Allow openssldir to be configured.

src/lib.rs

@@ -1,7 +1,7 @@
 extern crate cc;
 
 use std::env;
-use std::ffi::OsStr;
+use std::ffi::{OsStr, OsString};
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
@@ -18,6 +18,8 @@ pub struct Build {
     out_dir: Option<PathBuf>,
     target: Option<String>,
     host: Option<String>,
+    // Only affects non-windows builds for now.
+    openssl_dir: Option<PathBuf>,
 }
 
 pub struct Artifacts {
@@ -34,6 +36,7 @@ impl Build {
             out_dir: env::var_os("OUT_DIR").map(|s| PathBuf::from(s).join("openssl-build")),
             target: env::var("TARGET").ok(),
             host: env::var("HOST").ok(),
+            openssl_dir: Some(PathBuf::from("/usr/local/ssl")),
         }
     }
 
@@ -52,6 +55,11 @@ impl Build {
         self
     }
 
+    pub fn openssl_dir<P: AsRef<Path>>(&mut self, path: P) -> &mut Build {
+        self.openssl_dir = Some(path.as_ref().to_path_buf());
+        self
+    }
+
     fn cmd_make(&self) -> Command {
         let host = &self.host.as_ref().expect("HOST dir not set")[..];
         if host.contains("dragonfly")
@@ -154,11 +162,18 @@ impl Build {
 
         // Specify that openssl directory where things are loaded at runtime is
         // not inside our build directory. Instead this should be located in the
-        // default locations of the OpenSSL build scripts.
+        // default locations of the OpenSSL build scripts, or as specified by whatever
+        // configured this builder.
         if target.contains("windows") {
             configure.arg("--openssldir=SYS$MANAGER:[OPENSSL]");
         } else {
-            configure.arg("--openssldir=/usr/local/ssl");
+            let openssl_dir = self
+                .openssl_dir
+                .as_ref()
+                .expect("path to the openssl directory must be set");
+            let mut dir_arg: OsString = "--openssldir=".into();
+            dir_arg.push(openssl_dir);
+            configure.arg(dir_arg);
         }
 
         configure