From 2327b87304055e29e466d5653420bf35578cbedd Mon Sep 17 00:00:00 2001
From: Adam Sutton <dev@adamsutton.me.uk>
Date: Sun, 23 Jun 2013 13:34:01 +0100
Subject: [PATCH] misc: fix and simplify string procesing bug

previously this could create wildly inaccurate results for numbers with
a larger number of fractional digits. Combined with inaccuracy of representing
some numbers this could result in a roundtrip str -> double -> str ending
up with complete garbage.
---
 src/misc/dbl.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/misc/dbl.c b/src/misc/dbl.c
index 05e5a6dd..a3fed6e3 100644
--- a/src/misc/dbl.c
+++ b/src/misc/dbl.c
@@ -31,31 +31,32 @@
 double
 my_str2double(const char *str, const char **endp)
 {
-  double ret = 1.0f;
-  int n = 0, m = 0, o = 0, e = 0;
+  double ret = 0.0, t = 0.1;
+  int n = 0, e = 0;
 
+  /* Negative */
   if(*str == '-') {
-    ret = -1.0f;
+    n = 1;
     str++;
   }
 
+  /* Integer */
   while(*str >= '0' && *str <= '9')
-    n = n * 10 + *str++ - '0';
-
-  if(*str != '.') {
-    ret *= n;
-  } else {
+    ret = ret * 10 + *str++ - '0';
 
+  /* Fracton */
+  if(*str == '.') {
     str++;
-
     while(*str >= '0' && *str <= '9') {
-      o = o * 10 + *str++ - '0';
-      m--;
+      ret += (*str++ - '0') * t;
+      t /= 10;
     }
-
-    ret *= (n + pow(10, m) * o);
   }
 
+  /* Negate */
+  if (n) ret *= -1;
+
+  /* Exponential */
   if(*str == 'e' || *str == 'E') {
     int esign = 1;
     str++;