Support Host I/O operations

Cargo.toml

@@ -14,6 +14,7 @@ categories = ["development-tools::debugging", "embedded", "emulators", "network-
 exclude = ["examples/**/*.elf", "examples/**/*.o"]
 
 [dependencies]
+bitflags = "1.2.1"
 cfg-if = "0.1.10"
 log = "0.4"
 managed = { version = "0.8", default-features = false }

README.md

@@ -75,6 +75,8 @@ Of course, most use-cases will want to support additional debugging features as
     -   Get section/segment relocation offsets from the target
 -   Custom `monitor` Commands
     -   Extend the GDB protocol with custom debug commands using GDB's `monitor` command
+-   Get target memory map
+-   Perform Host I/O operations
 
 _Note:_ GDB features are implemented on an as-needed basis by `gdbstub`'s contributors. If there's a missing GDB feature that you'd like `gdbstub` to implement, please file an issue and/or open a PR!
 

examples/armv4t/gdb/host_io.rs

@@ -0,0 +1,47 @@
+use gdbstub::target;
+
+use crate::emu::Emu;
+
+use gdbstub::common::{HostMode, HostOpenFlags};
+use gdbstub::target::ext::host_io::PreadOutput;
+
+impl target::ext::host_io::HostIo for Emu {
+    fn open(&self, filename: &[u8], _flags: HostOpenFlags, _mode: HostMode) -> i64 {
+        if filename == b"/proc/1/maps" {
+            1
+        } else {
+            -1
+        }
+    }
+
+    fn pread(
+        &self,
+        fd: usize,
+        count: u32,
+        offset: u32,
+        output: &mut PreadOutput<'_>,
+    ) -> Result<(), Self::Error> {
+        if fd == 1 {
+            let maps = b"0x55550000-0x55550078 r-x 0 0 0\n";
+            let len = maps.len();
+            let count: usize = count as usize;
+            let offset: usize = offset as usize;
+            output.write(&maps[offset.min(len)..(offset + count).min(len)]);
+            Ok(())
+        } else {
+            Err("pread failed")
+        }
+    }
+
+    fn close(&self, fd: usize) -> i64 {
+        if fd == 1 {
+            0
+        } else {
+            -1
+        }
+    }
+
+    fn setfs(&self, _fd: usize) -> i64 {
+        0
+    }
+}

examples/armv4t/gdb/mod.rs

@@ -17,6 +17,7 @@ use crate::emu::{Emu, Event};
 mod breakpoints;
 mod catch_syscalls;
 mod extended_mode;
+mod host_io;
 mod memory_map;
 mod monitor_cmd;
 mod section_offsets;
@@ -94,6 +95,11 @@ impl Target for Emu {
     fn catch_syscalls(&mut self) -> Option<target::ext::catch_syscalls::CatchSyscallsOps<Self>> {
         Some(self)
     }
+
+    #[inline(always)]
+    fn host_io(&mut self) -> Option<target::ext::host_io::HostIoOps<Self>> {
+        Some(self)
+    }
 }
 
 impl Emu {

src/common.rs

@@ -1,7 +1,59 @@
 //! Common types and definitions.
 
+use bitflags::bitflags;
+
 /// Thread ID
 pub type Tid = core::num::NonZeroUsize;
 
 /// Process ID
 pub type Pid = core::num::NonZeroUsize;
+
+bitflags! {
+    // The read/write flags below may look a little weird, but that is the way
+    // they are defined in the protocol.
+    /// Host flags for opening files.
+    pub struct HostOpenFlags: u32 {
+        /// A read-only file.
+        const O_RDONLY = 0x0;
+        /// A write-only file.
+        const O_WRONLY = 0x1;
+        /// A read-write file.
+        const O_RDWR = 0x2;
+        /// Append to an existing file.
+        const O_APPEND = 0x8;
+        /// Create a non-existent file.
+        const O_CREAT = 0x200;
+        /// Truncate an existing file.
+        const O_TRUNC = 0x400;
+        /// Exclusive access.
+        const O_EXCL = 0x800;
+    }
+}
+
+bitflags! {
+    /// Host file permissions.
+    pub struct HostMode: u32 {
+        /// A regular file.
+        const S_IFREG = 0o100000;
+        /// A directory.
+        const S_IFDIR = 0o40000;
+        /// User read permissions.
+        const S_IRUSR = 0o400;
+        /// User write permissions.
+        const S_IWUSR = 0o200;
+        /// User execute permissions.
+        const S_IXUSR = 0o100;
+        /// Group read permissions.
+        const S_IRGRP = 0o40;
+        /// Group write permissions
+        const S_IWGRP = 0o20;
+        /// Group execute permissions.
+        const S_IXGRP = 0o10;
+        /// World read permissions.
+        const S_IROTH = 0o4;
+        /// World write permissions
+        const S_IWOTH = 0o2;
+        /// World execute permissions.
+        const S_IXOTH = 0o1;
+    }
+}

src/gdbstub_impl/ext/host_io.rs

@@ -0,0 +1,69 @@
+use super::prelude::*;
+use crate::arch::Arch;
+use crate::protocol::commands::ext::HostIo;
+use crate::target::ext::host_io::PreadOutput;
+
+impl<T: Target, C: Connection> GdbStubImpl<T, C> {
+    pub(crate) fn handle_host_io(
+        &mut self,
+        res: &mut ResponseWriter<C>,
+        target: &mut T,
+        command: HostIo,
+    ) -> Result<HandlerStatus, Error<T::Error, C::Error>> {
+        let ops = match target.host_io() {
+            Some(ops) => ops,
+            None => return Ok(HandlerStatus::Handled),
+        };
+
+        crate::__dead_code_marker!("host_io", "impl");
+
+        let handler_status = match command {
+            HostIo::vFileOpen(cmd) => {
+                let ret = ops.open(cmd.filename, cmd.flags, cmd.mode);
+                res.write_str("F")?;
+                res.write_num(ret)?;
+                HandlerStatus::Handled
+            }
+            HostIo::vFileClose(cmd) => {
+                let ret = ops.close(cmd.fd);
+                res.write_str("F")?;
+                res.write_num(ret)?;
+                HandlerStatus::Handled
+            }
+            HostIo::vFilePread(cmd) => {
+                let count = <T::Arch as Arch>::Usize::from_be_bytes(cmd.count)
+                    .ok_or(Error::TargetMismatch)?;
+                let offset = <T::Arch as Arch>::Usize::from_be_bytes(cmd.offset)
+                    .ok_or(Error::TargetMismatch)?;
+                let mut err: Result<_, Error<T::Error, C::Error>> = Ok(());
+                let mut callback = |data: &[u8]| {
+                    let e = (|| {
+                        res.write_str("F")?;
+                        res.write_num(data.len())?;
+                        res.write_str(";")?;
+                        res.write_binary(data)?;
+                        Ok(())
+                    })();
+
+                    if let Err(e) = e {
+                        err = Err(e)
+                    }
+                };
+
+                ops.pread(cmd.fd, count, offset, &mut PreadOutput::new(&mut callback))
+                    .map_err(Error::TargetError)?;
+                err?;
+
+                HandlerStatus::Handled
+            }
+            HostIo::vFileSetfs(cmd) => {
+                let ret = ops.setfs(cmd.fd);
+                res.write_str("F")?;
+                res.write_num(ret)?;
+                HandlerStatus::Handled
+            }
+        };
+
+        Ok(handler_status)
+    }
+}

src/gdbstub_impl/ext/mod.rs

@@ -15,6 +15,7 @@ mod base;
 mod breakpoints;
 mod catch_syscalls;
 mod extended_mode;
+mod host_io;
 mod memory_map;
 mod monitor_cmd;
 mod reverse_exec;

src/gdbstub_impl/mod.rs

@@ -579,6 +579,7 @@ impl<T: Target, C: Connection> GdbStubImpl<T, C> {
             Command::ReverseCont(cmd) => self.handle_reverse_cont(res, target, cmd),
             Command::ReverseStep(cmd) => self.handle_reverse_step(res, target, cmd),
             Command::MemoryMap(cmd) => self.handle_memory_map(res, target, cmd),
+            Command::HostIo(cmd) => self.handle_host_io(res, target, cmd),
         }
     }
 }

src/protocol/commands.rs

@@ -223,6 +223,13 @@ commands! {
         "qXfer:memory-map:read" => _qXfer_memory_map::qXferMemoryMapRead,
     }
 
+    host_io use 'a {
+        "vFile:open" => _vFile_open::vFileOpen<'a>,
+        "vFile:close" => _vFile_close::vFileClose,
+        "vFile:pread" => _vFile_pread::vFilePread<'a>,
+        "vFile:setfs" => _vFile_setfs::vFileSetfs,
+    }
+
     catch_syscalls use 'a {
         "QCatchSyscalls" => _QCatchSyscalls::QCatchSyscalls<'a>,
     }

src/protocol/commands/_vFile_close.rs

@@ -0,0 +1,23 @@
+use super::prelude::*;
+
+#[derive(Debug)]
+pub struct vFileClose {
+    pub fd: usize,
+}
+
+impl<'a> ParseCommand<'a> for vFileClose {
+    fn from_packet(buf: PacketBuf<'a>) -> Option<Self> {
+        let body = buf.into_body();
+        if body.is_empty() {
+            return None;
+        }
+
+        match body {
+            [b':', body @ ..] => {
+                let fd = decode_hex(body).ok()?;
+                Some(vFileClose{fd})
+            },
+            _ => None,
+        }
+    }
+}

src/protocol/commands/_vFile_open.rs

@@ -0,0 +1,30 @@
+use super::prelude::*;
+
+use crate::common::{HostOpenFlags, HostMode};
+
+#[derive(Debug)]
+pub struct vFileOpen<'a> {
+    pub filename: &'a [u8],
+    pub flags: HostOpenFlags,
+    pub mode: HostMode,
+}
+
+impl<'a> ParseCommand<'a> for vFileOpen<'a> {
+    fn from_packet(buf: PacketBuf<'a>) -> Option<Self> {
+        let body = buf.into_body();
+        if body.is_empty() {
+            return None;
+        }
+
+        match body {
+            [b':', body @ ..] => {
+                let mut body = body.splitn_mut_no_panic(3, |b| *b == b',');
+                let filename = decode_hex_buf(body.next()?).ok()?;
+                let flags = HostOpenFlags::from_bits_truncate(decode_hex(body.next()?).ok()?);
+                let mode = HostMode::from_bits_truncate(decode_hex(body.next()?).ok()?);
+                Some(vFileOpen{filename, flags, mode})
+            },
+            _ => None,
+        }
+    }
+}

src/protocol/commands/_vFile_pread.rs

@@ -0,0 +1,28 @@
+use super::prelude::*;
+
+#[derive(Debug)]
+pub struct vFilePread<'a> {
+    pub fd: usize,
+    pub count: &'a [u8],
+    pub offset: &'a [u8],
+}
+
+impl<'a> ParseCommand<'a> for vFilePread<'a> {
+    fn from_packet(buf: PacketBuf<'a>) -> Option<Self> {
+        let body = buf.into_body();
+        if body.is_empty() {
+            return None;
+        }
+
+        match body {
+            [b':', body @ ..] => {
+                let mut body = body.splitn_mut_no_panic(3, |b| *b == b',');
+                let fd = decode_hex(body.next()?).ok()?;
+                let count = decode_hex_buf(body.next()?).ok()?;
+                let offset = decode_hex_buf(body.next()?).ok()?;
+                Some(vFilePread{fd, count, offset})
+            },
+            _ => None,
+        }
+    }
+}

src/protocol/commands/_vFile_setfs.rs

@@ -0,0 +1,23 @@
+use super::prelude::*;
+
+#[derive(Debug)]
+pub struct vFileSetfs {
+    pub fd: usize,
+}
+
+impl<'a> ParseCommand<'a> for vFileSetfs {
+    fn from_packet(buf: PacketBuf<'a>) -> Option<Self> {
+        let body = buf.into_body();
+        if body.is_empty() {
+            return None;
+        }
+
+        match body {
+            [b':', body @ ..] => {
+                let fd = decode_hex(body).ok()?;
+                Some(vFileSetfs{fd})
+            },
+            _ => None,
+        }
+    }
+}

src/protocol/console_output.rs

@@ -30,7 +30,7 @@ impl<'a> fmt::Write for ConsoleOutput<'a> {
 }
 
 impl<'a> ConsoleOutput<'a> {
-    pub(crate) fn new(callback: &'a mut dyn FnMut(&[u8])) -> ConsoleOutput<'a> {
+    pub(crate) fn new(callback: &'a mut dyn FnMut(&[u8])) -> Self {
         ConsoleOutput {
             #[cfg(feature = "alloc")]
             buf: Vec::new(),