streams: sockets are non-blocking and can timeout

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.

Author: ethomson

ci/test.sh

@@ -271,9 +271,13 @@ if [ -z "$SKIP_ONLINE_TESTS" ]; then
 
 	export GITTEST_REMOTE_REDIRECT_INITIAL="http://localhost:9000/initial-redirect/libgit2/TestGitRepository"
 	export GITTEST_REMOTE_REDIRECT_SUBSEQUENT="http://localhost:9000/subsequent-redirect/libgit2/TestGitRepository"
+	export GITTEST_REMOTE_SPEED_SLOW="http://localhost:9000/speed-9600/test.git"
+	export GITTEST_REMOTE_SPEED_TIMESOUT="http://localhost:9000/speed-0.5/test.git"
 	run_test online
 	unset GITTEST_REMOTE_REDIRECT_INITIAL
 	unset GITTEST_REMOTE_REDIRECT_SUBSEQUENT
+	unset GITTEST_REMOTE_SPEED_SLOW
+	unset GITTEST_REMOTE_SPEED_TIMESOUT
 
 	# Run the online tests that immutably change global state separately
 	# to avoid polluting the test environment.

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

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;
 
 /**

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);

src/libgit2/libgit2.c

@@ -48,6 +48,8 @@ extern size_t git_indexer__max_objects;
 extern bool git_disable_pack_keep_file_checks;
 extern int git_odb__packed_priority;
 extern int git_odb__loose_priority;
+extern int git_socket_stream__connect_timeout;
+extern int git_socket_stream__timeout;
 
 char *git__user_agent;
 char *git__ssl_ciphers;
@@ -436,6 +438,40 @@ int git_libgit2_opts(int key, ...)
 		error = git_sysdir_set(GIT_SYSDIR_HOME, va_arg(ap, const char *));
 		break;
 
+	case GIT_OPT_GET_SERVER_CONNECT_TIMEOUT:
+		*(va_arg(ap, int *)) = git_socket_stream__connect_timeout;
+		break;
+
+	case GIT_OPT_SET_SERVER_CONNECT_TIMEOUT:
+		{
+			int timeout = va_arg(ap, int);
+
+			if (timeout < 0) {
+				git_error_set(GIT_ERROR_INVALID, "invalid connect timeout");
+				error = -1;
+			} else {
+				git_socket_stream__connect_timeout = timeout;
+			}
+		}
+		break;
+
+	case GIT_OPT_GET_SERVER_TIMEOUT:
+		*(va_arg(ap, int *)) = git_socket_stream__timeout;
+		break;
+
+	case GIT_OPT_SET_SERVER_TIMEOUT:
+		{
+			int timeout = va_arg(ap, int);
+
+			if (timeout < 0) {
+				git_error_set(GIT_ERROR_INVALID, "invalid timeout");
+				error = -1;
+			} else {
+				git_socket_stream__timeout = timeout;
+			}
+		}
+		break;
+
 	default:
 		git_error_set(GIT_ERROR_INVALID, "invalid option key");
 		error = -1;