add string functions:

 * isdigit
 * snprintf
 * vprintf
 * vsprintf
 * vsnprintf

include/kernel/string.h

@@ -8,9 +8,12 @@
 #define _KERNEL_STRING_H_
 
 #include <kernel/types.h>
+#include <stdarg.h>
+#include <limits.h>
 
 
 int sprintf(char *str, const char *format, ...);
+int snprintf(char *str, size_t size, const char *format, ...);
 int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t n);
 char *strpbrk(const char *s, const char *accept);
@@ -25,8 +28,14 @@ void *memcpy(void *dest, const void *src, size_t n);
 char *strcpy(char *dest, const char *src);
 void bzero(void *s, size_t n);
 
+int isdigit(int c);
 int isspace(int c);
 int atoi(const char *nptr);
 
 
+int vprintf(const char *format, va_list ap);
+int vsprintf(char *str, const char *format, va_list ap);
+int vsnprintf(char *str, size_t size, const char *format, va_list ap);
+
+
 #endif /* _KERNEL_STRING_H_ */

lib/Makefile

@@ -4,6 +4,7 @@ lib-$(CONFIG_PAGE_MAP)	+= page.o
 lib-$(CONFIG_AR)	+= ar.o
 lib-$(CONFIG_CHUNK)	+= chunk.o
 lib-y			+= string.o
+lib-y			+= vsnprintf.o
 lib-y			+= elf.o
 lib-y			+= data_proc_tracker.o
 lib-y			+= data_proc_task.o

lib/string.c

@@ -17,6 +17,7 @@
 #include <kernel/export.h>
 #include <kernel/types.h>
 #include <kernel/string.h>
+#include <kernel/printk.h>
 
 
 /**
@@ -25,7 +26,6 @@
  * @returns <0, 0 or > 0 if s1 is less than, matches or greater than s2
  */
 
-#include <kernel/printk.h>
 int strcmp(const char *s1, const char *s2)
 {
 	unsigned char c1, c2;
@@ -350,11 +350,6 @@ EXPORT_SYMBOL(bzero);
 
 
 
-#include <stdarg.h>
-#include <limits.h>
-
-int vsnprintf(char *str, size_t size, const char *format, va_list ap);
-
 /**
  * @brief print a string into a buffer
  *
@@ -380,6 +375,66 @@ int sprintf(char *str, const char *format, ...)
 EXPORT_SYMBOL(sprintf);
 
 
+/**
+ * @brief print a string into a buffer of a given maximum size
+ *
+ * @param str    the destination buffer
+ * @param size	 the size of the destination buffer
+ * @param format the format string buffer
+ * @param ...    arguments to the format string
+ *
+ * @return the number of characters written to buf
+ */
+
+int snprintf(char *str, size_t size, const char *format, ...)
+{
+	int n;
+	va_list ap;
+
+
+	va_start(ap, format);
+	n = vsnprintf(str, size, format, ap);
+	va_end(ap);
+
+	return n;
+}
+EXPORT_SYMBOL(snprintf);
+
+
+/**
+ * @brief format a string and print it into a buffer
+ *
+ * @param str    the destination buffer
+ * @param format the format string buffer
+ * @param ...    arguments to the format string
+ *
+ * @return the number of characters written to buf
+  */
+
+int vsprintf(char *str, const char *format, va_list ap)
+{
+	return vsnprintf(str, INT_MAX, format, ap);
+}
+EXPORT_SYMBOL(vsprintf);
+
+
+
+/**
+ * @brief format a string and print it to the standard output
+ *
+ * @param format the format string buffer
+ * @param ...    arguments to the format string
+ *
+ * @return the number of characters written to stdout
+  */
+
+int vprintf(const char *format, va_list ap)
+{
+	return vsnprintf(NULL, INT_MAX, format, ap);
+}
+EXPORT_SYMBOL(vprintf);
+
+
 /**
  * @brief check if a character is a white space
  *
@@ -416,6 +471,21 @@ int isspace(int c)
 }
 EXPORT_SYMBOL(isspace);
 
+
+/**
+ * @brief check if a character is a digit
+ *
+ * @param c the character to test
+ *
+ * @returns 0 if not a digit
+ */
+
+int isdigit(int c)
+{
+        return '0' <= c && c <= '9';
+}
+EXPORT_SYMBOL(isdigit);
+
 /**
  * @brief convert a string to an integer
  *