Added size check to reading ELF

Author Mitja Felicijan <mitja.felicijan@gmail.com> 2024-09-19 20:59:33 +0200
Committer Mitja Felicijan <mitja.felicijan@gmail.com> 2024-09-19 20:59:33 +0200
Commit df02649423ac08b9793d49ad9613e6b2a0ec2de1 (patch)
-rw-r--r-- zig-elf/main.zig 20
1 files changed, 7 insertions, 13 deletions
diff --git a/zig-elf/main.zig b/zig-elf/main.zig
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// $ readelf -h ./elf
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// $ readelf -h ./elf
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// https://github.com/bminor/binutils-gdb/blob/master/binutils/readelf.c
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// https://github.com/bminor/binutils-gdb/blob/master/binutils/readelf.c
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 3 
  
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// There is still a problem with packed structs and aligment padding
 
  
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// better referenced in these two threads (sometime struct is not aligned
 
  
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// properly or even has 1 byte more than its C alternative):
 
  
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//  - https://ziggit.dev/t/mapping-64-u8-buffer-to-a-struct/6052/19
 
  
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//  - https://ziggit.dev/t/wrong-sizes-of-extern-packed-structs/6053/6
 
  
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const std = @import("std");
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const std = @import("std");
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const Elf64ExecutionHeader = packed struct {
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const Elf64ExecutionHeader = packed struct {
...
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    var file = try std.fs.cwd().openFile("./elf", .{});
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    var file = try std.fs.cwd().openFile("./elf", .{});
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    defer file.close();
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    defer file.close();
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    var buffer: [64]u8 = undefined;
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    var buffer: [64]u8 align(@alignOf(Elf64ExecutionHeader)) = undefined;
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    _ = try file.read(buffer[0..]);
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    _ = try file.read(buffer[0..@sizeOf(Elf64ExecutionHeader)]);
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    const header: *Elf64ExecutionHeader = @ptrCast(@alignCast(&buffer));
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    const header: *Elf64ExecutionHeader = @ptrCast(&buffer);
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    std.debug.print("sizeOf(Elf64ExecutionHeader) = {}\n", .{@sizeOf(Elf64ExecutionHeader)});
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    std.debug.print("sizeOf(Elf64ExecutionHeader) = {}\n", .{@sizeOf(Elf64ExecutionHeader)});
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    std.debug.print("bitSizeOf(Elf64ExecutionHeader) = {} ({}/8={d})\n", .{
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    std.debug.print("bitSizeOf(Elf64ExecutionHeader) = {} ({}/8={d})\n", .{
...
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    std.debug.print("Processor-specific flags: 0x{X:0>2}\n", .{header.flags});
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    std.debug.print("Processor-specific flags: 0x{X:0>2}\n", .{header.flags});
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    std.debug.print("ELF header size in bytes: {}\n", .{header.ehsize});
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    std.debug.print("ELF header size in bytes: {}\n", .{header.ehsize});
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    std.debug.print("Program header table entry size: {}\n", .{header.phentsize});
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    std.debug.print("Program header table entry size: {}\n", .{header.phentsize});
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    // std.debug.print("Program header table entry count: {}\n", .{header.phnum});
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    std.debug.print("Program header table entry count: {}\n", .{header.phnum});
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    // std.debug.print("Section header table entry size: {}\n", .{header.shentsize});
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    std.debug.print("Section header table entry size: {}\n", .{header.shentsize});
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    // std.debug.print("Section header table entry count: {}\n", .{header.shnum});
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    std.debug.print("Section header table entry count: {}\n", .{header.shnum});
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    // std.debug.print("Section header string table index: {}\n", .{header.shstrndx});
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    std.debug.print("Section header string table index: {}\n", .{header.shstrndx});
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}
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}