1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149

use core::{fmt, slice};

use crate::endian::Endianness;
use crate::macho;
use crate::read::{
    ReadRef, Relocation, RelocationEncoding, RelocationFlags, RelocationKind, RelocationTarget,
    SectionIndex, SymbolIndex,
};

use super::{MachHeader, MachOFile};

/// An iterator for the relocations in a [`MachOSection32`](super::MachOSection32).
pub type MachORelocationIterator32<'data, 'file, Endian = Endianness, R = &'data [u8]> =
    MachORelocationIterator<'data, 'file, macho::MachHeader32<Endian>, R>;
/// An iterator for the relocations in a [`MachOSection64`](super::MachOSection64).
pub type MachORelocationIterator64<'data, 'file, Endian = Endianness, R = &'data [u8]> =
    MachORelocationIterator<'data, 'file, macho::MachHeader64<Endian>, R>;

/// An iterator for the relocations in a [`MachOSection`](super::MachOSection).
pub struct MachORelocationIterator<'data, 'file, Mach, R = &'data [u8]>
where
    Mach: MachHeader,
    R: ReadRef<'data>,
{
    pub(super) file: &'file MachOFile<'data, Mach, R>,
    pub(super) relocations: slice::Iter<'data, macho::Relocation<Mach::Endian>>,
}

impl<'data, 'file, Mach, R> Iterator for MachORelocationIterator<'data, 'file, Mach, R>
where
    Mach: MachHeader,
    R: ReadRef<'data>,
{
    type Item = (u64, Relocation);

    fn next(&mut self) -> Option<Self::Item> {
        let mut paired_addend = 0;
        loop {
            let reloc = self.relocations.next()?;
            let endian = self.file.endian;
            let cputype = self.file.header.cputype(endian);
            if reloc.r_scattered(endian, cputype) {
                // FIXME: handle scattered relocations
                // We need to add `RelocationTarget::Address` for this.
                continue;
            }
            let reloc = reloc.info(self.file.endian);
            let flags = RelocationFlags::MachO {
                r_type: reloc.r_type,
                r_pcrel: reloc.r_pcrel,
                r_length: reloc.r_length,
            };
            let mut encoding = RelocationEncoding::Generic;
            let kind = match cputype {
                macho::CPU_TYPE_ARM => match (reloc.r_type, reloc.r_pcrel) {
                    (macho::ARM_RELOC_VANILLA, false) => RelocationKind::Absolute,
                    _ => RelocationKind::Unknown,
                },
                macho::CPU_TYPE_ARM64 | macho::CPU_TYPE_ARM64_32 => {
                    match (reloc.r_type, reloc.r_pcrel) {
                        (macho::ARM64_RELOC_UNSIGNED, false) => RelocationKind::Absolute,
                        (macho::ARM64_RELOC_ADDEND, _) => {
                            paired_addend = i64::from(reloc.r_symbolnum)
                                .wrapping_shl(64 - 24)
                                .wrapping_shr(64 - 24);
                            continue;
                        }
                        _ => RelocationKind::Unknown,
                    }
                }
                macho::CPU_TYPE_X86 => match (reloc.r_type, reloc.r_pcrel) {
                    (macho::GENERIC_RELOC_VANILLA, false) => RelocationKind::Absolute,
                    _ => RelocationKind::Unknown,
                },
                macho::CPU_TYPE_X86_64 => match (reloc.r_type, reloc.r_pcrel) {
                    (macho::X86_64_RELOC_UNSIGNED, false) => RelocationKind::Absolute,
                    (macho::X86_64_RELOC_SIGNED, true) => {
                        encoding = RelocationEncoding::X86RipRelative;
                        RelocationKind::Relative
                    }
                    (macho::X86_64_RELOC_BRANCH, true) => {
                        encoding = RelocationEncoding::X86Branch;
                        RelocationKind::Relative
                    }
                    (macho::X86_64_RELOC_GOT, true) => RelocationKind::GotRelative,
                    (macho::X86_64_RELOC_GOT_LOAD, true) => {
                        encoding = RelocationEncoding::X86RipRelativeMovq;
                        RelocationKind::GotRelative
                    }
                    _ => RelocationKind::Unknown,
                },
                _ => RelocationKind::Unknown,
            };
            let size = 8 << reloc.r_length;
            let target = if reloc.r_extern {
                RelocationTarget::Symbol(SymbolIndex(reloc.r_symbolnum as usize))
            } else {
                RelocationTarget::Section(SectionIndex(reloc.r_symbolnum as usize))
            };
            let implicit_addend = paired_addend == 0;
            let mut addend = paired_addend;
            if reloc.r_pcrel {
                // For PC relative relocations on some architectures, the
                // addend does not include the offset required due to the
                // PC being different from the place of the relocation.
                // This differs from other file formats, so adjust the
                // addend here to account for this.
                match cputype {
                    macho::CPU_TYPE_X86 => {
                        addend -= 1 << reloc.r_length;
                    }
                    macho::CPU_TYPE_X86_64 => {
                        addend -= 1 << reloc.r_length;
                        match reloc.r_type {
                            macho::X86_64_RELOC_SIGNED_1 => addend -= 1,
                            macho::X86_64_RELOC_SIGNED_2 => addend -= 2,
                            macho::X86_64_RELOC_SIGNED_4 => addend -= 4,
                            _ => {}
                        }
                    }
                    // TODO: maybe missing support for some architectures and relocations
                    _ => {}
                }
            }
            return Some((
                reloc.r_address as u64,
                Relocation {
                    kind,
                    encoding,
                    size,
                    target,
                    addend,
                    implicit_addend,
                    flags,
                },
            ));
        }
    }
}

impl<'data, 'file, Mach, R> fmt::Debug for MachORelocationIterator<'data, 'file, Mach, R>
where
    Mach: MachHeader,
    R: ReadRef<'data>,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("MachORelocationIterator").finish()
    }
}