[kvm-unit-tests PATCH v2 1/3] lib/string: Add stroull and strtoll

[<ahmeddan@amazon.com>]

From: Daniele Ahmed <ahmeddan@amazon.com>

Add the two functions strtoull and strtoll.
This is in preparation for an update
in x86/msr.c to write 64b values
that are given as inputs as strings by
a user.

Signed-off-by: Daniele Ahmed <ahmeddan@amazon.com>
---
 lib/stdlib.h |  2 ++
 lib/string.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)

diff --git a/lib/stdlib.h b/lib/stdlib.h
index 33c00e8..48e10f0 100644
--- a/lib/stdlib.h
+++ b/lib/stdlib.h
@@ -9,5 +9,7 @@
 
 long int strtol(const char *nptr, char **endptr, int base);
 unsigned long int strtoul(const char *nptr, char **endptr, int base);
+long long int strtoll(const char *nptr, char **endptr, int base);
+unsigned long long strtoull(const char *nptr, char **endptr, int base);
 
 #endif /* _STDLIB_H_ */
diff --git a/lib/string.c b/lib/string.c
index ffc7c7e..dacd927 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -242,6 +242,80 @@ unsigned long int strtoul(const char *nptr, char **endptr, int base)
     return __strtol(nptr, endptr, base, false);
 }
 
+static unsigned long long __strtoll(const char *nptr, char **endptr,
+                              int base, bool is_signed) {
+    unsigned long long acc = 0;
+    const char *s = nptr;
+    int neg, c;
+
+    assert(base == 0 || (base >= 2 && base <= 36));
+
+    while (isspace(*s))
+        s++;
+
+    if (*s == '-') {
+        neg = 1;
+        s++;
+    } else {
+        neg = 0;
+        if (*s == '+')
+            s++;
+    }
+
+    if (base == 0 || base == 16) {
+        if (*s == '0') {
+            s++;
+            if (*s == 'x' || *s == 'X') {
+                 s++;
+                 base = 16;
+            } else if (base == 0)
+                 base = 8;
+        } else if (base == 0)
+            base = 10;
+    }
+
+    while (*s) {
+        if (*s >= '0' && *s < '0' + base && *s <= '9')
+            c = *s - '0';
+        else if (*s >= 'a' && *s < 'a' + base - 10)
+            c = *s - 'a' + 10;
+        else if (*s >= 'A' && *s < 'A' + base - 10)
+            c = *s - 'A' + 10;
+        else
+            break;
+
+        if (is_signed) {
+            long long sacc = (long long)acc;
+            assert(!check_mul_overflow(sacc, base));
+            assert(!check_add_overflow(sacc * base, c));
+        } else {
+            assert(!check_mul_overflow(acc, base));
+            assert(!check_add_overflow(acc * base, c));
+        }
+
+        acc = acc * base + c;
+        s++;
+    }
+
+    if (neg)
+        acc = -acc;
+
+    if (endptr)
+        *endptr = (char *)s;
+
+    return acc;
+}
+
+long long int strtoll(const char *nptr, char **endptr, int base)
+{
+    return __strtoll(nptr, endptr, base, true);
+}
+
+unsigned long long int strtoull(const char *nptr, char **endptr, int base)
+{
+    return __strtoll(nptr, endptr, base, false);
+}
+
 long atol(const char *ptr)
 {
     return strtol(ptr, NULL, 10);
-- 
2.32.0




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