stage2 Elf linker: fill in bswapAllFields

I moved it to std.elf since it could be used there and added test

1 files changed, 23 insertions, 20 deletions

diff --git a/lib/std/elf.zig b/lib/std/elf.zig
index e644c6631a..26674288a4 100644
--- a/lib/std/elf.zig
+++ b/lib/std/elf.zig
@@ -422,16 +422,8 @@ pub fn ProgramHeaderIterator(ParseSource: anytype) type {
                 if (self.elf_header.endian == std.builtin.endian) return phdr;
 
                 // Convert fields to native endianness.
-                return Elf64_Phdr{
-                    .p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
-                    .p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
-                    .p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
-                    .p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
-                    .p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
-                    .p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
-                    .p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
-                    .p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
-                };
+                bswapAllFields(Elf64_Phdr, &phdr);
+                return phdr;
             }
 
             var phdr: Elf32_Phdr = undefined;
@@ -442,16 +434,7 @@ pub fn ProgramHeaderIterator(ParseSource: anytype) type {
             // ELF endianness does NOT match native endianness.
             if (self.elf_header.endian != std.builtin.endian) {
                 // Convert fields to native endianness.
-                phdr = .{
-                    .p_type = @byteSwap(@TypeOf(phdr.p_type), phdr.p_type),
-                    .p_offset = @byteSwap(@TypeOf(phdr.p_offset), phdr.p_offset),
-                    .p_vaddr = @byteSwap(@TypeOf(phdr.p_vaddr), phdr.p_vaddr),
-                    .p_paddr = @byteSwap(@TypeOf(phdr.p_paddr), phdr.p_paddr),
-                    .p_filesz = @byteSwap(@TypeOf(phdr.p_filesz), phdr.p_filesz),
-                    .p_memsz = @byteSwap(@TypeOf(phdr.p_memsz), phdr.p_memsz),
-                    .p_flags = @byteSwap(@TypeOf(phdr.p_flags), phdr.p_flags),
-                    .p_align = @byteSwap(@TypeOf(phdr.p_align), phdr.p_align),
-                };
+                bswapAllFields(Elf32_Phdr, &phdr);
             }
 
             // Convert 32-bit header to 64-bit.
@@ -562,6 +545,26 @@ pub fn int32(need_bswap: bool, int_32: anytype, comptime Int64: anytype) Int64 {
     }
 }
 
+pub fn bswapAllFields(comptime S: type, ptr: *S) void {
+    if (@typeInfo(S) != .Struct) @compileError("bswapAllFields expects a struct as the first argument");
+    inline for (std.meta.fields(S)) |f| {
+        @field(ptr, f.name) = @byteSwap(f.field_type, @field(ptr, f.name));
+    }
+}
+test "bswapAllFields" {
+    var s: Elf32_Chdr = .{
+        .ch_type = 0x12341234,
+        .ch_size = 0x56785678,
+        .ch_addralign = 0x12124242,
+    };
+    bswapAllFields(Elf32_Chdr, &s);
+    std.testing.expectEqual(Elf32_Chdr{
+        .ch_type = 0x34123412,
+        .ch_size = 0x78567856,
+        .ch_addralign = 0x42421212,
+    }, s);
+}
+
 pub const EI_NIDENT = 16;
 
 pub const EI_CLASS = 4;