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incubator-nuttx/libc/stdio/lib_sscanf.c

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/****************************************************************************
* libc/stdio/lib_sscanf.c
*
* Copyright (C) 2007, 2008, 2011-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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
* COPYRIGHT OWNER OR CONTRIBUTORS 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/compiler.h>
#include <sys/types.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <debug.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MAXLN 128
#ifndef MIN
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
#ifndef MAX
# define MAX(a,b) (((a) > (b)) ? (a) : (b))
#endif
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Global Function Prototypes
****************************************************************************/
int vsscanf(FAR const char *buf, FAR const char *fmt, va_list ap);
/****************************************************************************
* Global Constant Data
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Constant Data
****************************************************************************/
static const char spaces[] = " \t\n\r\f\v";
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Function: findwidth
*
* Description:
* Try to figure out the width of the input data.
*
****************************************************************************/
static int findwidth(FAR const char *buf, FAR const char *fmt)
{
FAR const char *next = fmt + 1;
/* No... is there a space after the format? Or does the format string end
* here?
*/
if (isspace(*next) || *next == 0)
{
/* Use the input up until the first white space is encountered. */
return strcspn(buf, spaces);
}
/* No.. Another possibility is the format character is followed by
* some recognizable delimiting value.
*/
if (*next != '%')
{
/* If so we will say that the string ends there if we can find that
* delimiter in the input string.
*/
FAR const char *ptr = strchr(buf, *next);
if (ptr)
{
return (int)(ptr - buf);
}
}
/* No... the format has no delimiter and is back-to-back with the next
* format (or is followed by a delimiter that does not exist in the
* input string). At this point we just bail and Use the input up until
* the first white space is encountered.
*
* NOTE: This means that values from the following format may be
* concatenated with the first. This is a bug. We have no generic way of
* determining the width of the data if there is no fieldwidth, no space
* separating the input, and no usable delimiter character.
*/
return strcspn(buf, spaces);
}
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Function: sscanf
*
* Description:
* ANSI standard sscanf implementation.
*
****************************************************************************/
int sscanf(FAR const char *buf, FAR const char *fmt, ...)
{
va_list ap;
int count;
va_start(ap, fmt);
count = vsscanf((FAR const char*)buf, fmt, ap);
va_end(ap);
return count;
}
/****************************************************************************
* Function: vsscanf
*
* Description:
* ANSI standard vsscanf implementation.
*
****************************************************************************/
int vsscanf(FAR const char *buf, FAR const char *fmt, va_list ap)
{
FAR const char *bufstart;
FAR char *tv;
FAR const char *tc;
bool lflag;
bool noassign;
int count;
int width;
int base = 10;
char tmp[MAXLN];
lvdbg("vsscanf: buf=\"%s\" fmt=\"%s\"\n", buf, fmt);
/* Remember the start of the input buffer. We will need this for %n
* calculations.
*/
bufstart = buf;
/* Parse the format, extracting values from the input buffer as needed */
count = 0;
width = 0;
noassign = false;
lflag = false;
/* Loop until all characters in the fmt string have been processed. We
* may have to continue loop after reaching the end the input data in
* order to handle trailing %n format specifiers.
*/
while (*fmt)
{
/* Skip over white space */
while (isspace(*fmt))
{
fmt++;
}
/* Check for a conversion specifier */
if (*fmt == '%')
{
lvdbg("vsscanf: Specifier found\n");
/* Check for qualifiers on the conversion specifier */
fmt++;
for (; *fmt; fmt++)
{
lvdbg("vsscanf: Processing %c\n", *fmt);
if (strchr("dibouxcsefgn%", *fmt))
{
break;
}
if (*fmt == '*')
{
noassign = true;
}
else if (*fmt == 'l' || *fmt == 'L')
{
/* NOTE: Missing check for long long ('ll') */
lflag = true;
}
else if (*fmt >= '1' && *fmt <= '9')
{
for (tc = fmt; isdigit(*fmt); fmt++);
strncpy(tmp, tc, fmt - tc);
tmp[fmt - tc] = '\0';
width = atoi(tmp);
fmt--;
}
}
/* Process %s: String conversion */
if (*fmt == 's')
{
lvdbg("vsscanf: Performing string conversion\n");
/* Get a pointer to the char * value. We need to do this even
* if we have reached the end of the input data in order to
* update the 'ap' variable.
*/
tv = NULL; /* To avoid warnings about begin uninitialized */
if (!noassign)
{
tv = va_arg(ap, char*);
tv[0] = '\0';
}
/* But we only perform the data conversion is we still have
* bytes remaining in the input data stream.
*/
if (*buf)
{
/* Skip over white space */
while (isspace(*buf))
{
buf++;
}
/* Was a fieldwidth specified? */
if (!width)
{
/* No... Guess a field width using some heuristics */
int tmpwidth = findwidth(buf, fmt);
width = MIN(sizeof(tmp) - 1, tmpwidth);
}
/* Copy the string (if we are making an assignment) */
if (!noassign)
{
strncpy(tv, buf, width);
tv[width] = '\0';
count++;
}
/* Update the buffer pointer past the string in the input */
buf += width;
}
}
/* Process %c: Character conversion */
else if (*fmt == 'c')
{
lvdbg("vsscanf: Performing character conversion\n");
/* Get a pointer to the char * value. We need to do this even
* if we have reached the end of the input data in order to
* update the 'ap' variable.
*/
tv = NULL; /* To avoid warnings about beign uninitialized */
if (!noassign)
{
tv = va_arg(ap, char*);
tv[0] = '\0';
}
/* But we only perform the data conversion is we still have
* bytes remaining in the input data stream.
*/
if (*buf)
{
/* Was a field width specified? */
if (!width)
{
/* No, then width is this one single character */
width = 1;
}
/* Copy the character(s) (if we are making an assignment) */
if (!noassign)
{
strncpy(tv, buf, width);
tv[width] = '\0';
count++;
}
/* Update the buffer pointer past the character(s) in the
* input
*/
buf += width;
}
}
/* Process %d, %o, %b, %x, %u: Various integer conversions */
else if (strchr("dobxu", *fmt))
{
FAR long *plong = NULL;
FAR int *pint = NULL;
bool sign;
lvdbg("vsscanf: Performing integer conversion\n");
/* Get a pointer to the integer value. We need to do this even
* if we have reached the end of the input data in order to
* update the 'ap' variable.
*/
if (!noassign)
{
/* We have to check whether we need to return a long or an
* int.
*/
if (lflag)
{
plong = va_arg(ap, long*);
*plong = 0;
}
else
{
pint = va_arg(ap, int*);
*pint = 0;
}
}
/* But we only perform the data conversion if we still have
* bytes remaining in the input data stream.
*/
if (*buf)
{
FAR char *endptr;
int errsave;
long tmplong;
/* Skip over any white space before the integer string */
while (isspace(*buf))
{
buf++;
}
/* The base of the integer conversion depends on the
* specific conversion specification.
*/
sign = false;
switch (*fmt)
{
default:
case 'd':
sign = true;
case 'u':
base = 10;
break;
case 'X':
case 'x':
base = 16;
break;
case 'o':
base = 8;
break;
case 'b':
base = 2;
break;
}
/* Was a field width specified? */
if (!width)
{
/* No... Guess a field width using some heuristics */
int tmpwidth = findwidth(buf, fmt);
width = MIN(sizeof(tmp) - 1, tmpwidth);
}
/* Copy the numeric string into a temporary working
* buffer.
*/
strncpy(tmp, buf, width);
tmp[width] = '\0';
lvdbg("vsscanf: tmp[]=\"%s\"\n", tmp);
/* Perform the integer conversion */
/* Preserve the errno value */
errsave = get_errno();
set_errno(0);
if (sign)
{
tmplong = strtol(tmp, &endptr, base);
}
else
{
tmplong = strtoul(tmp, &endptr, base);
}
/* Check if the number was successfully converted */
if (tmp == endptr || get_errno() == ERANGE)
{
return count;
}
/* Move by the actual number of characters converted */
buf += (endptr - tmp);
set_errno(errsave);
if (!noassign)
{
/* We have to check whether we need to return a long
* or an int.
*/
if (lflag)
{
lvdbg("vsscanf: Return %ld to 0x%p\n",
tmplong, plong);
*plong = tmplong;
}
else
{
lvdbg("vsscanf: Return %ld to 0x%p\n",
tmplong, pint);
*pint = (int)tmplong;
}
count++;
}
}
}
/* Process %f: Floating point conversion */
else if (*fmt == 'f' || *fmt == 'F')
{
#ifdef CONFIG_HAVE_DOUBLE
FAR double_t *pd = NULL;
#endif
FAR float *pf = NULL;
lvdbg("vsscanf: Performing floating point conversion\n");
/* Get a pointer to the double value. We need to do this even
* if we have reached the end of the input data in order to
* update the 'ap' variable.
*/
if (!noassign)
{
/* We have to check whether we need to return a float or a
* double.
*/
#ifdef CONFIG_HAVE_DOUBLE
if (lflag)
{
pd = va_arg(ap, double_t*);
*pd = 0.0;
}
else
#endif
{
pf = va_arg(ap, float*);
*pf = 0.0;
}
}
#ifdef CONFIG_LIBC_FLOATINGPOINT
/* But we only perform the data conversion is we still have
* bytes remaining in the input data stream.
*/
if (*buf)
{
/* Skip over any white space before the real string */
while (isspace(*buf))
{
buf++;
}
/* Was a fieldwidth specified? */
if (!width)
{
/* No... Guess a field width using some heuristics */
width = findwidth(buf, fmt);
}
/* Copy the real string into a temporary working buffer. */
strncpy(tmp, buf, width);
tmp[width] = '\0';
buf += width;
lvdbg("vsscanf: tmp[]=\"%s\"\n", tmp);
/* Perform the floating point conversion */
if (!noassign)
{
/* strtod always returns a double */
FAR char *endptr;
int errsave;
double_t dvalue;
/* Preserve the errno value */
errsave = get_errno();
set_errno(0);
dvalue = strtod(tmp, &endptr);
/* Check if the number was successfully converted */
if (tmp == endptr || get_errno() == ERANGE)
{
return count;
}
set_errno(errsave);
/* We have to check whether we need to return a float
* or a double.
*/
#ifdef CONFIG_HAVE_DOUBLE
if (lflag)
{
lvdbg("vsscanf: Return %f to %p\n", dvalue, pd);
*pd = dvalue;
}
else
#endif
{
lvdbg("vsscanf: Return %f to %p\n", dvalue, pf);
*pf = (float)dvalue;
}
count++;
}
}
#endif
}
/* Process %n: Character count */
else if (*fmt == 'n')
{
lvdbg("vsscanf: Performing character count\n");
if (!noassign)
{
size_t nchars = (size_t)(buf - bufstart);
/* Note %n does not count as a conversion */
if (lflag)
{
FAR long *plong = va_arg(ap, long*);
*plong = (long)nchars;
}
else
{
FAR int *pint = va_arg(ap, int*);
*pint = (int)nchars;
}
}
}
width = 0;
noassign = false;
lflag = false;
fmt++;
}
/* It is not a conversion specifier */
else if (*buf)
{
/* Skip over any leading spaces in the input buffer */
while (isspace(*buf))
{
buf++;
}
/* Skip over matching characters in the buffer and format */
if (*fmt != *buf)
{
break;
}
else
{
fmt++;
buf++;
}
}
else
{
/* NULL terminator encountered */
break;
}
}
/* sscanf is required to return EOF if the input ends before the first
* matching failure or conversion.
*/
return count ? count : EOF;
}
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