elf: correctly format output .eh_frame when emitting relocatable

2 files changed, 47 insertions, 6 deletions

diff --git a/src/link/Elf/Object.zig b/src/link/Elf/Object.zig
index 0a4232d3b1..ce9b83c9bb 100644
--- a/src/link/Elf/Object.zig
+++ b/src/link/Elf/Object.zig
@@ -687,7 +687,6 @@ pub fn initRelaSections(self: Object, elf_file: *Elf) !void {
         const out_shdr = &elf_file.shdrs.items[out_shndx];
         out_shdr.sh_addralign = @alignOf(elf.Elf64_Rela);
         out_shdr.sh_entsize = @sizeOf(elf.Elf64_Rela);
-        out_shdr.sh_info = self.initOutputSection(elf_file, atom.inputShdr(elf_file)) catch unreachable;
     }
 }
 
@@ -695,13 +694,18 @@ pub fn addAtomsToRelaSections(self: Object, elf_file: *Elf) !void {
     for (self.atoms.items) |atom_index| {
         const atom = elf_file.atom(atom_index) orelse continue;
         if (!atom.flags.alive) continue;
-        const shndx = atom.relocsShndx() orelse continue;
-        const shdr = self.shdrs.items[shndx];
-        const out_shndx = self.initOutputSection(elf_file, shdr) catch unreachable;
+        const shndx = blk: {
+            const shndx = atom.relocsShndx() orelse continue;
+            const shdr = self.shdrs.items[shndx];
+            break :blk self.initOutputSection(elf_file, shdr) catch unreachable;
+        };
+        const shdr = &elf_file.shdrs.items[shndx];
+        shdr.sh_info = atom.outputShndx().?;
+        shdr.sh_link = elf_file.symtab_section_index.?;
 
         const gpa = elf_file.base.allocator;
         const gop = try elf_file.output_rela_sections.getOrPut(gpa, atom.outputShndx().?);
-        if (!gop.found_existing) gop.value_ptr.* = .{ .shndx = out_shndx };
+        if (!gop.found_existing) gop.value_ptr.* = .{ .shndx = shndx };
         try gop.value_ptr.atom_list.append(gpa, atom_index);
     }
 }
diff --git a/src/link/Elf/eh_frame.zig b/src/link/Elf/eh_frame.zig
index 3657a3f5b7..73857d03d2 100644
--- a/src/link/Elf/eh_frame.zig
+++ b/src/link/Elf/eh_frame.zig
@@ -268,7 +268,11 @@ pub fn calcEhFrameSize(elf_file: *Elf) !usize {
         }
     }
 
-    return offset + 4; // NULL terminator
+    if (!elf_file.isRelocatable()) {
+        offset += 4; // NULL terminator
+    }
+
+    return offset;
 }
 
 pub fn calcEhFrameHdrSize(elf_file: *Elf) usize {
@@ -373,6 +377,39 @@ pub fn writeEhFrame(elf_file: *Elf, writer: anytype) !void {
     try writer.writeInt(u32, 0, .little);
 }
 
+pub fn writeEhFrameObject(elf_file: *Elf, writer: anytype) !void {
+    const gpa = elf_file.base.allocator;
+
+    for (elf_file.objects.items) |index| {
+        const object = elf_file.file(index).?.object;
+
+        for (object.cies.items) |cie| {
+            if (!cie.alive) continue;
+            try writer.writeAll(cie.data(elf_file));
+        }
+    }
+
+    for (elf_file.objects.items) |index| {
+        const object = elf_file.file(index).?.object;
+
+        for (object.fdes.items) |fde| {
+            if (!fde.alive) continue;
+
+            const contents = try gpa.dupe(u8, fde.data(elf_file));
+            defer gpa.free(contents);
+
+            std.mem.writeInt(
+                i32,
+                contents[4..8],
+                @truncate(@as(i64, @intCast(fde.out_offset + 4)) - @as(i64, @intCast(fde.cie(elf_file).out_offset))),
+                .little,
+            );
+
+            try writer.writeAll(contents);
+        }
+    }
+}
+
 fn emitReloc(elf_file: *Elf, rec: anytype, sym: *const Symbol, rel: elf.Elf64_Rela) elf.Elf64_Rela {
     const r_offset = rec.address(elf_file) + rel.r_offset - rec.offset;
     const r_type = rel.r_type();