1 files changed, 41 insertions, 0 deletions
diff --git a/cli/unix_util.rs b/cli/unix_util.rs
new file mode 100644
index 000000000..4aa8ef55d
--- /dev/null
+++ b/cli/unix_util.rs
@@ -0,0 +1,41 @@
+/// Raise soft file descriptor limit to hard file descriptor limit.
+/// This is the difference between `ulimit -n` and `ulimit -n -H`.
+pub fn raise_fd_limit() {
+  #[cfg(unix)]
+  unsafe {
+    let mut limits = libc::rlimit {
+      rlim_cur: 0,
+      rlim_max: 0,
+    };
+
+    if 0 != libc::getrlimit(libc::RLIMIT_NOFILE, &mut limits) {
+      return;
+    }
+
+    if limits.rlim_cur == libc::RLIM_INFINITY {
+      return;
+    }
+
+    // No hard limit? Do a binary search for the effective soft limit.
+    if limits.rlim_max == libc::RLIM_INFINITY {
+      let mut min = limits.rlim_cur;
+      let mut max = 1 << 20;
+
+      while min + 1 < max {
+        limits.rlim_cur = min + (max - min) / 2;
+        match libc::setrlimit(libc::RLIMIT_NOFILE, &limits) {
+          0 => min = limits.rlim_cur,
+          _ => max = limits.rlim_cur,
+        }
+      }
+
+      return;
+    }
+
+    // Raise the soft limit to the hard limit.
+    if limits.rlim_cur < limits.rlim_max {
+      limits.rlim_cur = limits.rlim_max;
+      libc::setrlimit(libc::RLIMIT_NOFILE, &limits);
+    }
+  }
+}