lib/kstrtox: common code between kstrto*() and simple_strto*() functions

Currently termination logic (\0 or \n\0) is hardcoded in _kstrtoull(),
avoid that for code reuse between kstrto*() and simple_strtoull().
Essentially, make them different only in termination logic.

simple_strtoull() (and scanf(), BTW) ignores integer overflow, that's a
bug we currently don't have guts to fix, making KSTRTOX_OVERFLOW hack
necessary.

Almost forgot: patch shrinks code size by about ~80 bytes on x86_64.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 68 insertions, 48 deletions

diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index 5e066759f55..7a94c8f14e2 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -18,26 +18,40 @@
 #include <linux/module.h>
 #include <linux/types.h>
 #include <asm/uaccess.h>
+#include "kstrtox.h"
 
-static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
+const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
 {
-        unsigned long long acc;
-        int ok;
-
-        if (base == 0) {
+        if (*base == 0) {
                 if (s[0] == '0') {
                         if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
-                                base = 16;
+                                *base = 16;
                         else
-                                base = 8;
+                                *base = 8;
                 } else
-                        base = 10;
+                        *base = 10;
         }
-        if (base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
+        if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
                 s += 2;
+        return s;
+}
 
-        acc = 0;
-        ok = 0;
+/*
+ * Convert non-negative integer string representation in explicitly given radix
+ * to an integer.
+ * Return number of characters consumed maybe or-ed with overflow bit.
+ * If overflow occurs, result integer (incorrect) is still returned.
+ *
+ * Don't you dare use this function.
+ */
+unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *res)
+{
+        unsigned int rv;
+        int overflow;
+
+        *res = 0;
+        rv = 0;
+        overflow = 0;
         while (*s) {
                 unsigned int val;
 
@@ -45,23 +59,40 @@ static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
                         val = *s - '0';
                 else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
                         val = _tolower(*s) - 'a' + 10;
-                else if (*s == '\n' && *(s + 1) == '\0')
-                        break;
                 else
-                        return -EINVAL;
+                        break;
 
                 if (val >= base)
-                        return -EINVAL;
-                if (acc > div_u64(ULLONG_MAX - val, base))
-                        return -ERANGE;
-                acc = acc * base + val;
-                ok = 1;
-
+                        break;
+                if (*res > div_u64(ULLONG_MAX - val, base))
+                        overflow = 1;
+                *res = *res * base + val;
+                rv++;
                 s++;
         }
-        if (!ok)
+        if (overflow)
+                rv |= KSTRTOX_OVERFLOW;
+        return rv;
+}
+
+static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
+{
+        unsigned long long _res;
+        unsigned int rv;
+
+        s = _parse_integer_fixup_radix(s, &base);
+        rv = _parse_integer(s, base, &_res);
+        if (rv & KSTRTOX_OVERFLOW)
+                return -ERANGE;
+        rv &= ~KSTRTOX_OVERFLOW;
+        if (rv == 0)
+                return -EINVAL;
+        s += rv;
+        if (*s == '\n')
+                s++;
+        if (*s)
                 return -EINVAL;
-        *res = acc;
+        *res = _res;
         return 0;
 }
 
diff --git a/lib/kstrtox.h b/lib/kstrtox.h
new file mode 100644
index 00000000000..f13eeeaf441
--- /dev/null
+++ b/lib/kstrtox.h
@@ -0,0 +1,8 @@
+#ifndef _LIB_KSTRTOX_H
+#define _LIB_KSTRTOX_H
+
+#define KSTRTOX_OVERFLOW        (1U << 31)
+const char *_parse_integer_fixup_radix(const char *s, unsigned int *base);
+unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *res);
+
+#endif
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d7222a9c826..c1a3927326e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -31,17 +31,7 @@
 #include <asm/div64.h>
 #include <asm/sections.h>       /* for dereference_function_descriptor() */
 
-static unsigned int simple_guess_base(const char *cp)
-{
-        if (cp[0] == '0') {
-                if (_tolower(cp[1]) == 'x' && isxdigit(cp[2]))
-                        return 16;
-                else
-                        return 8;
-        } else {
-                return 10;
-        }
-}
+#include "kstrtox.h"
 
 /**
  * simple_strtoull - convert a string to an unsigned long long
@@ -51,23 +41,14 @@ static unsigned int simple_guess_base(const char *cp)
  */
 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
 {
-        unsigned long long result = 0;
+        unsigned long long result;
+        unsigned int rv;
 
-        if (!base)
-                base = simple_guess_base(cp);
+        cp = _parse_integer_fixup_radix(cp, &base);
+        rv = _parse_integer(cp, base, &result);
+        /* FIXME */
+        cp += (rv & ~KSTRTOX_OVERFLOW);
 
-        if (base == 16 && cp[0] == '0' && _tolower(cp[1]) == 'x')
-                cp += 2;
-
-        while (isxdigit(*cp)) {
-                unsigned int value;
-
-                value = isdigit(*cp) ? *cp - '0' : _tolower(*cp) - 'a' + 10;
-                if (value >= base)
-                        break;
-                result = result * base + value;
-                cp++;
-        }
         if (endp)
                 *endp = (char *)cp;