[WIP] size limit for command line

windows/process: fix some obvious issues, create some more

It looks like I really can't get away with the whole storing error
thing as they don't have Copy. Maybe I will end up using the ugly
problem enum thing like I did with Unix too. Grrr...

unix: incremental size, no strlen

windows: sort the error type out

unix, windows: add temporary dead_code

unix: cache envp

Windows: draft traits for raw args and custom escapers

Windows: raw args trait

Windows: minor rename while I figure out where to put sized

unix: minor error stuff

windows: very rough xargs

minor: run formatter

it wants tight lines!

Windows commandext: apply review suggestions

Attempt at code reuse

Windows builds. Unix not so much.

It builds! Uh.

fixup! re-enable set_errno on linux

cleanup after slighty botched rebase

remove a redundant macro arg

appease tidy

process_common: subtract page size for headroom

Cargo.lock

@@ -263,7 +263,14 @@ dependencies = [
  "cargo-util",
  "clap",
  "crates-io",
+<<<<<<< HEAD
  "crossbeam-utils 0.8.3",
+||||||| parent of 1725fb7e1bd (actually get size adjustment to work)
+ "crossbeam-utils 0.8.0",
+=======
+ "crossbeam-utils 0.8.0",
+ "crypto-hash",
+>>>>>>> 1725fb7e1bd (actually get size adjustment to work)
  "curl",
  "curl-sys",
  "env_logger 0.8.1",
@@ -5569,11 +5576,12 @@ checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 
 [[package]]
 name = "vergen"
-version = "5.1.0"
+version = "5.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dfbc87f9a7a9d61b15d51d1d3547284f67b6b4f1494ce3fc5814c101f35a5183"
+checksum = "adf0b57f76a4f7e9673db1e7ffa4541d215ae8336fee45f5c1378bdeb22a0314"
 dependencies = [
  "anyhow",
+ "cfg-if 1.0.0",
  "chrono",
  "enum-iterator",
  "getset",

library/std/src/os/unix/process.rs

@@ -1,5 +1,4 @@
 //! Unix-specific extensions to primitives in the `std::process` module.
-
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::ffi::OsStr;
@@ -10,6 +9,9 @@ use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 
+use crate::sys_common::process_ext;
+impl_command_sized! { prelude }
+
 /// Unix-specific extensions to the [`process::Command`] builder.
 ///
 /// This trait is sealed: it cannot be implemented outside the standard library.
@@ -335,3 +337,25 @@ impl IntoRawFd for process::ChildStderr {
 pub fn parent_id() -> u32 {
     crate::sys::os::getppid()
 }
+
+fn maybe_arg_ext(celf: &mut sys::process::Command, arg: impl Arg) -> io::Result<()> {
+    celf.maybe_arg(arg.to_plain())
+}
+
+fn args_ext(
+    celf: &mut process::Command,
+    args: impl IntoIterator<Item = impl Arg>,
+) -> &mut process::Command {
+    for arg in args {
+        celf.arg(arg.to_plain());
+    }
+    celf
+}
+
+#[unstable(feature = "command_sized", issue = "74549")]
+#[cfg(unix)] // doc hack
+impl process_ext::CommandSized for process::Command {
+    impl_command_sized! { marg  maybe_arg_ext }
+    impl_command_sized! { margs maybe_arg_ext }
+    impl_command_sized! { xargs args_ext }
+}

library/std/src/os/windows/process.rs

@@ -2,11 +2,38 @@
 
 #![stable(feature = "process_extensions", since = "1.2.0")]
 
+use crate::ffi::{OsStr, OsString};
+use crate::io;
 use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
 use crate::process;
 use crate::sealed::Sealed;
 use crate::sys;
-use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
+use crate::os::windows::ffi::OsStrExt;
+#[unstable(feature = "windows_raw_cmdline", issue = "74549")]
+pub use crate::sys_common::process_ext::{Arg, Problem};
+use crate::sys_common::{process_ext, AsInner, AsInnerMut, FromInner, IntoInner};
+use core::convert::TryFrom;
+
+/// Argument type with no escaping.
+#[unstable(feature = "windows_raw_cmdline", issue = "74549")]
+pub struct RawArg<'a>(&'a OsStr);
+
+// FIXME: Inhibiting doc on non-Windows due to mismatching trait methods.
+#[cfg(any(windows))]
+#[doc(cfg(windows))]
+#[unstable(feature = "windows_raw_cmdline", issue = "74549")]
+impl Arg for RawArg<'_> {
+    fn append_to(&self, cmd: &mut Vec<u16>, _fq: bool) -> Result<usize, Problem> {
+        cmd.extend(self.0.encode_wide());
+        self.arg_size(_fq)
+    }
+    fn arg_size(&self, _: bool) -> Result<usize, Problem> {
+        Ok(self.0.encode_wide().count() + 1)
+    }
+    fn to_os_string(&self) -> OsString {
+        OsStr::to_os_string(&(self.0))
+    }
+}
 
 #[stable(feature = "process_extensions", since = "1.2.0")]
 impl FromRawHandle for process::Stdio {
@@ -125,6 +152,13 @@ pub trait CommandExt: Sealed {
     /// [2]: <https://msdn.microsoft.com/en-us/library/17w5ykft.aspx>
     #[unstable(feature = "windows_process_extensions_force_quotes", issue = "82227")]
     fn force_quotes(&mut self, enabled: bool) -> &mut process::Command;
+    /// Pass an argument with custom escape rules.
+    #[unstable(feature = "windows_raw_cmdline", issue = "74549")]
+    fn arg_ext(&mut self, arg: impl Arg) -> &mut process::Command;
+
+    /// Pass arguments with custom escape rules.
+    #[unstable(feature = "windows_raw_cmdline", issue = "74549")]
+    fn args_ext(&mut self, args: impl IntoIterator<Item = impl Arg>) -> &mut process::Command;
 }
 
 #[stable(feature = "windows_process_extensions", since = "1.16.0")]
@@ -138,4 +172,25 @@ impl CommandExt for process::Command {
         self.as_inner_mut().force_quotes(enabled);
         self
     }
+
+    fn arg_ext(&mut self, arg: impl Arg) -> &mut process::Command {
+        self.as_inner_mut().arg_ext(arg);
+        self
+    }
+
+    fn args_ext(&mut self, args: impl IntoIterator<Item = impl Arg>) -> &mut process::Command {
+        for arg in args {
+            self.arg_ext(arg);
+        }
+        self
+    }
+}
+
+// FIXME: export maybe_arg_ext so the macro doesn't explicitly reach for as_inner_mut()
+#[unstable(feature = "command_sized", issue = "74549")]
+#[cfg(windows)] // doc hack
+impl process_ext::CommandSized for process::Command {
+    impl_command_sized! { marg  sys::process::Command::maybe_arg_ext }
+    impl_command_sized! { margs sys::process::Command::maybe_arg_ext }
+    impl_command_sized! { xargs process::Command::args_ext }
 }

library/std/src/sys/unix/os.rs

@@ -73,7 +73,7 @@ pub fn errno() -> i32 {
 }
 
 /// Sets the platform-specific value of errno
-#[cfg(all(not(target_os = "linux"), not(target_os = "dragonfly")))] // needed for readdir and syscall!
+#[cfg(not(any(target_os = "dragonfly", target_os = "vxworks")))] // needed for readdir and syscall!
 #[allow(dead_code)] // but not all target cfgs actually end up using it
 pub fn set_errno(e: i32) {
     unsafe { *errno_location() = e as c_int }

library/std/src/sys/unix/process/mod.rs

@@ -1,4 +1,4 @@
-pub use self::process_common::{Command, CommandArgs, ExitCode, Stdio, StdioPipes};
+pub use self::process_common::{Arg, Command, CommandArgs, ExitCode, Problem, Stdio, StdioPipes};
 pub use self::process_inner::{ExitStatus, Process};
 pub use crate::ffi::OsString as EnvKey;
 pub use crate::sys_common::process::CommandEnvs;