compat.c

关于tor匿名通信的源代码

/* Copyright (c) 2003-2004, Roger Dingledine
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char compat_c_id[] =
  "$Id$";

/**
 * \file compat.c
 * \brief Wrappers to make calls more portable.  This code defines
 * functions such as tor_malloc, tor_snprintf, get/set various data types,
 * renaming, setting socket options, switching user IDs.  It is basically
 * where the non-portable items are conditionally included depending on
 * the platform.
 **/

/* This is required on rh7 to make strptime not complain.
 * We also need it to make memmem get defined (where available)
 */
#define _GNU_SOURCE

#include "orconfig.h"
#include "compat.h"

#ifdef MS_WINDOWS
#include <process.h>
#include <windows.h>
#endif

#ifdef HAVE_UNAME
#include <sys/utsname.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_SYS_FCNTL_H
#include <sys/fcntl.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#ifdef HAVE_GRP_H
#include <grp.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifndef HAVE_GETTIMEOFDAY
#ifdef HAVE_FTIME
#include <sys/timeb.h>
#endif
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h> /* FreeBSD needs this to know what version it is */
#endif
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#ifdef HAVE_PTHREAD_H
#include <pthread.h>
#endif
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif
#ifdef HAVE_UTIME_H
#include <utime.h>
#endif
#ifdef HAVE_SYS_UTIME_H
#include <sys/utime.h>
#endif
#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#ifdef HAVE_SYS_SYSLIMITS_H
#include <sys/syslimits.h>
#endif

#ifdef USE_BSOCKETS
#include <bsocket.h>
#endif

#include "log.h"
#include "util.h"
#include "container.h"

/* Inline the strl functions if the platform doesn't have them. */
#ifndef HAVE_STRLCPY
#include "strlcpy.c"
#endif
#ifndef HAVE_STRLCAT
#include "strlcat.c"
#endif

#ifndef INADDR_NONE
/* This is used by inet_addr, but apparently Solaris doesn't define it
 * anyplace. */
#define INADDR_NONE ((unsigned long) -1)
#endif

#ifdef HAVE_SYS_MMAN_H
/** Implementation for tor_mmap_t: holds the regular tor_mmap_t, along
 * with extra fields needed for mmap()-based memory mapping. */
typedef struct tor_mmap_impl_t {
  tor_mmap_t base;
  size_t mapping_size; /**< Size of the actual mapping. (This is this file
                        * size, rounded up to the nearest page.) */
} tor_mmap_impl_t;

/** Try to create a memory mapping for <b>filename</b> and return it.  On
 * failure, return NULL.  Sets errno properly, using ERANGE to mean
 * "empty file". */
tor_mmap_t *
tor_mmap_file(const char *filename)
{
  int fd; /* router file */
  char *string;
  int page_size;
  tor_mmap_impl_t *res;
  size_t size, filesize;

  tor_assert(filename);

  fd = open(filename, O_RDONLY, 0);
  if (fd<0) {
    int save_errno = errno;
    int severity = (errno == ENOENT) ? LOG_INFO : LOG_WARN;
    log_fn(severity, LD_FS,"Could not open \"%s\" for mmap(): %s",filename,
           strerror(errno));
    errno = save_errno;
    return NULL;
  }

  size = filesize = (size_t) lseek(fd, 0, SEEK_END);
  lseek(fd, 0, SEEK_SET);
  /* ensure page alignment */
  page_size = getpagesize();
  size += (size%page_size) ? page_size-(size%page_size) : 0;

  if (!size) {
    /* Zero-length file. If we call mmap on it, it will succeed but
     * return NULL, and bad things will happen. So just fail. */
    log_info(LD_FS,"File \"%s\" is empty. Ignoring.",filename);
    errno = ERANGE;
    close(fd);
    return NULL;
  }

  string = mmap(0, size, PROT_READ, MAP_PRIVATE, fd, 0);
  close(fd);
  if (string == MAP_FAILED) {
    int save_errno = errno;
    log_warn(LD_FS,"Could not mmap file \"%s\": %s", filename,
             strerror(errno));
    errno = save_errno;
    return NULL;
  }

  res = tor_malloc_zero(sizeof(tor_mmap_impl_t));
  res->base.data = string;
  res->base.size = filesize;
  res->mapping_size = size;

  return &(res->base);
}
/** Release storage held for a memory mapping. */
void
tor_munmap_file(tor_mmap_t *handle)
{
  tor_mmap_impl_t *h = SUBTYPE_P(handle, tor_mmap_impl_t, base);
  munmap((char*)h->base.data, h->mapping_size);
  tor_free(h);
}
#elif defined(MS_WINDOWS)
/** Implementation for tor_mmap_t: holds the regular tor_mmap_t, along
 * with extra fields needed for WIN32 memory mapping. */
typedef struct win_mmap_t {
  tor_mmap_t base;
  HANDLE file_handle;
  HANDLE mmap_handle;
} win_mmap_t;
tor_mmap_t *
tor_mmap_file(const char *filename)
{
  win_mmap_t *res = tor_malloc_zero(sizeof(win_mmap_t));
  int empty = 0;
  res->file_handle = INVALID_HANDLE_VALUE;
  res->mmap_handle = NULL;

  res->file_handle = CreateFile(filename,
                                GENERIC_READ, FILE_SHARE_READ,
                                NULL,
                                OPEN_EXISTING,
                                FILE_ATTRIBUTE_NORMAL,
                                0);

  if (res->file_handle == INVALID_HANDLE_VALUE)
    goto win_err;

  res->base.size = GetFileSize(res->file_handle, NULL);

  if (res->base.size == 0) {
    log_info(LD_FS,"File \"%s\" is empty. Ignoring.",filename);
    empty = 1;
    goto err;
  }

  res->mmap_handle = CreateFileMapping(res->file_handle,
                                       NULL,
                                       PAGE_READONLY,
#if SIZEOF_SIZE_T > 4
                                       (res->base.size >> 32),
#else
                                       0,
#endif
                                       (res->base.size & 0xfffffffful),
                                       NULL);
  if (res->mmap_handle == NULL)
    goto win_err;
  res->base.data = (char*) MapViewOfFile(res->mmap_handle,
                                         FILE_MAP_READ,
                                         0, 0, 0);
  if (!res->base.data)
    goto win_err;

  return &(res->base);
 win_err: {
    DWORD e = GetLastError();
    int severity = (e == ERROR_FILE_NOT_FOUND || e == ERROR_PATH_NOT_FOUND) ?
      LOG_INFO : LOG_WARN;
    char *msg = format_win32_error(e);
    log_fn(severity, LD_FS, "Couldn't mmap file \"%s\": %s", filename, msg);
    tor_free(msg);
    if (e == ERROR_FILE_NOT_FOUND || e == ERROR_PATH_NOT_FOUND)
      errno = ENOENT;
    else
      errno = EINVAL;
  }
 err:
  if (empty)
    errno = ERANGE;
  tor_munmap_file(&res->base);
  return NULL;
}
void
tor_munmap_file(tor_mmap_t *handle)
{
  win_mmap_t *h = SUBTYPE_P(handle, win_mmap_t, base);
  if (handle->data)
    /* This is an ugly cast, but without it, "data" in struct tor_mmap_t would
       have to be redefined as non-const. */
    UnmapViewOfFile( (LPVOID) handle->data);

  if (h->mmap_handle != NULL)
    CloseHandle(h->mmap_handle);
  if (h->file_handle != INVALID_HANDLE_VALUE)
    CloseHandle(h->file_handle);
  tor_free(h);
}
#else
tor_mmap_t *
tor_mmap_file(const char *filename)
{
  struct stat st;
  char *res = read_file_to_str(filename, RFTS_BIN|RFTS_IGNORE_MISSING, &st);
  tor_mmap_t *handle;
  if (! res)
    return NULL;
  handle = tor_malloc_zero(sizeof(tor_mmap_t));
  handle->data = res;
  handle->size = st.st_size;
  return handle;
}
void
tor_munmap_file(tor_mmap_t *handle)
{
  char *d = (char*)handle->data;
  tor_free(d);
  memset(handle, 0, sizeof(tor_mmap_t));
  tor_free(handle);
}
#endif

/** Replacement for snprintf.  Differs from platform snprintf in two
 * ways: First, always NUL-terminates its output.  Second, always
 * returns -1 if the result is truncated.  (Note that this return
 * behavior does <i>not</i> conform to C99; it just happens to be
 * easier to emulate "return -1" with conformant implementations than
 * it is to emulate "return number that would be written" with
 * non-conformant implementations.) */
int
tor_snprintf(char *str, size_t size, const char *format, ...)
{
  va_list ap;
  int r;
  va_start(ap,format);
  r = tor_vsnprintf(str,size,format,ap);
  va_end(ap);
  return r;
}

/** Replacement for vsnprintf; behavior differs as tor_snprintf differs from
 * snprintf.
 */
int
tor_vsnprintf(char *str, size_t size, const char *format, va_list args)
{
  int r;
  if (size == 0)
    return -1; /* no place for the NUL */
  if (size > SIZE_T_CEILING)
    return -1;
#ifdef MS_WINDOWS
  r = _vsnprintf(str, size, format, args);
#else
  r = vsnprintf(str, size, format, args);
#endif
  str[size-1] = '\0';
  if (r < 0 || ((size_t)r) >= size)
    return -1;
  return r;
}

/** Given <b>hlen</b> bytes at <b>haystack</b> and <b>nlen</b> bytes at
 * <b>needle</b>, return a pointer to the first occurrence of the needle
 * within the haystack, or NULL if there is no such occurrence.
 *
 * Requires that nlen be greater than zero.
 */
const void *
tor_memmem(const void *_haystack, size_t hlen,
           const void *_needle, size_t nlen)
{
#if defined(HAVE_MEMMEM) && (!defined(__GNUC__) || __GNUC__ >= 2)
  tor_assert(nlen);
  return memmem(_haystack, hlen, _needle, nlen);
#else
  /* This isn't as fast as the GLIBC implementation, but it doesn't need to
   * be. */
  const char *p, *end;
  const char *haystack = (const char*)_haystack;
  const char *needle = (const char*)_needle;
  char first;
  tor_assert(nlen);

  p = haystack;
  end = haystack + hlen;
  first = *(const char*)needle;
  while ((p = memchr(p, first, end-p))) {
    if (p+nlen > end)
      return NULL;
    if (!memcmp(p, needle, nlen))
      return p;
    ++p;
  }
  return NULL;
#endif
}

#ifdef MS_WINDOWS
/** Take a filename and return a pointer to its final element.  This
 * function is called on __FILE__ to fix a MSVC nit where __FILE__
 * contains the full path to the file.  This is bad, because it
 * confuses users to find the home directory of the person who
 * compiled the binary in their warrning messages.
 */
const char *
tor_fix_source_file(const char *fname)
{
  const char *cp1, *cp2, *r;
  cp1 = strrchr(fname, '/');
  cp2 = strrchr(fname, '\\');
  if (cp1 && cp2) {
    r = (cp1<cp2)?(cp2+1):(cp1+1);
  } else if (cp1) {
    r = cp1+1;
  } else if (cp2) {
    r = cp2+1;
  } else {
    r = fname;
  }
  return r;
}
#endif

/**
 * Read a 16-bit value beginning at <b>cp</b>.  Equivalent to
 * *(uint16_t*)(cp), but will not cause segfaults on platforms that forbid
 * unaligned memory access.
 */
uint16_t
get_uint16(const char *cp)
{
  uint16_t v;
  memcpy(&v,cp,2);
  return v;
}
/**
 * Read a 32-bit value beginning at <b>cp</b>.  Equivalent to
 * *(uint32_t*)(cp), but will not cause segfaults on platforms that forbid
 * unaligned memory access.