Added reading of ELF binaries in Zig

Author Mitja Felicijan <mitja.felicijan@gmail.com> 2024-09-19 14:13:59 +0200
Committer Mitja Felicijan <mitja.felicijan@gmail.com> 2024-09-19 14:13:59 +0200
Commit 9eb604113b9a531331897e14fafe0bef7f62d236 (patch)
-rw-r--r-- README.md 1
-rw-r--r-- zig-elf/.clang-format 4
-rw-r--r-- zig-elf/Makefile 5
-rwxr-xr-x zig-elf/elf bin 0 B -> 15.7 KB
-rw-r--r-- zig-elf/elf-64-gen.pdf bin 0 B -> 168.4 KB
-rw-r--r-- zig-elf/elf.c 6
-rw-r--r-- zig-elf/elf.png bin 0 B -> 318.4 KB
-rw-r--r-- zig-elf/main.zig 51
8 files changed, 67 insertions, 0 deletions
diff --git a/README.md b/README.md
...
35 
| [zig-tlv-encoding](./zig-tlv-encoding) | zig-0.13.0 | Naive implementation of TLV encoding in Zig.                   |
 35 
| [zig-tlv-encoding](./zig-tlv-encoding) | zig-0.13.0 | Naive implementation of TLV encoding in Zig.                   |
36 
| [zig-embed](./zig-embed)               | zig-0.13.0 | Embedding external resources in compiled binary.               |
 36 
| [zig-embed](./zig-embed)               | zig-0.13.0 | Embedding external resources in compiled binary.               |
37 
| [zig-struct-bin](./zig-struct-bin)     | zig-0.13.0 | Save a struct into binary file and then reading it back.       |
 37 
| [zig-struct-bin](./zig-struct-bin)     | zig-0.13.0 | Save a struct into binary file and then reading it back.       |
 
  
 38 
| [zig-elf](./zig-elf)                   | zig-0.14.0 | Read execution header of Elf64 format in Zig.                  |
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## License
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## License
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...
diff --git a/zig-elf/.clang-format b/zig-elf/.clang-format 
  
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BasedOnStyle: LLVM
 
  
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ColumnLimit: 120
 
  
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IndentWidth: 4
 
  
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diff --git a/zig-elf/Makefile b/zig-elf/Makefile 
  
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default:
 
  
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	zig run main.zig
 
  
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elf:
 
  
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	clang -o elf elf.c
diff --git a/zig-elf/elf b/zig-elf/elf
diff --git a/zig-elf/elf-64-gen.pdf b/zig-elf/elf-64-gen.pdf
diff --git a/zig-elf/elf.c b/zig-elf/elf.c 
  
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#include <stdio.h>
 
  
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int main(void) {
 
  
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  printf("Oh, hi Mark!\n");
 
  
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  return 0;
 
  
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}
diff --git a/zig-elf/elf.png b/zig-elf/elf.png
diff --git a/zig-elf/main.zig b/zig-elf/main.zig 
  
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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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// 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 Elf64ExecutionHeader = packed struct {
 
  
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    ident: u128,
 
  
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    type: u16,
 
  
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    machine: u16,
 
  
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    version: u32,
 
  
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    entry: u64,
 
  
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    phoff: u64,
 
  
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    shoff: u64,
 
  
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    flags: u32,
 
  
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    ehsize: u16,
 
  
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    phentsize: u16,
 
  
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    phnum: u16,
 
  
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    shentsize: u16,
 
  
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    shnum: u16,
 
  
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    shstrndx: u16,
 
  
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};
 
  
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pub fn main() !void {
 
  
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    var file = try std.fs.cwd().openFile("./elf", .{});
 
  
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    defer file.close();
 
  
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    var buffer: [64]u8 = undefined;
 
  
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    _ = try file.read(buffer[0..]);
 
  
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    const header: *Elf64ExecutionHeader = @ptrCast(@alignCast(&buffer));
 
  
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    std.debug.print("Object file type: {}\n", .{header.type});
 
  
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    std.debug.print("Architecture: {}\n", .{header.machine});
 
  
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    std.debug.print("Object file version: 0x{X:0>2}\n", .{header.version});
 
  
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    std.debug.print("Entry point virtual address: 0x{X:0>2}\n", .{header.entry});
 
  
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    std.debug.print("Program header table file offset: {}\n", .{header.phoff});
 
  
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    std.debug.print("Section header table file offset: {}\n", .{header.shoff});
 
  
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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("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("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 string table index: {}\n", .{header.shstrndx});
 
  
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}