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abiAndDynamicLinkerFromFile: return an error when the file is not act…
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…ually dynamic
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@git-bruh @andrewrk
git-bruh authored and andrewrk committed Aug 24, 2024
1 parent 9374725 commit 0e34bfa
Showing 1 changed file with 67 additions and 51 deletions.
118 changes: 67 additions & 51 deletions lib/std/zig/system.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -436,6 +436,7 @@ pub const AbiAndDynamicLinkerFromFileError = error{
Unexpected,
UnexpectedEndOfFile,
NameTooLong,
StaticElfFile,
};

pub fn abiAndDynamicLinkerFromFile(
Expand Down Expand Up @@ -481,6 +482,8 @@ pub fn abiAndDynamicLinkerFromFile(
if (phentsize > @sizeOf(elf.Elf64_Phdr)) return error.InvalidElfFile;

var ph_i: u16 = 0;
var got_dyn_section: bool = false;

while (ph_i < phnum) {
// Reserve some bytes so that we can deref the 64-bit struct fields
// even when the ELF file is 32-bits.
Expand All @@ -496,61 +499,69 @@ pub fn abiAndDynamicLinkerFromFile(
const ph64: *elf.Elf64_Phdr = @ptrCast(@alignCast(&ph_buf[ph_buf_i]));
const p_type = elfInt(is_64, need_bswap, ph32.p_type, ph64.p_type);
switch (p_type) {
elf.PT_INTERP => if (look_for_ld) {
const p_offset = elfInt(is_64, need_bswap, ph32.p_offset, ph64.p_offset);
const p_filesz = elfInt(is_64, need_bswap, ph32.p_filesz, ph64.p_filesz);
if (p_filesz > result.dynamic_linker.buffer.len) return error.NameTooLong;
const filesz: usize = @intCast(p_filesz);
_ = try preadAtLeast(file, result.dynamic_linker.buffer[0..filesz], p_offset, filesz);
// PT_INTERP includes a null byte in filesz.
const len = filesz - 1;
// dynamic_linker.max_byte is "max", not "len".
// We know it will fit in u8 because we check against dynamic_linker.buffer.len above.
result.dynamic_linker.len = @intCast(len);

// Use it to determine ABI.
const full_ld_path = result.dynamic_linker.buffer[0..len];
for (ld_info_list) |ld_info| {
const standard_ld_basename = fs.path.basename(ld_info.ld.get().?);
if (std.mem.endsWith(u8, full_ld_path, standard_ld_basename)) {
result.abi = ld_info.abi;
break;
elf.PT_INTERP => {
got_dyn_section = true;

if (look_for_ld) {
const p_offset = elfInt(is_64, need_bswap, ph32.p_offset, ph64.p_offset);
const p_filesz = elfInt(is_64, need_bswap, ph32.p_filesz, ph64.p_filesz);
if (p_filesz > result.dynamic_linker.buffer.len) return error.NameTooLong;
const filesz: usize = @intCast(p_filesz);
_ = try preadAtLeast(file, result.dynamic_linker.buffer[0..filesz], p_offset, filesz);
// PT_INTERP includes a null byte in filesz.
const len = filesz - 1;
// dynamic_linker.max_byte is "max", not "len".
// We know it will fit in u8 because we check against dynamic_linker.buffer.len above.
result.dynamic_linker.len = @intCast(len);

// Use it to determine ABI.
const full_ld_path = result.dynamic_linker.buffer[0..len];
for (ld_info_list) |ld_info| {
const standard_ld_basename = fs.path.basename(ld_info.ld.get().?);
if (std.mem.endsWith(u8, full_ld_path, standard_ld_basename)) {
result.abi = ld_info.abi;
break;
}
}
}
},
// We only need this for detecting glibc version.
elf.PT_DYNAMIC => if (builtin.target.os.tag == .linux and result.isGnuLibC() and
query.glibc_version == null)
{
var dyn_off = elfInt(is_64, need_bswap, ph32.p_offset, ph64.p_offset);
const p_filesz = elfInt(is_64, need_bswap, ph32.p_filesz, ph64.p_filesz);
const dyn_size: usize = if (is_64) @sizeOf(elf.Elf64_Dyn) else @sizeOf(elf.Elf32_Dyn);
const dyn_num = p_filesz / dyn_size;
var dyn_buf: [16 * @sizeOf(elf.Elf64_Dyn)]u8 align(@alignOf(elf.Elf64_Dyn)) = undefined;
var dyn_i: usize = 0;
dyn: while (dyn_i < dyn_num) {
// Reserve some bytes so that we can deref the 64-bit struct fields
// even when the ELF file is 32-bits.
const dyn_reserve: usize = @sizeOf(elf.Elf64_Dyn) - @sizeOf(elf.Elf32_Dyn);
const dyn_read_byte_len = try preadAtLeast(
file,
dyn_buf[0 .. dyn_buf.len - dyn_reserve],
dyn_off,
dyn_size,
);
var dyn_buf_i: usize = 0;
while (dyn_buf_i < dyn_read_byte_len and dyn_i < dyn_num) : ({
dyn_i += 1;
dyn_off += dyn_size;
dyn_buf_i += dyn_size;
}) {
const dyn32: *elf.Elf32_Dyn = @ptrCast(@alignCast(&dyn_buf[dyn_buf_i]));
const dyn64: *elf.Elf64_Dyn = @ptrCast(@alignCast(&dyn_buf[dyn_buf_i]));
const tag = elfInt(is_64, need_bswap, dyn32.d_tag, dyn64.d_tag);
const val = elfInt(is_64, need_bswap, dyn32.d_val, dyn64.d_val);
if (tag == elf.DT_RUNPATH) {
rpath_offset = val;
break :dyn;
elf.PT_DYNAMIC => {
got_dyn_section = true;

if (builtin.target.os.tag == .linux and result.isGnuLibC() and
query.glibc_version == null)
{
var dyn_off = elfInt(is_64, need_bswap, ph32.p_offset, ph64.p_offset);
const p_filesz = elfInt(is_64, need_bswap, ph32.p_filesz, ph64.p_filesz);
const dyn_size: usize = if (is_64) @sizeOf(elf.Elf64_Dyn) else @sizeOf(elf.Elf32_Dyn);
const dyn_num = p_filesz / dyn_size;
var dyn_buf: [16 * @sizeOf(elf.Elf64_Dyn)]u8 align(@alignOf(elf.Elf64_Dyn)) = undefined;
var dyn_i: usize = 0;
dyn: while (dyn_i < dyn_num) {
// Reserve some bytes so that we can deref the 64-bit struct fields
// even when the ELF file is 32-bits.
const dyn_reserve: usize = @sizeOf(elf.Elf64_Dyn) - @sizeOf(elf.Elf32_Dyn);
const dyn_read_byte_len = try preadAtLeast(
file,
dyn_buf[0 .. dyn_buf.len - dyn_reserve],
dyn_off,
dyn_size,
);
var dyn_buf_i: usize = 0;
while (dyn_buf_i < dyn_read_byte_len and dyn_i < dyn_num) : ({
dyn_i += 1;
dyn_off += dyn_size;
dyn_buf_i += dyn_size;
}) {
const dyn32: *elf.Elf32_Dyn = @ptrCast(@alignCast(&dyn_buf[dyn_buf_i]));
const dyn64: *elf.Elf64_Dyn = @ptrCast(@alignCast(&dyn_buf[dyn_buf_i]));
const tag = elfInt(is_64, need_bswap, dyn32.d_tag, dyn64.d_tag);
const val = elfInt(is_64, need_bswap, dyn32.d_val, dyn64.d_val);
if (tag == elf.DT_RUNPATH) {
rpath_offset = val;
break :dyn;
}
}
}
}
Expand All @@ -560,6 +571,10 @@ pub fn abiAndDynamicLinkerFromFile(
}
}

if (!got_dyn_section) {
return error.StaticElfFile;
}

if (builtin.target.os.tag == .linux and result.isGnuLibC() and
query.glibc_version == null)
{
Expand Down Expand Up @@ -1124,6 +1139,7 @@ fn detectAbiAndDynamicLinker(
error.Unexpected,
error.UnexpectedEndOfFile,
error.NameTooLong,
error.StaticElfFile,
// Finally, we fall back on the standard path.
=> |e| {
std.log.warn("Encountered error: {s}, falling back to default ABI and dynamic linker.", .{@errorName(e)});
Expand Down

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