fix bugs in em mapdir, improve it for relative paths, use it more

lib/emscripten/src/syscalls/mod.rs

@@ -96,9 +96,12 @@ pub fn ___syscall6(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int
 pub fn ___syscall12(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall12 (chdir) {}", _which);
     let path_ptr = varargs.get_str(ctx);
-    let real_path = get_cstr_path(ctx, path_ptr)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(path_ptr);
+    let real_path_owned = get_cstr_path(ctx, path_ptr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path_ptr
+    };
     let ret = unsafe { chdir(real_path) };
     debug!(
         "=> path: {:?}, ret: {}",
@@ -129,12 +132,18 @@ pub fn ___syscall38(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> i32 {
     debug!("emscripten::___syscall38 (rename)");
     let old_path = varargs.get_str(ctx);
     let new_path = varargs.get_str(ctx);
-    let real_old_path = get_cstr_path(ctx, old_path)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(old_path);
-    let real_new_path = get_cstr_path(ctx, new_path)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(new_path);
+    let real_old_path_owned = get_cstr_path(ctx, old_path);
+    let real_old_path = if let Some(ref rp) = real_old_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        old_path
+    };
+    let real_new_path_owned = get_cstr_path(ctx, new_path);
+    let real_new_path = if let Some(ref rp) = real_new_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        new_path
+    };
     let result = unsafe { rename(real_old_path, real_new_path) };
     debug!(
         "=> old_path: {}, new_path: {}, result: {}",
@@ -149,9 +158,12 @@ pub fn ___syscall38(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> i32 {
 pub fn ___syscall40(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall40 (rmdir)");
     let pathname_addr = varargs.get_str(ctx);
-    let real_path = get_cstr_path(ctx, pathname_addr)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(pathname_addr);
+    let real_path_owned = get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
     unsafe { rmdir(real_path) }
 }
 
@@ -433,16 +445,19 @@ pub fn ___syscall195(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
     let pathname_addr = varargs.get_str(ctx);
     let buf: u32 = varargs.get(ctx);
 
-    let real_path = get_cstr_path(ctx, pathname_addr)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(pathname_addr);
+    let real_path_owned = get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
 
     unsafe {
         let mut _stat: stat = std::mem::zeroed();
         let ret = stat(real_path, &mut _stat);
         debug!(
             "=> pathname: {}, buf: {} = {}, last os error: {}",
-            std::ffi::CStr::from_ptr(pathname_addr).to_str().unwrap(),
+            std::ffi::CStr::from_ptr(real_path).to_str().unwrap(),
             buf,
             ret,
             Error::last_os_error()

lib/emscripten/src/syscalls/unix.rs

@@ -108,9 +108,12 @@ pub fn ___syscall5(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int
     let pathname_addr = varargs.get_str(ctx);
     let flags: i32 = varargs.get(ctx);
     let mode: u32 = varargs.get(ctx);
-    let real_path = utils::get_cstr_path(ctx, pathname_addr)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(pathname_addr);
+    let real_path_owned = utils::get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
     let _path_str = unsafe { std::ffi::CStr::from_ptr(real_path).to_str().unwrap() };
     let fd = unsafe { open(real_path, flags, mode) };
     debug!(
@@ -158,12 +161,18 @@ pub fn ___syscall83(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int
 
     let path1 = varargs.get_str(ctx);
     let path2 = varargs.get_str(ctx);
-    let real_path1 = utils::get_cstr_path(ctx, path1)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(path1);
-    let real_path2 = utils::get_cstr_path(ctx, path2)
-        .map(|cstr| cstr.as_c_str() as *const _ as *const i8)
-        .unwrap_or(path2);
+    let real_path1_owned = utils::get_cstr_path(ctx, path1);
+    let real_path1 = if let Some(ref rp) = real_path1_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path1
+    };
+    let real_path2_owned = utils::get_cstr_path(ctx, path2);
+    let real_path2 = if let Some(ref rp) = real_path2_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path2
+    };
     let result = unsafe { symlink(real_path1, real_path2) };
     debug!(
         "=> path1: {}, path2: {}, result: {}",
@@ -191,12 +200,18 @@ pub fn ___syscall194(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
 pub fn ___syscall198(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall198 (lchown) {}", _which);
     let path_ptr = varargs.get_str(ctx);
+    let real_path_owned = utils::get_cstr_path(ctx, path_ptr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path_ptr
+    };
     let uid: uid_t = varargs.get(ctx);
     let gid: gid_t = varargs.get(ctx);
-    let result = unsafe { lchown(path_ptr, uid, gid) };
+    let result = unsafe { lchown(real_path, uid, gid) };
     debug!(
         "=> path: {}, uid: {}, gid: {}, result: {}",
-        unsafe { std::ffi::CStr::from_ptr(path_ptr).to_str().unwrap() },
+        unsafe { std::ffi::CStr::from_ptr(real_path).to_str().unwrap() },
         uid,
         gid,
         result,
@@ -226,10 +241,16 @@ pub fn ___syscall212(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
     debug!("emscripten::___syscall212 (chown) {}", _which);
 
     let pathname_addr = varargs.get_str(ctx);
+    let real_path_owned = utils::get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
     let owner: u32 = varargs.get(ctx);
     let group: u32 = varargs.get(ctx);
 
-    unsafe { chown(pathname_addr, owner, group) }
+    unsafe { chown(real_path, owner, group) }
 }
 
 /// madvise
@@ -249,11 +270,17 @@ pub fn ___syscall219(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
 pub fn ___syscall33(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall33 (access) {}", _which);
     let path = varargs.get_str(ctx);
+    let real_path_owned = utils::get_cstr_path(ctx, path);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path
+    };
     let amode: c_int = varargs.get(ctx);
-    let result = unsafe { access(path, amode) };
+    let result = unsafe { access(real_path, amode) };
     debug!(
         "=> path: {}, amode: {}, result: {}",
-        unsafe { std::ffi::CStr::from_ptr(path).to_str().unwrap() },
+        unsafe { std::ffi::CStr::from_ptr(real_path).to_str().unwrap() },
         amode,
         result
     );
@@ -271,8 +298,14 @@ pub fn ___syscall34(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int
 pub fn ___syscall39(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall39 (mkdir) {}", _which);
     let pathname_addr = varargs.get_str(ctx);
+    let real_path_owned = utils::get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
     let mode: u32 = varargs.get(ctx);
-    unsafe { mkdir(pathname_addr, mode as _) }
+    unsafe { mkdir(real_path, mode as _) }
 }
 
 /// dup
@@ -771,6 +804,12 @@ pub fn ___syscall122(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
 pub fn ___syscall196(ctx: &mut Ctx, _which: i32, mut varargs: VarArgs) -> i32 {
     debug!("emscripten::___syscall196 (lstat64) {}", _which);
     let path = varargs.get_str(ctx);
+    let real_path_owned = utils::get_cstr_path(ctx, path);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        path
+    };
     let buf_ptr: u32 = varargs.get(ctx);
     unsafe {
         let mut stat: stat = std::mem::zeroed();
@@ -781,9 +820,9 @@ pub fn ___syscall196(ctx: &mut Ctx, _which: i32, mut varargs: VarArgs) -> i32 {
         let stat_ptr = &mut stat as *mut stat;
 
         #[cfg(target_os = "macos")]
-        let ret = lstat64(path, stat_ptr);
+        let ret = lstat64(real_path, stat_ptr);
         #[cfg(not(target_os = "macos"))]
-        let ret = lstat(path, stat_ptr);
+        let ret = lstat(real_path, stat_ptr);
 
         debug!("ret: {}", ret);
         if ret != 0 {

lib/emscripten/src/syscalls/windows.rs

@@ -1,4 +1,4 @@
-use crate::utils::copy_cstr_into_wasm;
+use crate::utils::{copy_cstr_into_wasm, get_cstr_path};
 use crate::varargs::VarArgs;
 use libc::mkdir;
 use libc::open;
@@ -19,9 +19,15 @@ pub fn ___syscall5(ctx: &mut Ctx, which: c_int, mut varargs: VarArgs) -> c_int {
     #[cfg(not(feature = "debug"))]
     let _ = which;
     let pathname_addr = varargs.get_str(ctx);
+    let real_path_owned = get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
     let flags: i32 = varargs.get(ctx);
     let mode: u32 = varargs.get(ctx);
-    let path_str = unsafe { std::ffi::CStr::from_ptr(pathname_addr).to_str().unwrap() };
+    let path_str = unsafe { std::ffi::CStr::from_ptr(real_path).to_str().unwrap() };
     match path_str {
         "/dev/urandom" => {
             // create a fake urandom file for windows, super hacky
@@ -47,7 +53,7 @@ pub fn ___syscall5(ctx: &mut Ctx, which: c_int, mut varargs: VarArgs) -> c_int {
             fd
         }
         _ => {
-            let fd = unsafe { open(pathname_addr, flags, mode) };
+            let fd = unsafe { open(real_path, flags, mode) };
             debug!(
                 "=> pathname: {}, flags: {}, mode: {} = fd: {}\npath: {}",
                 path_str, flags, mode, fd, path_str
@@ -95,7 +101,13 @@ pub fn ___syscall39(ctx: &mut Ctx, which: c_int, mut varargs: VarArgs) -> c_int
     #[cfg(not(feature = "debug"))]
     let _ = which;
     let pathname_addr = varargs.get_str(ctx);
-    unsafe { mkdir(pathname_addr) }
+    let real_path_owned = get_cstr_path(ctx, pathname_addr);
+    let real_path = if let Some(ref rp) = real_path_owned {
+        rp.as_c_str().as_ptr()
+    } else {
+        pathname_addr
+    };
+    unsafe { mkdir(real_path) }
 }
 
 /// dup

lib/emscripten/src/utils.rs

@@ -208,12 +208,36 @@ pub fn read_string_from_wasm(memory: &Memory, offset: u32) -> String {
 /// This function trys to find an entry in mapdir
 /// translating paths into their correct value
 pub fn get_cstr_path(ctx: &mut Ctx, path: *const i8) -> Option<std::ffi::CString> {
+    use std::collections::VecDeque;
+
     let path_str = unsafe { std::ffi::CStr::from_ptr(path).to_str().unwrap() }.to_string();
-    if let Some(val) = get_emscripten_data(ctx).mapped_dirs.get(&path_str) {
-        std::ffi::CString::new(val.to_string_lossy().as_bytes()).ok()
-    } else {
-        None
+    let data = get_emscripten_data(ctx);
+    let path = PathBuf::from(path_str);
+    let mut prefix_added = false;
+    let mut components = path.components().collect::<VecDeque<_>>();
+    // TODO(mark): handle absolute/non-canonical/non-relative paths too (this
+    // functionality should be shared among the abis)
+    if components.len() == 1 {
+        components.push_front(std::path::Component::CurDir);
+        prefix_added = true;
+    }
+    let mut cumulative_path = PathBuf::new();
+    for c in components.into_iter() {
+        cumulative_path.push(c);
+        if let Some(val) = data
+            .mapped_dirs
+            .get(&cumulative_path.to_string_lossy().to_string())
+        {
+            let rest_of_path = if !prefix_added {
+                path.strip_prefix(cumulative_path).ok()?
+            } else {
+                &path
+            };
+            let rebased_path = val.join(rest_of_path);
+            return std::ffi::CString::new(rebased_path.to_string_lossy().as_bytes()).ok();
+        }
     }
+    None
 }
 
 /// gets the current directory

src/bin/wasmer.rs

@@ -445,9 +445,6 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
             .instantiate(&import_object)
             .map_err(|e| format!("Can't instantiate module: {:?}", e))?;
 
-        if !mapped_dirs.is_empty() {
-            eprintln!("WARN: mapdir is not implemented for emscripten targets");
-        }
         wasmer_emscripten::run_emscripten_instance(
             &module,
             &mut instance,