xref: /openbsd-src/gnu/usr.bin/texinfo/lib/tempname.c (revision a1acfa9b69ad64eb720639240c8438f11107dc85)
1*a1acfa9bSespie /* tempname.c - generate the name of a temporary file.
2*a1acfa9bSespie 
3*a1acfa9bSespie    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
4*a1acfa9bSespie    2000, 2001, 2002, 2003 Free Software Foundation, Inc.
5*a1acfa9bSespie 
6*a1acfa9bSespie    This program is free software; you can redistribute it and/or modify
7*a1acfa9bSespie    it under the terms of the GNU General Public License as published by
8*a1acfa9bSespie    the Free Software Foundation; either version 2, or (at your option)
9*a1acfa9bSespie    any later version.
10*a1acfa9bSespie 
11*a1acfa9bSespie    This program is distributed in the hope that it will be useful,
12*a1acfa9bSespie    but WITHOUT ANY WARRANTY; without even the implied warranty of
13*a1acfa9bSespie    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14*a1acfa9bSespie    GNU General Public License for more details.
15*a1acfa9bSespie 
16*a1acfa9bSespie    You should have received a copy of the GNU General Public License along
17*a1acfa9bSespie    with this program; if not, write to the Free Software Foundation,
18*a1acfa9bSespie    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
19*a1acfa9bSespie 
20*a1acfa9bSespie #if HAVE_CONFIG_H
21*a1acfa9bSespie # include <config.h>
22*a1acfa9bSespie #endif
23*a1acfa9bSespie 
24*a1acfa9bSespie #include <sys/types.h>
25*a1acfa9bSespie #include <assert.h>
26*a1acfa9bSespie 
27*a1acfa9bSespie #include <errno.h>
28*a1acfa9bSespie #ifndef __set_errno
29*a1acfa9bSespie # define __set_errno(Val) errno = (Val)
30*a1acfa9bSespie #endif
31*a1acfa9bSespie 
32*a1acfa9bSespie #include <stdio.h>
33*a1acfa9bSespie #ifndef P_tmpdir
34*a1acfa9bSespie # define P_tmpdir "/tmp"
35*a1acfa9bSespie #endif
36*a1acfa9bSespie #ifndef TMP_MAX
37*a1acfa9bSespie # define TMP_MAX 238328
38*a1acfa9bSespie #endif
39*a1acfa9bSespie #ifndef __GT_FILE
40*a1acfa9bSespie # define __GT_FILE	0
41*a1acfa9bSespie # define __GT_BIGFILE	1
42*a1acfa9bSespie # define __GT_DIR	2
43*a1acfa9bSespie # define __GT_NOCREATE	3
44*a1acfa9bSespie #endif
45*a1acfa9bSespie 
46*a1acfa9bSespie #include <stddef.h>
47*a1acfa9bSespie #include <stdlib.h>
48*a1acfa9bSespie #include <string.h>
49*a1acfa9bSespie 
50*a1acfa9bSespie #if HAVE_FCNTL_H || _LIBC
51*a1acfa9bSespie # include <fcntl.h>
52*a1acfa9bSespie #endif
53*a1acfa9bSespie 
54*a1acfa9bSespie #if HAVE_SYS_TIME_H || _LIBC
55*a1acfa9bSespie # include <sys/time.h>
56*a1acfa9bSespie #endif
57*a1acfa9bSespie 
58*a1acfa9bSespie #if HAVE_STDINT_H || _LIBC
59*a1acfa9bSespie # include <stdint.h>
60*a1acfa9bSespie #endif
61*a1acfa9bSespie #if HAVE_INTTYPES_H
62*a1acfa9bSespie # include <inttypes.h>
63*a1acfa9bSespie #endif
64*a1acfa9bSespie 
65*a1acfa9bSespie #if HAVE_UNISTD_H || _LIBC
66*a1acfa9bSespie # include <unistd.h>
67*a1acfa9bSespie #endif
68*a1acfa9bSespie 
69*a1acfa9bSespie #include <sys/stat.h>
70*a1acfa9bSespie #if STAT_MACROS_BROKEN
71*a1acfa9bSespie # undef S_ISDIR
72*a1acfa9bSespie #endif
73*a1acfa9bSespie #if !defined S_ISDIR && defined S_IFDIR
74*a1acfa9bSespie # define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
75*a1acfa9bSespie #endif
76*a1acfa9bSespie #if !S_IRUSR && S_IREAD
77*a1acfa9bSespie # define S_IRUSR S_IREAD
78*a1acfa9bSespie #endif
79*a1acfa9bSespie #if !S_IRUSR
80*a1acfa9bSespie # define S_IRUSR 00400
81*a1acfa9bSespie #endif
82*a1acfa9bSespie #if !S_IWUSR && S_IWRITE
83*a1acfa9bSespie # define S_IWUSR S_IWRITE
84*a1acfa9bSespie #endif
85*a1acfa9bSespie #if !S_IWUSR
86*a1acfa9bSespie # define S_IWUSR 00200
87*a1acfa9bSespie #endif
88*a1acfa9bSespie #if !S_IXUSR && S_IEXEC
89*a1acfa9bSespie # define S_IXUSR S_IEXEC
90*a1acfa9bSespie #endif
91*a1acfa9bSespie #if !S_IXUSR
92*a1acfa9bSespie # define S_IXUSR 00100
93*a1acfa9bSespie #endif
94*a1acfa9bSespie 
95*a1acfa9bSespie #if _LIBC
96*a1acfa9bSespie # define struct_stat64 struct stat64
97*a1acfa9bSespie #else
98*a1acfa9bSespie # define struct_stat64 struct stat
99*a1acfa9bSespie # define __getpid getpid
100*a1acfa9bSespie # define __gettimeofday gettimeofday
101*a1acfa9bSespie # define __mkdir mkdir
102*a1acfa9bSespie # define __open open
103*a1acfa9bSespie # define __open64 open
104*a1acfa9bSespie # define __lxstat64(version, path, buf) lstat (path, buf)
105*a1acfa9bSespie # define __xstat64(version, path, buf) stat (path, buf)
106*a1acfa9bSespie #endif
107*a1acfa9bSespie 
108*a1acfa9bSespie #if ! (HAVE___SECURE_GETENV || _LIBC)
109*a1acfa9bSespie # define __secure_getenv getenv
110*a1acfa9bSespie #endif
111*a1acfa9bSespie 
112*a1acfa9bSespie #ifdef _LIBC
113*a1acfa9bSespie # include <hp-timing.h>
114*a1acfa9bSespie # if HP_TIMING_AVAIL
115*a1acfa9bSespie #  define RANDOM_BITS(Var) \
116*a1acfa9bSespie   if (__builtin_expect (value == UINT64_C (0), 0))			      \
117*a1acfa9bSespie     {									      \
118*a1acfa9bSespie       /* If this is the first time this function is used initialize	      \
119*a1acfa9bSespie 	 the variable we accumulate the value in to some somewhat	      \
120*a1acfa9bSespie 	 random value.  If we'd not do this programs at startup time	      \
121*a1acfa9bSespie 	 might have a reduced set of possible names, at least on slow	      \
122*a1acfa9bSespie 	 machines.  */							      \
123*a1acfa9bSespie       struct timeval tv;						      \
124*a1acfa9bSespie       __gettimeofday (&tv, NULL);					      \
125*a1acfa9bSespie       value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;		      \
126*a1acfa9bSespie     }									      \
127*a1acfa9bSespie   HP_TIMING_NOW (Var)
128*a1acfa9bSespie # endif
129*a1acfa9bSespie #endif
130*a1acfa9bSespie 
131*a1acfa9bSespie /* Use the widest available unsigned type if uint64_t is not
132*a1acfa9bSespie    available.  The algorithm below extracts a number less than 62**6
133*a1acfa9bSespie    (approximately 2**35.725) from uint64_t, so ancient hosts where
134*a1acfa9bSespie    uintmax_t is only 32 bits lose about 3.725 bits of randomness,
135*a1acfa9bSespie    which is better than not having mkstemp at all.  */
136*a1acfa9bSespie #if !defined UINT64_MAX && !defined uint64_t
137*a1acfa9bSespie # define uint64_t uintmax_t
138*a1acfa9bSespie #endif
139*a1acfa9bSespie 
140*a1acfa9bSespie /* Return nonzero if DIR is an existent directory.  */
141*a1acfa9bSespie static int
direxists(const char * dir)142*a1acfa9bSespie direxists (const char *dir)
143*a1acfa9bSespie {
144*a1acfa9bSespie   struct_stat64 buf;
145*a1acfa9bSespie   return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
146*a1acfa9bSespie }
147*a1acfa9bSespie 
148*a1acfa9bSespie /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
149*a1acfa9bSespie    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
150*a1acfa9bSespie    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
151*a1acfa9bSespie    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
152*a1acfa9bSespie    doesn't exist, none of the searched dirs exists, or there's not
153*a1acfa9bSespie    enough space in TMPL. */
154*a1acfa9bSespie int
__path_search(char * tmpl,size_t tmpl_len,const char * dir,const char * pfx,int try_tmpdir)155*a1acfa9bSespie __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
156*a1acfa9bSespie 	       int try_tmpdir)
157*a1acfa9bSespie {
158*a1acfa9bSespie   const char *d;
159*a1acfa9bSespie   size_t dlen, plen;
160*a1acfa9bSespie 
161*a1acfa9bSespie   if (!pfx || !pfx[0])
162*a1acfa9bSespie     {
163*a1acfa9bSespie       pfx = "file";
164*a1acfa9bSespie       plen = 4;
165*a1acfa9bSespie     }
166*a1acfa9bSespie   else
167*a1acfa9bSespie     {
168*a1acfa9bSespie       plen = strlen (pfx);
169*a1acfa9bSespie       if (plen > 5)
170*a1acfa9bSespie 	plen = 5;
171*a1acfa9bSespie     }
172*a1acfa9bSespie 
173*a1acfa9bSespie   if (try_tmpdir)
174*a1acfa9bSespie     {
175*a1acfa9bSespie       d = __secure_getenv ("TMPDIR");
176*a1acfa9bSespie       if (d != NULL && direxists (d))
177*a1acfa9bSespie 	dir = d;
178*a1acfa9bSespie       else if (dir != NULL && direxists (dir))
179*a1acfa9bSespie 	/* nothing */ ;
180*a1acfa9bSespie       else
181*a1acfa9bSespie 	dir = NULL;
182*a1acfa9bSespie     }
183*a1acfa9bSespie   if (dir == NULL)
184*a1acfa9bSespie     {
185*a1acfa9bSespie       if (direxists (P_tmpdir))
186*a1acfa9bSespie 	dir = P_tmpdir;
187*a1acfa9bSespie       else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
188*a1acfa9bSespie 	dir = "/tmp";
189*a1acfa9bSespie       else
190*a1acfa9bSespie 	{
191*a1acfa9bSespie 	  __set_errno (ENOENT);
192*a1acfa9bSespie 	  return -1;
193*a1acfa9bSespie 	}
194*a1acfa9bSespie     }
195*a1acfa9bSespie 
196*a1acfa9bSespie   dlen = strlen (dir);
197*a1acfa9bSespie   while (dlen > 1 && dir[dlen - 1] == '/')
198*a1acfa9bSespie     dlen--;			/* remove trailing slashes */
199*a1acfa9bSespie 
200*a1acfa9bSespie   /* check we have room for "${dir}/${pfx}XXXXXX\0" */
201*a1acfa9bSespie   if (tmpl_len < dlen + 1 + plen + 6 + 1)
202*a1acfa9bSespie     {
203*a1acfa9bSespie       __set_errno (EINVAL);
204*a1acfa9bSespie       return -1;
205*a1acfa9bSespie     }
206*a1acfa9bSespie 
207*a1acfa9bSespie   sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
208*a1acfa9bSespie   return 0;
209*a1acfa9bSespie }
210*a1acfa9bSespie 
211*a1acfa9bSespie /* These are the characters used in temporary filenames.  */
212*a1acfa9bSespie static const char letters[] =
213*a1acfa9bSespie "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
214*a1acfa9bSespie 
215*a1acfa9bSespie /* Generate a temporary file name based on TMPL.  TMPL must match the
216*a1acfa9bSespie    rules for mk[s]temp (i.e. end in "XXXXXX").  The name constructed
217*a1acfa9bSespie    does not exist at the time of the call to __gen_tempname.  TMPL is
218*a1acfa9bSespie    overwritten with the result.
219*a1acfa9bSespie 
220*a1acfa9bSespie    KIND may be one of:
221*a1acfa9bSespie    __GT_NOCREATE:	simply verify that the name does not exist
222*a1acfa9bSespie 			at the time of the call.
223*a1acfa9bSespie    __GT_FILE:		create the file using open(O_CREAT|O_EXCL)
224*a1acfa9bSespie 			and return a read-write fd.  The file is mode 0600.
225*a1acfa9bSespie    __GT_BIGFILE:	same as __GT_FILE but use open64().
226*a1acfa9bSespie    __GT_DIR:		create a directory, which will be mode 0700.
227*a1acfa9bSespie 
228*a1acfa9bSespie    We use a clever algorithm to get hard-to-predict names. */
229*a1acfa9bSespie int
__gen_tempname(char * tmpl,int kind)230*a1acfa9bSespie __gen_tempname (char *tmpl, int kind)
231*a1acfa9bSespie {
232*a1acfa9bSespie   int len;
233*a1acfa9bSespie   char *XXXXXX;
234*a1acfa9bSespie   static uint64_t value;
235*a1acfa9bSespie   uint64_t random_time_bits;
236*a1acfa9bSespie   unsigned int count;
237*a1acfa9bSespie   int fd = -1;
238*a1acfa9bSespie   int save_errno = errno;
239*a1acfa9bSespie   struct_stat64 st;
240*a1acfa9bSespie 
241*a1acfa9bSespie   /* A lower bound on the number of temporary files to attempt to
242*a1acfa9bSespie      generate.  The maximum total number of temporary file names that
243*a1acfa9bSespie      can exist for a given template is 62**6.  It should never be
244*a1acfa9bSespie      necessary to try all these combinations.  Instead if a reasonable
245*a1acfa9bSespie      number of names is tried (we define reasonable as 62**3) fail to
246*a1acfa9bSespie      give the system administrator the chance to remove the problems.  */
247*a1acfa9bSespie   unsigned int attempts_min = 62 * 62 * 62;
248*a1acfa9bSespie 
249*a1acfa9bSespie   /* The number of times to attempt to generate a temporary file.  To
250*a1acfa9bSespie      conform to POSIX, this must be no smaller than TMP_MAX.  */
251*a1acfa9bSespie   unsigned int attempts = attempts_min < TMP_MAX ? TMP_MAX : attempts_min;
252*a1acfa9bSespie 
253*a1acfa9bSespie   len = strlen (tmpl);
254*a1acfa9bSespie   if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
255*a1acfa9bSespie     {
256*a1acfa9bSespie       __set_errno (EINVAL);
257*a1acfa9bSespie       return -1;
258*a1acfa9bSespie     }
259*a1acfa9bSespie 
260*a1acfa9bSespie   /* This is where the Xs start.  */
261*a1acfa9bSespie   XXXXXX = &tmpl[len - 6];
262*a1acfa9bSespie 
263*a1acfa9bSespie   /* Get some more or less random data.  */
264*a1acfa9bSespie #ifdef RANDOM_BITS
265*a1acfa9bSespie   RANDOM_BITS (random_time_bits);
266*a1acfa9bSespie #else
267*a1acfa9bSespie # if HAVE_GETTIMEOFDAY || _LIBC
268*a1acfa9bSespie   {
269*a1acfa9bSespie     struct timeval tv;
270*a1acfa9bSespie     __gettimeofday (&tv, NULL);
271*a1acfa9bSespie     random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
272*a1acfa9bSespie   }
273*a1acfa9bSespie # else
274*a1acfa9bSespie   random_time_bits = time (NULL);
275*a1acfa9bSespie # endif
276*a1acfa9bSespie #endif
277*a1acfa9bSespie   value += random_time_bits ^ __getpid ();
278*a1acfa9bSespie 
279*a1acfa9bSespie   for (count = 0; count < attempts; value += 7777, ++count)
280*a1acfa9bSespie     {
281*a1acfa9bSespie       uint64_t v = value;
282*a1acfa9bSespie 
283*a1acfa9bSespie       /* Fill in the random bits.  */
284*a1acfa9bSespie       XXXXXX[0] = letters[v % 62];
285*a1acfa9bSespie       v /= 62;
286*a1acfa9bSespie       XXXXXX[1] = letters[v % 62];
287*a1acfa9bSespie       v /= 62;
288*a1acfa9bSespie       XXXXXX[2] = letters[v % 62];
289*a1acfa9bSespie       v /= 62;
290*a1acfa9bSespie       XXXXXX[3] = letters[v % 62];
291*a1acfa9bSespie       v /= 62;
292*a1acfa9bSespie       XXXXXX[4] = letters[v % 62];
293*a1acfa9bSespie       v /= 62;
294*a1acfa9bSespie       XXXXXX[5] = letters[v % 62];
295*a1acfa9bSespie 
296*a1acfa9bSespie       switch (kind)
297*a1acfa9bSespie 	{
298*a1acfa9bSespie 	case __GT_FILE:
299*a1acfa9bSespie 	  fd = __open (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
300*a1acfa9bSespie 	  break;
301*a1acfa9bSespie 
302*a1acfa9bSespie 	case __GT_BIGFILE:
303*a1acfa9bSespie 	  fd = __open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
304*a1acfa9bSespie 	  break;
305*a1acfa9bSespie 
306*a1acfa9bSespie 	case __GT_DIR:
307*a1acfa9bSespie 	  fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
308*a1acfa9bSespie 	  break;
309*a1acfa9bSespie 
310*a1acfa9bSespie 	case __GT_NOCREATE:
311*a1acfa9bSespie 	  /* This case is backward from the other three.  __gen_tempname
312*a1acfa9bSespie 	     succeeds if __xstat fails because the name does not exist.
313*a1acfa9bSespie 	     Note the continue to bypass the common logic at the bottom
314*a1acfa9bSespie 	     of the loop.  */
315*a1acfa9bSespie 	  if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
316*a1acfa9bSespie 	    {
317*a1acfa9bSespie 	      if (errno == ENOENT)
318*a1acfa9bSespie 		{
319*a1acfa9bSespie 		  __set_errno (save_errno);
320*a1acfa9bSespie 		  return 0;
321*a1acfa9bSespie 		}
322*a1acfa9bSespie 	      else
323*a1acfa9bSespie 		/* Give up now. */
324*a1acfa9bSespie 		return -1;
325*a1acfa9bSespie 	    }
326*a1acfa9bSespie 	  continue;
327*a1acfa9bSespie 
328*a1acfa9bSespie 	default:
329*a1acfa9bSespie 	  assert (! "invalid KIND in __gen_tempname");
330*a1acfa9bSespie 	}
331*a1acfa9bSespie 
332*a1acfa9bSespie       if (fd >= 0)
333*a1acfa9bSespie 	{
334*a1acfa9bSespie 	  __set_errno (save_errno);
335*a1acfa9bSespie 	  return fd;
336*a1acfa9bSespie 	}
337*a1acfa9bSespie       else if (errno != EEXIST)
338*a1acfa9bSespie 	return -1;
339*a1acfa9bSespie     }
340*a1acfa9bSespie 
341*a1acfa9bSespie   /* We got out of the loop because we ran out of combinations to try.  */
342*a1acfa9bSespie   __set_errno (EEXIST);
343*a1acfa9bSespie   return -1;
344*a1acfa9bSespie }
345