158 lines
4.4 KiB
C
158 lines
4.4 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* This file is shared between libc and the kernel, so don't put anything
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* in here that won't work in both contexts.
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*/
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#ifdef _KERNEL
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#include <types.h>
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#include <lib.h>
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#else
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#include <stdio.h>
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#endif /* _KERNEL */
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#include <stdarg.h>
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/*
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* Standard C string/IO function: printf into a character buffer.
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*/
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/*
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* Context structure for snprintf: buffer to print into, maximum
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* length, and index of the next character to write.
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*
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* Note that while the length argument to snprintf includes space for
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* a null terminator, SNP.buflen does not. This is to make something
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* vaguely reasonable happen if a length of 0 is passed to snprintf.
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*/
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typedef struct {
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char *buf;
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size_t buflen;
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size_t bufpos;
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} SNP;
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/*
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* Send function for snprintf. This is the function handed to the
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* printf guts. It gets called with mydata pointing to the context,
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* and some string data of length LEN in DATA. DATA is not necessarily
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* null-terminated.
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*/
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static
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void
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__snprintf_send(void *mydata, const char *data, size_t len)
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{
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SNP *snp = mydata;
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unsigned i;
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/* For each character we're sent... */
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for (i=0; i<len; i++) {
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/* If we aren't past the length, */
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if (snp->bufpos < snp->buflen) {
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/* store the character */
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snp->buf[snp->bufpos] = data[i];
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/* and increment the position. */
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snp->bufpos++;
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}
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}
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}
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/*
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* The va_list version of snprintf.
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*/
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int
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vsnprintf(char *buf, size_t len, const char *fmt, va_list ap)
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{
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int chars;
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SNP snp;
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/*
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* Fill in the context structure.
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* We set snp.buflen to the number of characters that can be
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* written (excluding the null terminator) so as not to have
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* to special-case the possibility that we got passed a length
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* of zero elsewhere.
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*/
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snp.buf = buf;
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if (len==0) {
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snp.buflen = 0;
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}
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else {
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snp.buflen = len-1;
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}
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snp.bufpos = 0;
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/* Call __vprintf to do the actual work. */
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chars = __vprintf(__snprintf_send, &snp, fmt, ap);
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/*
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* Add a null terminator. If the length *we were passed* is greater
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* than zero, we reserved a space in the buffer for the terminator,
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* so this won't overflow. If the length we were passed is zero,
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* nothing will have been or should be written anyway, and buf
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* might even be NULL. (C99 explicitly endorses this possibility.)
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*/
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if (len > 0) {
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buf[snp.bufpos] = 0;
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}
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/*
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* Return the number of characters __vprintf processed.
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* According to C99, snprintf should return this number, not
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* the number of characters actually stored, and should not
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* return -1 on overflow but only on other errors. (All none
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* of them since we don't do multibyte characters...)
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*/
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return chars;
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}
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/*
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* snprintf - hand off to vsnprintf.
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*/
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int
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snprintf(char *buf, size_t len, const char *fmt, ...)
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{
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int chars;
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va_list ap;
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va_start(ap, fmt);
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chars = vsnprintf(buf, len, fmt, ap);
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va_end(ap);
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return chars;
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}
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