From: Alan T. DeKok <aland@freeradius.org>
Date: Sat, 27 Aug 2022 12:52:18 +0000 (-0400)
Subject: make prepend work, and update doecs and tests to match
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8df2d3a77c3db0ef5fd49fe14008cbaa6bc7cdee;p=thirdparty%2Ffreeradius-server.git

make prepend work, and update doecs and tests to match
---

diff --git a/doc/antora/modules/reference/pages/unlang/edit.adoc b/doc/antora/modules/reference/pages/unlang/edit.adoc
index d16dc720f71..34ce7d4237c 100644
--- a/doc/antora/modules/reference/pages/unlang/edit.adoc
+++ b/doc/antora/modules/reference/pages/unlang/edit.adoc
@@ -391,12 +391,18 @@ The operators also apply to variable-sized values.
 | :=       | Override the attribute with the contents with the _<rhs>_.  If the attribute already exists, its value is over-written.  If the attribute does not exist, it is created, and the contents set to thex value of the _<rhs>_
 | +=       | Perform string append.  The contents of the _<rhs>_ are appended to the _<attribute>_.
 | -=       | Inverse of string append. The contents of the _<rhs>_ are deleted from from the _<attribute>_, if the `_<rhs>_` is a suffix of _<attribute>_ 
-| ^=       | Perform logical "xor".  The contents of the _<rhs>_ are "xor"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
-| \|=       | Perform logical "or".  The value of the _<attribute>_ is "or"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
-| &=        | Perform logical "and".  The value of the _<attribute>_ is "and"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
-| <\<=       | Perform left shift / truncation.  The first _<rhs>_ bytes of _<attribute>_ are dropped. i.e. shifted off of the start of the string.
-| >>=       | Perform right shift / truncation.  The last _<rhs>_ bytes of _<attribute>_ are dropped. i.e. shifted off of the end of the string.
+| ^=       | For `string`, performs a "prepend" operation.  The contents of the _<rhs>_ are prepended to the _<attribute>_.  This is the opposite of `+=`.
+|          | For `octets`, perform logical "xor".  The value of the _<attribute>_ is "or"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
+| \|=      | Perform logical "or".  The value of the _<attribute>_ is "or"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
+| &=       | Perform logical "and".  The value of the _<attribute>_ is "and"ed with the contents of the _<rhs>_.  Both strings must be of the same length.
+| <\<=     | Perform left shift / truncation.  The first _<rhs>_ bytes of _<attribute>_ are dropped. i.e. shifted off of the start of the string.
+| >>=      | Perform right shift / truncation.  The last _<rhs>_ bytes of _<attribute>_ are dropped. i.e. shifted off of the end of the string.
 |=====
 
+Note that the `^=` operator behaves differently for `string` and
+`octets`.  The output of "xor"ing two strings is likely to be binary
+data, and therefore not a printable string.  As a result, it is more
+useful for strings to have `^-` be a "prepend" operation.
+
 // Copyright (C) 2021 Network RADIUS SAS.  Licenced under CC-by-NC 4.0.
 // Development of this documentation was sponsored by Network RADIUS SAS.
diff --git a/src/lib/util/calc.c b/src/lib/util/calc.c
index 276db9e8bd5..6043502c315 100644
--- a/src/lib/util/calc.c
+++ b/src/lib/util/calc.c
@@ -966,6 +966,18 @@ static int calc_string(TALLOC_CTX *ctx, fr_value_box_t *dst, fr_value_box_t cons
 		fr_value_box_bstrndup_shallow(dst, dst->enumv, buf, len, a->tainted | b->tainted);
 		break;
 
+	case T_XOR:		/* is prepend for strings */
+		buf = talloc_array(ctx, char, len + 1);
+		if (!buf) goto oom;
+
+		len = a->vb_length + b->vb_length;
+		memcpy(buf, b->vb_strvalue, b->vb_length);
+		memcpy(buf + b->vb_length, a->vb_strvalue, a->vb_length);
+		buf[len] = '\0';
+
+		fr_value_box_bstrndup_shallow(dst, dst->enumv, buf, len, a->tainted | b->tainted);
+		break;
+
 	case T_SUB:
 		/*
 		 *  The inverse of add!
diff --git a/src/tests/keywords/edit-string b/src/tests/keywords/edit-string
new file mode 100644
index 00000000000..e93921b6765
--- /dev/null
+++ b/src/tests/keywords/edit-string
@@ -0,0 +1,27 @@
+#
+#  PRE: edit
+#
+&Tmp-String-0 := "foo"
+&Tmp-String-0 ^= "bar"
+
+if (&Tmp-String-0 != "barfoo") {
+	test_fail
+}
+
+&Tmp-String-0 := "foo"
+&Tmp-String-0 += "bar"
+
+if (&Tmp-String-0 != "foobar") {
+	test_fail
+}
+
+#
+#  Subtract is the inverse of add.
+#
+&Tmp-String-0 -= "bar"
+
+if (&Tmp-String-0 != "foo") {
+	test_fail
+}
+
+success