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simplify loading interpreter

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Pascal Zittlau
2025-10-24 16:34:36 +02:00
parent 8fb72a9928
commit 5825d12b97
1 changed files with 19 additions and 29 deletions
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26
src/main.zig
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@@ -43,8 +43,8 @@ pub fn main() !void {
// Map file into memory
const file = try lookupFile(mem.sliceTo(std.os.argv[arg_index], 0));
var buffer: [128]u8 = undefined;
var file_reader = file.reader(&buffer);
var file_buffer: [128]u8 = undefined;
var file_reader = file.reader(&file_buffer);
log(.info, "--- Loading executable: {s} ---", .{std.os.argv[arg_index]});
const ehdr = try elf.Header.read(&file_reader.interface);
const base = try loadStaticElf(ehdr, &file_reader);
@@ -52,36 +52,26 @@ pub fn main() !void {
log(.info, "Executable loaded: base=0x{x}, entry=0x{x}", .{ base, entry });
// Check for dynamic linker
const maybe_interp: ?std.fs.File = interp: {
var maybe_interp_base: ?usize = null;
var maybe_interp_entry: ?usize = null;
var phdrs = ehdr.iterateProgramHeaders(&file_reader);
while (try phdrs.next()) |phdr| {
if (phdr.p_type != elf.PT_INTERP) continue;
var interp_path: [max_interp_path_length]u8 = undefined;
try file_reader.seekTo(phdr.p_offset);
if (try file_reader.read(interp_path[0..phdr.p_filesz]) != phdr.p_filesz)
return UnfinishedReadError.UnfinishedRead;
assert(interp_path[phdr.p_filesz - 1] == 0); // Must be zero terminated
log(.info, "Found interpreter path: {s}", .{interp_path[0 .. phdr.p_filesz - 1]});
break :interp try std.fs.cwd().openFile(
const interp = try std.fs.cwd().openFile(
interp_path[0 .. phdr.p_filesz - 1],
.{ .mode = .read_only },
);
}
break :interp null;
};
// We don't need the file anymore. But we reuse the buffer if we need to load the interpreter.
// Therefore deinit everything to make sure we don't use it anymore.
file_reader = undefined;
file.close();
var maybe_interp_base: ?usize = null;
var maybe_interp_entry: ?usize = null;
if (maybe_interp) |interp| {
// TODO: If we have an interpreter we could/should unload the elf file because it will be
// loaded by the dynamic linker anyway.
log(.info, "--- Loading interpreter ---", .{});
var interp_reader = interp.reader(&buffer);
var interp_buffer: [128]u8 = undefined;
var interp_reader = interp.reader(&interp_buffer);
const interp_ehdr = try elf.Header.read(&interp_reader.interface);
assert(interp_ehdr.type == elf.ET.DYN);
const interp_base = try loadStaticElf(interp_ehdr, &interp_reader);