Support linking against reentrant-configured curses

NCurses headers contain this conditional "#define cur_term":

	print  "#elif @cf_cv_enable_reentrant@"
	print  "NCURSES_WRAPPED_VAR(TERMINAL *, cur_term);"
	print  "#define cur_term   NCURSES_PUBLIC_VAR(cur_term())"
	print  "#else"

OpenSUSE Tumbleweed uses this configuration option; For reentrancy, cur_term
is a function.  If the NCurses autoconf variable @NCURSES_WRAP_PREFIX@
is not changed from its default, the function is called _nc_cur_term.

I'm not sure if we have a need to support non-default @NCURSES_WRAP_PREFIX@
but if we do there are various ways;
- search for the symbol with the cur_term suffix
- figure out the prefix based on the local curses installation,
  for example by looking at the header files.

Fixes #10243

build.rs

@@ -30,29 +30,42 @@ fn main() {
 
     // Handle case where CMake has found curses for us and where we have to find it ourselves.
     rsconf::rebuild_if_env_changed("CURSES_LIBRARY_LIST");
-    if let Ok(lib_path_list) = env::var("CURSES_LIBRARY_LIST") {
+    let curses_libraries = if let Ok(lib_path_list) = env::var("CURSES_LIBRARY_LIST") {
         let lib_paths = lib_path_list.split(',').filter(|s| !s.is_empty());
         let curses_libnames: Vec<_> = lib_paths
             .map(|libpath| {
                 let stem = Path::new(libpath).file_stem().unwrap().to_str().unwrap();
                 // Ubuntu-32bit-fetched-pcre2's ncurses doesn't have the "lib" prefix.
-                stem.strip_prefix("lib").unwrap_or(stem)
+                stem.strip_prefix("lib").unwrap_or(stem).to_string()
             })
             .collect();
         // We don't need to test the libs because presumably CMake already did
         rsconf::link_libraries(&curses_libnames, LinkType::Default);
+        curses_libnames
     } else {
-        let mut curses_found = false;
-        for lib in ["ncurses", "curses"] {
+        let mut curses_libraries = vec![];
+        let libs = ["ncurses", "curses"];
+        for lib in libs {
             if target.has_library(lib) && target.has_symbol("setupterm", lib) {
                 rsconf::link_library(lib, LinkType::Default);
-                curses_found = true;
+                curses_libraries.push(lib.to_string());
                 break;
             }
         }
 
-        if !curses_found {
-            rsconf::warn!("Could not locate a compatible curses library!");
+        if curses_libraries.is_empty() {
+            panic!("Could not locate a compatible curses library (tried {libs:?})");
+        }
+        curses_libraries
+    };
+
+    for lib in curses_libraries {
+        if target.has_symbol("_nc_cur_term", &lib) {
+            rsconf::enable_cfg("_nc_cur_term");
+            if target.has_symbol("cur_term", &lib) {
+                rsconf::warn!("curses provides both cur_term and _nc_cur_term");
+            }
+            break;
         }
     }
 }

docker/opensuse-tumbleweed.docker

@@ -0,0 +1,39 @@
+FROM opensuse/tumbleweed:latest
+LABEL org.opencontainers.image.source=https://github.com/fish-shell/fish-shell
+
+ENV LANG C.UTF-8
+ENV LC_ALL C.UTF-8
+
+RUN zypper --non-interactive install \
+  bash \
+  cmake \
+  diffutils \
+  gcc-c++ \
+  git-core \
+  ncurses-devel \
+  ninja \
+  pcre2-devel \
+  python311 \
+  python311-pip \
+  python311-pexpect \
+  openssl \
+  procps \
+  tmux \
+  sudo \
+  rust \
+  cargo
+
+RUN usermod -p $(openssl passwd -1 fish) root
+
+RUN groupadd -g 1000 fishuser \
+  && useradd  -p $(openssl passwd -1 fish) -d /home/fishuser -m -u 1000 -g 1000 fishuser \
+  && mkdir -p /home/fishuser/fish-build \
+  && mkdir /fish-source \
+  && chown -R fishuser:fishuser /home/fishuser /fish-source
+
+USER fishuser
+WORKDIR /home/fishuser
+
+COPY fish_run_tests.sh /
+
+CMD /fish_run_tests.sh

src/curses.rs

@@ -62,8 +62,10 @@ mod sys {
     pub type putc_t = extern "C" fn(tputs_arg) -> libc::c_int;
 
     extern "C" {
-        /// The ncurses `cur_term` TERMINAL pointer.
+        #[cfg(not(have_nc_cur_term))]
         pub static mut cur_term: *const core::ffi::c_void;
+        #[cfg(have_nc_cur_term)]
+        pub fn have_nc_cur_term() -> *const core::ffi::c_void;
 
         /// setupterm(3) is a low-level call to begin doing any sort of `term.h`/`curses.h` work.
         /// It's called internally by ncurses's `initscr()` and `newterm()`, but the C++ code called
@@ -77,6 +79,9 @@ mod sys {
         /// Frees the `cur_term` TERMINAL  pointer.
         pub fn del_curterm(term: *const core::ffi::c_void) -> libc::c_int;
 
+        /// Sets the `cur_term` TERMINAL  pointer.
+        pub fn set_curterm(term: *const core::ffi::c_void) -> *const core::ffi::c_void;
+
         /// Checks for the presence of a termcap flag identified by the first two characters of
         /// `id`.
         pub fn tgetflag(id: *const libc::c_char) -> libc::c_int;
@@ -95,6 +100,19 @@ mod sys {
         pub fn tputs(str: *const libc::c_char, affcnt: libc::c_int, putc: putc_t) -> libc::c_int;
     }
 }
+
+/// The ncurses `cur_term` TERMINAL pointer.
+fn get_curterm() -> *const core::ffi::c_void {
+    #[cfg(have_nc_cur_term)]
+    unsafe {
+        sys::have_nc_cur_term()
+    }
+    #[cfg(not(have_nc_cur_term))]
+    unsafe {
+        sys::cur_term
+    }
+}
+
 pub use sys::tputs_arg as TputsArg;
 
 /// The safe wrapper around curses functionality, initialized by a successful call to [`setup()`]
@@ -434,7 +452,7 @@ where
     let result = unsafe {
         // If cur_term is already initialized for a different $TERM value, calling setupterm() again
         // will leak memory. Call del_curterm() first to free previously allocated resources.
-        let _ = sys::del_curterm(cur_term);
+        let _ = sys::del_curterm(get_curterm());
 
         let mut err = 0;
         if let Some(term) = term {
@@ -469,8 +487,8 @@ pub fn reset() {
         unsafe {
             // Ignore the result of del_curterm() as the only documented error is that
             // `cur_term` was already null.
-            let _ = sys::del_curterm(cur_term);
-            sys::cur_term = core::ptr::null();
+            let _ = sys::del_curterm(get_curterm());
+            let _ = sys::set_curterm(core::ptr::null());
         }
         *term = None;
     }