            if (rec.alive) {
-                size += 1;
+            if (!rec.alive) continue;
+            size += @sizeOf(macho.compact_unwind_entry);
+            nreloc += 1;
+            if (rec.getPersonality(macho_file)) |_| {
+                nreloc += 1;
+            }
+            if (rec.getLsdaAtom(macho_file)) |_| {
+                nreloc += 1;
             }
         }
     }
-    return size * @sizeOf(macho.compact_unwind_entry);
+
+    const sect = &macho_file.sections.items(.header)[sect_index];
+    sect.size = size;
+    sect.nreloc = nreloc;
+    sect.@"align" = 3;
 }
 
 fn allocateSections(macho_file: *MachO) !void {