Function dl_iterate_phdr [src]

Prototype

 pub fn dl_iterate_phdr( context: anytype, comptime Error: type, comptime callback: fn (info: *dl_phdr_info, size: usize, context: @TypeOf(context)) Error!void, ) Error!void

Parameters

Error: typecallback: fn (info: *dl_phdr_info, size: usize, context: @TypeOf(context)) Error!void

Source

  pub fn dl_iterate_phdr(
    context: anytype,
    comptime Error: type,
    comptime callback: fn (info: *dl_phdr_info, size: usize, context: @TypeOf(context)) Error!void,
) Error!void {
    const Context = @TypeOf(context);
    const elf = std.elf;
    const dl = @import("dynamic_library.zig");

    switch (builtin.object_format) {
        .elf, .c => {},
        else => @compileError("dl_iterate_phdr is not available for this target"),
    }

    if (builtin.link_libc) {
        switch (system.dl_iterate_phdr(struct {
            fn callbackC(info: *dl_phdr_info, size: usize, data: ?*anyopaque) callconv(.c) c_int {
                const context_ptr: *const Context = @ptrCast(@alignCast(data));
                callback(info, size, context_ptr.*) catch |err| return @intFromError(err);
                return 0;
            }
        }.callbackC, @ptrCast(@constCast(&context)))) {
            0 => return,
            else => |err| return @as(Error, @errorCast(@errorFromInt(@as(std.meta.Int(.unsigned, @bitSizeOf(anyerror)), @intCast(err))))),
        }
    }

    const elf_base = std.process.getBaseAddress();
    const ehdr: *elf.Ehdr = @ptrFromInt(elf_base);
    // Make sure the base address points to an ELF image.
    assert(mem.eql(u8, ehdr.e_ident[0..4], elf.MAGIC));
    const n_phdr = ehdr.e_phnum;
    const phdrs = (@as([*]elf.Phdr, @ptrFromInt(elf_base + ehdr.e_phoff)))[0..n_phdr];

    var it = dl.linkmap_iterator(phdrs) catch unreachable;

    // The executable has no dynamic link segment, create a single entry for
    // the whole ELF image.
    if (it.end()) {
        // Find the base address for the ELF image, if this is a PIE the value
        // is non-zero.
        const base_address = for (phdrs) |*phdr| {
            if (phdr.p_type == elf.PT_PHDR) {
                break @intFromPtr(phdrs.ptr) - phdr.p_vaddr;
                // We could try computing the difference between _DYNAMIC and
                // the p_vaddr of the PT_DYNAMIC section, but using the phdr is
                // good enough (Is it?).
            }
        } else unreachable;

        var info = dl_phdr_info{
            .addr = base_address,
            .name = "/proc/self/exe",
            .phdr = phdrs.ptr,
            .phnum = ehdr.e_phnum,
        };

        return callback(&info, @sizeOf(dl_phdr_info), context);
    }

    // Last return value from the callback function.
    while (it.next()) |entry| {
        var phdr: [*]elf.Phdr = undefined;
        var phnum: u16 = undefined;

        if (entry.l_addr != 0) {
            const elf_header: *elf.Ehdr = @ptrFromInt(entry.l_addr);
            phdr = @ptrFromInt(entry.l_addr + elf_header.e_phoff);
            phnum = elf_header.e_phnum;
        } else {
            // This is the running ELF image
            phdr = @ptrFromInt(elf_base + ehdr.e_phoff);
            phnum = ehdr.e_phnum;
        }

        var info = dl_phdr_info{
            .addr = entry.l_addr,
            .name = entry.l_name,
            .phdr = phdr,
            .phnum = phnum,
        };

        try callback(&info, @sizeOf(dl_phdr_info), context);
    }
}  