Fix venv_pex.rs pex symlink on Unix.

Cargo.toml

@@ -118,6 +118,7 @@ log = "0.4"
 logging_timer = "1.1"
 nix = {  version = "0.31", features = ["fs"] }
 owo-colors = "4.3"
+pathdiff = "0.2"
 pep440_rs = "0.7"
 pep508_rs = "0.9"
 python-pkginfo = "0.6"

crates/pexrs/Cargo.toml

@@ -14,5 +14,6 @@ itertools = { workspace = true }
 log = { workspace = true }
 logging_timer = { workspace = true }
 pex = { path = "../pex" }
+platform = { path = "../platform" }
 regex = { workspace = true }
 venv = { path = "../venv" }

crates/pexrs/src/lib.rs

@@ -112,9 +112,10 @@ fn prepare_venv<'a>(
         #[cfg(unix)]
         if let Some(sh_boot_seed_dir) = sh_boot_seed_dir {
             fs::create_dir_all(&sh_boot_seed_dir)?;
-            std::os::unix::fs::symlink(
+            platform::unix::symlink(
                 venv_dir.join("pex"),
                 sh_boot_seed_dir.join(venv_interpreter.most_specific_exe_name()),
+                true,
             )?;
         }
         Virtualenv::enclosing(venv_interpreter)

crates/platform/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2024"
 [dependencies]
 anyhow = { workspace = true }
 fs-err = { workspace = true }
+pathdiff = { workspace = true }
 
 # N.B.: Although is_executable is cross-platform, we only use it for Windows. The nix unistd access
 # function is more robust that the check is_executable does on unix.

crates/platform/src/lib.rs

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #[cfg(unix)]
-mod unix;
+pub mod unix;
 
 #[cfg(windows)]
 mod windows;

crates/platform/src/unix.rs

@@ -1,18 +1,35 @@
 // Copyright 2026 Pex project contributors.
 // SPDX-License-Identifier: Apache-2.0
 
+use std::borrow::Cow;
 use std::fs::File;
 use std::os::unix::ffi::OsStrExt;
-use std::os::unix::fs::{PermissionsExt, symlink};
+use std::os::unix::fs::PermissionsExt;
 use std::path::Path;
 
 use anyhow::{anyhow, bail};
 use nix::errno::Errno;
 use nix::unistd;
 use nix::unistd::AccessFlags;
 
-pub fn link_or_copy(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> anyhow::Result<()> {
-    symlink(src, dst).map_err(anyhow::Error::new)
+pub fn link_or_copy(
+    src: impl AsRef<Path>,
+    dst: impl AsRef<Path>,
+    relative: bool,
+) -> anyhow::Result<()> {
+    symlink(src, dst, relative)
+}
+
+pub fn symlink(src: impl AsRef<Path>, dst: impl AsRef<Path>, relative: bool) -> anyhow::Result<()> {
+    let src = if relative
+        && let Some(rel_base) = dst.as_ref().parent()
+        && let Some(rel_path) = pathdiff::diff_paths(src.as_ref(), rel_base)
+    {
+        Cow::Owned(rel_path)
+    } else {
+        Cow::Borrowed(src.as_ref())
+    };
+    std::os::unix::fs::symlink(src, dst).map_err(anyhow::Error::new)
 }
 
 pub fn is_executable(path: impl AsRef<Path>) -> anyhow::Result<bool> {

crates/platform/src/windows.rs

@@ -7,7 +7,11 @@ use std::path::Path;
 use fs_err as fs;
 use is_executable::IsExecutable;
 
-pub fn link_or_copy(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> anyhow::Result<()> {
+pub fn link_or_copy(
+    src: impl AsRef<Path>,
+    dst: impl AsRef<Path>,
+    _relative: bool,
+) -> anyhow::Result<()> {
     fs::hard_link(&src, &dst)
         .or_else(|_| fs::copy(src, dst).map(|_| ()))
         .map_err(anyhow::Error::new)

crates/venv/src/venv_pex.rs

@@ -263,7 +263,7 @@ if __name__ == "__main__":
         )
     )?;
     mark_executable(main_py_fp.file_mut())?;
-    link_or_copy(&main_py, venv.prefix().join("pex"))
+    link_or_copy(&main_py, venv.prefix().join("pex"), true)
 }
 
 fn write_repl<'a>(

crates/venv/src/virtualenv.rs

@@ -129,7 +129,11 @@ fn create_pep_405_venv<'a>(
     )?;
     let scripts_dir = path.join(SCRIPTS_DIR);
     fs::create_dir_all(&scripts_dir)?;
-    link_or_copy(&base_interpreter.realpath, scripts_dir.join(PYTHON_EXE))?;
+    link_or_copy(
+        &base_interpreter.realpath,
+        scripts_dir.join(PYTHON_EXE),
+        false,
+    )?;
     let site_packages_relpath = site_packages_relpath(&base_interpreter);
     fs::create_dir_all(path.join(site_packages_relpath.as_ref()))?;
     Ok(site_packages_relpath)