ratelimit fix: omit the limit parameter from the database lookup

[exim.git] / src / src / string.c

/* $Cambridge: exim/src/src/string.c,v 1.3 2005/05/23 16:58:56 fanf2 Exp $ */

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge 1995 - 2005 */
/* See the file NOTICE for conditions of use and distribution. */

/* Miscellaneous string-handling functions. Some are not required for
utilities and tests, and are cut out by the COMPILE_UTILITY macro. */


#include "exim.h"


#ifndef COMPILE_UTILITY
/*************************************************
*            Test for IP address                 *
*************************************************/

/* This used just to be a regular expression, but with IPv6 things are a bit
more complicated. If the address contains a colon, it is assumed to be a v6
address (assuming HAVE_IPV6 is set). If a mask is permitted and one is present,
and maskptr is not NULL, its offset is placed there.

Arguments:
  s         a string
  maskptr   NULL if no mask is permitted to follow
            otherwise, points to an int where the offset of '/' is placed

Returns:    0 if the string is not a textual representation of an IP address
            4 if it is an IPv4 address
            6 if it is an IPv6 address
*/

int
string_is_ip_address(uschar *s, int *maskptr)
{
int i;
int yield = 4;

/* If an optional mask is permitted, check for it. If found, pass back the
offset. */

if (maskptr != NULL)
  {
  uschar *ss = s + Ustrlen(s);
  *maskptr = 0;
  if (s != ss && isdigit(*(--ss)))
    {
    while (ss > s && isdigit(ss[-1])) ss--;
    if (ss > s && *(--ss) == '/') *maskptr = ss - s;
    }
  }

/* A colon anywhere in the string => IPv6 address */

if (Ustrchr(s, ':') != NULL)
  {
  BOOL had_double_colon = FALSE;
  BOOL v4end = FALSE;
  int count = 0;

  yield = 6;

  /* An IPv6 address must start with hex digit or double colon. A single
  colon is invalid. */

  if (*s == ':' && *(++s) != ':') return 0;

  /* Now read up to 8 components consisting of up to 4 hex digits each. There
  may be one and only one appearance of double colon, which implies any number
  of binary zero bits. The number of preceding components is held in count. */

  for (count = 0; count < 8; count++)
    {
    /* If the end of the string is reached before reading 8 components, the
    address is valid provided a double colon has been read. This also applies
    if we hit the / that introduces a mask or the % that introduces the
    interface specifier (scope id) of a link-local address. */

    if (*s == 0 || *s == '%' || *s == '/') return had_double_colon? yield : 0;

    /* If a component starts with an additional colon, we have hit a double
    colon. This is permitted to appear once only, and counts as at least
    one component. The final component may be of this form. */

    if (*s == ':')
      {
      if (had_double_colon) return 0;
      had_double_colon = TRUE;
      s++;
      continue;
      }

    /* If the remainder of the string contains a dot but no colons, we
    can expect a trailing IPv4 address. This is valid if either there has
    been no double-colon and this is the 7th component (with the IPv4 address
    being the 7th & 8th components), OR if there has been a double-colon
    and fewer than 6 components. */

    if (Ustrchr(s, ':') == NULL && Ustrchr(s, '.') != NULL)
      {
      if ((!had_double_colon && count != 6) ||
          (had_double_colon && count > 6)) return 0;
      v4end = TRUE;
      yield = 6;
      break;
      }

    /* Check for at least one and not more than 4 hex digits for this
    component. */

    if (!isxdigit(*s++)) return 0;
    if (isxdigit(*s) && isxdigit(*(++s)) && isxdigit(*(++s))) s++;

    /* If the component is terminated by colon and there is more to
    follow, skip over the colon. If there is no more to follow the address is
    invalid. */

    if (*s == ':' && *(++s) == 0) return 0;
    }

  /* If about to handle a trailing IPv4 address, drop through. Otherwise
  all is well if we are at the end of the string or at the mask or at a percent
  sign, which introduces the interface specifier (scope id) of a link local
  address. */

  if (!v4end) return (*s == 0 || *s == '%' || *s == '/')? yield : 0;
  }

/* Test for IPv4 address, which may be the tail-end of an IPv6 address. */

for (i = 0; i < 4; i++)
  {
  if (i != 0 && *s++ != '.') return 0;
  if (!isdigit(*s++)) return 0;
  if (isdigit(*s) && isdigit(*(++s))) s++;
  }

return (*s == 0 || *s == '/')? yield : 0;
}
#endif  /* COMPILE_UTILITY */


/*************************************************
*              Format message size               *
*************************************************/

/* Convert a message size in bytes to printing form, rounding
according to the magnitude of the number. A value of zero causes
a string of spaces to be returned.

Arguments:
  size        the message size in bytes
  buffer      where to put the answer

Returns:      pointer to the buffer
              a string of exactly 5 characters is normally returned
*/

uschar *
string_format_size(int size, uschar *buffer)
{
if (size == 0) Ustrcpy(CS buffer, "     ");
else if (size < 1024) sprintf(CS buffer, "%5d", size);
else if (size < 10*1024)
  sprintf(CS buffer, "%4.1fK", (double)size / 1024.0);
else if (size < 1024*1024)
  sprintf(CS buffer, "%4dK", (size + 512)/1024);
else if (size < 10*1024*1024)
  sprintf(CS buffer, "%4.1fM", (double)size / (1024.0 * 1024.0));
else
  sprintf(CS buffer, "%4dM", (size + 512 * 1024)/(1024*1024));
return buffer;
}



#ifndef COMPILE_UTILITY
/*************************************************
*       Convert a number to base 62 format       *
*************************************************/

/* Convert a long integer into an ASCII base 62 string. For Cygwin the value of
BASE_62 is actually 36. Always return exactly 6 characters plus zero, in a
static area.

Argument: a long integer
Returns:  pointer to base 62 string
*/

uschar *
string_base62(unsigned long int value)
{
static uschar yield[7];
uschar *p = yield + sizeof(yield) - 1;
*p = 0;
while (p > yield)
  {
  *(--p) = base62_chars[value % BASE_62];
  value /= BASE_62;
  }
return yield;
}
#endif  /* COMPILE_UTILITY */



#ifndef COMPILE_UTILITY
/*************************************************
*          Interpret escape sequence             *
*************************************************/

/* This function is called from several places where escape sequences are to be
interpreted in strings.

Arguments:
  pp       points a pointer to the initiating "\" in the string;
           the pointer gets updated to point to the final character
Returns:   the value of the character escape
*/

int
string_interpret_escape(uschar **pp)
{
int ch;
uschar *p = *pp;
ch = *(++p);
if (isdigit(ch) && ch != '8' && ch != '9')
  {
  ch -= '0';
  if (isdigit(p[1]) && p[1] != '8' && p[1] != '9')
    {
    ch = ch * 8 + *(++p) - '0';
    if (isdigit(p[1]) && p[1] != '8' && p[1] != '9')
      ch = ch * 8 + *(++p) - '0';
    }
  }
else switch(ch)
  {
  case 'n':  ch = '\n'; break;
  case 'r':  ch = '\r'; break;
  case 't':  ch = '\t'; break;
  case 'x':
  ch = 0;
  if (isxdigit(p[1]))
    {
    ch = ch * 16 +
      Ustrchr(hex_digits, tolower(*(++p))) - hex_digits;
    if (isxdigit(p[1])) ch = ch * 16 +
      Ustrchr(hex_digits, tolower(*(++p))) - hex_digits;
    }
  break;
  }
*pp = p;
return ch;
}
#endif  /* COMPILE_UTILITY */



#ifndef COMPILE_UTILITY
/*************************************************
*          Ensure string is printable            *
*************************************************/

/* This function is called for critical strings. It checks for any
non-printing characters, and if any are found, it makes a new copy
of the string with suitable escape sequences. It is most often called by the
macro string_printing(), which sets allow_tab TRUE.

Arguments:
  s             the input string
  allow_tab     TRUE to allow tab as a printing character

Returns:        string with non-printers encoded as printing sequences
*/

uschar *
string_printing2(uschar *s, BOOL allow_tab)
{
int nonprintcount = 0;
int length = 0;
uschar *t = s;
uschar *ss, *tt;

while (*t != 0)
  {
  int c = *t++;
  if (!mac_isprint(c) || (!allow_tab && c == '\t')) nonprintcount++;
  length++;
  }

if (nonprintcount == 0) return s;

/* Get a new block of store guaranteed big enough to hold the
expanded string. */

ss = store_get(length + nonprintcount * 4 + 1);

/* Copy everying, escaping non printers. */

t = s;
tt = ss;

while (*t != 0)
  {
  int c = *t;
  if (mac_isprint(c) && (allow_tab || c != '\t')) *tt++ = *t++; else
    {
    *tt++ = '\\';
    switch (*t)
      {
      case '\n': *tt++ = 'n'; break;
      case '\r': *tt++ = 'r'; break;
      case '\b': *tt++ = 'b'; break;
      case '\v': *tt++ = 'v'; break;
      case '\f': *tt++ = 'f'; break;
      case '\t': *tt++ = 't'; break;
      default: sprintf(CS tt, "%03o", *t); tt += 3; break;
      }
    t++;
    }
  }
*tt = 0;
return ss;
}
#endif  /* COMPILE_UTILITY */




/*************************************************
*            Copy and save string                *
*************************************************/

/* This function assumes that memcpy() is faster than strcpy().

Argument: string to copy
Returns:  copy of string in new store
*/

uschar *
string_copy(uschar *s)
{
int len = Ustrlen(s) + 1;
uschar *ss = store_get(len);
memcpy(ss, s, len);
return ss;
}



/*************************************************
*     Copy and save string in malloc'd store     *
*************************************************/

/* This function assumes that memcpy() is faster than strcpy().

Argument: string to copy
Returns:  copy of string in new store
*/

uschar *
string_copy_malloc(uschar *s)
{
int len = Ustrlen(s) + 1;
uschar *ss = store_malloc(len);
memcpy(ss, s, len);
return ss;
}



/*************************************************
*       Copy, lowercase and save string          *
*************************************************/

/*
Argument: string to copy
Returns:  copy of string in new store, with letters lowercased
*/

uschar *
string_copylc(uschar *s)
{
uschar *ss = store_get(Ustrlen(s) + 1);
uschar *p = ss;
while (*s != 0) *p++ = tolower(*s++);
*p = 0;
return ss;
}



/*************************************************
*       Copy and save string, given length       *
*************************************************/

/* It is assumed the data contains no zeros. A zero is added
onto the end.

Arguments:
  s         string to copy
  n         number of characters

Returns:    copy of string in new store
*/

uschar *
string_copyn(uschar *s, int n)
{
uschar *ss = store_get(n + 1);
Ustrncpy(ss, s, n);
ss[n] = 0;
return ss;
}


/*************************************************
* Copy, lowercase, and save string, given length *
*************************************************/

/* It is assumed the data contains no zeros. A zero is added
onto the end.

Arguments:
  s         string to copy
  n         number of characters

Returns:    copy of string in new store, with letters lowercased
*/

uschar *
string_copynlc(uschar *s, int n)
{
uschar *ss = store_get(n + 1);
uschar *p = ss;
while (n-- > 0) *p++ = tolower(*s++);
*p = 0;
return ss;
}



/*************************************************
*   Copy returned DNS domain name, de-escaping   *
*************************************************/

/* If a domain name contains top-bit characters, some resolvers return
the fully qualified name with those characters turned into escapes. The
convention is a backslash followed by _decimal_ digits. We convert these
back into the original binary values. This will be relevant when
allow_utf8_domains is set true and UTF-8 characters are used in domain
names. Backslash can also be used to escape other characters, though we
shouldn't come across them in domain names.

Argument:   the domain name string
Returns:    copy of string in new store, de-escaped
*/

uschar *
string_copy_dnsdomain(uschar *s)
{
uschar *yield;
uschar *ss = yield = store_get(Ustrlen(s) + 1);

while (*s != 0)
  {
  if (*s != '\\')
    {
    *ss++ = *s++;
    }
  else if (isdigit(s[1]))
    {
    *ss++ = (s[1] - '0')*100 + (s[2] - '0')*10 + s[3] - '0';
    s += 4;
    }
  else if (*(++s) != 0)
    {
    *ss++ = *s++;
    }
  }

*ss = 0;
return yield;
}


#ifndef COMPILE_UTILITY
/*************************************************
*     Copy space-terminated or quoted string     *
*************************************************/

/* This function copies from a string until its end, or until whitespace is
encountered, unless the string begins with a double quote, in which case the
terminating quote is sought, and escaping within the string is done. The length
of a de-quoted string can be no longer than the original, since escaping always
turns n characters into 1 character.

Argument:  pointer to the pointer to the first character, which gets updated
Returns:   the new string
*/

uschar *
string_dequote(uschar **sptr)
{
uschar *s = *sptr;
uschar *t, *yield;

/* First find the end of the string */

if (*s != '\"')
  {
  while (*s != 0 && !isspace(*s)) s++;
  }
else
  {
  s++;
  while (*s != 0 && *s != '\"')
    {
    if (*s == '\\') (void)string_interpret_escape(&s);
    s++;
    }
  if (*s != 0) s++;
  }

/* Get enough store to copy into */

t = yield = store_get(s - *sptr + 1);
s = *sptr;

/* Do the copy */

if (*s != '\"')
  {
  while (*s != 0 && !isspace(*s)) *t++ = *s++;
  }
else
  {
  s++;
  while (*s != 0 && *s != '\"')
    {
    if (*s == '\\') *t++ = string_interpret_escape(&s);
      else *t++ = *s;
    s++;
    }
  if (*s != 0) s++;
  }

/* Update the pointer and return the terminated copy */

*sptr = s;
*t = 0;
return yield;
}
#endif  /* COMPILE_UTILITY */



/*************************************************
*          Format a string and save it           *
*************************************************/

/* The formatting is done by string_format, which checks the length of
everything.

Arguments:
  format    a printf() format - deliberately char * rather than uschar *
              because it will most usually be a literal string
  ...       arguments for format

Returns:    pointer to fresh piece of store containing sprintf'ed string
*/

uschar *
string_sprintf(char *format, ...)
{
va_list ap;
uschar buffer[STRING_SPRINTF_BUFFER_SIZE];
va_start(ap, format);
if (!string_vformat(buffer, sizeof(buffer), format, ap))
  log_write(0, LOG_MAIN|LOG_PANIC_DIE,
    "string_sprintf expansion was longer than %d", sizeof(buffer));
va_end(ap);
return string_copy(buffer);
}



/*************************************************
*         Case-independent strncmp() function    *
*************************************************/

/*
Arguments:
  s         first string
  t         second string
  n         number of characters to compare

Returns:    < 0, = 0, or > 0, according to the comparison
*/

int
strncmpic(uschar *s, uschar *t, int n)
{
while (n--)
  {
  int c = tolower(*s++) - tolower(*t++);
  if (c) return c;
  }
return 0;
}


/*************************************************
*         Case-independent strcmp() function     *
*************************************************/

/*
Arguments:
  s         first string
  t         second string

Returns:    < 0, = 0, or > 0, according to the comparison
*/

int
strcmpic(uschar *s, uschar *t)
{
while (*s != 0)
  {
  int c = tolower(*s++) - tolower(*t++);
  if (c != 0) return c;
  }
return *t;
}


/*************************************************
*         Case-independent strstr() function     *
*************************************************/

/* The third argument specifies whether whitespace is required
to follow the matched string.

Arguments:
  s              string to search
  t              substring to search for
  space_follows  if TRUE, match only if whitespace follows

Returns:         pointer to substring in string, or NULL if not found
*/

uschar *
strstric(uschar *s, uschar *t, BOOL space_follows)
{
uschar *p = t;
uschar *yield = NULL;
int cl = tolower(*p);
int cu = toupper(*p);

while (*s)
  {
  if (*s == cl || *s == cu)
    {
    if (yield == NULL) yield = s;
    if (*(++p) == 0)
      {
      if (!space_follows || s[1] == ' ' || s[1] == '\n' ) return yield;
      yield = NULL;
      p = t;
      }
    cl = tolower(*p);
    cu = toupper(*p);
    s++;
    }
  else if (yield != NULL)
    {
    yield = NULL;
    p = t;
    cl = tolower(*p);
    cu = toupper(*p);
    }
  else s++;
  }
return NULL;
}



#ifndef COMPILE_UTILITY
/*************************************************
*       Get next string from separated list      *
*************************************************/

/* Leading and trailing space is removed from each item. The separator in the
list is controlled by the int pointed to by the separator argument as follows:

  If its value is > 0 it is used as the delimiter.
    (If its value is actually > UCHAR_MAX there is only one item in the list.
    This is used for some cases when called via functions that sometimes
    plough through lists, and sometimes are given single items.)
  If its value is <= 0, the string is inspected for a leading <x, where
    x is an ispunct() value. If found, it is used as the delimiter. If not
    found: (a) if separator == 0, ':' is used
           (b) if separator <0, then -separator is used
    In all cases the value of the separator that is used is written back to
      the int so that it is used on subsequent calls as we progress through
      the list.

The separator can always be represented in the string by doubling.

Arguments:
  listptr    points to a pointer to the current start of the list; the
             pointer gets updated to point after the end of the next item
  separator  a pointer to the separator character in an int (see above)
  buffer     where to put a copy of the next string in the list; or
               NULL if the next string is returned in new memory
  buflen     when buffer is not NULL, the size of buffer; otherwise ignored

Returns:     pointer to buffer, containing the next substring,
             or NULL if no more substrings
*/

uschar *
string_nextinlist(uschar **listptr, int *separator, uschar *buffer, int buflen)
{
register int p = 0;
register int sep = *separator;
register uschar *s = *listptr;

if (s == NULL) return NULL;
while (isspace(*s)) s++;

if (sep <= 0)
  {
  if (*s == '<' && ispunct(s[1]))
    {
    sep = s[1];
    s += 2;
    while (isspace(*s)) s++;
    }
  else
    {
    sep = (sep == 0)? ':' : -sep;
    }
  *separator = sep;
  }

if (*s == 0) return NULL;

/* Handle the case when a buffer is provided. */

if (buffer != NULL)
  {
  for (; *s != 0; s++)
    {
    if (*s == sep && *(++s) != sep) break;
    if (p < buflen - 1) buffer[p++] = *s;
    }
  while (p > 0 && isspace(buffer[p-1])) p--;
  buffer[p] = 0;
  }

/* Handle the case when a buffer is not provided. */

else
  {
  /* We know that *s != 0 at this point. However, it might be pointing to a
  separator, which could indicate an empty string, or could be doubled to
  indicate a separator character as data at the start of a string. */

  if (*s == sep)
    {
    s++;
    if (*s != sep) buffer = string_copy(US"");
    }

  if (buffer == NULL)
    {
    int size = 0;
    int ptr = 0;
    uschar *ss;
    for (;;)
      {
      for (ss = s + 1; *ss != 0 && *ss != sep; ss++);
      buffer = string_cat(buffer, &size, &ptr, s, ss-s);
      s = ss;
      if (*s == 0 || *(++s) != sep) break;
      }
    while (ptr > 0 && isspace(buffer[ptr-1])) ptr--;
    buffer[ptr] = 0;
    }
  }

/* Update the current pointer and return the new string */

*listptr = s;
return buffer;
}
#endif  /* COMPILE_UTILITY */



#ifndef COMPILE_UTILITY
/*************************************************
*             Add chars to string                *
*************************************************/

/* This function is used when building up strings of unknown length. Room is
always left for a terminating zero to be added to the string that is being
built. This function does not require the string that is being added to be NUL
terminated, because the number of characters to add is given explicitly. It is
sometimes called to extract parts of other strings.

Arguments:
  string   points to the start of the string that is being built, or NULL
             if this is a new string that has no contents yet
  size     points to a variable that holds the current capacity of the memory
             block (updated if changed)
  ptr      points to a variable that holds the offset at which to add
             characters, updated to the new offset
  s        points to characters to add
  count    count of characters to add; must not exceed the length of s, if s
             is a C string

If string is given as NULL, *size and *ptr should both be zero.

Returns:   pointer to the start of the string, changed if copied for expansion.
           Note that a NUL is not added, though space is left for one. This is
           because string_cat() is often called multiple times to build up a
           string - there's no point adding the NUL till the end.
*/

uschar *
string_cat(uschar *string, int *size, int *ptr, const uschar *s, int count)
{
int p = *ptr;

if (p + count >= *size)
  {
  int oldsize = *size;

  /* Mostly, string_cat() is used to build small strings of a few hundred
  characters at most. There are times, however, when the strings are very much
  longer (for example, a lookup that returns a vast number of alias addresses).
  To try to keep things reasonable, we use increments whose size depends on the
  existing length of the string. */

  int inc = (oldsize < 4096)? 100 : 1024;
  while (*size <= p + count) *size += inc;

  /* New string */

  if (string == NULL) string = store_get(*size);

  /* Try to extend an existing allocation. If the result of calling
  store_extend() is false, either there isn't room in the current memory block,
  or this string is not the top item on the dynamic store stack. We then have
  to get a new chunk of store and copy the old string. When building large
  strings, it is helpful to call store_release() on the old string, to release
  memory blocks that have become empty. (The block will be freed if the string
  is at its start.) However, we can do this only if we know that the old string
  was the last item on the dynamic memory stack. This is the case if it matches
  store_last_get. */

  else if (!store_extend(string, oldsize, *size))
    {
    BOOL release_ok = store_last_get[store_pool] == string;
    uschar *newstring = store_get(*size);
    memcpy(newstring, string, p);
    if (release_ok) store_release(string);
    string = newstring;
    }
  }

/* Because we always specify the exact number of characters to copy, we can
use memcpy(), which is likely to be more efficient than strncopy() because the
latter has to check for zero bytes. */

memcpy(string + p, s, count);
*ptr = p + count;
return string;
}
#endif  /* COMPILE_UTILITY */



#ifndef COMPILE_UTILITY
/*************************************************
*        Append strings to another string        *
*************************************************/

/* This function can be used to build a string from many other strings.
It calls string_cat() to do the dirty work.

Arguments:
  string   points to the start of the string that is being built, or NULL
             if this is a new string that has no contents yet
  size     points to a variable that holds the current capacity of the memory
             block (updated if changed)
  ptr      points to a variable that holds the offset at which to add
             characters, updated to the new offset
  count    the number of strings to append
  ...      "count" uschar* arguments, which must be valid zero-terminated
             C strings

Returns:   pointer to the start of the string, changed if copied for expansion.
           The string is not zero-terminated - see string_cat() above.
*/

uschar *
string_append(uschar *string, int *size, int *ptr, int count, ...)
{
va_list ap;
int i;

va_start(ap, count);
for (i = 0; i < count; i++)
  {
  uschar *t = va_arg(ap, uschar *);
  string = string_cat(string, size, ptr, t, Ustrlen(t));
  }
va_end(ap);

return string;
}
#endif



/*************************************************
*        Format a string with length checks      *
*************************************************/

/* This function is used to format a string with checking of the length of the
output for all conversions. It protects Exim from absent-mindedness when
calling functions like debug_printf and string_sprintf, and elsewhere. There
are two different entry points to what is actually the same function, depending
on whether the variable length list of data arguments are given explicitly or
as a va_list item.

The formats are the usual printf() ones, with some omissions (never used) and
two additions for strings: %S forces lower case, %#s or %#S prints nothing for
a NULL string. Without the # "NULL" is printed (useful in debugging). There is
also the addition of %D, which inserts the date in the form used for
datestamped log files.

Arguments:
  buffer       a buffer in which to put the formatted string
  buflen       the length of the buffer
  format       the format string - deliberately char * and not uschar *
  ... or ap    variable list of supplementary arguments

Returns:       TRUE if the result fitted in the buffer
*/

BOOL
string_format(uschar *buffer, int buflen, char *format, ...)
{
BOOL yield;
va_list ap;
va_start(ap, format);
yield = string_vformat(buffer, buflen, format, ap);
va_end(ap);
return yield;
}


BOOL
string_vformat(uschar *buffer, int buflen, char *format, va_list ap)
{
BOOL yield = TRUE;
int width, precision;
char *fp = format;             /* Deliberately not unsigned */
uschar *p = buffer;
uschar *last = buffer + buflen - 1;

string_datestamp_offset = -1;  /* Datestamp not inserted */

/* Scan the format and handle the insertions */

while (*fp != 0)
  {
  int *nptr;
  int slen;
  char *null = "NULL";         /* ) These variables */
  char *item_start, *s;        /* ) are deliberately */
  char newformat[16];          /* ) not unsigned */

  /* Non-% characters just get copied verbatim */

  if (*fp != '%')
    {
    if (p >= last) { yield = FALSE; break; }
    *p++ = (uschar)*fp++;
    continue;
    }

  /* Deal with % characters. Pick off the width and precision, for checking
  strings, skipping over the flag and modifier characters. */

  item_start = fp;
  width = precision = -1;

  if (strchr("-+ #0", *(++fp)) != NULL)
    {
    if (*fp == '#') null = "";
    fp++;
    }

  if (isdigit((uschar)*fp))
    {
    width = *fp++ - '0';
    while (isdigit((uschar)*fp)) width = width * 10 + *fp++ - '0';
    }
  else if (*fp == '*')
    {
    width = va_arg(ap, int);
    fp++;
    }

  if (*fp == '.')
    {
    if (*(++fp) == '*')
      {
      precision = va_arg(ap, int);
      fp++;
      }
    else
      {
      precision = 0;
      while (isdigit((uschar)*fp))
        precision = precision*10 + *fp++ - '0';
      }
    }

  if (strchr("hlL", *fp) != NULL) fp++;

  /* Handle each specific format type. */

  switch (*fp++)
    {
    case 'n':
    nptr = va_arg(ap, int *);
    *nptr = p - buffer;
    break;

    case 'd':
    case 'o':
    case 'u':
    case 'x':
    case 'X':
    if (p >= last - 12) { yield = FALSE; goto END_FORMAT; }
    strncpy(newformat, item_start, fp - item_start);
    newformat[fp - item_start] = 0;
    sprintf(CS p, newformat, va_arg(ap, int));
    while (*p) p++;
    break;

    case 'p':
    if (p >= last - 24) { yield = FALSE; goto END_FORMAT; }
    strncpy(newformat, item_start, fp - item_start);
    newformat[fp - item_start] = 0;
    sprintf(CS p, newformat, va_arg(ap, void *));
    while (*p) p++;
    break;

    /* %f format is inherently insecure if the numbers that it may be
    handed are unknown (e.g. 1e300). However, in Exim, %f is used for
    printing load averages, and these are actually stored as integers
    (load average * 1000) so the size of the numbers is constrained.
    It is also used for formatting sending rates, where the simplicity
    of the format prevents overflow. */

    case 'f':
    case 'e':
    case 'E':
    case 'g':
    case 'G':
    if (precision < 0) precision = 6;
    if (p >= last - precision - 8) { yield = FALSE; goto END_FORMAT; }
    strncpy(newformat, item_start, fp - item_start);
    newformat[fp-item_start] = 0;
    sprintf(CS p, newformat, va_arg(ap, double));
    while (*p) p++;
    break;

    /* String types */

    case '%':
    if (p >= last) { yield = FALSE; goto END_FORMAT; }
    *p++ = '%';
    break;

    case 'c':
    if (p >= last) { yield = FALSE; goto END_FORMAT; }
    *p++ = va_arg(ap, int);
    break;

    case 'D':                   /* Insert datestamp for log file names */
    s = CS tod_stamp(tod_log_datestamp);
    string_datestamp_offset = p - buffer;   /* Passed back via global */
    goto INSERT_STRING;

    case 's':
    case 'S':                   /* Forces *lower* case */
    s = va_arg(ap, char *);

    INSERT_STRING:              /* Come to from %D above */
    if (s == NULL) s = null;
    slen = Ustrlen(s);

    /* If the width is specified, check that there is a precision
    set; if not, set it to the width to prevent overruns of long
    strings. */

    if (width >= 0)
      {
      if (precision < 0) precision = width;
      }

    /* If a width is not specified and the precision is specified, set
    the width to the precision, or the string length if shorted. */

    else if (precision >= 0)
      {
      width = (precision < slen)? precision : slen;
      }

    /* If neither are specified, set them both to the string length. */

    else width = precision = slen;

    /* Check string space, and add the string to the buffer if ok. If
    not OK, add part of the string (debugging uses this to show as
    much as possible). */

    if (p >= last - width)
      {
      yield = FALSE;
      width = precision = last - p - 1;
      }
    sprintf(CS p, "%*.*s", width, precision, s);
    if (fp[-1] == 'S')
      while (*p) { *p = tolower(*p); p++; }
    else
      while (*p) p++;
    if (!yield) goto END_FORMAT;
    break;

    /* Some things are never used in Exim; also catches junk. */

    default:
    strncpy(newformat, item_start, fp - item_start);
    newformat[fp-item_start] = 0;
    log_write(0, LOG_MAIN|LOG_PANIC_DIE, "string_format: unsupported type "
      "in \"%s\" in \"%s\"", newformat, format);
    break;
    }
  }

/* Ensure string is complete; return TRUE if got to the end of the format */

END_FORMAT:

*p = 0;
return yield;
}



#ifndef COMPILE_UTILITY
/*************************************************
*       Generate an "open failed" message        *
*************************************************/

/* This function creates a message after failure to open a file. It includes a
string supplied as data, adds the strerror() text, and if the failure was
"Permission denied", reads and includes the euid and egid.

Arguments:
  eno           the value of errno after the failure
  format        a text format string - deliberately not uschar *
  ...           arguments for the format string

Returns:        a message, in dynamic store
*/

uschar *
string_open_failed(int eno, char *format, ...)
{
va_list ap;
uschar buffer[1024];

Ustrcpy(buffer, "failed to open ");
va_start(ap, format);

/* Use the checked formatting routine to ensure that the buffer
does not overflow. It should not, since this is called only for internally
specified messages. If it does, the message just gets truncated, and there
doesn't seem much we can do about that. */

(void)string_vformat(buffer+15, sizeof(buffer) - 15, format, ap);

return (eno == EACCES)?
  string_sprintf("%s: %s (euid=%ld egid=%ld)", buffer, strerror(eno),
    (long int)geteuid(), (long int)getegid()) :
  string_sprintf("%s: %s", buffer, strerror(eno));
}
#endif  /* COMPILE_UTILITY */



#ifndef COMPILE_UTILITY
/*************************************************
*        Generate local prt for logging          *
*************************************************/

/* This function is a subroutine for use in string_log_address() below.

Arguments:
  addr        the address being logged
  yield       the current dynamic buffer pointer
  sizeptr     points to current size
  ptrptr      points to current insert pointer

Returns:      the new value of the buffer pointer
*/

static uschar *
string_get_localpart(address_item *addr, uschar *yield, int *sizeptr,
  int *ptrptr)
{
if (testflag(addr, af_include_affixes) && addr->prefix != NULL)
  yield = string_cat(yield, sizeptr, ptrptr, addr->prefix,
    Ustrlen(addr->prefix));
yield = string_cat(yield, sizeptr, ptrptr, addr->local_part,
  Ustrlen(addr->local_part));
if (testflag(addr, af_include_affixes) && addr->suffix != NULL)
  yield = string_cat(yield, sizeptr, ptrptr, addr->suffix,
    Ustrlen(addr->suffix));
return yield;
}


/*************************************************
*          Generate log address list             *
*************************************************/

/* This function generates a list consisting of an address and its parents, for
use in logging lines. For saved onetime aliased addresses, the onetime parent
field is used. If the address was delivered by a transport with rcpt_include_
affixes set, the af_include_affixes bit will be set in the address. In that
case, we include the affixes here too.

Arguments:
  addr          bottom (ultimate) address
  all_parents   if TRUE, include all parents
  success       TRUE for successful delivery

Returns:        a string in dynamic store
*/

uschar *
string_log_address(address_item *addr, BOOL all_parents, BOOL success)
{
int size = 64;
int ptr = 0;
BOOL add_topaddr = TRUE;
uschar *yield = store_get(size);
address_item *topaddr;

/* Find the ultimate parent */

for (topaddr = addr; topaddr->parent != NULL; topaddr = topaddr->parent);

/* We start with just the local part for pipe, file, and reply deliveries, and
for successful local deliveries from routers that have the log_as_local flag
set. File deliveries from filters can be specified as non-absolute paths in
cases where the transport is goin to complete the path. If there is an error
before this happens (expansion failure) the local part will not be updated, and
so won't necessarily look like a path. Add extra text for this case. */

if (testflag(addr, af_pfr) ||
      (success &&
       addr->router != NULL && addr->router->log_as_local &&
       addr->transport != NULL && addr->transport->info->local))
  {
  if (testflag(addr, af_file) && addr->local_part[0] != '/')
    yield = string_cat(yield, &size, &ptr, CUS"save ", 5);
  yield = string_get_localpart(addr, yield, &size, &ptr);
  }

/* Other deliveries start with the full address. It we have split it into local
part and domain, use those fields. Some early failures can happen before the
splitting is done; in those cases use the original field. */

else
  {
  if (addr->local_part != NULL)
    {
    yield = string_get_localpart(addr, yield, &size, &ptr);
    yield = string_cat(yield, &size, &ptr, US"@", 1);
    yield = string_cat(yield, &size, &ptr, addr->domain,
      Ustrlen(addr->domain) );
    }
  else
    {
    yield = string_cat(yield, &size, &ptr, addr->address, Ustrlen(addr->address));
    }
  yield[ptr] = 0;

  /* If the address we are going to print is the same as the top address,
  and all parents are not being included, don't add on the top address. First
  of all, do a caseless comparison; if this succeeds, do a caseful comparison
  on the local parts. */

  if (strcmpic(yield, topaddr->address) == 0 &&
      Ustrncmp(yield, topaddr->address, Ustrchr(yield, '@') - yield) == 0 &&
      addr->onetime_parent == NULL &&
      (!all_parents || addr->parent == NULL || addr->parent == topaddr))
    add_topaddr = FALSE;
  }

/* If all parents are requested, or this is a local pipe/file/reply, and
there is at least one intermediate parent, show it in brackets, and continue
with all of them if all are wanted. */

if ((all_parents || testflag(addr, af_pfr)) &&
    addr->parent != NULL &&
    addr->parent != topaddr)
  {
  uschar *s = US" (";
  address_item *addr2;
  for (addr2 = addr->parent; addr2 != topaddr; addr2 = addr2->parent)
    {
    yield = string_cat(yield, &size, &ptr, s, 2);
    yield = string_cat(yield, &size, &ptr, addr2->address, Ustrlen(addr2->address));
    if (!all_parents) break;
    s = US", ";
    }
  yield = string_cat(yield, &size, &ptr, US")", 1);
  }

/* Add the top address if it is required */

if (add_topaddr)
  {
  yield = string_cat(yield, &size, &ptr, US" <", 2);

  if (addr->onetime_parent == NULL)
    yield = string_cat(yield, &size, &ptr, topaddr->address,
      Ustrlen(topaddr->address));
  else
    yield = string_cat(yield, &size, &ptr, addr->onetime_parent,
      Ustrlen(addr->onetime_parent));

  yield = string_cat(yield, &size, &ptr, US">", 1);
  }

yield[ptr] = 0;  /* string_cat() leaves space */
return yield;
}
#endif  /* COMPILE_UTILITY */





/*************************************************
**************************************************
*             Stand-alone test program           *
**************************************************
*************************************************/

#ifdef STAND_ALONE
int main(void)
{
uschar buffer[256];

printf("Testing is_ip_address\n");

while (fgets(CS buffer, sizeof(buffer), stdin) != NULL)
  {
  int offset;
  buffer[Ustrlen(buffer) - 1] = 0;
  printf("%d\n", string_is_ip_address(buffer, NULL));
  printf("%d %d %s\n", string_is_ip_address(buffer, &offset), offset, buffer);
  }

printf("Testing string_nextinlist\n");

while (fgets(CS buffer, sizeof(buffer), stdin) != NULL)
  {
  uschar *list = buffer;
  uschar *lp1, *lp2;
  uschar item[256];
  int sep1 = 0;
  int sep2 = 0;

  if (*list == '<')
    {
    sep1 = sep2 = list[1];
    list += 2;
    }

  lp1 = lp2 = list;
  for (;;)
    {
    uschar *item1 = string_nextinlist(&lp1, &sep1, item, sizeof(item));
    uschar *item2 = string_nextinlist(&lp2, &sep2, NULL, 0);

    if (item1 == NULL && item2 == NULL) break;
    if (item == NULL || item2 == NULL || Ustrcmp(item1, item2) != 0)
      {
      printf("***ERROR\nitem1=\"%s\"\nitem2=\"%s\"\n",
        (item1 == NULL)? "NULL" : CS item1,
        (item2 == NULL)? "NULL" : CS item2);
      break;
      }
    else printf("  \"%s\"\n", CS item1);
    }
  }

/* This is a horrible lash-up, but it serves its purpose. */

printf("Testing string_format\n");

while (fgets(CS buffer, sizeof(buffer), stdin) != NULL)
  {
  void *args[3];
  double dargs[3];
  int dflag = 0;
  int n = 0;
  int count;
  int countset = 0;
  uschar format[256];
  uschar outbuf[256];
  uschar *s;
  buffer[Ustrlen(buffer) - 1] = 0;

  s = Ustrchr(buffer, ',');
  if (s == NULL) s = buffer + Ustrlen(buffer);

  Ustrncpy(format, buffer, s - buffer);
  format[s-buffer] = 0;

  if (*s == ',') s++;

  while (*s != 0)
    {
    uschar *ss = s;
    s = Ustrchr(ss, ',');
    if (s == NULL) s = ss + Ustrlen(ss);

    if (isdigit(*ss))
      {
      Ustrncpy(outbuf, ss, s-ss);
      if (Ustrchr(outbuf, '.') != NULL)
        {
        dflag = 1;
        dargs[n++] = Ustrtod(outbuf, NULL);
        }
      else
        {
        args[n++] = (void *)Uatoi(outbuf);
        }
      }

    else if (Ustrcmp(ss, "*") == 0)
      {
      args[n++] = (void *)(&count);
      countset = 1;
      }

    else
      {
      uschar *sss = malloc(s - ss + 1);
      Ustrncpy(sss, ss, s-ss);
      args[n++] = sss;
      }

    if (*s == ',') s++;
    }

  if (!dflag) printf("%s\n", string_format(outbuf, sizeof(outbuf), CS format,
    args[0], args[1], args[2])? "True" : "False");

  else printf("%s\n", string_format(outbuf, sizeof(outbuf), CS format,
    dargs[0], dargs[1], dargs[2])? "True" : "False");

  printf("%s\n", CS outbuf);
  if (countset) printf("count=%d\n", count);
  }

return 0;
}
#endif

/* End of string.c */