fix signed overflows at most-negative values in ato(i|l|ll)

patch by Pascal Cuoq (with minor tweaks to comments)

diff --git a/src/stdlib/atoi.c b/src/stdlib/atoi.c
index 648b154f134049558cd74f676a1835abfe706f6a..9baca7b895a0e2f5c3cfab1554f8dcdd280431b9 100644 (file)
--- a/src/stdlib/atoi.c
+++ b/src/stdlib/atoi.c
@@ -9,7 +9,8 @@ int atoi(const char *s)
        case '-': neg=1;
        case '+': s++;
        }
+       /* Compute n as a negative number to avoid overflow on INT_MIN */
        while (isdigit(*s))
-               n = 10*n + *s++ - '0';
-       return neg ? -n : n;
+               n = 10*n - (*s++ - '0');
+       return neg ? n : -n;
 }

diff --git a/src/stdlib/atol.c b/src/stdlib/atol.c
index 9c91bba9d915dbe1760918f7af76ab548b324717..140ea3ea3fa27ce690bd61d8a7520efa28e3aad1 100644 (file)
--- a/src/stdlib/atol.c
+++ b/src/stdlib/atol.c
@@ -10,7 +10,8 @@ long atol(const char *s)
        case '-': neg=1;
        case '+': s++;
        }
+       /* Compute n as a negative number to avoid overflow on LONG_MIN */
        while (isdigit(*s))
-               n = 10*n + *s++ - '0';
-       return neg ? -n : n;
+               n = 10*n - (*s++ - '0');
+       return neg ? n : -n;
 }

diff --git a/src/stdlib/atoll.c b/src/stdlib/atoll.c
index 0e03e0a1a9496b9c8e041c7a26fd4d63b1174bd3..b69304895a35c9143ec27ac61ec3a2d24c7a5a59 100644 (file)
--- a/src/stdlib/atoll.c
+++ b/src/stdlib/atoll.c
@@ -10,7 +10,8 @@ long long atoll(const char *s)
        case '-': neg=1;
        case '+': s++;
        }
+       /* Compute n as a negative number to avoid overflow on LLONG_MIN */
        while (isdigit(*s))
-               n = 10*n + *s++ - '0';
-       return neg ? -n : n;
+               n = 10*n - (*s++ - '0');
+       return neg ? n : -n;
 }