libpayload: BSD solutions contributed by Uwe
[coreboot.git] / payloads / libpayload / libc / printf.c
diff --git a/payloads/libpayload/libc/printf.c b/payloads/libpayload/libc/printf.c
new file mode 100644 (file)
index 0000000..8be713c
--- /dev/null
@@ -0,0 +1,816 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * It has originally been taken from the HelenOS project
+ * (http://www.helenos.eu), and slightly modified for our purposes.
+ *
+ * Copyright (C) 2001-2004 Jakub Jermar
+ * Copyright (C) 2006 Josef Cejka
+ * Copyright (C) 2008 Uwe Hermann <uwe@hermann-uwe.de>
+ * 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.
+ */
+
+#include <libpayload.h>
+#include <stdarg.h>
+
+/** Structure for specifying output methods for different printf clones. */
+struct printf_spec {
+       /* Output function, returns count of printed characters or EOF. */
+       int (*write) (void *, size_t, void *);
+       /* Support data - output stream specification, its state, locks, ... */
+       void *data;
+};
+
+/** Show prefixes 0x or 0. */
+#define __PRINTF_FLAG_PREFIX           0x00000001
+/** Signed / unsigned number. */
+#define __PRINTF_FLAG_SIGNED           0x00000002
+/** Print leading zeroes. */
+#define __PRINTF_FLAG_ZEROPADDED       0x00000004
+/** Align to left. */
+#define __PRINTF_FLAG_LEFTALIGNED      0x00000010
+/** Always show + sign. */
+#define __PRINTF_FLAG_SHOWPLUS         0x00000020
+/** Print space instead of plus. */
+#define __PRINTF_FLAG_SPACESIGN                0x00000040
+/** Show big characters. */
+#define __PRINTF_FLAG_BIGCHARS         0x00000080
+/** Number has - sign. */
+#define __PRINTF_FLAG_NEGATIVE         0x00000100
+
+/**
+ * Buffer big enough for 64-bit number printed in base 2, sign, prefix and 0
+ * to terminate string (last one is only for better testing end of buffer by
+ * zero-filling subroutine).
+ */
+#define PRINT_NUMBER_BUFFER_SIZE       (64 + 5)
+
+/** Enumeration of possible arguments types. */
+typedef enum {
+       PrintfQualifierByte = 0,
+       PrintfQualifierShort,
+       PrintfQualifierInt,
+       PrintfQualifierLong,
+       PrintfQualifierLongLong,
+       PrintfQualifierPointer,
+} qualifier_t;
+
+static char digits_small[] = "0123456789abcdef";
+static char digits_big[] = "0123456789ABCDEF";
+
+/**
+ * Print one or more characters without adding newline.
+ *
+ * @param buf  Buffer of >= count bytesi size. NULL pointer is not allowed!
+ * @param count        Number of characters to print.
+ * @param ps   Output method and its data.
+ * @return     Number of characters printed.
+ */
+static int printf_putnchars(const char *buf, size_t count,
+                           struct printf_spec *ps)
+{
+       return ps->write((void *)buf, count, ps->data);
+}
+
+/**
+ * Print a string without adding a newline.
+ *
+ * @param str  String to print.
+ * @param ps   Write function specification and support data.
+ * @return     Number of characters printed.
+ */
+static int printf_putstr(const char *str, struct printf_spec *ps)
+{
+       size_t count;
+
+       if (str == NULL) {
+               char *nullstr = "(NULL)";
+               return printf_putnchars(nullstr, strlen(nullstr), ps);
+       }
+
+       count = strlen(str);
+
+       return ps->write((void *)str, count, ps->data);
+}
+
+/**
+ * Print one character.
+ *
+ * @param c    Character to be printed.
+ * @param ps   Output method.
+ * @return     Number of characters printed.
+ */
+static int printf_putchar(int c, struct printf_spec *ps)
+{
+       unsigned char ch = c;
+
+       return ps->write((void *)&ch, 1, ps->data);
+}
+
+/**
+ * Print one formatted character.
+ *
+ * @param c    Character to print.
+ * @param width        Width modifier.
+ * @param flags        Flags that change the way the character is printed.
+ * @return     Number of characters printed, negative value on failure.
+ */
+static int print_char(char c, int width, uint64_t flags, struct printf_spec *ps)
+{
+       int counter = 0;
+
+       if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
+               while (--width > 0) {
+                       if (printf_putchar(' ', ps) > 0)
+                               ++counter;
+               }
+       }
+
+       if (printf_putchar(c, ps) > 0)
+               counter++;
+
+       while (--width > 0) {
+               if (printf_putchar(' ', ps) > 0)
+                       ++counter;
+       }
+
+       return ++counter;
+}
+
+/**
+ * Print string.
+ *
+ * @param s            String to be printed.
+ * @param width                Width modifier.
+ * @param precision    Precision modifier.
+ * @param flags                Flags that modify the way the string is printed.
+ * @return             Number of characters printed, negative value on failure.
+ */
+static int print_string(char *s, int width, unsigned int precision,
+                       uint64_t flags, struct printf_spec *ps)
+{
+       int counter = 0, retval;
+       size_t size;
+
+       if (s == NULL)
+               return printf_putstr("(NULL)", ps);
+       size = strlen(s);
+       /* Print leading spaces. */
+       if (precision == 0)
+               precision = size;
+       width -= precision;
+
+       if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
+               while (width-- > 0) {
+                       if (printf_putchar(' ', ps) == 1)
+                               counter++;
+               }
+       }
+
+       if ((retval = printf_putnchars(s, MIN(size, precision), ps)) < 0)
+               return -counter;
+       counter += retval;
+
+       while (width-- > 0) {
+               if (printf_putchar(' ', ps) == 1)
+                       ++counter;
+       }
+
+       return counter;
+}
+
+/**
+ * Print a number in a given base.
+ *
+ * Print significant digits of a number in given base.
+ *
+ * @param num          Number to print.
+ * @param widt         Width modifier.h
+ * @param precision    Precision modifier.
+ * @param base         Base to print the number in (must be between 2 and 16).
+ * @param flags                Flags that modify the way the number is printed.
+ * @return             Number of characters printed.
+ */
+static int print_number(uint64_t num, int width, int precision, int base,
+                       uint64_t flags, struct printf_spec *ps)
+{
+       char *digits = digits_small;
+       char d[PRINT_NUMBER_BUFFER_SIZE];
+       char *ptr = &d[PRINT_NUMBER_BUFFER_SIZE - 1];
+       int size = 0;           /* Size of number with all prefixes and signs. */
+       int number_size;        /* Size of plain number. */
+       char sgn;
+       int retval;
+       int counter = 0;
+
+       if (flags & __PRINTF_FLAG_BIGCHARS)
+               digits = digits_big;
+
+       *ptr-- = 0;             /* Put zero at end of string. */
+
+       if (num == 0) {
+               *ptr-- = '0';
+               size++;
+       } else {
+               do {
+                       *ptr-- = digits[num % base];
+                       size++;
+               } while (num /= base);
+       }
+
+       number_size = size;
+
+       /*
+        * Collect the sum of all prefixes/signs/... to calculate padding and
+        * leading zeroes.
+        */
+       if (flags & __PRINTF_FLAG_PREFIX) {
+               switch (base) {
+               case 2: /* Binary formating is not standard, but useful. */
+                       size += 2;
+                       break;
+               case 8:
+                       size++;
+                       break;
+               case 16:
+                       size += 2;
+                       break;
+               }
+       }
+
+       sgn = 0;
+       if (flags & __PRINTF_FLAG_SIGNED) {
+               if (flags & __PRINTF_FLAG_NEGATIVE) {
+                       sgn = '-';
+                       size++;
+               } else if (flags & __PRINTF_FLAG_SHOWPLUS) {
+                       sgn = '+';
+                       size++;
+               } else if (flags & __PRINTF_FLAG_SPACESIGN) {
+                       sgn = ' ';
+                       size++;
+               }
+       }
+
+       if (flags & __PRINTF_FLAG_LEFTALIGNED)
+               flags &= ~__PRINTF_FLAG_ZEROPADDED;
+
+       /*
+        * If the number is leftaligned or precision is specified then
+        * zeropadding is ignored.
+        */
+       if (flags & __PRINTF_FLAG_ZEROPADDED) {
+               if ((precision == 0) && (width > size))
+                       precision = width - size + number_size;
+       }
+
+       /* Print leading spaces. */
+       if (number_size > precision) {
+               /* Print the whole number not only a part. */
+               precision = number_size;
+       }
+
+       width -= precision + size - number_size;
+
+       if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
+               while (width-- > 0) {
+                       if (printf_putchar(' ', ps) == 1)
+                               counter++;
+               }
+       }
+
+       /* Print sign. */
+       if (sgn) {
+               if (printf_putchar(sgn, ps) == 1)
+                       counter++;
+       }
+
+       /* Print prefix. */
+       if (flags & __PRINTF_FLAG_PREFIX) {
+               switch (base) {
+               case 2: /* Binary formating is not standard, but useful. */
+                       if (printf_putchar('0', ps) == 1)
+                               counter++;
+                       if (flags & __PRINTF_FLAG_BIGCHARS) {
+                               if (printf_putchar('B', ps) == 1)
+                                       counter++;
+                       } else {
+                               if (printf_putchar('b', ps) == 1)
+                                       counter++;
+                       }
+                       break;
+               case 8:
+                       if (printf_putchar('o', ps) == 1)
+                               counter++;
+                       break;
+               case 16:
+                       if (printf_putchar('0', ps) == 1)
+                               counter++;
+                       if (flags & __PRINTF_FLAG_BIGCHARS) {
+                               if (printf_putchar('X', ps) == 1)
+                                       counter++;
+                       } else {
+                               if (printf_putchar('x', ps) == 1)
+                                       counter++;
+                       }
+                       break;
+               }
+       }
+
+       /* Print leading zeroes. */
+       precision -= number_size;
+       while (precision-- > 0) {
+               if (printf_putchar('0', ps) == 1)
+                       counter++;
+       }
+
+       /* Print number itself. */
+       if ((retval = printf_putstr(++ptr, ps)) > 0)
+               counter += retval;
+
+       /* Print ending spaces. */
+       while (width-- > 0) {
+               if (printf_putchar(' ', ps) == 1)
+                       counter++;
+       }
+
+       return counter;
+}
+
+/** Print formatted string.
+ *
+ * Print string formatted according to the fmt parameter and variadic arguments.
+ * Each formatting directive must have the following form:
+ * 
+ *     \% [ FLAGS ] [ WIDTH ] [ .PRECISION ] [ TYPE ] CONVERSION
+ *
+ * FLAGS:@n
+ *     - "#"   Force to print prefix.For \%o conversion, the prefix is 0, for
+ *             \%x and \%X prefixes are 0x and 0X and for conversion \%b the
+ *             prefix is 0b.
+ *
+ *     - "-"   Align to left.
+ *
+ *     - "+"   Print positive sign just as negative.
+ *
+ *     - " "   If the printed number is positive and "+" flag is not set,
+ *             print space in place of sign.
+ *
+ *     - "0"   Print 0 as padding instead of spaces. Zeroes are placed between
+ *             sign and the rest of the number. This flag is ignored if "-"
+ *             flag is specified.
+ * 
+ * WIDTH:@n
+ *     - Specify the minimal width of a printed argument. If it is bigger,
+ *     width is ignored. If width is specified with a "*" character instead of
+ *     number, width is taken from parameter list. And integer parameter is
+ *     expected before parameter for processed conversion specification. If
+ *     this value is negative its absolute value is taken and the "-" flag is
+ *     set.
+ *
+ * PRECISION:@n
+ *     - Value precision. For numbers it specifies minimum valid numbers.
+ *     Smaller numbers are printed with leading zeroes. Bigger numbers are not
+ *     affected. Strings with more than precision characters are cut off. Just
+ *     as with width, an "*" can be used used instead of a number. An integer
+ *     value is then expected in parameters. When both width and precision are
+ *     specified using "*", the first parameter is used for width and the
+ *     second one for precision.
+ * 
+ * TYPE:@n
+ *     - "hh"  Signed or unsigned char.@n
+ *     - "h"   Signed or unsigned short.@n
+ *     - ""    Signed or unsigned int (default value).@n
+ *     - "l"   Signed or unsigned long int.@n
+ *     - "ll"  Signed or unsigned long long int.@n
+ * 
+ * 
+ * CONVERSION:@n
+ *     - %     Print percentile character itself.
+ *
+ *     - c     Print single character.
+ *
+ *     - s     Print zero terminated string. If a NULL value is passed as
+ *             value, "(NULL)" is printed instead.
+ * 
+ *     - P, p  Print value of a pointer. Void * value is expected and it is
+ *             printed in hexadecimal notation with prefix (as with \%#X / \%#x
+ *             for 32-bit or \%#X / \%#x for 64-bit long pointers).
+ *
+ *     - b     Print value as unsigned binary number. Prefix is not printed by
+ *             default. (Nonstandard extension.)
+ * 
+ *     - o     Print value as unsigned octal number. Prefix is not printed by
+ *             default. 
+ *
+ *     - d, i  Print signed decimal number. There is no difference between d
+ *             and i conversion.
+ *
+ *     - u     Print unsigned decimal number.
+ *
+ *     - X, x  Print hexadecimal number with upper- or lower-case. Prefix is
+ *             not printed by default.
+ * 
+ * All other characters from fmt except the formatting directives are printed in
+ * verbatim.
+ *
+ * @param fmt  Formatting NULL terminated string.
+ * @param ps   TODO.
+ * @param ap   TODO.
+ * @return     Number of characters printed, negative value on failure.
+ */
+static int printf_core(const char *fmt, struct printf_spec *ps, va_list ap)
+{
+       int i = 0;              /* Index of the currently processed char from fmt */
+       int j = 0;              /* Index to the first not printed nonformating character */
+       int end;
+       int counter;            /* Counter of printed characters */
+       int retval;             /* Used to store return values from called functions */
+       char c;
+       qualifier_t qualifier;  /* Type of argument */
+       int base;               /* Base in which a numeric parameter will be printed */
+       uint64_t number;        /* Argument value */
+       size_t size;            /* Byte size of integer parameter */
+       int width, precision;
+       uint64_t flags;
+
+       counter = 0;
+
+       while ((c = fmt[i])) {
+               /* Control character. */
+               if (c == '%') {
+                       /* Print common characters if any processed. */
+                       if (i > j) {
+                               if ((retval = printf_putnchars(&fmt[j],
+                                   (size_t) (i - j), ps)) < 0) {
+                                       counter = -counter;
+                                       goto out;       /* Error */
+                               }
+                               counter += retval;
+                       }
+
+                       j = i;
+                       /* Parse modifiers. */
+                       flags = 0;
+                       end = 0;
+
+                       do {
+                               ++i;
+                               switch (c = fmt[i]) {
+                               case '#':
+                                       flags |= __PRINTF_FLAG_PREFIX;
+                                       break;
+                               case '-':
+                                       flags |= __PRINTF_FLAG_LEFTALIGNED;
+                                       break;
+                               case '+':
+                                       flags |= __PRINTF_FLAG_SHOWPLUS;
+                                       break;
+                               case ' ':
+                                       flags |= __PRINTF_FLAG_SPACESIGN;
+                                       break;
+                               case '0':
+                                       flags |= __PRINTF_FLAG_ZEROPADDED;
+                                       break;
+                               default:
+                                       end = 1;
+                               };
+
+                       } while (end == 0);
+
+                       /* Width & '*' operator. */
+                       width = 0;
+                       if (isdigit(fmt[i])) {
+                               while (isdigit(fmt[i])) {
+                                       width *= 10;
+                                       width += fmt[i++] - '0';
+                               }
+                       } else if (fmt[i] == '*') {
+                               /* Get width value from argument list. */
+                               i++;
+                               width = (int)va_arg(ap, int);
+                               if (width < 0) {
+                                       /* Negative width sets '-' flag. */
+                                       width *= -1;
+                                       flags |= __PRINTF_FLAG_LEFTALIGNED;
+                               }
+                       }
+
+                       /* Precision and '*' operator. */
+                       precision = 0;
+                       if (fmt[i] == '.') {
+                               ++i;
+                               if (isdigit(fmt[i])) {
+                                       while (isdigit(fmt[i])) {
+                                               precision *= 10;
+                                               precision += fmt[i++] - '0';
+                                       }
+                               } else if (fmt[i] == '*') {
+                                       /* Get precision from argument list. */
+                                       i++;
+                                       precision = (int)va_arg(ap, int);
+                                       /* Ignore negative precision. */
+                                       if (precision < 0)
+                                               precision = 0;
+                               }
+                       }
+
+                       switch (fmt[i++]) {
+                       /** @todo unimplemented qualifiers:
+                        * t ptrdiff_t - ISO C 99
+                        */
+                       case 'h':       /* char or short */
+                               qualifier = PrintfQualifierShort;
+                               if (fmt[i] == 'h') {
+                                       i++;
+                                       qualifier = PrintfQualifierByte;
+                               }
+                               break;
+                       case 'l':       /* long or long long */
+                               qualifier = PrintfQualifierLong;
+                               if (fmt[i] == 'l') {
+                                       i++;
+                                       qualifier = PrintfQualifierLongLong;
+                               }
+                               break;
+                       default:
+                               /* default type */
+                               qualifier = PrintfQualifierInt;
+                               --i;
+                       }
+
+                       base = 10;
+
+                       switch (c = fmt[i]) {
+                       /* String and character conversions */
+                       case 's':
+                               if ((retval = print_string(va_arg(ap, char *),
+                                   width, precision, flags, ps)) < 0) {
+                                       counter = -counter;
+                                       goto out;
+                               };
+                               counter += retval;
+                               j = i + 1;
+                               goto next_char;
+                       case 'c':
+                               c = va_arg(ap, unsigned int);
+                               retval = print_char(c, width, flags, ps);
+                               if (retval < 0) {
+                                       counter = -counter;
+                                       goto out;
+                               };
+                               counter += retval;
+                               j = i + 1;
+                               goto next_char;
+
+                       /* Integer values */
+                       case 'P':       /* pointer */
+                               flags |= __PRINTF_FLAG_BIGCHARS;
+                       case 'p':
+                               flags |= __PRINTF_FLAG_PREFIX;
+                               base = 16;
+                               qualifier = PrintfQualifierPointer;
+                               break;
+                       case 'b':
+                               base = 2;
+                               break;
+                       case 'o':
+                               base = 8;
+                               break;
+                       case 'd':
+                       case 'i':
+                               flags |= __PRINTF_FLAG_SIGNED;
+                       case 'u':
+                               break;
+                       case 'X':
+                               flags |= __PRINTF_FLAG_BIGCHARS;
+                       case 'x':
+                               base = 16;
+                               break;
+                       case '%': /* percentile itself */
+                               j = i;
+                               goto next_char;
+                       default: /* Bad formatting */
+                               /*
+                                * Unknown format. Now, j is the index of '%'
+                                * so we will print whole bad format sequence.
+                                */
+                               goto next_char;
+                       }
+
+                       /* Print integers. */
+                       /* Print number. */
+                       switch (qualifier) {
+                       case PrintfQualifierByte:
+                               size = sizeof(unsigned char);
+                               number = (uint64_t) va_arg(ap, unsigned int);
+                               break;
+                       case PrintfQualifierShort:
+                               size = sizeof(unsigned short);
+                               number = (uint64_t) va_arg(ap, unsigned int);
+                               break;
+                       case PrintfQualifierInt:
+                               size = sizeof(unsigned int);
+                               number = (uint64_t) va_arg(ap, unsigned int);
+                               break;
+                       case PrintfQualifierLong:
+                               size = sizeof(unsigned long);
+                               number = (uint64_t) va_arg(ap, unsigned long);
+                               break;
+                       case PrintfQualifierLongLong:
+                               size = sizeof(unsigned long long);
+                               number = (uint64_t) va_arg(ap, unsigned long long);
+                               break;
+                       case PrintfQualifierPointer:
+                               size = sizeof(void *);
+                               number = (uint64_t) (unsigned long)va_arg(ap, void *);
+                               break;
+                       default:        /* Unknown qualifier */
+                               counter = -counter;
+                               goto out;
+                       }
+
+                       if (flags & __PRINTF_FLAG_SIGNED) {
+                               if (number & (0x1 << (size * 8 - 1))) {
+                                       flags |= __PRINTF_FLAG_NEGATIVE;
+
+                                       if (size == sizeof(uint64_t)) {
+                                               number = -((int64_t) number);
+                                       } else {
+                                               number = ~number;
+                                               number &= ~(0xFFFFFFFFFFFFFFFFll << (size * 8));
+                                               number++;
+                                       }
+                               }
+                       }
+
+                       if ((retval = print_number(number, width, precision,
+                                                  base, flags, ps)) < 0) {
+                               counter = -counter;
+                               goto out;
+                       }
+
+                       counter += retval;
+                       j = i + 1;
+               }
+next_char:
+               ++i;
+       }
+
+       if (i > j) {
+               if ((retval = printf_putnchars(&fmt[j],
+                   (u64) (i - j), ps)) < 0) {
+                       counter = -counter;
+                       goto out;       /* Error */
+
+               }
+               counter += retval;
+       }
+
+out:
+       return counter;
+}
+
+int sprintf(char *str, const char *fmt, ...)
+{
+       int ret;
+       va_list args;
+
+       va_start(args, fmt);
+       ret = vsprintf(str, fmt, args);
+       va_end(args);
+
+       return ret;
+}
+
+struct vsnprintf_data {
+       size_t size;            /* Total space for string */
+       size_t len;             /* Count of currently used characters */
+       char *string;           /* Destination string */
+};
+
+/**
+ * Write string to given buffer.
+ *
+ * Write at most data->size characters including trailing zero. According to
+ * C99, snprintf() has to return number of characters that would have been
+ * written if enough space had been available. Hence the return value is not
+ * number of really printed characters but size of the input string.
+ * Number of really used characters is stored in data->len.
+ *
+ * @param str  Source string to print.
+ * @param count        Size of source string.
+ * @param data Structure with destination string, counter of used space
+ *              and total string size.
+ * @return Number of characters to print (not characters really printed!).
+ */
+static int vsnprintf_write(const char *str, size_t count,
+                          struct vsnprintf_data *data)
+{
+       size_t i;
+
+       i = data->size - data->len;
+       if (i == 0)
+               return count;
+
+       /* We have only one free byte left in buffer => write trailing zero. */
+       if (i == 1) {
+               data->string[data->size - 1] = 0;
+               data->len = data->size;
+               return count;
+       }
+
+       /*
+        * We have not enough space for whole string with the trailing
+        * zero => print only a part of string.
+        */
+       if (i <= count) {
+               memcpy((void *)(data->string + data->len), (void *)str, i - 1);
+               data->string[data->size - 1] = 0;
+               data->len = data->size;
+               return count;
+       }
+
+       /* Buffer is big enough to print whole string. */
+       memcpy((void *)(data->string + data->len), (void *)str, count);
+       data->len += count;
+       /*
+        * Put trailing zero at end, but not count it into data->len so
+        * it could be rewritten next time.
+        */
+       data->string[data->len] = 0;
+
+       return count;
+}
+
+int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
+{
+       struct vsnprintf_data data = { size, 0, str };
+       struct printf_spec ps =
+           { (int (*)(void *, size_t, void *))vsnprintf_write, &data };
+
+       /* Print 0 at end of string - fix case that nothing will be printed. */
+       if (size > 0)
+               str[0] = 0;
+
+       /* vsnprintf_write() ensures that str will be terminated by zero. */
+       return printf_core(fmt, &ps, ap);
+}
+
+int vsprintf(char *str, const char *fmt, va_list ap)
+{
+       return vsnprintf(str, (size_t) - 1, fmt, ap);
+}
+
+int printf(const char *fmt, ...)
+{
+       int ret;
+       va_list args;
+
+       va_start(args, fmt);
+       ret = vprintf(fmt, args);
+       va_end(args);
+
+       return ret;
+}
+
+static int vprintf_write(const char *str, size_t count, void *unused)
+{
+       size_t i;
+
+       for (i = 0; i < count; i++)
+               putchar(str[i]);
+
+       return i;
+}
+
+int vprintf(const char *fmt, va_list ap)
+{
+       struct printf_spec ps =
+           { (int (*)(void *, size_t, void *))vprintf_write, NULL };
+
+       return printf_core(fmt, &ps, ap);
+}