cups/tempfile.c

   1 /*
   2  * Temp file utilities for CUPS.
   3  *
   4  * Copyright © 2007-2018 by Apple Inc.
   5  * Copyright © 1997-2006 by Easy Software Products.
   6  *
   7  * Licensed under Apache License v2.0.  See the file "LICENSE" for more
   8  * information.
   9  */
  10
  11 /*
  12  * Include necessary headers...
  13  */
  14
  15 #include "cups-private.h"
  16 #include <stdlib.h>
  17 #include <fcntl.h>
  18 #include <sys/stat.h>
  19 #if defined(WIN32) || defined(__EMX__)
  20 #  include <io.h>
  21 #else
  22 #  include <unistd.h>
  23 #endif /* WIN32 || __EMX__ */
  24
  25
  26 /*
  27  * 'cupsTempFd()' - Creates a temporary file.
  28  *
  29  * The temporary filename is returned in the filename buffer.
  30  * The temporary file is opened for reading and writing.
  31  */
  32
  33 int                                     /* O - New file descriptor or -1 on error */
  34 cupsTempFd(char *filename,              /* I - Pointer to buffer */
  35            int  len)                    /* I - Size of buffer */
  36 {
  37   int           fd;                     /* File descriptor for temp file */
  38   int           tries;                  /* Number of tries */
  39   const char    *tmpdir;                /* TMPDIR environment var */
  40 #if defined(__APPLE__) || defined(WIN32)
  41   char          tmppath[1024];          /* Temporary directory */
  42 #endif /* __APPLE__ || WIN32 */
  43 #ifdef WIN32
  44   DWORD         curtime;                /* Current time */
  45 #else
  46   struct timeval curtime;               /* Current time */
  47 #endif /* WIN32 */
  48
  49
  50  /*
  51   * See if TMPDIR is defined...
  52   */
  53
  54 #ifdef WIN32
  55   if ((tmpdir = getenv("TEMP")) == NULL)
  56   {
  57     GetTempPath(sizeof(tmppath), tmppath);
  58     tmpdir = tmppath;
  59   }
  60
  61 #elif defined(__APPLE__)
  62  /*
  63   * On macOS and iOS, the TMPDIR environment variable is not always the best
  64   * location to place temporary files due to sandboxing.  Instead, the confstr
  65   * function should be called when running as a normal process (not a child of
  66   * cupsd) to get the proper per-user, per-process TMPDIR value.  We know
  67   * whether the process is running as a child of cupsd by the presence of the
  68   * "SOFTWARE" environment variable that cupsd sets.
  69   */
  70
  71   tmpdir = getenv("TMPDIR");
  72
  73   if (!getenv("SOFTWARE") || !tmpdir)
  74   {
  75     if (confstr(_CS_DARWIN_USER_TEMP_DIR, tmppath, sizeof(tmppath)))
  76       tmpdir = tmppath;
  77     else
  78       tmpdir = "/private/tmp";          /* This should never happen */
  79   }
  80
  81 #else
  82  /*
  83   * Previously we put root temporary files in the default CUPS temporary
  84   * directory under /var/spool/cups.  However, since the scheduler cleans
  85   * out temporary files there and runs independently of the user apps, we
  86   * don't want to use it unless specifically told to by cupsd.
  87   */
  88
  89   if ((tmpdir = getenv("TMPDIR")) == NULL)
  90     tmpdir = "/tmp";
  91 #endif /* WIN32 */
  92
  93  /*
  94   * Make the temporary name using the specified directory...
  95   */
  96
  97   tries = 0;
  98
  99   do
 100   {
 101 #ifdef WIN32
 102    /*
 103     * Get the current time of day...
 104     */
 105
 106     curtime =  GetTickCount() + tries;
 107
 108    /*
 109     * Format a string using the hex time values...
 110     */
 111
 112     snprintf(filename, (size_t)len - 1, "%s/%05lx%08lx", tmpdir, GetCurrentProcessId(), curtime);
 113 #else
 114    /*
 115     * Get the current time of day...
 116     */
 117
 118     gettimeofday(&curtime, NULL);
 119
 120    /*
 121     * Format a string using the hex time values...
 122     */
 123
 124     snprintf(filename, (size_t)len - 1, "%s/%05x%08x", tmpdir, (unsigned)getpid(), (unsigned)(curtime.tv_sec + curtime.tv_usec + tries));
 125 #endif /* WIN32 */
 126
 127    /*
 128     * Open the file in "exclusive" mode, making sure that we don't
 129     * stomp on an existing file or someone's symlink crack...
 130     */
 131
 132 #ifdef WIN32
 133     fd = open(filename, _O_CREAT | _O_RDWR | _O_TRUNC | _O_BINARY,
 134               _S_IREAD | _S_IWRITE);
 135 #elif defined(O_NOFOLLOW)
 136     fd = open(filename, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW, 0600);
 137 #else
 138     fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
 139 #endif /* WIN32 */
 140
 141     if (fd < 0 && errno != EEXIST)
 142       break;
 143
 144     tries ++;
 145   }
 146   while (fd < 0 && tries < 1000);
 147
 148  /*
 149   * Return the file descriptor...
 150   */
 151
 152   return (fd);
 153 }
 154
 155
 156 /*
 157  * 'cupsTempFile()' - Generates a temporary filename.
 158  *
 159  * The temporary filename is returned in the filename buffer.
 160  * This function is deprecated and will no longer generate a temporary
 161  * filename - use @link cupsTempFd@ or @link cupsTempFile2@ instead.
 162  *
 163  * @deprecated@
 164  */
 165
 166 char *                                  /* O - Filename or @code NULL@ on error */
 167 cupsTempFile(char *filename,            /* I - Pointer to buffer */
 168              int  len)                  /* I - Size of buffer */
 169 {
 170   (void)len;
 171
 172   if (filename)
 173     *filename = '\0';
 174
 175   return (NULL);
 176 }
 177
 178
 179 /*
 180  * 'cupsTempFile2()' - Creates a temporary CUPS file.
 181  *
 182  * The temporary filename is returned in the filename buffer.
 183  * The temporary file is opened for writing.
 184  *
 185  * @since CUPS 1.2/macOS 10.5@
 186  */
 187
 188 cups_file_t *                           /* O - CUPS file or @code NULL@ on error */
 189 cupsTempFile2(char *filename,           /* I - Pointer to buffer */
 190               int  len)                 /* I - Size of buffer */
 191 {
 192   cups_file_t   *file;                  /* CUPS file */
 193   int           fd;                     /* File descriptor */
 194
 195
 196   if ((fd = cupsTempFd(filename, len)) < 0)
 197     return (NULL);
 198   else if ((file = cupsFileOpenFd(fd, "w")) == NULL)
 199   {
 200     close(fd);
 201     unlink(filename);
 202     return (NULL);
 203   }
 204   else
 205     return (file);
 206 }