1*0Sstevel@tonic-gate /* 2*0Sstevel@tonic-gate * CDDL HEADER START 3*0Sstevel@tonic-gate * 4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the 5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only 6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance 7*0Sstevel@tonic-gate * with the License. 8*0Sstevel@tonic-gate * 9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 11*0Sstevel@tonic-gate * See the License for the specific language governing permissions 12*0Sstevel@tonic-gate * and limitations under the License. 13*0Sstevel@tonic-gate * 14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 19*0Sstevel@tonic-gate * 20*0Sstevel@tonic-gate * CDDL HEADER END 21*0Sstevel@tonic-gate */ 22*0Sstevel@tonic-gate /* 23*0Sstevel@tonic-gate * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24*0Sstevel@tonic-gate * Use is subject to license terms. 25*0Sstevel@tonic-gate */ 26*0Sstevel@tonic-gate 27*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 28*0Sstevel@tonic-gate 29*0Sstevel@tonic-gate /* Copyright (c) 1988 AT&T */ 30*0Sstevel@tonic-gate /* All Rights Reserved */ 31*0Sstevel@tonic-gate 32*0Sstevel@tonic-gate 33*0Sstevel@tonic-gate /* 34*0Sstevel@tonic-gate * mktemp() expects a string with up to six trailing 'X's. 35*0Sstevel@tonic-gate * These will be overlaid with letters, digits and symbols from 36*0Sstevel@tonic-gate * the portable filename character set. If every combination thus 37*0Sstevel@tonic-gate * inserted leads to an existing file name, the string is shortened 38*0Sstevel@tonic-gate * to length zero and a pointer to a null string is returned. 39*0Sstevel@tonic-gate * 40*0Sstevel@tonic-gate * The guarantee made by mktime() to the caller is that the 41*0Sstevel@tonic-gate * generated file name string will not match the string 42*0Sstevel@tonic-gate * produced by any other concurrent process using mktemp(). 43*0Sstevel@tonic-gate * To guarantee uniqueness across the process-id space, 44*0Sstevel@tonic-gate * the process-id of the caller is encoded into the string. 45*0Sstevel@tonic-gate * To allow repeated calls within the same process to generate 46*0Sstevel@tonic-gate * different strings on each call, a sequence number is encoded 47*0Sstevel@tonic-gate * into the string along with process-id. 48*0Sstevel@tonic-gate * 49*0Sstevel@tonic-gate * The encoding is performed using radix-64 (6 bits per character), 50*0Sstevel@tonic-gate * with 64 characters taken from the portable file name character set. 51*0Sstevel@tonic-gate * This allows the six X's to be a representation of a 36-bit integer 52*0Sstevel@tonic-gate * composed of bit fields: 53*0Sstevel@tonic-gate * ( pid | seq ) 54*0Sstevel@tonic-gate * where the process-id occupies the high-order bits and the sequence 55*0Sstevel@tonic-gate * number occupies the low-order bits. The size of the pid field is 56*0Sstevel@tonic-gate * not fixed at the traditional 15 bits (MAXPID = 30000); the system 57*0Sstevel@tonic-gate * now allows a larger process-id space and MAXPID is obtained from 58*0Sstevel@tonic-gate * the system with a call to sysconf(_SC_MAXPID). 59*0Sstevel@tonic-gate * 60*0Sstevel@tonic-gate * mktime() should fail if fewer than six X's are presented to it. 61*0Sstevel@tonic-gate * However, this has been traditionally accepted and is preserved 62*0Sstevel@tonic-gate * in the present code. The consequence is that the 36-bit integer 63*0Sstevel@tonic-gate * is reduced to a (6*N)-bit integer, where N is the number of X's. 64*0Sstevel@tonic-gate * mktime() fails immediately if the resulting integer is not large 65*0Sstevel@tonic-gate * enough to contain MAXPID. 66*0Sstevel@tonic-gate * 67*0Sstevel@tonic-gate * In an attempt to confuse and thwart hackers, the starting 68*0Sstevel@tonic-gate * sequence number is randomized using the current time. 69*0Sstevel@tonic-gate */ 70*0Sstevel@tonic-gate 71*0Sstevel@tonic-gate #define XCNT 6 72*0Sstevel@tonic-gate #pragma weak mktemp = _mktemp 73*0Sstevel@tonic-gate 74*0Sstevel@tonic-gate #include "synonyms.h" 75*0Sstevel@tonic-gate #include "mtlib.h" 76*0Sstevel@tonic-gate #include <sys/types.h> 77*0Sstevel@tonic-gate #include <string.h> 78*0Sstevel@tonic-gate #include <unistd.h> 79*0Sstevel@tonic-gate #include <thread.h> 80*0Sstevel@tonic-gate #include <synch.h> 81*0Sstevel@tonic-gate #include <sys/stat.h> 82*0Sstevel@tonic-gate #include <errno.h> 83*0Sstevel@tonic-gate #include <sys/time.h> 84*0Sstevel@tonic-gate #include <stdlib.h> 85*0Sstevel@tonic-gate #include <stdio.h> 86*0Sstevel@tonic-gate #include <sys/param.h> 87*0Sstevel@tonic-gate 88*0Sstevel@tonic-gate /* 89*0Sstevel@tonic-gate * 64-bit digits, must be from the POSIX "portable file name character set". 90*0Sstevel@tonic-gate */ 91*0Sstevel@tonic-gate static char 92*0Sstevel@tonic-gate chars[64] = { 93*0Sstevel@tonic-gate 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 94*0Sstevel@tonic-gate 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 95*0Sstevel@tonic-gate 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 96*0Sstevel@tonic-gate 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 97*0Sstevel@tonic-gate '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.', '_', 98*0Sstevel@tonic-gate }; 99*0Sstevel@tonic-gate 100*0Sstevel@tonic-gate /* 101*0Sstevel@tonic-gate * Find highest one bit set. 102*0Sstevel@tonic-gate * Returns bit number of highest bit that is set. 103*0Sstevel@tonic-gate * Low order bit is number 0, high order bit is number 31. 104*0Sstevel@tonic-gate */ 105*0Sstevel@tonic-gate static int 106*0Sstevel@tonic-gate highbit(uint_t i) 107*0Sstevel@tonic-gate { 108*0Sstevel@tonic-gate int h = 0; 109*0Sstevel@tonic-gate 110*0Sstevel@tonic-gate if (i & 0xffff0000) 111*0Sstevel@tonic-gate h += 16, i >>= 16; 112*0Sstevel@tonic-gate if (i & 0xff00) 113*0Sstevel@tonic-gate h += 8, i >>= 8; 114*0Sstevel@tonic-gate if (i & 0xf0) 115*0Sstevel@tonic-gate h += 4, i >>= 4; 116*0Sstevel@tonic-gate if (i & 0xc) 117*0Sstevel@tonic-gate h += 2, i >>= 2; 118*0Sstevel@tonic-gate if (i & 0x2) 119*0Sstevel@tonic-gate h += 1; 120*0Sstevel@tonic-gate return (h); 121*0Sstevel@tonic-gate } 122*0Sstevel@tonic-gate 123*0Sstevel@tonic-gate char * 124*0Sstevel@tonic-gate mktemp(char *as) 125*0Sstevel@tonic-gate { 126*0Sstevel@tonic-gate /* statics are protected by this static mutex */ 127*0Sstevel@tonic-gate static mutex_t mktemp_lock = DEFAULTMUTEX; 128*0Sstevel@tonic-gate static int pidshift = 0; 129*0Sstevel@tonic-gate static int previous_try = 0; 130*0Sstevel@tonic-gate static pid_t previous_pid = 0; 131*0Sstevel@tonic-gate static int previous_xcnt = XCNT; 132*0Sstevel@tonic-gate 133*0Sstevel@tonic-gate pid_t pid; 134*0Sstevel@tonic-gate int try; 135*0Sstevel@tonic-gate int tryshift; 136*0Sstevel@tonic-gate int max_try; 137*0Sstevel@tonic-gate char *s; 138*0Sstevel@tonic-gate char *first_x; 139*0Sstevel@tonic-gate int len; 140*0Sstevel@tonic-gate uint_t xcnt; 141*0Sstevel@tonic-gate struct stat64 buf; 142*0Sstevel@tonic-gate 143*0Sstevel@tonic-gate if (as == NULL || *as == '\0') /* If the string passed is null then */ 144*0Sstevel@tonic-gate return (as); /* a pointer to a null string is returned. */ 145*0Sstevel@tonic-gate 146*0Sstevel@tonic-gate lmutex_lock(&mktemp_lock); 147*0Sstevel@tonic-gate 148*0Sstevel@tonic-gate pid = getpid(); 149*0Sstevel@tonic-gate if (pid != previous_pid) { /* first time or first after fork() */ 150*0Sstevel@tonic-gate /* 151*0Sstevel@tonic-gate * Randomize the starting sequence number in 152*0Sstevel@tonic-gate * an attempt to confuse and thwart hackers. 153*0Sstevel@tonic-gate * Use the low 12 bits of the time in milliseconds. 154*0Sstevel@tonic-gate */ 155*0Sstevel@tonic-gate struct timeval tm; 156*0Sstevel@tonic-gate 157*0Sstevel@tonic-gate (void) gettimeofday(&tm, NULL); 158*0Sstevel@tonic-gate previous_try = (tm.tv_sec * 1000 + tm.tv_usec / 1000) & 0xfff; 159*0Sstevel@tonic-gate previous_pid = pid; 160*0Sstevel@tonic-gate previous_xcnt = XCNT; 161*0Sstevel@tonic-gate } 162*0Sstevel@tonic-gate 163*0Sstevel@tonic-gate /* for all possible values of pid, 0 <= pid < (1 << pidshift) */ 164*0Sstevel@tonic-gate if (pidshift == 0) /* one-time initialization */ 165*0Sstevel@tonic-gate pidshift = highbit((uint_t)MAXPID) + 1; 166*0Sstevel@tonic-gate 167*0Sstevel@tonic-gate /* count the X's */ 168*0Sstevel@tonic-gate xcnt = 0; 169*0Sstevel@tonic-gate len = (int)strlen(as); 170*0Sstevel@tonic-gate s = as + (len - 1); 171*0Sstevel@tonic-gate while ((len != 0) && (xcnt < XCNT) && (*s == 'X')) { 172*0Sstevel@tonic-gate xcnt++; 173*0Sstevel@tonic-gate len--; 174*0Sstevel@tonic-gate --s; 175*0Sstevel@tonic-gate } 176*0Sstevel@tonic-gate first_x = s + 1; /* Remember pointer to the first X */ 177*0Sstevel@tonic-gate 178*0Sstevel@tonic-gate /* fail if we don't have enough X's to represent MAXPID */ 179*0Sstevel@tonic-gate if ((tryshift = xcnt * 6 - pidshift) < 0) { 180*0Sstevel@tonic-gate /* 181*0Sstevel@tonic-gate * Some broken programs call mktemp() repeatedly, 182*0Sstevel@tonic-gate * passing the same string without reinserting the X's. 183*0Sstevel@tonic-gate * Check to see if this is such a call by testing 184*0Sstevel@tonic-gate * the trailing characters of the string for a 185*0Sstevel@tonic-gate * match with the process-id. 186*0Sstevel@tonic-gate */ 187*0Sstevel@tonic-gate uint64_t xpid = 0; /* reconstructed pid */ 188*0Sstevel@tonic-gate 189*0Sstevel@tonic-gate s = as + len; 190*0Sstevel@tonic-gate for (xcnt = previous_xcnt; xcnt && s > as; xcnt--) { 191*0Sstevel@tonic-gate int c; 192*0Sstevel@tonic-gate int i; 193*0Sstevel@tonic-gate 194*0Sstevel@tonic-gate c = *--s; 195*0Sstevel@tonic-gate for (i = 0; i < 64; i++) 196*0Sstevel@tonic-gate if (c == chars[i]) 197*0Sstevel@tonic-gate break; 198*0Sstevel@tonic-gate if (i == 64) 199*0Sstevel@tonic-gate goto fail; 200*0Sstevel@tonic-gate xpid = xpid * 64 + i; 201*0Sstevel@tonic-gate } 202*0Sstevel@tonic-gate xpid >>= (previous_xcnt * 6 - pidshift); 203*0Sstevel@tonic-gate xpid &= ((1 << pidshift) - 1); 204*0Sstevel@tonic-gate 205*0Sstevel@tonic-gate if (xpid == pid && 206*0Sstevel@tonic-gate lstat64(as, &buf) == -1 && errno == ENOENT) { 207*0Sstevel@tonic-gate lmutex_unlock(&mktemp_lock); 208*0Sstevel@tonic-gate return (as); 209*0Sstevel@tonic-gate } 210*0Sstevel@tonic-gate 211*0Sstevel@tonic-gate goto fail; 212*0Sstevel@tonic-gate } 213*0Sstevel@tonic-gate 214*0Sstevel@tonic-gate /* we can try sequence numbers in the range 0 <= try < max_try */ 215*0Sstevel@tonic-gate max_try = 1 << tryshift; 216*0Sstevel@tonic-gate if (previous_try >= max_try) 217*0Sstevel@tonic-gate previous_try = 0; 218*0Sstevel@tonic-gate 219*0Sstevel@tonic-gate try = previous_try; 220*0Sstevel@tonic-gate for (;;) { 221*0Sstevel@tonic-gate /* num is up to a 36-bit integer ... */ 222*0Sstevel@tonic-gate uint64_t num = ((uint64_t)pid << tryshift) + (uint64_t)try; 223*0Sstevel@tonic-gate int i; 224*0Sstevel@tonic-gate 225*0Sstevel@tonic-gate /* ... which we represent backwards in base 64 */ 226*0Sstevel@tonic-gate for (i = 0, s = first_x; i < xcnt; i++) { 227*0Sstevel@tonic-gate *s++ = chars[num & 077]; 228*0Sstevel@tonic-gate num >>= 6; 229*0Sstevel@tonic-gate } 230*0Sstevel@tonic-gate 231*0Sstevel@tonic-gate if (lstat64(as, &buf) == -1) { 232*0Sstevel@tonic-gate if (errno != ENOENT) 233*0Sstevel@tonic-gate break; /* unrecoverable error */ 234*0Sstevel@tonic-gate /* remember where we left off for the next call */ 235*0Sstevel@tonic-gate previous_try = try + 1; 236*0Sstevel@tonic-gate previous_xcnt = xcnt; 237*0Sstevel@tonic-gate lmutex_unlock(&mktemp_lock); 238*0Sstevel@tonic-gate return (as); 239*0Sstevel@tonic-gate } 240*0Sstevel@tonic-gate 241*0Sstevel@tonic-gate if (++try == max_try) 242*0Sstevel@tonic-gate try = 0; 243*0Sstevel@tonic-gate if (try == previous_try) 244*0Sstevel@tonic-gate break; 245*0Sstevel@tonic-gate } 246*0Sstevel@tonic-gate 247*0Sstevel@tonic-gate fail: 248*0Sstevel@tonic-gate lmutex_unlock(&mktemp_lock); 249*0Sstevel@tonic-gate *as = '\0'; 250*0Sstevel@tonic-gate return (as); 251*0Sstevel@tonic-gate } 252