From 1564e92940fcc50e566bc5031dbc73540523688d Mon Sep 17 00:00:00 2001 From: Alex Crichton Date: Sat, 4 Jun 2016 22:30:17 -0700 Subject: [PATCH] rustc: Try to contain prepends to PATH This commit attempts to bring our prepends to PATH on Windows when loading plugins because we've been seeing quite a few issues with failing to spawn a process on Windows, the leading theory of which is that PATH is too large as a result of this. Currently this is mostly a stab in the dark as it's not confirmed to actually fix the problem, but it's probably not a bad change to have anyway! cc #33844 Closes #17360 --- src/librustc_driver/driver.rs | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs index 96a1bdf62dea7..156f177619335 100644 --- a/src/librustc_driver/driver.rs +++ b/src/librustc_driver/driver.rs @@ -669,12 +669,24 @@ pub fn phase_2_configure_and_expand<'a>(sess: &Session, // dependent dlls. Note that this uses cfg!(windows) as opposed to // targ_cfg because syntax extensions are always loaded for the host // compiler, not for the target. - let mut _old_path = OsString::new(); + // + // This is somewhat of an inherently racy operation, however, as + // multiple threads calling this function could possibly continue + // extending PATH far beyond what it should. To solve this for now we + // just don't add any new elements to PATH which are already there + // within PATH. This is basically a targeted fix at #17360 for rustdoc + // which runs rustc in parallel but has been seen (#33844) to cause + // problems with PATH becoming too long. + let mut old_path = OsString::new(); if cfg!(windows) { - _old_path = env::var_os("PATH").unwrap_or(_old_path); + old_path = env::var_os("PATH").unwrap_or(old_path); let mut new_path = sess.host_filesearch(PathKind::All) .get_dylib_search_paths(); - new_path.extend(env::split_paths(&_old_path)); + for path in env::split_paths(&old_path) { + if !new_path.contains(&path) { + new_path.push(path); + } + } env::set_var("PATH", &env::join_paths(new_path).unwrap()); } let features = sess.features.borrow(); @@ -694,7 +706,7 @@ pub fn phase_2_configure_and_expand<'a>(sess: &Session, syntax_exts, krate); if cfg!(windows) { - env::set_var("PATH", &_old_path); + env::set_var("PATH", &old_path); } *sess.available_macros.borrow_mut() = macro_names; ret