Add GLib's regex library into Lua

While Lua's built-in pattern support is ok for simple things, many people end
up wanting a real regex engine. Since Wireshark already includes the GLib
Regex library (a wrapper for PCRE), it makes sense to expose that library to
Lua scripts. This has been done using Lrexlib, one of the most popular regex
bindings for Lua. Lrexlib didn't support binding GLib's Regex in particular -
it does for PCRE but GLib is a different API - so I've done that. A fairly
thorough testsuite came along with that, which has been incorporated into the
wireshark wslua testuites as well in this commit.

Change-Id: I05811d1edf7af8d7c9f4f081de6850f31c0717c7
Reviewed-on: https://code.wireshark.org/review/332
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 266 insertions, 0 deletions

diff --git a/epan/wslua/lrexlib.c b/epan/wslua/lrexlib.c
new file mode 100644
index 0000000000..21038fa1e3
--- /dev/null
+++ b/epan/wslua/lrexlib.c
@@ -0,0 +1,266 @@
+/* common.c */
+/* See Copyright Notice in the file LICENSE */
+
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include "lua.h"
+#include "lauxlib.h"
+#include "lrexlib.h"
+
+#define N_ALIGN sizeof(int)
+
+/* the table must be on Lua stack top */
+int get_int_field (lua_State *L, const char* field)
+{
+  int val;
+  lua_getfield (L, -1, field);
+  val = (int) lua_tointeger (L, -1);
+  lua_pop (L, 1);
+  return val;
+}
+
+/* the table must be on Lua stack top */
+void set_int_field (lua_State *L, const char* field, int val)
+{
+  lua_pushinteger (L, val);
+  lua_setfield (L, -2, field);
+}
+
+void *Lmalloc(lua_State *L, size_t size) {
+  void *ud;
+  lua_Alloc lalloc = lua_getallocf(L, &ud);
+  return lalloc(ud, NULL, 0, size);
+}
+
+void *Lrealloc(lua_State *L, void *p, size_t osize, size_t nsize) {
+  void *ud;
+  lua_Alloc lalloc = lua_getallocf(L, &ud);
+  return lalloc(ud, p, osize, nsize);
+}
+
+void Lfree(lua_State *L, void *p, size_t osize) {
+  void *ud;
+  lua_Alloc lalloc = lua_getallocf(L, &ud);
+  lalloc(ud, p, osize, 0);
+}
+
+/* This function fills a table with string-number pairs.
+   The table can be passed as the 1-st lua-function parameter,
+   otherwise it is created. The return value is the filled table.
+*/
+int get_flags (lua_State *L, const flag_pair **arrs) {
+  const flag_pair *p;
+  const flag_pair **pp;
+  int nparams = lua_gettop(L);
+
+  if(nparams == 0)
+    lua_newtable(L);
+  else {
+    if(!lua_istable(L, 1))
+      luaL_argerror(L, 1, "not a table");
+    if(nparams > 1)
+      lua_pushvalue(L, 1);
+  }
+
+  for(pp=arrs; *pp; ++pp) {
+    for(p=*pp; p->key; ++p) {
+      lua_pushstring(L, p->key);
+      lua_pushinteger(L, p->val);
+      lua_rawset(L, -3);
+    }
+  }
+  return 1;
+}
+
+const char *get_flag_key (const flag_pair *fp, int val) {
+  for (; fp->key; ++fp) {
+    if (fp->val == val)
+      return fp->key;
+  }
+  return NULL;
+}
+
+/* Classes */
+
+/*
+ *  class TFreeList
+ *  ***************
+ *  Simple array of pointers to TBuffer's.
+ *  The array has fixed capacity (not expanded automatically).
+ */
+
+void freelist_init (TFreeList *fl) {
+  fl->top = 0;
+}
+
+void freelist_add (TFreeList *fl, TBuffer *buf) {
+  fl->list[fl->top++] = buf;
+}
+
+void freelist_free (TFreeList *fl) {
+  while (fl->top > 0)
+    buffer_free (fl->list[--fl->top]);
+}
+
+/*
+ *  class TBuffer
+ *  *************
+ *  Auto-extensible array of characters for building long strings incrementally.
+ *    * Differs from luaL_Buffer in that:
+ *       *  its operations do not change Lua stack top position
+ *       *  buffer_addvalue does not extract the value from Lua stack
+ *       *  buffer_pushresult does not have to be the last operation
+ *    * Uses TFreeList class:
+ *       *  for inserting itself into a TFreeList instance for future clean-up
+ *       *  calls freelist_free prior to calling luaL_error.
+ *    * Has specialized "Z-operations" for maintaining mixed string/integer
+ *      array:  bufferZ_addlstring, bufferZ_addnum and bufferZ_next.
+ *       *  if the array is intended to be "mixed", then the methods
+ *          buffer_addlstring and buffer_addvalue must not be used
+ *          (the application will crash on bufferZ_next).
+ *       *  conversely, if the array is not intended to be "mixed",
+ *          then the method bufferZ_next must not be used.
+ */
+
+enum { ID_NUMBER, ID_STRING };
+
+void buffer_init (TBuffer *buf, size_t sz, lua_State *L, TFreeList *fl) {
+  buf->arr = Lmalloc(L, sz);
+  if (!buf->arr) {
+    freelist_free (fl);
+    luaL_error (L, "malloc failed");
+  }
+  buf->size = sz;
+  buf->top = 0;
+  buf->L = L;
+  buf->freelist = fl;
+  freelist_add (fl, buf);
+}
+
+void buffer_free (TBuffer *buf) {
+  Lfree(buf->L, buf->arr, buf->size);
+}
+
+void buffer_clear (TBuffer *buf) {
+  buf->top = 0;
+}
+
+void buffer_pushresult (TBuffer *buf) {
+  lua_pushlstring (buf->L, buf->arr, buf->top);
+}
+
+void buffer_addbuffer (TBuffer *trg, TBuffer *src) {
+  buffer_addlstring (trg, src->arr, src->top);
+}
+
+void buffer_addlstring (TBuffer *buf, const void *src, size_t sz) {
+  size_t newtop = buf->top + sz;
+  if (newtop > buf->size) {
+    char *p = (char*) Lrealloc (buf->L, buf->arr, buf->size, 2 * newtop);   /* 2x expansion */
+    if (!p) {
+      freelist_free (buf->freelist);
+      luaL_error (buf->L, "realloc failed");
+    }
+    buf->arr = p;
+    buf->size = 2 * newtop;
+  }
+  if (src)
+    memcpy (buf->arr + buf->top, src, sz);
+  buf->top = newtop;
+}
+
+void buffer_addvalue (TBuffer *buf, int stackpos) {
+  size_t len;
+  const char *p = lua_tolstring (buf->L, stackpos, &len);
+  buffer_addlstring (buf, p, len);
+}
+
+void bufferZ_addlstring (TBuffer *buf, const void *src, size_t len) {
+  int n;
+  size_t header[2] = { ID_STRING };
+  header[1] = len;
+  buffer_addlstring (buf, header, sizeof (header));
+  buffer_addlstring (buf, src, len);
+  n = len % N_ALIGN;
+  if (n) buffer_addlstring (buf, NULL, N_ALIGN - n);
+}
+
+void bufferZ_addnum (TBuffer *buf, size_t num) {
+  size_t header[2] = { ID_NUMBER };
+  header[1] = num;
+  buffer_addlstring (buf, header, sizeof (header));
+}
+
+/* 1. When called repeatedly on the same TBuffer, its existing data
+      is discarded and overwritten by the new data.
+   2. The TBuffer's array is never shrunk by this function.
+*/
+void bufferZ_putrepstring (TBuffer *BufRep, int reppos, int nsub) {
+  char dbuf[] = { 0, 0 };
+  size_t replen;
+  const char *p = lua_tolstring (BufRep->L, reppos, &replen);
+  const char *end = p + replen;
+  BufRep->top = 0;
+  while (p < end) {
+    const char *q;
+    for (q = p; q < end && *q != '%'; ++q)
+      {}
+    if (q != p)
+      bufferZ_addlstring (BufRep, p, q - p);
+    if (q < end) {
+      if (++q < end) {  /* skip % */
+        if (isdigit (*q)) {
+          int num;
+          *dbuf = *q;
+          num = (int) strtol (dbuf, NULL, 10);
+          if (num == 1 && nsub == 0)
+            num = 0;
+          else if (num > nsub) {
+            freelist_free (BufRep->freelist);
+            luaL_error (BufRep->L, "invalid capture index");
+          }
+          bufferZ_addnum (BufRep, num);
+        }
+        else bufferZ_addlstring (BufRep, q, 1);
+      }
+      p = q + 1;
+    }
+    else break;
+  }
+}
+
+/******************************************************************************
+  The intended use of this function is as follows:
+        size_t iter = 0;
+        while (bufferZ_next (buf, &iter, &num, &str)) {
+          if (str) do_something_with_string (str, num);
+          else     do_something_with_number (num);
+        }
+*******************************************************************************
+*/
+int bufferZ_next (TBuffer *buf, size_t *iter, size_t *num, const char **str) {
+  if (*iter < buf->top) {
+    size_t *ptr_header = (size_t*)(buf->arr + *iter);
+    *num = ptr_header[1];
+    *iter += 2 * sizeof (size_t);
+    *str = NULL;
+    if (*ptr_header == ID_STRING) {
+      int n;
+      *str = buf->arr + *iter;
+      *iter += *num;
+      n = *iter % N_ALIGN;
+      if (n) *iter += (N_ALIGN - n);
+    }
+    return 1;
+  }
+  return 0;
+}
+
+#if LUA_VERSION_NUM > 501
+int luaL_typerror (lua_State *L, int narg, const char *tname) {
+  const char *msg = lua_pushfstring(L, "%s expected, got %s",
+                                    tname, luaL_typename(L, narg));
+  return luaL_argerror(L, narg, msg);
+}
+#endif