Index: uspace/lib/posix/stdlib/strtol.c
===================================================================
--- uspace/lib/posix/stdlib/strtol.c	(revision 230fcfe45c32bef719d48089c7cb84cffedc15a2)
+++ uspace/lib/posix/stdlib/strtol.c	(revision 230fcfe45c32bef719d48089c7cb84cffedc15a2)
@@ -0,0 +1,253 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libposix
+ * @{
+ */
+/** @file
+ */
+
+#define LIBPOSIX_INTERNAL
+
+#include "../internal/common.h"
+#include "../stdlib.h"
+#include <errno.h>  // FIXME: use POSIX errno
+#include "../limits.h"
+#include "../ctype.h"
+
+// TODO: documentation
+
+static inline bool is_digit_in_base(int c, int base)
+{
+	if (base <= 10) {
+		return c >= '0' && c < '0' + base;
+	} else {
+		return isdigit(c) ||
+		    (tolower(c) >= 'a' && tolower(c) < ('a' + base - 10));
+	}
+}
+
+static inline int get_digit_in_base(int c, int base)
+{
+	if (c <= '9') {
+		return c - '0';
+	} else {
+		return 10 + tolower(c) - 'a';
+	}
+}
+
+static inline unsigned long long internal_strtol(
+    const char *restrict nptr, char **restrict endptr, int base,
+    const long long min_value, const unsigned long long max_value,
+    bool *restrict out_negative)
+{
+	if (nptr == NULL) {
+		errno = EINVAL;
+		return 0;
+	}
+	
+	if (base < 0 || base == 1 || base > 36) {
+		errno = EINVAL;
+		return 0;
+	}
+	
+	unsigned long long real_max_value = max_value;
+	
+	/* Current index in the input string. */
+	int i = 0;
+	bool negative = false;
+	
+	/* Skip whitespace. */
+	while (isspace(nptr[i])) {
+		i++;
+	}
+	
+	/* Parse sign. */
+	switch (nptr[i]) {
+	case '-':
+		negative = true;
+		real_max_value = -min_value;
+		/* fallthrough */
+	case '+':
+		i++;
+	}
+	
+	/* Figure out the base. */
+	switch (base) {
+	case 0:
+		if (nptr[i] == '0') {
+			if (tolower(nptr[i + 1]) == 'x') {
+				base = 16;
+				i += 2;
+			} else {
+				base = 8;
+			}
+		} else {
+			base = 10;
+		}
+		break;
+	case 16:
+		if (nptr[i] == '0' && tolower(nptr[i + 1]) == 'x') {
+			i += 2;
+		}
+		break;
+	}
+	
+	if (!is_digit_in_base(nptr[i], base)) {
+		/* No digits to parse, invalid input. */
+		
+		errno = EINVAL;
+		if (endptr != NULL) {
+			*endptr = (char *) nptr;
+		}
+		return 0;
+	}
+	
+	/* Maximal value to which a digit can be added without a risk
+	 * of overflow.
+	 */
+	unsigned long long max_safe_value = (real_max_value - base + 1) / base;
+	
+	unsigned long long result = 0;
+	
+	if (real_max_value == 0) {
+		/* Special case when a negative number is parsed as
+		 * unsigned integer. Only -0 is accepted.
+		 */
+		
+		while (is_digit_in_base(nptr[i], base)) {
+			if (nptr[i] != '0') {
+				errno = ERANGE;
+				result = max_value;
+			}
+			i++;
+		}
+	}
+	
+	while (is_digit_in_base(nptr[i], base)) {
+		int digit = get_digit_in_base(nptr[i], base);
+		
+		if (result > max_safe_value) {
+			/* corner case, check for overflow */
+			
+			unsigned long long
+			    boundary = (real_max_value - digit) / base;
+			
+			if (result > boundary) {
+				/* overflow */
+				errno = ERANGE;
+				result = max_value;
+				break;
+			}
+		}
+		
+		result = result * base + digit;
+		i++;
+	}
+	
+	if (endptr != NULL) {
+		/* Move the pointer to the end of the number,
+		 * in case it isn't there already.
+		 */
+		while (is_digit_in_base(nptr[i], base)) {
+			i++;
+		}
+		
+		*endptr = (char *) &nptr[i];
+	}
+	if (out_negative != NULL) {
+		*out_negative = negative;
+	}
+	return result;
+}
+
+int posix_atoi(const char *nptr)
+{
+	bool neg = false;
+	unsigned long long result =
+	    internal_strtol(nptr, NULL, 10, INT_MIN, INT_MAX, &neg);
+
+	return (int) (neg ? -result : result);
+}
+
+long posix_atol(const char *nptr)
+{
+	bool neg = false;
+	unsigned long long result =
+	    internal_strtol(nptr, NULL, 10, LONG_MIN, LONG_MAX, &neg);
+
+	return (long) (neg ? -result : result);
+}
+
+long long posix_atoll(const char *nptr)
+{
+	bool neg = false;
+	unsigned long long result =
+	    internal_strtol(nptr, NULL, 10, LLONG_MIN, LLONG_MAX, &neg);
+
+	return (long long) (neg ? -result : result);
+}
+
+long posix_strtol(const char *restrict nptr, char **restrict endptr, int base)
+{
+	bool neg = false;
+	unsigned long long result =
+	    internal_strtol(nptr, endptr, base, LONG_MIN, LONG_MAX, &neg);
+
+	return (long) (neg ? -result : result);
+}
+
+long long posix_strtoll(
+    const char *restrict nptr, char **restrict endptr, int base)
+{
+	bool neg = false;
+	unsigned long long result =
+	    internal_strtol(nptr, endptr, base, LLONG_MIN, LLONG_MAX, &neg);
+
+	return (long long) (neg ? -result : result);
+}
+
+unsigned long posix_strtoul(
+    const char *restrict nptr, char **restrict endptr, int base)
+{
+	unsigned long long result =
+	    internal_strtol(nptr, endptr, base, 0, ULONG_MAX, NULL);
+
+	return (unsigned long) result;
+}
+
+unsigned long long posix_strtoull(
+    const char *restrict nptr, char **restrict endptr, int base)
+{
+	return internal_strtol(nptr, endptr, base, 0, ULLONG_MAX, NULL);
+}
+
+
+/** @}
+ */
+