LunaCON: implement 'qsubstr' command. Add source/lunatic/test/qsubstr.con.

In C-CON's qsubstr, error if <start> is not in [0 .. MAXQUOTELEN-1]
or <length> is negative.

git-svn-id: https://svn.eduke32.com/eduke32@4583 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/source/gameexec.c

@@ -2083,6 +2083,18 @@ skip_check:
                     continue;
                 }
 
+                if ((unsigned)st >= MAXQUOTELEN)
+                {
+                    CON_ERRPRINTF("invalid start position %d\n", st);
+                    continue;
+                }
+
+                if (ln < 0)
+                {
+                    CON_ERRPRINTF("invalid length %d\n", ln);
+                    continue;
+                }
+
                 {
                     char *s1 = ScriptQuotes[q1];
                     char *s2 = ScriptQuotes[q2];

polymer/eduke32/source/lunatic/control.lua

@@ -713,6 +713,33 @@ function _qstrlen(qnum)
     return strlen(bcheck.quote_idx(qnum))
 end
 
+function _qsubstr(qdst, qsrc, start, length)
+    local cstr_dst = bcheck.quote_idx(qdst)
+    local cstr_src = bcheck.quote_idx(qsrc)
+
+    if (not (start >= 0 and start < MAXQUOTELEN)) then
+        error("invalid start position "..start, 2)
+    end
+
+    if (not (length >= 0)) then  -- NOTE: no check for start+length!
+        error("invalid length "..length, 2)
+    end
+
+    local si = 0
+    while (cstr_src[si] ~= 0 and si < start) do
+        si = si+1
+    end
+
+    for i=0,math.huge do
+        cstr_dst[i] = cstr_src[si + i]
+
+        if (si + i == MAXQUOTELEN-1 or i==length or cstr_dst[i] == 0) then
+            cstr_dst[i] = 0
+            break
+        end
+    end
+end
+
 function _qstrcpy(qdst, qsrc)
     local cstr_dst = bcheck.quote_idx(qdst)
     local cstr_src = bcheck.quote_idx(qsrc)

polymer/eduke32/source/lunatic/lunacon.lua

@@ -2667,7 +2667,7 @@ local Cinner = {
     qstrncat = cmd(R,R)
         / handle.NYI,
     qsubstr = cmd(R,R,R,R)
-        / handle.NYI,
+        / "_con._qsubstr(%1,%2,%3,%4)",
     quote = cmd(D)
         / "_con._quote(_pli,%1)",
     userquote = cmd(R)

polymer/eduke32/source/lunatic/test/qsubstr.con

@@ -0,0 +1,71 @@
+// Tests for the qsubstr command.
+// This one should be safe to run in C-CON.
+
+// overlong string at definition (should warn)
+define QSRC 400
+definequote QSRC -123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789-123456789=123456789
+define QSRC_SHORT 401
+definequote QSRC_SHORT -123456789
+
+define QDST 500
+definequote QDST
+
+// for gettimedate
+gamevar sec 0 0
+gamevar x 0 0
+
+onevent EVENT_ENTERLEVEL
+    // first, a plain, non-border-case call
+    qsubstr QDST QSRC 10 10  // -> "-123456789"
+    userquote QDST
+
+    // length zero yields the empty string
+    qsubstr QDST QSRC 20 0  // -> ""
+    userquote QDST
+
+    // start+length > strlen of source: no error
+    qsubstr QDST QSRC_SHORT 8 6  // -> "89"
+    userquote QDST
+
+    // start == strlen of source
+    qsubstr QDST QSRC_SHORT 10 1  // -> ""
+    userquote QDST
+
+    // Make QDST contain
+    // -123456789<NUL>123456789-...
+    qstrcpy QDST QSRC_SHORT
+    qstrcpy QSRC_SHORT QSRC
+    qstrcpy QSRC_SHORT QDST
+    userquote QSRC_SHORT  // -> "-123456789"
+
+    // start == strlen of source, trailing bytes after source <NUL>
+    qsubstr QDST QSRC_SHORT 10 2  // -> ""
+    userquote QDST
+
+    // start is beyond-<NUL> of the source
+    qsubstr QDST QSRC_SHORT 11 9  // -> ""
+    userquote QDST
+
+    // copy whole string (127 chars + 1 <NUL> == MAXQUOTELEN)
+    qsubstr QDST QSRC 0 1000  // -> "-123456789-123456789-...=123456"
+    userquote QDST
+
+    /** TESTS FOR source == dest **/
+
+    qsubstr QDST QDST 0 20  // -> "-123456789-123456789"
+    userquote QDST
+
+    qsubstr QDST QDST 5 10  // -> "56789-1234"
+    userquote QDST
+
+    /** TESTS FOR invalid input **/
+
+    gettimedate sec x x x x x x x
+    ifvarand sec 1
+        qsubstr QDST QSRC -1 10  // invalid start
+    else
+        qsubstr QDST QSRC 0 -1  // invalid length
+
+    // Reached only in C-CON:
+    qsubstr QDST QSRC 128 0  // invalid start
+endevent