pith/osdep/temp_nam.c

   1 /*
   2  * ========================================================================
   3  * Copyright 2013-2022 Eduardo Chappa
   4  * Copyright 2006-2008 University of Washington
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * ========================================================================
  13  */
  14
  15 #include <system.h>
  16
  17 #if     HAVE_FCNTL_H
  18 #include <fcntl.h>
  19 #endif
  20
  21 #include "canaccess.h"
  22 #include "temp_nam.h"
  23 #include "../charconv/utf8.h"
  24 #include "../charconv/filesys.h"
  25
  26
  27 #ifdef  _WINDOWS
  28
  29 #include <process.h>
  30
  31 #define ACCESSIBLE      (WRITE_ACCESS)
  32 #define PATH_SEP        "\\"
  33
  34 #else  /* UNIX */
  35
  36 #define ACCESSIBLE      (WRITE_ACCESS|EXECUTE_ACCESS)
  37 #define PATH_SEP        "/"
  38
  39 #endif /* UNIX */
  40
  41
  42 /*
  43  * Internal Prototypes
  44  */
  45 char    *was_nonexistent_tmp_name(char *, size_t, char *);
  46
  47
  48
  49 /*
  50  * This routine is derived from BSD4.3 code,
  51  * Copyright (c) 1987 Regents of the University of California.
  52  * All rights reserved.
  53  */
  54 #if defined(LIBC_SCCS) && !defined(lint)
  55 static char sccsid[] = "@(#)mktemp.c    5.7 (Berkeley) 6/27/88";
  56 #endif /* LIBC_SCCS and not lint */
  57
  58 char *
  59 was_nonexistent_tmp_name(char *as, size_t aslen, char *ext)
  60 {
  61     register char  *start, *trv;
  62     struct stat     sbuf;
  63     unsigned        pid;
  64     static unsigned n = 0;
  65     int             i;
  66     int             fd, tries = 0;
  67     int             f;
  68     static unsigned long r = 0;
  69
  70     if(r == 0L)
  71       r = (unsigned)getpid() + time((time_t *)0);
  72
  73     for(i = 5; i > 0; i--)
  74       r = 1664525 * r + 1013904223;
  75
  76     pid = ((unsigned)getpid() * 100) + n++;
  77
  78     pid += (r % 50000L);
  79
  80     /* extra X's get set to 0's */
  81     for(trv = as; *trv; ++trv)
  82       ;
  83
  84     /*
  85      * We should probably make the name random instead of having it
  86      * be the pid.
  87      */
  88     while(*--trv == 'X'){
  89         *trv = (pid % 10) + '0';
  90         pid /= 10;
  91     }
  92
  93     /* add the extension, enough room guaranteed by caller */
  94     if(ext && *ext){
  95         strncat(as, ".", aslen-strlen(as)-1);
  96         as[aslen-1] = '\0';
  97         strncat(as, ext, aslen-strlen(as)-1);
  98         as[aslen-1] = '\0';
  99     }
 100
 101     /*
 102      * Check for write permission on target directory; if you have
 103      * six X's and you can't write the directory, this will run for
 104      * a *very* long time.
 105      */
 106     for(start = ++trv; trv > as && *trv != PATH_SEP[0]; --trv)
 107       ;
 108
 109     if(*trv == PATH_SEP[0]){
 110 #ifdef  _WINDOWS
 111         char treplace;
 112
 113         if((trv - as == 2) && isalpha(as[0]) && as[1] == ':')
 114           trv++;
 115         treplace = *trv;
 116         *trv = '\0';
 117         if(our_stat(as==trv ? PATH_SEP : as, &sbuf) || !(sbuf.st_mode & S_IFDIR))
 118           return((char *)NULL);
 119
 120         *trv = treplace;
 121
 122 #else  /* UNIX */
 123
 124         *trv = '\0';
 125
 126         if(our_stat(as==trv ? PATH_SEP : as, &sbuf) || !(sbuf.st_mode & S_IFDIR))
 127           return((char *)NULL);
 128
 129         *trv = PATH_SEP[0];
 130
 131 #endif
 132     }
 133     else if (our_stat(".", &sbuf) == -1)
 134       return((char *)NULL);
 135
 136     for(;;){
 137         /*
 138          * Check with lstat to be sure we don't have
 139          * a symlink. If lstat fails and no such file, then we
 140          * have a winner. Otherwise, lstat shouldn't fail.
 141          * If lstat succeeds, then skip it because it exists.
 142          */
 143 #ifndef _WINDOWS
 144         if(our_lstat(as, &sbuf)){               /* lstat failed */
 145             if(errno == ENOENT){                /* no such file, success */
 146 #endif /* !_WINDOWS */
 147                 /*
 148                  * Create the file so that the
 149                  * evil ones don't have a chance to put something there
 150                  * that they can read or write before we create it
 151                  * ourselves.
 152                  */
 153                 f = O_CREAT|O_EXCL|O_WRONLY|O_BINARY;
 154
 155                 if((fd=our_open(as, f, 0600)) >= 0 && close(fd) == 0)
 156                   return(as);
 157                 else if(++tries > 3)            /* open failed unexpectedly */
 158                   return((char *)NULL);
 159 #ifndef _WINDOWS
 160             }
 161             else                                /* failed for unknown reason */
 162               return((char *)NULL);
 163         }
 164 #endif /* !_WINDOWS */
 165
 166         for(trv = start;;){
 167             if(!*trv)
 168               return((char *)NULL);
 169
 170             /*
 171              * Change the digits from the initial values into
 172              * lower case letters and try again.
 173              */
 174             if(*trv == 'z')
 175               *trv++ = 'a';
 176             else{
 177                 if(isdigit((unsigned char)*trv))
 178                   *trv = 'a';
 179                 else
 180                   ++*trv;
 181
 182                 break;
 183             }
 184         }
 185     }
 186     /*NOTREACHED*/
 187 }
 188
 189
 190 /*
 191  * This routine is derived from BSD4.3 code,
 192  * Copyright (c) 1988 Regents of the University of California.
 193  * All rights reserved.
 194  */
 195 #if defined(LIBC_SCCS) && !defined(lint)
 196 static char sccsid[] = "@(#)tmpnam.c    4.5 (Berkeley) 6/27/88";
 197 #endif /* LIBC_SCCS and not lint */
 198 /*----------------------------------------------------------------------
 199       Return a unique file name in a given directory.  This is not quite
 200       the same as the usual tempnam() function, though it is similar.
 201       We want it to use the TMPDIR/TMP/TEMP environment variable only if dir
 202       is NULL, instead of using it regardless if it is set.
 203       We also want it to be safer than tempnam().
 204       If we return a filename, we are saying that the file did not exist
 205       at the time this function was called (and it wasn't a symlink pointing
 206       to a file that didn't exist, either).
 207       If dir is NULL this is a temp file in a public directory. In that
 208       case we create the file with permission 0600 before returning.
 209
 210   Args: dir      -- The directory to create the name in
 211         prefix   -- Prefix of the name
 212
 213  Result: Malloc'd string equal to new name is returned.  It must be free'd
 214          by the caller.  Returns the string on success and NULL on failure.
 215   ----*/
 216 char *
 217 temp_nam(char *dir, char *prefix)
 218 {
 219     return(temp_nam_ext(dir, prefix, NULL));
 220 }
 221
 222
 223 /*----------------------------------------------------------------------
 224
 225      Like temp_nam but create a unique name with an extension.
 226
 227  Result: Malloc'd string equal to new name is returned.  It must be free'd
 228          by the caller.  Returns the string on success and NULL on failure.
 229   ----*/
 230 char *
 231 temp_nam_ext(char *dir, char *prefix, char *ext)
 232 {
 233     struct stat buf;
 234     size_t      l = 0, ll;
 235     char       *f, *name;
 236
 237     if(ext == NULL)
 238       ext = "";
 239
 240     if(!(name = (char *)malloc(MAXPATH * sizeof(char))))
 241         return((char *)NULL);
 242
 243     if(!dir && (f = getenv("TMPDIR")) && !our_stat(f, &buf) &&
 244                          (buf.st_mode&S_IFMT) == S_IFDIR &&
 245                          !can_access(f, ACCESSIBLE)){
 246         strncpy(name, f, MAXPATH-1);
 247         name[MAXPATH-1] = '\0';
 248         goto done;
 249     }
 250
 251     if(!dir && (f = getenv("TMP")) && !our_stat(f, &buf) &&
 252                          (buf.st_mode&S_IFMT) == S_IFDIR &&
 253                          !can_access(f, ACCESSIBLE)){
 254         strncpy(name, f, MAXPATH-1);
 255         name[MAXPATH-1] = '\0';
 256         goto done;
 257     }
 258
 259     if(!dir && (f = getenv("TEMP")) && !our_stat(f, &buf) &&
 260                          (buf.st_mode&S_IFMT) == S_IFDIR &&
 261                          !can_access(f, ACCESSIBLE)){
 262         strncpy(name, f, MAXPATH-1);
 263         name[MAXPATH-1] = '\0';
 264         goto done;
 265     }
 266
 267     if(dir){
 268         strncpy(name, dir, MAXPATH-1);
 269         name[MAXPATH-1] = '\0';
 270
 271 #ifdef  _WINDOWS
 272         if(!*dir || (isalpha(*dir) && *(dir+1) == ':' && !*(dir+2))){
 273             strncat(name, PATH_SEP, MAXPATH-strlen(name)-1);
 274             name[MAXPATH-1] = '\0';
 275         }
 276 #endif
 277
 278         if(!our_stat(name, &buf)
 279            && (buf.st_mode&S_IFMT) == S_IFDIR
 280            && !can_access(name, ACCESSIBLE)){
 281             strncpy(name, dir, MAXPATH-1);
 282             name[MAXPATH-1] = '\0';
 283             goto done;
 284         }
 285     }
 286
 287 #ifndef P_tmpdir
 288 #ifdef  _WINDOWS
 289 #define P_tmpdir        "\\tmp"
 290 #else  /* UNIX */
 291 #define P_tmpdir        "/usr/tmp"
 292 #endif /* UNIX */
 293 #endif
 294
 295     if(!our_stat(P_tmpdir, &buf) &&
 296                          (buf.st_mode&S_IFMT) == S_IFDIR &&
 297                          !can_access(P_tmpdir, ACCESSIBLE)){
 298         strncpy(name, P_tmpdir, MAXPATH-1);
 299         name[MAXPATH-1] = '\0';
 300         goto done;
 301     }
 302
 303 #ifndef _WINDOWS
 304     if(!our_stat("/tmp", &buf) &&
 305                          (buf.st_mode&S_IFMT) == S_IFDIR &&
 306                          !can_access("/tmp", ACCESSIBLE)){
 307         strncpy(name, "/tmp", MAXPATH-1);
 308         name[MAXPATH-1] = '\0';
 309         goto done;
 310     }
 311 #endif
 312
 313     free((void *)name);
 314     return((char *)NULL);
 315
 316 done:
 317     f = NULL;
 318     if(name[0] && *((f = &name[l=strlen(name)]) - 1) != PATH_SEP[0] && l+1 < MAXPATH){
 319         *f++ = PATH_SEP[0];
 320         *f = '\0';
 321         l++;
 322     }
 323
 324     if(prefix && (ll = strlen(prefix)) && l+ll < MAXPATH){
 325         strncpy(f, prefix, MAXPATH-(f-name));
 326         name[MAXPATH-1] = '\0';
 327         f += ll;
 328         l += ll;
 329     }
 330
 331     if(l+5+(ext[0] ? strlen(ext)+1 : 0) < MAXPATH){
 332         strncpy(f, "XXXXX", MAXPATH-(f-name));
 333         name[MAXPATH-1] = '\0';
 334     }
 335     else{
 336         free((void *)name);
 337         return((char *)NULL);
 338     }
 339
 340     return(was_nonexistent_tmp_name(name, MAXPATH, ext));
 341 }