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// $ readelf -h ./elf
// https://github.com/bminor/binutils-gdb/blob/master/binutils/readelf.c
// There is still a problem with packed structs and aligment padding
// better referenced in these two threads (sometime struct is not aligned
// properly or even has 1 byte more than its C alternative):
// - https://ziggit.dev/t/mapping-64-u8-buffer-to-a-struct/6052/19
// - https://ziggit.dev/t/wrong-sizes-of-extern-packed-structs/6053/6
const std = @import("std");
const Elf64ExecutionHeader = packed struct {
ident: u128,
type: u16,
machine: u16,
version: u32,
entry: u64,
phoff: u64,
shoff: u64,
flags: u32,
ehsize: u16,
phentsize: u16,
phnum: u16,
shentsize: u16,
shnum: u16,
shstrndx: u16,
};
pub fn main() !void {
var file = try std.fs.cwd().openFile("./elf", .{});
defer file.close();
var buffer: [64]u8 = undefined;
_ = try file.read(buffer[0..]);
const header: *Elf64ExecutionHeader = @ptrCast(@alignCast(&buffer));
std.debug.print("sizeOf(Elf64ExecutionHeader) = {}\n", .{@sizeOf(Elf64ExecutionHeader)});
std.debug.print("bitSizeOf(Elf64ExecutionHeader) = {} ({}/8={d})\n", .{
@bitSizeOf(Elf64ExecutionHeader),
@bitSizeOf(Elf64ExecutionHeader),
@bitSizeOf(Elf64ExecutionHeader) / 8,
});
std.debug.print("Object file type: {}\n", .{header.type});
std.debug.print("Architecture: {}\n", .{header.machine});
std.debug.print("Object file version: 0x{X:0>2}\n", .{header.version});
std.debug.print("Entry point virtual address: 0x{X:0>2}\n", .{header.entry});
std.debug.print("Program header table file offset: {}\n", .{header.phoff});
std.debug.print("Section header table file offset: {}\n", .{header.shoff});
std.debug.print("Processor-specific flags: 0x{X:0>2}\n", .{header.flags});
std.debug.print("ELF header size in bytes: {}\n", .{header.ehsize});
std.debug.print("Program header table entry size: {}\n", .{header.phentsize});
// std.debug.print("Program header table entry count: {}\n", .{header.phnum});
// std.debug.print("Section header table entry size: {}\n", .{header.shentsize});
// std.debug.print("Section header table entry count: {}\n", .{header.shnum});
// std.debug.print("Section header string table index: {}\n", .{header.shstrndx});
}
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