implode: Better invalid input validation and handling

Error on non-number and nan codepoint, would asserd before
Replace negative codepoint and surrogate range with unicode replacement character, would assert before

Fixes #1160

4 files changed, 25 insertions, 3 deletions

diff --git a/src/builtin.c b/src/builtin.c
index 3e99c376..8e1de2b5 100644
--- a/src/builtin.c
+++ b/src/builtin.c
@@ -1201,7 +1201,28 @@ static jv f_string_implode(jq_state *jq, jv a) {
   if (jv_get_kind(a) != JV_KIND_ARRAY) {
     return ret_error(a, jv_string("implode input must be an array"));
   }
-  return jv_string_implode(a);
+
+  int len = jv_array_length(jv_copy(a));
+  jv s = jv_string_empty(len);
+
+  for (int i = 0; i < len; i++) {
+    jv n = jv_array_get(jv_copy(a), i);
+    if (jv_get_kind(n) != JV_KIND_NUMBER || jvp_number_is_nan(n)) {
+      jv_free(a);
+      jv_free(s);
+      return type_error(n, "can't be imploded, unicode codepoint needs to be numeric");
+    }
+
+    int nv = jv_number_value(n);
+    jv_free(n);
+    // outside codepoint range or in utf16 surrogate pair range
+    if (nv < 0 || nv > 0x10FFFF || (nv >= 0xD800 && nv <= 0xDFFF))
+      nv = 0xFFFD; // U+FFFD REPLACEMENT CHARACTER
+    s = jv_string_append_codepoint(s, nv);
+  }
+
+  jv_free(a);
+  return s;
 }
 
 static jv f_setpath(jq_state *jq, jv a, jv b, jv c) { return jv_setpath(a, b, c); }
diff --git a/src/jv.c b/src/jv.c
index 159b3f27..b4ee8a2e 100644
--- a/src/jv.c
+++ b/src/jv.c
@@ -1368,7 +1368,8 @@ jv jv_string_implode(jv j) {
     assert(JVP_HAS_KIND(n, JV_KIND_NUMBER));
     int nv = jv_number_value(n);
     jv_free(n);
-    if (nv > 0x10FFFF)
+    // outside codepoint range or in utf16 surrogate pair range
+    if (nv < 0 || nv > 0x10FFFF || (nv >= 0xD800 && nv <= 0xDFFF))
       nv = 0xFFFD; // U+FFFD REPLACEMENT CHARACTER
     s = jv_string_append_codepoint(s, nv);
   }
diff --git a/src/jv.h b/src/jv.h
index 8c96f822..446ffb06 100644
--- a/src/jv.h
+++ b/src/jv.h
@@ -63,6 +63,7 @@ jv jv_number(double);
 jv jv_number_with_literal(const char*);
 double jv_number_value(jv);
 int jv_is_integer(jv);
+int jvp_number_is_nan(jv);
 
 int jv_number_has_literal(jv n);
 const char* jv_number_get_literal(jv);
diff --git a/src/jv_type_private.h b/src/jv_type_private.h
index 5996282b..a25254dc 100644
--- a/src/jv_type_private.h
+++ b/src/jv_type_private.h
@@ -2,6 +2,5 @@
 #define JV_TYPE_PRIVATE
 
 int jvp_number_cmp(jv, jv);
-int jvp_number_is_nan(jv);
 
 #endif //JV_TYPE_PRIVATE