4 files changed, 74 insertions, 2 deletions

diff --git a/core/Cargo.toml b/core/Cargo.toml
index 034cc2fd..caafe03c 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -4,3 +4,4 @@ version = "0.1.0"
 authors = ["Justus Winter <justus@pep-project.org>"]
 
 [dependencies]
+tempdir = "0.3.5"
diff --git a/core/src/lib.rs b/core/src/lib.rs
index 1ef2cf54..bfd3cf9d 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -1,9 +1,12 @@
 //! Core functionality.
 
+extern crate tempdir;
+
 use std::env;
 use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
+use tempdir::TempDir;
 
 /// A `&Context` for Sequoia.
 ///
@@ -39,6 +42,8 @@ pub struct Context {
     home: PathBuf,
     lib: PathBuf,
     network_policy: NetworkPolicy,
+    ephemeral: bool,
+    temp_dir: Option<TempDir>,
 }
 
 /// Returns $PREXIX, or a reasonable default prefix.
@@ -73,6 +78,8 @@ impl Context {
                 .join(".sequoia"),
             lib: prefix().join("lib").join("sequoia"),
             network_policy: NetworkPolicy::Encrypted,
+            ephemeral: false,
+            temp_dir: None,
         })
     }
 
@@ -96,6 +103,10 @@ impl Context {
         &self.network_policy
     }
 
+    /// Returns whether or not this is an ephemeral context.
+    pub fn ephemeral(&self) -> bool {
+        self.ephemeral
+    }
 }
 
 /// Represents a `Context` configuration.
@@ -113,13 +124,37 @@ impl Context {
 /// # Ok(())
 /// # }
 /// ```
+///
+/// You can create ephemeral context that are useful for tests and
+/// one-shot programs:
+///
+/// ```
+/// # use sequoia_core::{Context, Result};
+/// # use std::path::Path;
+/// # f().unwrap();
+/// # fn f() -> Result<()> {
+/// let c = Context::configure("org.example.my.test")
+///             .ephemeral().build()?;
+/// let ephemeral_home = c.home().to_path_buf();
+/// // Do some tests.
+/// drop(c);
+/// assert!(! ephemeral_home.exists());
+/// # Ok(())
+/// # }
+/// ```
 pub struct Config(Context);
 
 impl Config {
     /// Finalizes the configuration and returns a `Context`.
     pub fn build(self) -> Result<Context> {
-        let c = self.0;
-        fs::create_dir_all(c.home())?;
+        let mut c = self.0;
+        if c.ephemeral {
+            let tmp = TempDir::new("sequoia")?;
+            c.home = tmp.path().clone().to_path_buf();
+            c.temp_dir = Some(tmp);
+        } else {
+            fs::create_dir_all(c.home())?;
+        }
         Ok(c)
     }
 
@@ -155,6 +190,17 @@ impl Config {
     pub fn set_network_policy(&mut self, policy: NetworkPolicy) {
         self.0.network_policy = policy;
     }
+
+    /// Makes this context ephemeral.
+    pub fn ephemeral(mut self) -> Self {
+        self.set_ephemeral();
+        self
+    }
+
+    /// Makes this context ephemeral.
+    pub fn set_ephemeral(&mut self) {
+        self.0.ephemeral = true;
+    }
 }
 
 /* Error handling.  */
diff --git a/ffi/src/lib.rs b/ffi/src/lib.rs
index 034299c1..08a64c30 100644
--- a/ffi/src/lib.rs
+++ b/ffi/src/lib.rs
@@ -129,6 +129,13 @@ pub extern "system" fn sq_context_network_policy(ctx: Option<&Context>) -> uint8
     }
 }
 
+/// Returns whether or not this is an ephemeral context.
+#[no_mangle]
+pub extern "system" fn sq_context_ephemeral(ctx: Option<&Context>) -> uint8_t {
+    assert!(ctx.is_some());
+    if ctx.unwrap().ephemeral() { 1 } else { 0 }
+}
+
 
 /*  sequoia::Config.  */
 
@@ -186,6 +193,14 @@ pub extern "system" fn sq_config_network_policy(cfg: Option<&mut Config>,
     });
 }
 
+/// Makes this context ephemeral.
+#[no_mangle]
+pub extern "system" fn sq_config_ephemeral(cfg: Option<&mut Config>) {
+    assert!(cfg.is_some());
+    cfg.unwrap().set_ephemeral();
+}
+
+
 /* openpgp::types.  */
 
 /// Returns a KeyID with the given `id`.
diff --git a/ffi/src/sequoia.h b/ffi/src/sequoia.h
index c19db967..a39c63f4 100644
--- a/ffi/src/sequoia.h
+++ b/ffi/src/sequoia.h
@@ -94,6 +94,11 @@ const char *sq_context_lib(const struct sq_context *ctx);
 /*/
 uint8_t sq_context_network_policy(const struct sq_context *ctx);
 
+/*/
+/// Returns whether or not this is an ephemeral context.
+/*/
+uint8_t sq_context_ephemeral(const struct sq_context *ctx);
+
 
 /* sequoia::Config.  */
 
@@ -119,6 +124,11 @@ void sq_config_lib(struct sq_config *cfg, const char *lib);
 /*/
 void sq_config_network_policy(struct sq_config *cfg, uint8_t policy);
 
+/*/
+/// Makes this context ephemeral.
+/*/
+void sq_config_ephemeral(struct sq_config *cfg);
+
 
 /* sequoia::openpgp::types.  */