cc4a72243d
1) The loop for determining the line length read from a character offset before checking whether the offset is smaller than the given string length. This could have caused access outside the string buffer. 2) The routine for determining the line length first seeked for the offset of the last real character of the line and than added one for getting the length but only if the following character was '\n'. This has to be done for any other line-terminating character too. The only case where you don't want to do this is when the end of the whole string is reached. Issue #2967
99 lines
2.5 KiB
C++
99 lines
2.5 KiB
C++
/*
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* \brief Utility for safely writing multi-line text
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* \author Norman Feske
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* \date 2014-01-11
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*/
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/*
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* Copyright (C) 2014-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__UTIL__PRINT_LINES_H_
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#define _INCLUDE__UTIL__PRINT_LINES_H_
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#include <util/string.h>
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namespace Genode {
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template <size_t, typename FUNC>
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static inline void print_lines(char const *, size_t, FUNC const &);
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}
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/**
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* Print multi-line string
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*
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* \param MAX_LINE_LEN maximum line length, used to dimension a line buffer
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* on the stack
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* \param string character buffer, not necessarily null-terminated
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* \param len number of characters to print
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* \param func functor called for each line with 'char const *' as
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* argument
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*
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* In situations where a string is supplied by an untrusted client, we cannot
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* simply print the client-provided content as a single string becausewe cannot
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* expect the client to null-terminate the string properly. The 'Log_multiline'
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* class outputs the content line by line while keeping track of the content
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* size.
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*
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* The output stops when reaching the end of the buffer or when a null
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* character is encountered.
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*/
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template <Genode::size_t MAX_LINE_LEN, typename FUNC>
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void Genode::print_lines(char const *string, size_t len, FUNC const &func)
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{
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/* skip leading line breaks */
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for (; *string == '\n'; string++);
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/* number of space and tab characters used for indentation */
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size_t const num_indent_chars =
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({
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size_t n = 0;
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for (; string[n] == ' ' || string[n] == '\t'; n++);
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n;
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});
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char const * const first_line = string;
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while (*string && len) {
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/*
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* Skip indentation if the pattern is the same as for the first line.
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*/
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if (Genode::strcmp(first_line, string, num_indent_chars) == 0)
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string += num_indent_chars;
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size_t const line_len =
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({
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size_t i = 0;
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for (; i < len; i++) {
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if (string[i] == '\0' || string[i] == '\n') {
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/* the line length is the offset of the last real character + 1 */
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i++;
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break;
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}
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}
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i;
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});
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if (!line_len)
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break;
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/*
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* Copy line from (untrusted) caller to local line buffer
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*/
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char line_buf[MAX_LINE_LEN];
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Genode::strncpy(line_buf, string, Genode::min(line_len, sizeof(line_buf)));
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func(line_buf);
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string += line_len;
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len -= line_len;
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}
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}
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#endif /* _INCLUDE__UTIL__PRINT_LINES_H_ */
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