Lua replace fscanf

Rocklua was using the full fscanf implementation
to simply read %ld for the file:read("*n") function
wasting 1k on unneeded/unused functionality

Instead, I've implemented a filetol function to duplicate it
without the extra overhead using strtol which as an added bonus
ERANGE errors now resolve to LONG_MIN and LONGMAX instead of
integer overflow

filetol()
   reads long int from an open file, skips preceding
   whitespaces returns -1 if error, 1 on success.
   *num set to LONG_MAX or LONG_MIN on overflow.
   If number of digits is > than LUAI_MAXNUMBER2STR
   filepointer will continue till the next non digit
   but buffer will stop being filled with characters.
   Preceding zero is ignored.

Change-Id: Ia42d0f73c63a894625bca4581e9b7e1cc7387fd2

1 files changed, 63 insertions, 0 deletions

diff --git a/apps/plugins/lua/rockaux.c b/apps/plugins/lua/rockaux.c
index ba3a37343b..562d1654a7 100644
--- a/apps/plugins/lua/rockaux.c
+++ b/apps/plugins/lua/rockaux.c
@@ -8,6 +8,7 @@
  * $Id$
  *
  * Copyright (C) 2008 Dan Everton (safetydan)
+ * Copyright (C) 2018 William Wilgus
  * String function implementations taken from dietlibc 0.31 (GPLv2 License)
  *
  * This program is free software; you can redistribute it and/or
@@ -24,6 +25,8 @@
 #define _ROCKCONF_H_ /* Protect against unwanted include */
 #include "lua.h"
 
+extern long strtol(const char *nptr, char **endptr, int base);
+
 #if (CONFIG_PLATFORM & PLATFORM_NATIVE)
 int errno = 0;
 #endif
@@ -101,3 +104,63 @@ int get_current_path(lua_State *L, int level)
     lua_pushnil(L);    
     return 1;
 }
+
+/* filetol()
+   reads long int from an open file, skips preceding
+   whitespaces returns -1 if error, 1 on success.
+   *num set to LONG_MAX or LONG_MIN on overflow.
+   If number of digits is > than LUAI_MAXNUMBER2STR
+   filepointer will continue till the next non digit
+   but buffer will stop being filled with characters.
+   Preceding zero is ignored
+*/
+int filetol(int fd, long *num)
+{
+    static char buffer[LUAI_MAXNUMBER2STR];
+    int    retn = -1;
+    char   chbuf = 0;
+    size_t count = 0;
+    bool   neg   = false;
+    long   val;
+
+    while (rb->read(fd, &chbuf, 1) == 1)
+    {
+        if(!isspace(chbuf) || retn == 1)
+        {
+            if(chbuf == '0') /* strip preceeding zeros */
+            {
+                *num = 0;
+                retn = 1;
+            }
+            else if(chbuf == '-' && retn != 1)
+                neg = true;
+            else
+            {
+                rb->lseek(fd, -1, SEEK_CUR);
+                break;
+            }
+        }
+    }
+
+    while (rb->read(fd, &chbuf, 1) == 1)
+    {
+        if(!isdigit(chbuf))
+        {
+            rb->lseek(fd, -1, SEEK_CUR);
+            break;
+        }
+        else if (count < LUAI_MAXNUMBER2STR - 2)
+            buffer[count++] = chbuf;
+    }
+
+    if(count)
+    {
+        buffer[count] = '\0';
+        val = strtol(buffer, NULL, 10);
+        *num = (neg)? -val:val;
+        retn = 1;
+    }
+
+    return retn;
+}
+