streams: sockets are non-blocking and can timeoutethomson/nonblocking

Make socket I/O non-blocking and add optional timeouts.

Users may now set `GIT_OPT_SET_SERVER_CONNECT_TIMEOUT` to set a shorter
connection timeout. (The connect timeout cannot be longer than the
operating system default.) Users may also now configure the socket read
and write timeouts with `GIT_OPT_SET_SERVER_TIMEOUT`.

By default, connects still timeout based on the operating system
defaults (typically 75 seconds) and socket read and writes block.

Add a test against our custom testing git server that ensures that we
can timeout reads against a slow server.

3 files changed, 44 insertions, 4 deletions

diff --git a/include/git2/common.h b/include/git2/common.h
index f968deb23..ab6bc1333 100644
--- a/include/git2/common.h
+++ b/include/git2/common.h
@@ -224,7 +224,11 @@ typedef enum {
 	GIT_OPT_GET_OWNER_VALIDATION,
 	GIT_OPT_SET_OWNER_VALIDATION,
 	GIT_OPT_GET_HOMEDIR,
-	GIT_OPT_SET_HOMEDIR
+	GIT_OPT_SET_HOMEDIR,
+	GIT_OPT_SET_SERVER_CONNECT_TIMEOUT,
+	GIT_OPT_GET_SERVER_CONNECT_TIMEOUT,
+	GIT_OPT_SET_SERVER_TIMEOUT,
+	GIT_OPT_GET_SERVER_TIMEOUT
 } git_libgit2_opt_t;
 
 /**
@@ -480,6 +484,27 @@ typedef enum {
  *      >
  *      > - `path` directory of home directory.
  *
+ *   opts(GIT_OPT_GET_SERVER_CONNECT_TIMEOUT, int *timeout)
+ *      > Gets the timeout (in milliseconds) to attempt connections to
+ *      > a remote server.
+ *
+ *   opts(GIT_OPT_SET_SERVER_CONNECT_TIMEOUT, int timeout)
+ *      > Sets the timeout (in milliseconds) to attempt connections to
+ *      > a remote server. This is supported only for HTTP(S) connections
+ *      > and is not supported by SSH. Set to 0 to use the system default.
+ *      > Note that this may not be able to be configured longer than the
+ *      > system default, typically 75 seconds.
+ *
+ *   opts(GIT_OPT_GET_SERVER_TIMEOUT, int *timeout)
+ *      > Gets the timeout (in milliseconds) for reading from and writing
+ *      > to a remote server.
+ *
+ *   opts(GIT_OPT_SET_SERVER_TIMEOUT, int timeout)
+ *      > Sets the timeout (in milliseconds) for reading from and writing
+ *      > to a remote server. This is supported only for HTTP(S)
+ *      > connections and is not supported by SSH. Set to 0 to use the
+ *      > system default.
+ *
  * @param option Option key
  * @param ... value to set the option
  * @return 0 on success, <0 on failure
diff --git a/include/git2/errors.h b/include/git2/errors.h
index a61964bbb..98c2efbd4 100644
--- a/include/git2/errors.h
+++ b/include/git2/errors.h
@@ -58,7 +58,8 @@ typedef enum {
 	GIT_EMISMATCH       = -33,	/**< Hashsum mismatch in object */
 	GIT_EINDEXDIRTY     = -34,	/**< Unsaved changes in the index would be overwritten */
 	GIT_EAPPLYFAIL      = -35,	/**< Patch application failed */
-	GIT_EOWNER          = -36	/**< The object is not owned by the current user */
+	GIT_EOWNER          = -36,	/**< The object is not owned by the current user */
+	GIT_TIMEOUT         = -37	/**< The operation timed out */
 } git_error_code;
 
 /**
diff --git a/include/git2/sys/stream.h b/include/git2/sys/stream.h
index e0e03a2d7..3d28d09b3 100644
--- a/include/git2/sys/stream.h
+++ b/include/git2/sys/stream.h
@@ -29,8 +29,22 @@ GIT_BEGIN_DECL
 typedef struct git_stream {
 	int version;
 
-	int encrypted;
-	int proxy_support;
+	int encrypted : 1,
+	    proxy_support : 1;
+
+	/**
+	 * Timeout for read and write operations; can be set to `0` to
+	 * block indefinitely.
+	 */
+	int timeout;
+
+	/**
+	 * Timeout to connect to the remote server; can be set to `0`
+	 * to use the system defaults. This can be shorter than the
+	 * system default - often 75 seconds - but cannot be longer.
+	 */
+	int connect_timeout;
+
 	int GIT_CALLBACK(connect)(struct git_stream *);
 	int GIT_CALLBACK(certificate)(git_cert **, struct git_stream *);
 	int GIT_CALLBACK(set_proxy)(struct git_stream *, const git_proxy_options *proxy_opts);