1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2025 Hans Rosenfeld 24 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 25 * Use is subject to license terms. 26 */ 27 28 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 29 /* All Rights Reserved */ 30 31 #include "lint.h" 32 #include <mtlib.h> 33 #include <stdarg.h> 34 #include <values.h> 35 #include <errno.h> 36 #include <synch.h> 37 #include <thread.h> 38 #include <sys/types.h> 39 #include "print.h" 40 #include "libc.h" 41 #include <stdio_ext.h> 42 #include <upanic.h> 43 44 #ifdef _C89_INTMAX32 45 #pragma redefine_extname vsnprintf _vsnprintf_c89 46 #pragma redefine_extname snprintf _snprintf_c89 47 #endif 48 49 /* 50 * 32-bit shadow functions _vsnprintf_c89() and _snprintf_c89() are included 51 * here. 52 * When using the c89 compiler to build 32-bit applications, the size 53 * of intmax_t is 32-bits, otherwise the size of intmax_t is 64-bits. 54 * The shadow function uses 32-bit size of intmax_t for j conversion. 55 * The #pragma redefine_extname in <stdio.h> selects the proper routine 56 * at compile time for the user application. 57 * NOTE: the shadow functions only exist in the 32-bit library. 58 */ 59 60 int 61 vsnprintf(char *string, size_t n, const char *format, va_list ap) 62 { 63 ssize_t count; 64 FILE siop; 65 size_t max = MAXINT; 66 unsigned char tmpbuf[1]; /* dummy buffer for _doprnt() if n == 0 */ 67 68 /* 69 * The dummy FILE * created for vsnprintf has the _IOREAD 70 * flag set to distinguish it from printf and fprintf 71 * invocations. It also has the _IOWRT flag set to indicate 72 * it is writable, which is checked later by vfprintf(). 73 */ 74 siop._flag = _IOWRT | _IOREAD; 75 siop._cnt = n - 1; 76 siop._base = siop._ptr = (unsigned char *)string; 77 #ifdef _LP64 78 /* 79 * _bufend() (_realbufend()) should return NULL for v/snprintf, 80 * so PUT() macro in _doprnt() will bounds check. For 32-bit, 81 * there is no _end field, and _realbufend() will return NULL 82 * since it cannot find the dummy FILE structure in the linked 83 * list of FILE strucutres. See bug 4274368. 84 */ 85 siop._end = NULL; 86 #endif /* _LP64 */ 87 88 /* 89 * Mark the dummy FILE so that no locking is ever done. 90 */ 91 if (__fsetlocking(&siop, FSETLOCKING_BYCALLER) == -1) 92 upanic(NULL, 0); /* this should never happen */ 93 94 if (n == 0) { 95 /* 96 * When n==0, string may be NULL, so always use tmpbuf to 97 * guard for this case. No bytes should be transmitted to 98 * the buffer when n==0, so using tmpbuf instead of string 99 * (ie, if string is not NULL) should not matter. 100 */ 101 siop._base = siop._ptr = tmpbuf; 102 siop._cnt = 0; 103 } else if (n > max) { 104 errno = EOVERFLOW; 105 return (EOF); 106 } 107 108 count = vfprintf(&siop, format, ap); 109 110 *siop._ptr = '\0'; /* plant terminating null character */ 111 112 return ((int)count); 113 } 114 115 int 116 snprintf(char *string, size_t n, const char *format, ...) 117 { 118 int count; 119 va_list ap; 120 121 va_start(ap, format); 122 count = vsnprintf(string, n, format, ap); 123 va_end(ap); 124 125 return (count); 126 } 127