1 /* Copyright (C) 1991,92,93,94,95,96,97,98,99 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3 
4    The GNU C Library is free software; you can redistribute it and/or
5    modify it under the terms of the GNU Library General Public License as
6    published by the Free Software Foundation; either version 2 of the
7    License, or (at your option) any later version.
8 
9    The GNU C Library is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12    Library General Public License for more details.
13 
14    You should have received a copy of the GNU Library General Public
15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
16    see <http://www.gnu.org/licenses/>.  */
17 
18 /* March 11, 2002       Manuel Novoa III
19  *
20  * Modify code to remove dependency on libgcc long long arith support funcs.
21  */
22 
23 /* June 6, 2004       Erik Andersen
24  *
25  * Don't use brain damaged getpid() based randomness.
26  */
27 
28 /* April 15, 2005     Mike Frysinger
29  *
30  * Use brain damaged getpid() if real random fails.
31  */
32 
33 #include <stddef.h>
34 #include <stdint.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <unistd.h>
41 #include <assert.h>
42 #include <sys/types.h>
43 #include <sys/stat.h>
44 #include <sys/time.h>
45 #include "tempname.h"
46 
47 /* Return nonzero if DIR is an existent directory.  */
direxists(const char * dir)48 static int direxists (const char *dir)
49 {
50     struct stat buf;
51     return stat(dir, &buf) == 0 && S_ISDIR (buf.st_mode);
52 }
53 
54 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
55    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
56    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
57    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
58    doesn't exist, none of the searched dirs exists, or there's not
59    enough space in TMPL. */
___path_search(char * tmpl,size_t tmpl_len,const char * dir,const char * pfx)60 int ___path_search (char *tmpl, size_t tmpl_len, const char *dir,
61 	const char *pfx /*, int try_tmpdir*/)
62 {
63     /*const char *d; */
64     /* dir and pfx lengths should always fit into an int,
65        so don't bother using size_t here.  Especially since
66        the printf func requires an int for precision (%*s).  */
67     int dlen, plen;
68 
69     if (!pfx || !pfx[0])
70     {
71 	pfx = "file";
72 	plen = 4;
73     }
74     else
75     {
76 	plen = strlen (pfx);
77 	if (plen > 5)
78 	    plen = 5;
79     }
80 
81     /* Disable support for $TMPDIR */
82 #if 0
83     if (try_tmpdir)
84     {
85 	d = __secure_getenv ("TMPDIR");
86 	if (d != NULL && direxists (d))
87 	    dir = d;
88 	else if (dir != NULL && direxists (dir))
89 	    /* nothing */ ;
90 	else
91 	    dir = NULL;
92     }
93 #endif
94     if (dir == NULL)
95     {
96 	if (direxists (P_tmpdir))
97 	    dir = P_tmpdir;
98 	else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
99 	    dir = "/tmp";
100 	else
101 	{
102 	    __set_errno (ENOENT);
103 	    return -1;
104 	}
105     }
106 
107     dlen = strlen (dir);
108     while (dlen > 1 && dir[dlen - 1] == '/')
109 	dlen--;			/* remove trailing slashes */
110 
111     /* check we have room for "${dir}/${pfx}XXXXXX\0" */
112     if (tmpl_len < (size_t)dlen + 1 + plen + 6 + 1)
113     {
114 	__set_errno (EINVAL);
115 	return -1;
116     }
117 
118     sprintf (tmpl, "%.*s/%.*sXXXXXX", (int)dlen, dir, (int)plen, pfx);
119     return 0;
120 }
121 
122 /* These are the characters used in temporary filenames.  */
123 static const char letters[] =
124 "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
125 #define NUM_LETTERS (62)
126 
fillrand(unsigned char * buf,unsigned int len)127 static unsigned int fillrand(unsigned char *buf, unsigned int len)
128 {
129     int fd;
130     unsigned int result = -1;
131     fd = open("/dev/urandom", O_RDONLY);
132     if (fd < 0) {
133 	fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
134     }
135     if (fd >= 0) {
136 	result = read(fd, buf, len);
137 	close(fd);
138     }
139     return result;
140 }
141 
brain_damaged_fillrand(unsigned char * buf,unsigned int len)142 static void brain_damaged_fillrand(unsigned char *buf, unsigned int len)
143 {
144 	unsigned int i, k;
145 	struct timeval tv;
146 	uint32_t high, low, rh;
147 	static uint64_t value;
148 	gettimeofday(&tv, NULL);
149 	value += ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
150 	low = value & UINT32_MAX;
151 	high = value >> 32;
152 	for (i = 0; i < len; ++i) {
153 		rh = high % NUM_LETTERS;
154 		high /= NUM_LETTERS;
155 #define L ((UINT32_MAX % NUM_LETTERS + 1) % NUM_LETTERS)
156 		k = (low % NUM_LETTERS) + (L * rh);
157 #undef L
158 #define H ((UINT32_MAX / NUM_LETTERS) + ((UINT32_MAX % NUM_LETTERS + 1) / NUM_LETTERS))
159 		low = (low / NUM_LETTERS) + (H * rh) + (k / NUM_LETTERS);
160 #undef H
161 		k %= NUM_LETTERS;
162 		buf[i] = letters[k];
163 	}
164 }
165 
166 /* Generate a temporary file name based on TMPL.  TMPL must match the
167    rules for mk[s]temp (i.e. end in "XXXXXX").  The name constructed
168    does not exist at the time of the call to __gen_tempname.  TMPL is
169    overwritten with the result.
170 
171    KIND may be one of:
172    __GT_NOCREATE:       simply verify that the name does not exist
173                         at the time of the call. mode argument is ignored.
174    __GT_FILE:           create the file using open(O_CREAT|O_EXCL)
175                         and return a read-write fd with given mode.
176    __GT_BIGFILE:        same as __GT_FILE but use open64().
177    __GT_DIR:            create a directory with given mode.
178 
179 */
__gen_tempname(char * tmpl,int kind,mode_t mode)180 int attribute_hidden __gen_tempname (char *tmpl, int kind, mode_t mode)
181 {
182     char *XXXXXX;
183     unsigned int i;
184     int fd, save_errno = errno;
185     unsigned char randomness[6];
186     size_t len;
187 
188     len = strlen (tmpl);
189     /* This is where the Xs start.  */
190     XXXXXX = tmpl + len - 6;
191     if (len < 6 || strcmp (XXXXXX, "XXXXXX"))
192     {
193 	__set_errno (EINVAL);
194 	return -1;
195     }
196 
197     for (i = 0; i < TMP_MAX; ++i) {
198 	unsigned char j;
199 	/* Get some random data.  */
200 	if (fillrand(randomness, sizeof(randomness)) != sizeof(randomness)) {
201 	    /* if random device nodes failed us, lets use the braindamaged ver */
202 	    brain_damaged_fillrand(randomness, sizeof(randomness));
203 	}
204 	for (j = 0; j < sizeof(randomness); ++j)
205 	    XXXXXX[j] = letters[randomness[j] % NUM_LETTERS];
206 
207 	switch (kind) {
208 	    case __GT_NOCREATE:
209 		{
210 		    struct stat st;
211 		    if (stat (tmpl, &st) < 0) {
212 			if (errno == ENOENT) {
213 			    fd = 0;
214 			    goto restore_and_ret;
215 			} else
216 			    /* Give up now. */
217 			    return -1;
218 		    } else
219 			fd = 0;
220 		}
221 	    case __GT_FILE:
222 		fd = open (tmpl, O_RDWR | O_CREAT | O_EXCL, mode);
223 		break;
224 #if defined __UCLIBC_HAS_LFS__
225 	    case __GT_BIGFILE:
226 		fd = open64 (tmpl, O_RDWR | O_CREAT | O_EXCL, mode);
227 		break;
228 #endif
229 	    case __GT_DIR:
230 		fd = mkdir (tmpl, mode);
231 		break;
232 	    default:
233 		fd = -1;
234 		assert (! "invalid KIND in __gen_tempname");
235 	}
236 
237 	if (fd >= 0) {
238 restore_and_ret:
239 	    __set_errno (save_errno);
240 	    return fd;
241 	}
242 	else if (errno != EEXIST)
243 	    /* Any other error will apply also to other names we might
244 	       try, and there are 2^32 or so of them, so give up now. */
245 	    return -1;
246     }
247 
248     /* We got out of the loop because we ran out of combinations to try.  */
249     __set_errno (EEXIST);
250     return -1;
251 }
252