From: Agniva De Sarker <agnivade@yahoo.co.in>
Date: Wed, 28 Mar 2018 08:15:26 +0000 (+0530)
Subject: os: keep the $ if a variable is not detected
X-Git-Tag: go1.11beta1~1068
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7bf631e1fc55839a6bff404a91597326e1addc10;p=gostls13.git

os: keep the $ if a variable is not detected

If the character after $ cannot be detected as a valid
variable declaration, do not gobble the $.

Fixes #24345

Change-Id: Iec47be1f2e4f8147b8ceb64c30778eae8045b58f
Reviewed-on: https://go-review.googlesource.com/103055
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---

diff --git a/src/os/env.go b/src/os/env.go
index 4e0171f408..b3b615cb33 100644
--- a/src/os/env.go
+++ b/src/os/env.go
@@ -21,7 +21,12 @@ func Expand(s string, mapping func(string) string) string {
 		if s[j] == '$' && j+1 < len(s) {
 			buf = append(buf, s[i:j]...)
 			name, w := getShellName(s[j+1:])
-			buf = append(buf, mapping(name)...)
+			// If the name is empty, keep the $.
+			if name == "" {
+				buf = append(buf, s[j])
+			} else {
+				buf = append(buf, mapping(name)...)
+			}
 			j += w
 			i = j + 1
 		}
diff --git a/src/os/env_test.go b/src/os/env_test.go
index 16f1945638..78c8fe57cb 100644
--- a/src/os/env_test.go
+++ b/src/os/env_test.go
@@ -49,6 +49,8 @@ var expandTests = []struct {
 	{"${HOME}", "/usr/gopher"},
 	{"${H}OME", "(Value of H)OME"},
 	{"A$$$#$1$H$home_1*B", "APIDNARGSARGUMENT1(Value of H)/usr/foo*B"},
+	{"start$+middle$^end$", "start$+middle$^end$"},
+	{"mixed$|bag$$$", "mixed$|bagPID$"},
 }
 
 func TestExpand(t *testing.T) {