json_util.c

/*
 * $Id: json_util.c,v 1.4 2006/01/30 23:07:57 mclark Exp $
 *
 * Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
 * Michael Clark <michael@metaparadigm.com>
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the MIT license. See COPYING for details.
 *
 */

#include "config.h"
#undef realloc

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <limits.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif /* HAVE_SYS_TYPES_H */

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif /* HAVE_SYS_STAT_H */

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif /* HAVE_FCNTL_H */

#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */

#ifdef WIN32
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <io.h>
#endif /* defined(WIN32) */

#if !defined(HAVE_OPEN) && defined(WIN32)
# define open _open
#endif

#if !defined(HAVE_SNPRINTF) && defined(_MSC_VER)
  /* MSC has the version as _snprintf */
# define snprintf _snprintf
#elif !defined(HAVE_SNPRINTF)
# error You do not have snprintf on your system.
#endif /* HAVE_SNPRINTF */

#include "debug.h"
#include "printbuf.h"
#include "json_inttypes.h"
#include "json_object.h"
#include "json_tokener.h"
#include "json_util.h"

static int sscanf_is_broken = 0;
static int sscanf_is_broken_testdone = 0;
static void sscanf_is_broken_test(void);
static void _set_last_err(const char *err_fmt, ...);

static char _last_err[256] = "";

const char *json_util_get_last_err()
{
	if (_last_err[0] == '\0')
		return NULL;
	return _last_err;
}

static void _set_last_err(const char *err_fmt, ...)
{
	va_list ap;
	va_start(ap, err_fmt);
	// Ignore (attempted) overruns from snprintf
	(void)vsnprintf(_last_err, sizeof(_last_err), err_fmt, ap);
	va_end(ap);
}

struct json_object* json_object_from_fd(int fd)
{
  struct printbuf *pb;
  struct json_object *obj;
  char buf[JSON_FILE_BUF_SIZE];
  int ret;

  if(!(pb = printbuf_new())) {
    _set_last_err("json_object_from_file: printbuf_new failed\n");
    return NULL;
  }
  while((ret = read(fd, buf, JSON_FILE_BUF_SIZE)) > 0) {
    printbuf_memappend(pb, buf, ret);
  }
  if(ret < 0) {
    _set_last_err("json_object_from_fd: error reading fd %d: %s\n", fd, strerror(errno));
    printbuf_free(pb);
    return NULL;
  }
  obj = json_tokener_parse(pb->buf);
  printbuf_free(pb);
  return obj;
}

struct json_object* json_object_from_file(const char *filename)
{
  struct json_object *obj;
  int fd;

  if((fd = open(filename, O_RDONLY)) < 0) {
    _set_last_err("json_object_from_file: error opening file %s: %s\n",
	     filename, strerror(errno));
    return NULL;
  }
  obj = json_object_from_fd(fd);
  close(fd);
  return obj;
}

/* extended "format and write to file" function */

int json_object_to_file_ext(const char *filename, struct json_object *obj, int flags)
{
  const char *json_str;
  int fd, ret;
  unsigned int wpos, wsize;

  if(!obj) {
    _set_last_err("json_object_to_file: object is null\n");
    return -1;
  }

  if((fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, 0644)) < 0) {
    _set_last_err("json_object_to_file: error opening file %s: %s\n",
	     filename, strerror(errno));
    return -1;
  }

  if(!(json_str = json_object_to_json_string_ext(obj,flags))) {
    close(fd);
    return -1;
  }

  wsize = (unsigned int)(strlen(json_str) & UINT_MAX); /* CAW: probably unnecessary, but the most 64bit safe */
  wpos = 0;
  while(wpos < wsize) {
    if((ret = write(fd, json_str + wpos, wsize-wpos)) < 0) {
      close(fd);
      _set_last_err("json_object_to_file: error writing file %s: %s\n",
	     filename, strerror(errno));
      return -1;
    }

	/* because of the above check for ret < 0, we can safely cast and add */
    wpos += (unsigned int)ret;
  }

  close(fd);
  return 0;
}

// backwards compatible "format and write to file" function

int json_object_to_file(const char *filename, struct json_object *obj)
{
  return json_object_to_file_ext(filename, obj, JSON_C_TO_STRING_PLAIN);
}

int json_parse_double(const char *buf, double *retval)
{
  return (sscanf(buf, "%lf", retval)==1 ? 0 : 1);
}

/*
 * Not all implementations of sscanf actually work properly.
 * Check whether the one we're currently using does, and if
 * it's broken, enable the workaround code.
 */
static void sscanf_is_broken_test()
{
	int64_t num64;
	int ret_errno, is_int64_min, ret_errno2, is_int64_max;

	(void)sscanf(" -01234567890123456789012345", "%" SCNd64, &num64);
	ret_errno = errno;
	is_int64_min = (num64 == INT64_MIN);

	(void)sscanf(" 01234567890123456789012345", "%" SCNd64, &num64);
	ret_errno2 = errno;
	is_int64_max = (num64 == INT64_MAX);

	if (ret_errno != ERANGE || !is_int64_min ||
	    ret_errno2 != ERANGE || !is_int64_max)
	{
		MC_DEBUG("sscanf_is_broken_test failed, enabling workaround code\n");
		sscanf_is_broken = 1;
	}
}

int json_parse_int64(const char *buf, int64_t *retval)
{
	int64_t num64;
	const char *buf_sig_digits;
	int orig_has_neg;
	int saved_errno;

	if (!sscanf_is_broken_testdone)
	{
		sscanf_is_broken_test();
		sscanf_is_broken_testdone = 1;
	}

	// Skip leading spaces
	while (isspace((int)*buf) && *buf)
		buf++;

	errno = 0; // sscanf won't always set errno, so initialize
	if (sscanf(buf, "%" SCNd64, &num64) != 1)
	{
		MC_DEBUG("Failed to parse, sscanf != 1\n");
		return 1;
	}

	saved_errno = errno;
	buf_sig_digits = buf;
	orig_has_neg = 0;
	if (*buf_sig_digits == '-')
	{
		buf_sig_digits++;
		orig_has_neg = 1;
	}

	// Not all sscanf implementations actually work
	if (sscanf_is_broken && saved_errno != ERANGE)
	{
		char buf_cmp[100];
		char *buf_cmp_start = buf_cmp;
		int recheck_has_neg = 0;
		int buf_cmp_len;

		// Skip leading zeros, but keep at least one digit
		while (buf_sig_digits[0] == '0' && buf_sig_digits[1] != '\0')
			buf_sig_digits++;
		if (num64 == 0) // assume all sscanf impl's will parse -0 to 0
			orig_has_neg = 0; // "-0" is the same as just plain "0"

		snprintf(buf_cmp_start, sizeof(buf_cmp), "%" PRId64, num64);
		if (*buf_cmp_start == '-')
		{
			recheck_has_neg = 1;
			buf_cmp_start++;
		}
		// No need to skip leading spaces or zeros here.

		buf_cmp_len = strlen(buf_cmp_start);
		/**
		 * If the sign is different, or
		 * some of the digits are different, or
		 * there is another digit present in the original string
		 * then we have NOT successfully parsed the value.
		 */
		if (orig_has_neg != recheck_has_neg ||
		    strncmp(buf_sig_digits, buf_cmp_start, strlen(buf_cmp_start)) != 0 ||
			((int)strlen(buf_sig_digits) != buf_cmp_len &&
			 isdigit((int)buf_sig_digits[buf_cmp_len])
		    )
		   )
		{
			saved_errno = ERANGE;
		}
	}

	// Not all sscanf impl's set the value properly when out of range.
	// Always do this, even for properly functioning implementations,
	// since it shouldn't slow things down much.
	if (saved_errno == ERANGE)
	{
		if (orig_has_neg)
			num64 = INT64_MIN;
		else
			num64 = INT64_MAX;
	}
	*retval = num64;
	return 0;
}

#ifndef HAVE_REALLOC
void* rpl_realloc(void* p, size_t n)
{
	if (n == 0)
		n = 1;
	if (p == 0)
		return malloc(n);
	return realloc(p, n);
}
#endif

#define NELEM(a)        (sizeof(a) / sizeof(a[0]))
static const char* json_type_name[] = {
  /* If you change this, be sure to update the enum json_type definition too */
  "null",
  "boolean",
  "double",
  "int",
  "object",
  "array",
  "string",
};

const char *json_type_to_name(enum json_type o_type)
{
	int o_type_int = (int)o_type;
	if (o_type_int < 0 || o_type_int >= (int)NELEM(json_type_name))
	{
		_set_last_err("json_type_to_name: type %d is out of range [0,%d]\n", o_type, NELEM(json_type_name));
		return NULL;
	}
	return json_type_name[o_type];
}