support.c

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/***********************************************************************
 Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
***********************************************************************/
 
/***********************************************************************
  This module contains replacements for functions which are not
  available on all platforms. Where the functions are available
  natively, these are (mostly) just wrappers.
 
  Notice the function names here are prefixed by, eg, "fc".
  An alternative would be to use the "standard" function name, and
  provide the implementation only if required. However the method
  here has some advantages:
 
   - We can provide definite prototypes in support.h, rather than
   worrying about whether a system prototype exists, and if so where,
   and whether it is correct. (Note that whether or not configure
   finds a function and defines HAVE_FOO does not necessarily say
   whether or not there is a _prototype_ for the function available.)
 
   - We don't have to include fc_config.h in support.h, but can instead
   restrict it to this .c file.
 
   - We can add some extra stuff to these functions if we want.
 
  The main disadvantage is remembering to use these "fc" functions on
  systems which have the functions natively.
 
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
#include "fc_prehdrs.h"
 
#include <ctype.h>
#include <errno.h>
#include <math.h> /* ceil() */
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
 
#ifdef GENERATING_MAC
#include <events.h>             /* for WaitNextEvent() */
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef FREECIV_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>             /* usleep, fcntl, gethostname */
#endif
#ifdef HAVE_TIME_H
#include <time.h>               /* nanosleep */
#endif
#ifdef HAVE_SYS_UTSNAME_H
#include <sys/utsname.h>
#endif
#ifdef FREECIV_HAVE_LIBZ
#include <zlib.h>
#endif
#ifdef FREECIV_MSWINDOWS
#include <process.h>
#include <windows.h>
#endif /* FREECIV_MSWINDOWS */
#ifdef HAVE_STRINGS_H
#  include <strings.h>
#endif
#ifdef HAVE_LIBGEN_H
/* POSIX version of basename() */
#  include <libgen.h>
#endif
 
#ifdef FREECIV_HAVE_LIBZ
#include <zlib.h>
#endif
 
/* ICU */
#include "unicode/ustring.h"
 
/* utility */
#include "fciconv.h"
#include "fcintl.h"
#include "fcthread.h"
#include "log.h"
#include "mem.h"
#include "netintf.h"
 
#include "support.h"
 
static bool support_initialized = FALSE;
 
static int icu_buffer_uchars = 0;
static UChar *icu_buffer1 = NULL;
static UChar *icu_buffer2 = NULL;
fc_mutex icu_buffer_mutex;
 
#ifndef HAVE_WORKING_VSNPRINTF
static char *vsnprintf_buf = NULL;
static fc_mutex vsnprintf_mutex;
#endif /* HAVE_WORKING_VSNPRINTF */
 
#ifndef HAVE_LOCALTIME_R
static fc_mutex localtime_mutex;
#endif /* HAVE_LOCALTIME_R */
 
/************************************************************************/
static void icu_buffers_initial(void)
{
  if (icu_buffer1 == NULL) {
    icu_buffer_uchars = 1024;
    icu_buffer1 = fc_malloc((icu_buffer_uchars + 1) * sizeof(UChar));
    icu_buffer2 = fc_malloc((icu_buffer_uchars + 1) * sizeof(UChar));
 
    /* Make sure there's zero after the buffer published with cmp_buffer_uchars */
    icu_buffer1[icu_buffer_uchars] = 0;
    icu_buffer2[icu_buffer_uchars] = 0;
  }
}
 
/************************************************************************/
static void icu_buffers_increase(void)
{
  icu_buffer_uchars *= 1.5;
  icu_buffer1 = fc_realloc(icu_buffer1, (icu_buffer_uchars + 1) * sizeof(UChar));
  icu_buffer2 = fc_realloc(icu_buffer2, (icu_buffer_uchars + 1) * sizeof(UChar));
 
  /* Make sure there's zero after the buffer published with cmp_buffer_uchars */
  icu_buffer1[icu_buffer_uchars] = 0;
  icu_buffer2[icu_buffer_uchars] = 0;
}
 
/************************************************************************/
static void fc_strAPI_init(void)
{
  if (icu_buffer_uchars == 0) {
    fc_init_mutex(&icu_buffer_mutex);
    icu_buffers_initial();
  }
}
 
/************************************************************************/
static void fc_strAPI_free(void)
{
  if (icu_buffer1 != NULL) {
    free(icu_buffer1);
    icu_buffer1 = NULL;
    free(icu_buffer2);
    icu_buffer2 = NULL;
    icu_buffer_uchars = 0;
  }
  fc_destroy_mutex(&icu_buffer_mutex);
}
 
/************************************************************************/
int fc_strcasecmp(const char *str0, const char *str1)
{
  UErrorCode err_code = U_ZERO_ERROR;
  int len0;
  int len1;
  bool enough_mem = FALSE;
  int ret;
 
  if (str0 == NULL) {
    return -1;
  }
  if (str1 == NULL) {
    return 1;
  }
 
  if (icu_buffer_uchars == 0) {
    fc_strAPI_init();
  }
 
  fc_allocate_mutex(&icu_buffer_mutex);
 
  while (!enough_mem) {
    UErrorCode err_code0 = U_ZERO_ERROR;
    UErrorCode err_code1 = U_ZERO_ERROR;
 
    u_strFromUTF8Lenient(icu_buffer1, icu_buffer_uchars, &len0, str0, -1, &err_code0);
    u_strFromUTF8Lenient(icu_buffer2, icu_buffer_uchars, &len1, str1, -1, &err_code1);
 
    /* No need to handle U_STRING_NOT_TERMINATED_WARNING here as there's '0' after
     * the buffers we were using */
    if (err_code0 == U_BUFFER_OVERFLOW_ERROR || err_code1 == U_BUFFER_OVERFLOW_ERROR) {
      icu_buffers_increase();
    } else {
      enough_mem = TRUE;
    }
  }
 
  ret = u_strCaseCompare(icu_buffer1, -1, icu_buffer2, -1,
                         0, &err_code);
 
  fc_release_mutex(&icu_buffer_mutex);
 
  return ret;
}
 
/************************************************************************/
int fc_strncasecmp(const char *str0, const char *str1, size_t n)
{
  UErrorCode err_code = U_ZERO_ERROR;
  int len0;
  int len1;
  bool enough_mem = FALSE;
  int ret;
 
  if (str0 == NULL) {
    return -1;
  }
  if (str1 == NULL) {
    return 1;
  }
 
  if (icu_buffer_uchars == 0) {
    fc_strAPI_init();
  }
 
  fc_allocate_mutex(&icu_buffer_mutex);
 
  while (!enough_mem) {
    UErrorCode err_code0 = U_ZERO_ERROR;
    UErrorCode err_code1 = U_ZERO_ERROR;
 
    u_strFromUTF8Lenient(icu_buffer1, icu_buffer_uchars, &len0, str0, -1, &err_code0);
    u_strFromUTF8Lenient(icu_buffer2, icu_buffer_uchars, &len1, str1, -1, &err_code1);
 
    /* No need to handle U_STRING_NOT_TERMINATED_WARNING here as there's '0' after
     * the buffers we were using */
    if (err_code0 == U_BUFFER_OVERFLOW_ERROR || err_code1 == U_BUFFER_OVERFLOW_ERROR) {
      icu_buffers_increase();
    } else {
      enough_mem = TRUE;
    }
  }
 
  if (len0 > n) {
    len0 = n;
  }
  if (len1 > n) {
    len1 = n;
  }
 
  ret = u_strCaseCompare(icu_buffer1, len0, icu_buffer2, len1,
                         0, &err_code);
 
  fc_release_mutex(&icu_buffer_mutex);
 
  return ret;
}
 
/************************************************************************/
void make_escapes(const char *str, char *buf, size_t buf_len)
{
  char *dest = buf;
  /* Sometimes we insert 2 characters at once ('\n' -> "\\n"), so keep
   * place for '\0' and an extra character. */
  const char *const max = buf + buf_len - 2;
 
  while (*str != '\0' && dest < max) {
    switch (*str) {
    case '\n':
      *dest++ = '\\';
      *dest++ = 'n';
      str++;
      break;
    case '\\':
    case '\"':
      *dest++ = '\\';
 
      fc__fallthrough;
    default:
      *dest++ = *str++;
      break;
    }
  }
  *dest = 0;
}
 
/************************************************************************/
void remove_escapes(const char *str, bool full_escapes,
                    char *buf, size_t buf_len)
{
  char *dest = buf;
  const char *const max = buf + buf_len - 1;
 
  while (*str != '\0' && dest < max) {
    if (*str == '\\' && *(str + 1) == '\n') {
      /* Escape followed by newline. Skip both */
      str += 2;
    } else if (full_escapes && *str == '\\') {
      str++;
      if (*str == 'n') {
        *dest++ = '\n';
        str++;
      }
    } else {
      *dest++ = *str++;
    }
  }
  *dest = '\0';
}
 
/************************************************************************/
size_t effectivestrlenquote(const char *str)
{
  int len;
  if (!str) {
    return 0;
  }
 
  len = strlen(str);
 
  if (str[0] == '"' && str[len-1] == '"') {
    return len - 2;
  }
 
  return len;
}
 
/************************************************************************/
int fc_strncasequotecmp(const char *str0, const char *str1, size_t n)
{
  size_t i;
  size_t len0;
  size_t len1;
  size_t cmplen;
 
  if (str0 == NULL) {
    return -1;
  }
  if (str1 == NULL) {
    return 1;
  }
 
  len0 = strlen(str0); /* TODO: We iterate string once already here, */
  len1 = strlen(str1); /*       could iterate only once */
 
  if (str0[0] == '"') {
    if (str0[len0 - 1] == '"') {
      /* Surrounded with quotes */
      str0++;
      len0 -= 2;
    }
  }
 
  if (str1[0] == '"') {
    if (str1[len1 - 1] == '"') {
      /* Surrounded with quotes */
      str1++;
      len1 -= 2;
    }
  }
 
  if (len0 < n || len1 < n) {
    /* One of the strings is shorter than what should be compared... */
    if (len0 != len1) {
      /* ...and another is longer than it. */
      return len0 - len1;
    }
 
    cmplen = len0; /* This avoids comparing ending quote */
  } else {
    cmplen = n;
  }
 
  for (i = 0; i < cmplen ; i++, str0++, str1++) {
    if (fc_tolower(*str0) != fc_tolower(*str1)) {
      return ((int) (unsigned char) fc_tolower(*str0))
             - ((int) (unsigned char) fc_tolower(*str1));
    }
  }
 
  /* All characters compared and all matched */
  return 0;
}
 
/************************************************************************/
char *fc_strcasestr(const char *haystack, const char *needle)
{
#ifdef HAVE_STRCASESTR
  return strcasestr(haystack, needle);
#else
  size_t haystacks;
  size_t needles;
  const char *p;
 
  if (NULL == needle || '\0' == *needle) {
    return (char *)haystack;
  }
  if (NULL == haystack || '\0' == *haystack) {
    return NULL;
  }
  haystacks = strlen(haystack);
  needles = strlen(needle);
  if (haystacks < needles) {
    return NULL;
  }
 
  for (p = haystack; p <= &haystack[haystacks - needles]; p++) {
    if (0 == fc_strncasecmp(p, needle, needles)) {
      return (char *)p;
    }
  }
  return NULL;
#endif /* HAVE_STRCASESTR */
}
 
/************************************************************************/
int fc_strcoll(const char *str0, const char *str1)
{
#if defined(ENABLE_NLS) && defined(HAVE_STRCOLL)
  return strcoll(str0, str1);
#elif defined(ENABLE_NLS) && defined(HAVE__STRCOLL)
  return _strcoll(str0, str1);
#else
  return strcmp(str0, str1);
#endif
}
 
/************************************************************************/
int fc_stricoll(const char *str0, const char *str1)
{
  /* We prefer _stricoll() over stricoll() since
   * latter is not declared in MinGW headers causing compiler
   * warning, preventing -Werror builds. */
#if defined(ENABLE_NLS) && defined(HAVE__STRICOLL)
  return _stricoll(str0, str1);
#elif defined(ENABLE_NLS) && defined(HAVE_STRICOLL)
  return stricoll(str0, str1);
#elif defined(ENABLE_NLS) && defined(HAVE_STRCASECOLL)
  return strcasecoll(str0, str1);
#else
  return fc_strcasecmp(str0, str1);
#endif
}
 
/************************************************************************/
FILE *fc_fopen(const char *filename, const char *opentype)
{
  FILE *result;
 
#ifdef FREECIV_MSWINDOWS
  char *real_filename = internal_to_local_string_malloc(filename);
#else  /* FREECIV_MSWINDOWS */
  const char *real_filename = filename;
#endif /* FREECIV_MSWINDOWS */
 
#ifdef HAVE_FOPEN_S
  if (fopen_s(&result, real_filename, opentype) != 0) {
    result = NULL;
  }
#else  /* HAVE_FOPEN_S */
  result = fopen(real_filename, opentype);
#endif /* HAVE_FOPEN_S */
 
#ifdef FREECIV_MSWINDOWS
  free(real_filename);
#endif /* FREECIV_MSWINDOWS */
 
  return result;
}
 
/************************************************************************/
#ifdef FREECIV_HAVE_LIBZ
gzFile fc_gzopen(const char *filename, const char *opentype)
{
#ifdef FREECIV_MSWINDOWS
  gzFile result;
  char *filename_in_local_encoding =
    internal_to_local_string_malloc(filename);
 
  result = gzopen(filename_in_local_encoding, opentype);
  free(filename_in_local_encoding);
  return result;
#else  /* FREECIV_MSWINDOWS */
  return gzopen(filename, opentype);
#endif /* FREECIV_MSWINDOWS */
}
#endif /* FREECIV_HAVE_LIBZ */
 
/************************************************************************/
int fc_remove(const char *filename)
{
#ifdef FREECIV_MSWINDOWS
  int result;
  char *filename_in_local_encoding =
    internal_to_local_string_malloc(filename);
 
  result = remove(filename_in_local_encoding);
  free(filename_in_local_encoding);
  return result;
#else  /* FREECIV_MSWINDOWS */
  return remove(filename);
#endif /* FREECIV_MSWINDOWS */
}
 
/************************************************************************/
int fc_stat(const char *filename, struct stat *buf)
{
#ifdef FREECIV_MSWINDOWS
  int result;
  char *filename_in_local_encoding =
    internal_to_local_string_malloc(filename);
 
  result = stat(filename_in_local_encoding, buf);
  free(filename_in_local_encoding);
  return result;
#else  /* FREECIV_MSWINDOWS */
  return stat(filename, buf);
#endif /* FREECIV_MSWINDOWS */
}
 
/************************************************************************/
fc_errno fc_get_errno(void)
{
#ifdef FREECIV_MSWINDOWS
  return GetLastError();
#else  /* FREECIV_MSWINDOWS */
  return errno;
#endif /* FREECIV_MSWINDOWS */
}
 
/************************************************************************/
const char *fc_strerror(fc_errno err)
{
#ifdef FREECIV_MSWINDOWS
  static char buf[256];
 
  if (!FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                     NULL, err, 0, buf, sizeof(buf), NULL)) {
    fc_snprintf(buf, sizeof(buf),
                _("error %ld (failed FormatMessage)"), err);
  }
  return buf;
#else  /* FREECIV_MSWINDOWS */
#ifdef HAVE_STRERROR
  static char buf[256];
 
  return local_to_internal_string_buffer(strerror(err),
                                         buf, sizeof(buf));
#else  /* HAVE_STRERROR */
  static char buf[64];
 
  fc_snprintf(buf, sizeof(buf),
              _("error %d (compiled without strerror)"), err);
  return buf;
#endif /* HAVE_STRERROR */
#endif /* FREECIV_MSWINDOWS */
}
 
/************************************************************************/
void fc_usleep(unsigned long usec)
{
#ifdef HAVE_NANOSLEEP
  struct timespec ts;
 
  if (usec >= 1000000) {
    ts.tv_sec = usec / 1000000;
    ts.tv_nsec = (usec % 1000000) * 1000;
  } else {
    ts.tv_sec = 0;
    ts.tv_nsec = usec * 1000;
  }
 
  nanosleep(&ts, NULL);
#else  /* HAVE_NANOSLEEP */
#ifdef HAVE_USLEEP
  usleep(usec);
#else  /* HAVE_USLEEP */
#ifdef HAVE_SNOOZE              /* BeOS */
  snooze(usec);
#else  /* HAVE_SNOOZE */
#ifdef GENERATING_MAC
  EventRecord the_event;        /* dummy - always be a null event */
 
  usec /= 16666;                /* microseconds to 1/60th seconds */
  if (usec < 1) {
    usec = 1;
  }
  /* supposed to give other application processor time for the mac */
  WaitNextEvent(0, &the_event, usec, 0L);
#else  /* GENERATING_MAC */
#ifdef FREECIV_MSWINDOWS
  Sleep(usec / 1000);
#else  /* FREECIV_MSWINDOWS */
  fc_timeval tv;
 
  tv.tv_sec = 0;
  tv.tv_usec = usec;
  /* FIXME: an interrupt can cause an EINTR return here.  In that case we
   * need to have another select call. */
  fc_select(0, NULL, NULL, NULL, &tv);
#endif /* FREECIV_MSWINDOWS */
#endif /* GENERATING_MAC */
#endif /* HAVE_SNOOZE */
#endif /* HAVE_USLEEP */
#endif /* HAVE_NANOSLEEP */
}
 
/************************************************************************/
char *fc_strrep_resize(char *str, size_t *len, const char *search,
                       const char *replace)
{
  size_t len_max;
 
  fc_assert_ret_val(str != NULL, NULL);
  fc_assert_ret_val(len != NULL, NULL);
  if (search == NULL || replace == NULL) {
    return str;
  }
 
  len_max = ceil((double)strlen(str) * strlen(replace) / strlen(search)) + 1;
  if ((*len) < len_max) {
    /* replace string is longer than search string; allocate enough memory
     * for the worst case */
    (*len) = len_max;
    str = fc_realloc(str, len_max);
  }
 
#ifndef FREECIV_NDEBUG
  bool success =
#endif
    fc_strrep(str, (*len), search, replace);
 
  /* Should never happen */
  fc_assert_ret_val_msg(success, NULL,
                        "Can't replace '%s' by '%s' in '%s'. Too small "
                        "size after reallocation: " SIZE_T_PRINTF ".",
                        search, replace, str, *len);
 
  return str;
}
 
/************************************************************************/
bool fc_strrep(char *str, size_t len, const char *search,
               const char *replace)
{
  size_t len_search, len_replace;
  char *s, *p;
 
  fc_assert_ret_val(str != NULL, FALSE);
  if (search == NULL || replace == NULL) {
    return TRUE;
  }
 
  len_search = strlen(search);
  len_replace = strlen(replace);
 
  s = str;
  while (s != NULL) {
    p = strstr(s, search);
    if (p == NULL) {
      /* nothing found */
      break;
    }
 
    if (len < (strlen(str) + len_replace - len_search + 1)) {
      /* sizeof(str) not large enough to do the replacement */
      return FALSE;
    }
 
    memmove(p + len_replace, p + len_search, strlen(p + len_search) + 1);
    memcpy(p, replace, len_replace);
    s = p + len_replace;
  }
 
  return TRUE;
}
 
/************************************************************************/
size_t fc_strlcpy(char *dest, const char *src, size_t n)
{
  bool enough_mem = FALSE;
  int slen;
  int dlen;
  UErrorCode err_code = U_ZERO_ERROR;
 
  fc_assert_ret_val(NULL != dest, -1);
  fc_assert_ret_val(NULL != src, -1);
  fc_assert_ret_val(0 < n, -1);
 
  if (icu_buffer_uchars == 0) {
    fc_strAPI_init();
  }
 
  fc_allocate_mutex(&icu_buffer_mutex);
 
  while (!enough_mem) {
    u_strFromUTF8(icu_buffer1, icu_buffer_uchars, &slen, src, -1, &err_code);
 
    /* No need to handle U_STRING_NOT_TERMINATED_WARNING here as there's '0' after
     * the buffers we were using */
    if (err_code == U_BUFFER_OVERFLOW_ERROR) {
      icu_buffers_increase();
      err_code = U_ZERO_ERROR;
    } else {
      enough_mem = TRUE;
    }
  }
 
  u_strToUTF8(dest, n - 1, &dlen, icu_buffer1, slen, &err_code);
 
  fc_release_mutex(&icu_buffer_mutex);
 
  dest[n - 1] = '\0';
 
  return dlen;
}
 
/************************************************************************/
size_t fc_strlcat(char *dest, const char *src, size_t n)
{
  size_t start;
 
  start = strlen(dest);
 
  fc_assert(start < n);
 
  return fc_strlcpy(dest + start, src, n - start) + start;
}
 
/************************************************************************/
/* This must be at least as big as PLAIN_FILE_BUF_SIZE in ioz.c */
#define VSNP_BUF_SIZE (8096*1024)
int fc_vsnprintf(char *str, size_t n, const char *format, va_list ap)
{
#ifdef HAVE_WORKING_VSNPRINTF
  int r;
#endif
 
  /* This may be overzealous, but I suspect any triggering of these to
   * be bugs.  */
 
  fc_assert_ret_val(0 < n, -1);
 
#ifdef HAVE_WORKING_VSNPRINTF
  r = vsnprintf(str, n, format, ap);
  str[n - 1] = 0;
 
  return r;
#else  /* HAVE_WORKING_VSNPRINTF */
  {
    /* Don't use fc_malloc() or log_*() here, since they may call
       fc_vsnprintf() if it fails.  */
    size_t len;
 
    if (n > VSNP_BUF_SIZE) {
      fprintf(stderr, "fc_vsnprintf() call with length " SIZE_T_PRINTF "."
              "Maximum supported is %d", n, VSNP_BUF_SIZE);
      exit(EXIT_FAILURE);
    }
 
    fc_allocate_mutex(&vsnprintf_mutex);
 
    if (vsnprintf_buf == NULL) {
      vsnprintf_buf = malloc(VSNP_BUF_SIZE);
 
      if (vsnprintf_buf == NULL) {
        fprintf(stderr, "Could not allocate %i bytes for vsnprintf() "
                "replacement.", VSNP_BUF_SIZE);
        fc_release_mutex(&vsnprintf_mutex);
        exit(EXIT_FAILURE);
      }
    }
 
    vsnprintf_buf[VSNP_BUF_SIZE - 1] = '\0';
 
#ifdef HAVE_VSNPRINTF
    vsnprintf(vsnprintf_buf, VSNP_BUF_SIZE, format, ap);
#else
    vsprintf(vsnprintf_buf, format, ap);
#endif /* HAVE_VSNPRINTF */
 
    len = strlen(vsnprintf_buf);
 
    if (len >= VSNP_BUF_SIZE - 1) {
      fprintf(stderr, "Overflow in vsnprintf replacement!"
              " (buffer size %d) aborting...\n", VSNP_BUF_SIZE);
      abort();
    }
    if (n >= len + 1) {
      memcpy(str, vsnprintf_buf, len + 1);
    } else {
      memcpy(str, vsnprintf_buf, n - 1);
      str[n - 1] = '\0';
    }
 
    fc_release_mutex(&vsnprintf_mutex);
 
    return len;
  }
#endif /* HAVE_WORKING_VSNPRINTF */
}
 
/************************************************************************/
int fc_snprintf(char *str, size_t n, const char *format, ...)
{
  int ret;
  va_list ap;
 
  va_start(ap, format);
  ret = fc_vsnprintf(str, n, format, ap);
  va_end(ap);
 
  return ret;
}
 
/************************************************************************/
int cat_snprintf(char *str, size_t n, const char *format, ...)
{
  size_t len;
  int ret;
  va_list ap;
 
  fc_assert_ret_val(0 < n, -1);
 
  len = strlen(str);
  fc_assert_ret_val(len < n, -1);
 
  va_start(ap, format);
  ret = fc_vsnprintf(str+len, n-len, format, ap);
  va_end(ap);
 
  return (-1 == ret ? -1 : ret + len);
}
 
/************************************************************************/
int fc_gethostname(char *buf, size_t len)
{
#ifdef HAVE_GETHOSTNAME
  return gethostname(buf, len);
#else
  return -1;
#endif
}
 
#ifdef FREECIV_SOCKET_ZERO_NOT_STDIN
/****************************************************************************
  Support for console I/O in case FREECIV_SOCKET_ZERO_NOT_STDIN.
****************************************************************************/
 
#define CONSOLE_BUF_SIZE 100
static char console_buf[CONSOLE_BUF_SIZE + 1];
 
/***************************************************************************/
 
#ifdef FREECIV_MSWINDOWS
static HANDLE console_thread = INVALID_HANDLE_VALUE;
 
/************************************************************************/
static DWORD WINAPI windows_console_thread(LPVOID arg)
{
  if (fgets(console_buf, CONSOLE_BUF_SIZE, stdin)) {
    char *s;
 
    if ((s = strchr(console_buf, '\n'))) {
      *s = '\0';
    }
  }
 
  return 0;
}
#endif /* FREECIV_MSWINDOWS */
 
/************************************************************************/
void fc_init_console(void)
{
#ifdef FREECIV_MSWINDOWS
  if (console_thread != INVALID_HANDLE_VALUE) {
    return;
  }
 
  console_buf[0] = '\0';
  console_thread = (HANDLE) CreateThread(NULL, 0, windows_console_thread,
                                         NULL, 0, NULL);
#else  /* FREECIV_MSWINDOWS */
  static bool initialized = FALSE;
 
  if (!initialized) {
    initialized = TRUE;
#ifdef HAVE_FILENO
    fc_nonblock(fileno(stdin));
#endif
  }
#endif /* FREECIV_MSWINDOWS */
}
 
/************************************************************************/
char *fc_read_console(void)
{
#ifdef FREECIV_MSWINDOWS
  if (WaitForSingleObject(console_thread, 0) == WAIT_OBJECT_0) {
    CloseHandle(console_thread);
    console_thread = INVALID_HANDLE_VALUE;
 
    return console_buf;
  }
 
  return NULL;
#else  /* FREECIV_MSWINDOWS */
  if (!feof(stdin)) {    /* input from server operator */
    static char *bufptr = console_buf;
 
    /* fetch chars until \n, or run out of space in buffer */
    /* blocks if fc_nonblock() in fc_init_console() failed */
    while ((*bufptr = fgetc(stdin)) != EOF) {
      if (*bufptr == '\n') {
        *bufptr = '\0';
      }
      if (*bufptr == '\0') {
        bufptr = console_buf;
 
        return console_buf;
      }
      if ((bufptr - console_buf) <= CONSOLE_BUF_SIZE) {
        bufptr++; /* prevent overrun */
      }
    }
  }
 
  return NULL;
#endif /* FREECIV_MSWINDOWS */
}
 
#endif /* FREECIV_SOCKET_ZERO_NOT_STDIN */
 
/************************************************************************/
bool is_reg_file_for_access(const char *name, bool write_access)
{
  struct stat tmp;
 
  if (fc_stat(name, &tmp) == 0) {
    return S_ISREG(tmp.st_mode);
  } else {
    return write_access && errno == ENOENT;
  }
}
 
/************************************************************************/
int fc_break_lines(char *str, size_t desired_len)
{
  size_t slen = (size_t)strlen(str);
  int num_lines = 0;
 
  /* At top of this loop, s points to the rest of string,
   * either at start or after inserted newline: */
 top:
  if (str && *str != '\0' && slen > desired_len) {
    char *c;
 
    num_lines++;
 
    /* check if there is already a newline: */
    for (c = str; c < str + desired_len; c++) {
      if (*c == '\n') {
        slen -= c + 1 - str;
        str = c + 1;
        goto top;
      }
    }
 
    /* find space and break: */
    for (c = str + desired_len; c > str; c--) {
      if (fc_isspace(*c)) {
        *c = '\n';
        slen -= c + 1 - str;
        str = c + 1;
        goto top;
      }
    }
 
    /* couldn't find a good break; settle for a bad one... */
    for (c = str + desired_len + 1; *c != '\0'; c++) {
      if (fc_isspace(*c)) {
        *c = '\n';
        slen -= c + 1 - str;
        str = c + 1;
        goto top;
      }
    }
  }
 
  return num_lines;
}
 
/****************************************************************************
  Character function wrappers
 
  These functions are wrappers for the libc character class functions,
  without any locale-dependent behavior. The character functions work as
  documented for ASCII. Bytes outside of the ASCII set will not be reported
  to belong to any character class, and will be left unchanged by
  transformations. This behavior is safe but not strictly correct
  forsingle-byte 8-bit- or UTF-8 encoded text; in UTF-8, any byte that is
  part of a multibyte sequence is non-ASCII.
****************************************************************************/
 
/************************************************************************/
bool fc_isalnum(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isalnum((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
bool fc_isalpha(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isalpha((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
bool fc_isdigit(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isdigit((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
bool fc_isprint(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isprint((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
bool fc_isspace(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isspace((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
bool fc_isupper(char c)
{
  if (128 <= (unsigned char) c) {
    return FALSE;
  }
  return isupper((int) ((unsigned char) c)) != 0;
}
 
/************************************************************************/
char fc_toupper(char c)
{
  if (128 <= (unsigned char) c) {
    return c;
  }
  return (char) toupper((int) ((unsigned char) c));
}
 
/************************************************************************/
char fc_tolower(char c)
{
  if (128 <= (unsigned char) c) {
    return c;
  }
  return (char) tolower((int) ((unsigned char) c));
}
 
/************************************************************************/
const char *fc_basename(const char *path)
{
  static char buf[2048];
 
  /* Copy const parameter string to buffer that basename() can
   * modify */
  fc_strlcpy(buf, path, sizeof(buf));
 
  return basename(buf);
}
 
/************************************************************************/
struct tm *fc_localtime(const time_t *timep, struct tm *result)
{
#ifdef HAVE_LOCALTIME_R
  return localtime_r(timep, result);
#else  /* HAVE_LOCALTIME_R */
  fc_allocate_mutex(&localtime_mutex);
  memcpy(result, localtime(timep), sizeof(struct tm));
  fc_release_mutex(&localtime_mutex);
 
  return result;
#endif /* HAVE_LOCALTIME_R */
}
 
/************************************************************************/
int fc_at_quick_exit(void (*func)(void))
{
#ifdef HAVE_AT_QUICK_EXIT
  return at_quick_exit(func);
#else  /* HAVE_AT_QUICK_EXIT */
  return -1;
#endif /* HAVE_AT_QUICK_EXIT */
}
 
/************************************************************************/
void fc_support_init(void)
{
  fc_strAPI_init();
 
#ifndef HAVE_WORKING_VSNPRINTF
  fc_init_mutex(&vsnprintf_mutex);
#endif /* HAVE_WORKING_VSNPRINTF */
 
#ifndef HAVE_LOCALTIME_R
  fc_init_mutex(&localtime_mutex);
#endif /* HAVE_LOCALTIME_R */
 
  support_initialized = TRUE;
}
 
/************************************************************************/
void fc_support_free(void)
{
  support_initialized = FALSE;
 
#ifndef HAVE_WORKING_VSNPRINTF
  if (vsnprintf_buf != NULL) {
    free(vsnprintf_buf);
    vsnprintf_buf = NULL;
  }
  fc_destroy_mutex(&vsnprintf_mutex);
#endif /* HAVE_WORKING_VSNPRINTF */
 
#ifndef HAVE_LOCALTIME_R
  fc_destroy_mutex(&localtime_mutex);
#endif /* HAVE_LOCALTIME_R */
 
  fc_strAPI_free();
}
 
/************************************************************************/
bool are_support_services_available(void)
{
  return support_initialized;
}