config: add a way to see if a "remote" URL is local or not

This factors out some URL-parsing code from the transport layer so it
can be used by config as well.

Issue: #909
Signed-off-by: Jeremy Stribling <strib@alum.mit.edu>

3 files changed, 50 insertions, 14 deletions

diff --git a/config/config.go b/config/config.go
index a637f6d..2c3b8b9 100644
--- a/config/config.go
+++ b/config/config.go
@@ -8,6 +8,7 @@ import (
 	"sort"
 	"strconv"
 
+	"gopkg.in/src-d/go-git.v4/internal/url"
 	format "gopkg.in/src-d/go-git.v4/plumbing/format/config"
 )
 
@@ -399,3 +400,7 @@ func (c *RemoteConfig) marshal() *format.Subsection {
 
 	return c.raw
 }
+
+func (c *RemoteConfig) IsFirstURLLocal() bool {
+	return url.IsLocalEndpoint(c.URLs[0])
+}
diff --git a/internal/url/url.go b/internal/url/url.go
new file mode 100644
index 0000000..0f0d709
--- /dev/null
+++ b/internal/url/url.go
@@ -0,0 +1,37 @@
+package url
+
+import (
+	"regexp"
+)
+
+var (
+	isSchemeRegExp   = regexp.MustCompile(`^[^:]+://`)
+	scpLikeUrlRegExp = regexp.MustCompile(`^(?:(?P<user>[^@]+)@)?(?P<host>[^:\s]+):(?:(?P<port>[0-9]{1,5})/)?(?P<path>[^\\].*)$`)
+)
+
+// MatchesScheme returns true if the given string matches a URL-like
+// format scheme.
+func MatchesScheme(url string) bool {
+	return isSchemeRegExp.MatchString(url)
+}
+
+// MatchesScpLike returns true if the given string matches an SCP-like
+// format scheme.
+func MatchesScpLike(url string) bool {
+	return scpLikeUrlRegExp.MatchString(url)
+}
+
+// FindScpLikeComponents returns the user, host, port and path of the
+// given SCP-like URL.
+func FindScpLikeComponents(url string) (user, host, port, path string) {
+	m := scpLikeUrlRegExp.FindStringSubmatch(url)
+	return m[1], m[2], m[3], m[4]
+}
+
+// IsLocalEndpoint returns true if the given URL string specifies a
+// local file endpoint.  For example, on a Linux machine,
+// `/home/user/src/go-git` would match as a local endpoint, but
+// `https://github.com/src-d/go-git` would not.
+func IsLocalEndpoint(url string) bool {
+	return !MatchesScheme(url) && !MatchesScpLike(url)
+}
diff --git a/plumbing/transport/common.go b/plumbing/transport/common.go
index f7b882b..dcf9391 100644
--- a/plumbing/transport/common.go
+++ b/plumbing/transport/common.go
@@ -19,10 +19,10 @@ import (
 	"fmt"
 	"io"
 	"net/url"
-	"regexp"
 	"strconv"
 	"strings"
 
+	giturl "gopkg.in/src-d/go-git.v4/internal/url"
 	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp"
 	"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp/capability"
@@ -224,34 +224,28 @@ func getPath(u *url.URL) string {
 	return res
 }
 
-var (
-	isSchemeRegExp   = regexp.MustCompile(`^[^:]+://`)
-	scpLikeUrlRegExp = regexp.MustCompile(`^(?:(?P<user>[^@]+)@)?(?P<host>[^:\s]+):(?:(?P<port>[0-9]{1,5})/)?(?P<path>[^\\].*)$`)
-)
-
 func parseSCPLike(endpoint string) (*Endpoint, bool) {
-	if isSchemeRegExp.MatchString(endpoint) || !scpLikeUrlRegExp.MatchString(endpoint) {
+	if giturl.MatchesScheme(endpoint) || !giturl.MatchesScpLike(endpoint) {
 		return nil, false
 	}
 
-	m := scpLikeUrlRegExp.FindStringSubmatch(endpoint)
-
-	port, err := strconv.Atoi(m[3])
+	user, host, portStr, path := giturl.FindScpLikeComponents(endpoint)
+	port, err := strconv.Atoi(portStr)
 	if err != nil {
 		port = 22
 	}
 
 	return &Endpoint{
 		Protocol: "ssh",
-		User:     m[1],
-		Host:     m[2],
+		User:     user,
+		Host:     host,
 		Port:     port,
-		Path:     m[4],
+		Path:     path,
 	}, true
 }
 
 func parseFile(endpoint string) (*Endpoint, bool) {
-	if isSchemeRegExp.MatchString(endpoint) {
+	if giturl.MatchesScheme(endpoint) {
 		return nil, false
 	}