miri/shims/unix/linux/
foreign_items.rs

1use rustc_abi::CanonAbi;
2use rustc_middle::ty::Ty;
3use rustc_span::Symbol;
4use rustc_target::callconv::FnAbi;
5
6use self::shims::unix::linux::mem::EvalContextExt as _;
7use self::shims::unix::linux_like::eventfd::EvalContextExt as _;
8use self::shims::unix::linux_like::syscall::syscall;
9use crate::machine::{SIGRTMAX, SIGRTMIN};
10use crate::shims::unix::foreign_items::EvalContextExt as _;
11use crate::shims::unix::linux_like::epoll::EvalContextExt as _;
12use crate::shims::unix::linux_like::thread::prctl;
13use crate::shims::unix::*;
14use crate::*;
15
16// The documentation of glibc complains that the kernel never exposes
17// TASK_COMM_LEN through the headers, so it's assumed to always be 16 bytes
18// long including a null terminator.
19const TASK_COMM_LEN: u64 = 16;
20
21pub fn is_dyn_sym(name: &str) -> bool {
22    matches!(name, "gettid" | "statx")
23}
24
25impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
26pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
27    fn emulate_foreign_item_inner(
28        &mut self,
29        link_name: Symbol,
30        abi: &FnAbi<'tcx, Ty<'tcx>>,
31        args: &[OpTy<'tcx>],
32        dest: &MPlaceTy<'tcx>,
33    ) -> InterpResult<'tcx, EmulateItemResult> {
34        let this = self.eval_context_mut();
35
36        // See `fn emulate_foreign_item_inner` in `shims/foreign_items.rs` for the general pattern.
37
38        match link_name.as_str() {
39            // File related shims
40            "open64" => {
41                // `open64` is variadic, the third argument is only present when the second argument
42                // has O_CREAT (or on linux O_TMPFILE, but miri doesn't support that) set
43                let ([path_raw, flag], varargs) =
44                    this.check_shim_sig_variadic_lenient(abi, CanonAbi::C, link_name, args)?;
45                let result = this.open(path_raw, flag, varargs)?;
46                this.write_scalar(result, dest)?;
47            }
48            "pread64" => {
49                // FIXME: This does not have a direct test (#3179).
50                let [fd, buf, count, offset] = this.check_shim_sig(
51                    shim_sig!(extern "C" fn(i32, *mut _, usize, libc::off64_t) -> isize),
52                    link_name,
53                    abi,
54                    args,
55                )?;
56                let fd = this.read_scalar(fd)?.to_i32()?;
57                let buf = this.read_pointer(buf)?;
58                let count = this.read_target_usize(count)?;
59                let offset = this.read_scalar(offset)?.to_int(offset.layout.size)?;
60                this.read(fd, buf, count, Some(offset), dest)?;
61            }
62            "pwrite64" => {
63                // FIXME: This does not have a direct test (#3179).
64                let [fd, buf, n, offset] = this.check_shim_sig(
65                    shim_sig!(extern "C" fn(i32, *const _, usize, libc::off64_t) -> isize),
66                    link_name,
67                    abi,
68                    args,
69                )?;
70                let fd = this.read_scalar(fd)?.to_i32()?;
71                let buf = this.read_pointer(buf)?;
72                let count = this.read_target_usize(n)?;
73                let offset = this.read_scalar(offset)?.to_int(offset.layout.size)?;
74                trace!("Called pwrite64({:?}, {:?}, {:?}, {:?})", fd, buf, count, offset);
75                this.write(fd, buf, count, Some(offset), dest)?;
76            }
77            "lseek64" => {
78                // FIXME: This does not have a direct test (#3179).
79                let [fd, offset, whence] = this.check_shim_sig(
80                    shim_sig!(extern "C" fn(i32, libc::off64_t, i32) -> libc::off64_t),
81                    link_name,
82                    abi,
83                    args,
84                )?;
85                let fd = this.read_scalar(fd)?.to_i32()?;
86                let offset = this.read_scalar(offset)?.to_int(offset.layout.size)?;
87                let whence = this.read_scalar(whence)?.to_i32()?;
88                this.lseek(fd, offset, whence, dest)?;
89            }
90            "ftruncate64" => {
91                let [fd, length] = this.check_shim_sig(
92                    shim_sig!(extern "C" fn(i32, libc::off64_t) -> i32),
93                    link_name,
94                    abi,
95                    args,
96                )?;
97                let fd = this.read_scalar(fd)?.to_i32()?;
98                let length = this.read_scalar(length)?.to_int(length.layout.size)?;
99                let result = this.ftruncate64(fd, length)?;
100                this.write_scalar(result, dest)?;
101            }
102            "posix_fallocate64" => {
103                let [fd, offset, len] = this.check_shim_sig(
104                    shim_sig!(extern "C" fn(i32, libc::off64_t, libc::off64_t) -> i32),
105                    link_name,
106                    abi,
107                    args,
108                )?;
109
110                let fd = this.read_scalar(fd)?.to_i32()?;
111                let offset = this.read_scalar(offset)?.to_i64()?;
112                let len = this.read_scalar(len)?.to_i64()?;
113
114                let result = this.posix_fallocate(fd, offset, len)?;
115                this.write_scalar(result, dest)?;
116            }
117            "readdir64" => {
118                let [dirp] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
119                this.readdir(dirp, dest)?;
120            }
121            "sync_file_range" => {
122                let [fd, offset, nbytes, flags] =
123                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
124                let result = this.sync_file_range(fd, offset, nbytes, flags)?;
125                this.write_scalar(result, dest)?;
126            }
127            "statx" => {
128                let [dirfd, pathname, flags, mask, statxbuf] =
129                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
130                let result = this.linux_statx(dirfd, pathname, flags, mask, statxbuf)?;
131                this.write_scalar(result, dest)?;
132            }
133            // epoll, eventfd
134            "epoll_create1" => {
135                let [flag] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
136                let result = this.epoll_create1(flag)?;
137                this.write_scalar(result, dest)?;
138            }
139            "epoll_ctl" => {
140                let [epfd, op, fd, event] =
141                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
142                let result = this.epoll_ctl(epfd, op, fd, event)?;
143                this.write_scalar(result, dest)?;
144            }
145            "epoll_wait" => {
146                let [epfd, events, maxevents, timeout] =
147                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
148                this.epoll_wait(epfd, events, maxevents, timeout, dest)?;
149            }
150            "eventfd" => {
151                let [val, flag] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
152                let result = this.eventfd(val, flag)?;
153                this.write_scalar(result, dest)?;
154            }
155
156            // Threading
157            "pthread_setname_np" => {
158                let [thread, name] =
159                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
160                let res = match this.pthread_setname_np(
161                    this.read_scalar(thread)?,
162                    this.read_scalar(name)?,
163                    TASK_COMM_LEN,
164                    /* truncate */ false,
165                )? {
166                    ThreadNameResult::Ok => Scalar::from_u32(0),
167                    ThreadNameResult::NameTooLong => this.eval_libc("ERANGE"),
168                    // Act like we failed to open `/proc/self/task/$tid/comm`.
169                    ThreadNameResult::ThreadNotFound => this.eval_libc("ENOENT"),
170                };
171                this.write_scalar(res, dest)?;
172            }
173            "pthread_getname_np" => {
174                let [thread, name, len] =
175                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
176                // The function's behavior isn't portable between platforms.
177                // In case of glibc, the length of the output buffer must
178                // be not shorter than TASK_COMM_LEN.
179                let len = this.read_scalar(len)?;
180                let res = if len.to_target_usize(this)? >= TASK_COMM_LEN {
181                    match this.pthread_getname_np(
182                        this.read_scalar(thread)?,
183                        this.read_scalar(name)?,
184                        len,
185                        /* truncate*/ false,
186                    )? {
187                        ThreadNameResult::Ok => Scalar::from_u32(0),
188                        ThreadNameResult::NameTooLong => unreachable!(),
189                        // Act like we failed to open `/proc/self/task/$tid/comm`.
190                        ThreadNameResult::ThreadNotFound => this.eval_libc("ENOENT"),
191                    }
192                } else {
193                    this.eval_libc("ERANGE")
194                };
195                this.write_scalar(res, dest)?;
196            }
197            "gettid" => {
198                let [] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
199                let result = this.unix_gettid(link_name.as_str())?;
200                this.write_scalar(result, dest)?;
201            }
202            "prctl" => prctl(this, link_name, abi, args, dest)?,
203
204            // Dynamically invoked syscalls
205            "syscall" => {
206                syscall(this, link_name, abi, args, dest)?;
207            }
208
209            // Miscellaneous
210            "mmap64" => {
211                let [addr, length, prot, flags, fd, offset] =
212                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
213                let offset = this.read_scalar(offset)?.to_i64()?;
214                let ptr = this.mmap(addr, length, prot, flags, fd, offset.into())?;
215                this.write_scalar(ptr, dest)?;
216            }
217            "mremap" => {
218                let ([old_address, old_size, new_size, flags], _) =
219                    this.check_shim_sig_variadic_lenient(abi, CanonAbi::C, link_name, args)?;
220                let ptr = this.mremap(old_address, old_size, new_size, flags)?;
221                this.write_scalar(ptr, dest)?;
222            }
223            "__xpg_strerror_r" => {
224                let [errnum, buf, buflen] =
225                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
226                let result = this.strerror_r(errnum, buf, buflen)?;
227                this.write_scalar(result, dest)?;
228            }
229            "__errno_location" => {
230                let [] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
231                let errno_place = this.last_error_place()?;
232                this.write_scalar(errno_place.to_ref(this).to_scalar(), dest)?;
233            }
234            "__libc_current_sigrtmin" => {
235                let [] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
236
237                this.write_int(SIGRTMIN, dest)?;
238            }
239            "__libc_current_sigrtmax" => {
240                let [] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
241
242                this.write_int(SIGRTMAX, dest)?;
243            }
244
245            // Incomplete shims that we "stub out" just to get pre-main initialization code to work.
246            // These shims are enabled only when the caller is in the standard library.
247            "pthread_getattr_np" if this.frame_in_std() => {
248                let [_thread, _attr] =
249                    this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
250                this.write_null(dest)?;
251            }
252            "gnu_get_libc_version"
253                if this.frame_in_std()
254                    && this.tcx.sess.target.env == rustc_target::spec::Env::Gnu =>
255            {
256                let [] = this.check_shim_sig_lenient(abi, CanonAbi::C, link_name, args)?;
257                // We have to be at least version 2.26 so that std does not call `res_init`.
258                // This returns a C string, so we have to add a null terminator.
259                let version = "2.26\0";
260                let version = this.allocate_str_dedup(version)?;
261                this.write_pointer(version.ptr(), dest)?;
262            }
263
264            _ => return interp_ok(EmulateItemResult::NotSupported),
265        };
266
267        interp_ok(EmulateItemResult::NeedsReturn)
268    }
269}
miri/shims/unix/linux/foreign_items.rs

miri/shims/unix/linux/
foreign_items.rs
