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List:       tar-bug
Subject:    [Bug-tar] [PATCH] Allow escaped delimiter in transform replace expr.
From:       Charles McGarvey <chazmcgarvey () brokenzipper ! com>
Date:       2015-08-11 23:14:31
Message-ID: E1ZPJ3c-0006ys-E1 () vulcan ! local
[Download RAW message or body]

I was surprised today to discover that you cannot escape a delimiter in the
replace expression of a --transform option. GNU tar treats the delimiter like
any other non-special character, causing a literal backslash to also be
inserted in the replacement before the delimiter. Is this a bug? If so, here
is a patch with a possible fix (though I'd need some help to write a test).

Example:
tar -x --transform='s/foo/bar\/baz/'
# expecting "foo" to be replaced with "bar/baz", but get "bar\/baz" instead

---
 src/transform.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/transform.c b/src/transform.c
index cd9e27c..2fbcc64 100644
--- a/src/transform.c
+++ b/src/transform.c
@@ -378,13 +378,19 @@ parse_transform_expr (const char *expr)
 	      break;
 
 	    default:
-	      /* Try to be nice */
-	      {
-		char buf[2];
-		buf[0] = '\\';
-		buf[1] = *cur;
-		add_literal_segment (tf, buf, buf + 2);
-	      }
+              if (*cur == delim)
+                {
+                  add_char_segment (tf, delim);
+                  cur++;
+                }
+              else
+                {
+                  /* Try to be nice */
+                  char buf[2];
+                  buf[0] = '\\';
+                  buf[1] = *cur;
+                  add_literal_segment (tf, buf, buf + 2);
+                }
 	      cur++;
 	      break;
 	    }
-- 
2.5.0


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