stdbuf: Search libstdbuf without /proc

Author: oech3

Cargo.lock

@@ -427,6 +427,7 @@ regex = "1.10.4"
 rlimit = "0.11.0"
 rstest = "0.26.0"
 rustc-hash = "2.1.1"
+rustix = { version = "0.38", features = ["param", "runtime"] }
 rust-ini = "0.21.0"
 same-file = "1.0.6"
 self_cell = "1.0.4"

Cargo.toml

@@ -27,6 +27,9 @@ uucore = { workspace = true, features = ["parser-size"] }
 thiserror = { workspace = true }
 fluent = { workspace = true }
 
+[target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
+rustix = { workspace = true, optional = true }
+
 # "feat_external_libstdbuf": use an external libstdbuf.so for stdbuf instead of embedding it into
 # the stdbuf binary.
 # There are 2 use-cases:
@@ -45,7 +48,7 @@ fluent = { workspace = true }
 #    installation directory during the build. E.g. LIBSTDBUF_DIR="/usr/lib"
 
 [features]
-feat_external_libstdbuf = []
+feat_external_libstdbuf = ["dep:rustix"]
 
 [[bin]]
 name = "stdbuf"

src/uu/stdbuf/Cargo.toml

@@ -183,14 +183,26 @@ fn get_preload_env(_tmp_dir: &TempDir) -> UResult<(String, PathBuf)> {
     // Search paths in order:
     // 1. Directory where stdbuf is located (program_path)
     // 2. Compile-time directory from LIBSTDBUF_DIR
-    let mut search_paths: Vec<PathBuf> = Vec::new();
-
+    let mut search_paths: Vec<PathBuf> = Vec::with_capacity(2);
     // First, try to get the directory where stdbuf is running from
-    if let Ok(exe_path) = std::env::current_exe() {
-        if let Some(exe_dir) = exe_path.parent() {
+    // current_exe() depends on /proc at Linux...
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    use std::os::unix::ffi::OsStrExt;
+    {
+        let exe_path = rustix::param::linux_execfn().to_bytes();
+        if let Some(exe_dir) = std::path::Path::new(std::ffi::OsStr::from_bytes(exe_path)).parent()
+        {
             search_paths.push(exe_dir.to_path_buf());
         }
     }
+    #[cfg(not(any(target_os = "linux", target_os = "android")))]
+    {
+        if let Ok(exe_path) = std::env::current_exe() {
+            if let Some(exe_dir) = exe_path.parent() {
+                search_paths.push(exe_dir.to_path_buf());
+            }
+        }
+    }
 
     // Add the compile-time directory as fallback
     search_paths.push(PathBuf::from(LIBSTDBUF_DIR));