[reactos] 01/01: [CMD] Fix substring-substitute regression from commit cdc8e45b (use signed offsets).

[Hermès Bélusca-Maïto]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=f5ba9de2ee1ab825d9dd1…

commit f5ba9de2ee1ab825d9dd108fade57860db0fad79
Author:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
AuthorDate: Mon Sep 28 00:30:18 2020 +0200
Commit:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
CommitDate: Mon Sep 28 00:41:17 2020 +0200

    [CMD] Fix substring-substitute regression from commit cdc8e45b (use signed offsets).
---
 base/shell/cmd/cmd.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/base/shell/cmd/cmd.c b/base/shell/cmd/cmd.c
index a3253026f10..e92426d8cb3 100644
--- a/base/shell/cmd/cmd.c
+++ b/base/shell/cmd/cmd.c
@@ -1421,21 +1421,19 @@ do { \
     }
     else if (*Src == _T('~'))
     {
-        /* %VAR:~[start][,length]% - substring
+        /* %VAR:~[start][,length]% - Substring.
          * Negative values are offsets from the end.
          */
-        size_t Start = _tcstol(Src + 1, (PTSTR*)&Src, 0);
-        size_t End = VarLength;
+        SSIZE_T Start = _tcstol(Src + 1, (PTSTR*)&Src, 0);
+        SSIZE_T End = (SSIZE_T)VarLength;
         if (Start < 0)
             Start += VarLength;
-        Start = max(Start, 0);
-        Start = min(Start, VarLength);
+        Start = min(max(Start, 0), VarLength);
         if (*Src == _T(','))
         {
             End = _tcstol(Src + 1, (PTSTR*)&Src, 0);
             End += (End < 0) ? VarLength : Start;
-            End = max(End, Start);
-            End = min(End, VarLength);
+            End = min(max(End, Start), VarLength);
         }
         if (*Src++ != Delim)
             goto bad_subst;