[PATCH 4/6] tools/nolibc: fix integer overflow in i{64,}toa_r() and

[Thomas Weißschuh]

In twos complement the most negative number can not be negated.

Fixes: b1c21e7d99cd ("tools/nolibc/stdlib: add i64toa() and u64toa()")
Fixes: 66c397c4d2e1 ("tools/nolibc/stdlib: replace the ltoa() function with 
more efficient ones")
Signed-off-by: Thomas Weißschuh <li...@weissschuh.net>
---
 tools/include/nolibc/stdlib.h | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/tools/include/nolibc/stdlib.h b/tools/include/nolibc/stdlib.h
index 
86ad378ab1ea220559d5ab1adc4bb9972977ba9e..5e4b97810d49ac1b1bd79d6f779f6a748f188a39
 100644
--- a/tools/include/nolibc/stdlib.h
+++ b/tools/include/nolibc/stdlib.h
@@ -271,16 +271,12 @@ int utoa_r(unsigned long in, char *buffer)
 static __attribute__((unused))
 int itoa_r(long in, char *buffer)
 {
-       char *ptr = buffer;
-       int len = 0;
-
        if (in < 0) {
-               in = -in;
-               *(ptr++) = '-';
-               len++;
+               *(buffer++) = '-';
+               return 1 + utoa_r(-(unsigned long)in, buffer);
        }
-       len += utoa_r(in, ptr);
-       return len;
+
+       return utoa_r(in, buffer);
 }
 
 /* for historical compatibility, same as above but returns the pointer to the
@@ -407,16 +403,12 @@ int u64toa_r(uint64_t in, char *buffer)
 static __attribute__((unused))
 int i64toa_r(int64_t in, char *buffer)
 {
-       char *ptr = buffer;
-       int len = 0;
-
        if (in < 0) {
-               in = -in;
-               *(ptr++) = '-';
-               len++;
+               *(buffer++) = '-';
+               return 1 + u64toa_r(-(unsigned long long)in, buffer);
        }
-       len += u64toa_r(in, ptr);
-       return len;
+
+       return u64toa_r(in, buffer);
 }
 
 /* converts int64_t <in> to a string using the static itoa_buffer and returns

-- 
2.49.0