1 //===-- String type specifier converters for scanf --------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "src/stdio/scanf_core/string_converter.h" 10 11 #include "src/__support/CPP/limits.h" 12 #include "src/__support/ctype_utils.h" 13 #include "src/stdio/scanf_core/core_structs.h" 14 #include "src/stdio/scanf_core/reader.h" 15 16 #include <stddef.h> 17 18 namespace LIBC_NAMESPACE { 19 namespace scanf_core { 20 convert_string(Reader * reader,const FormatSection & to_conv)21int convert_string(Reader *reader, const FormatSection &to_conv) { 22 // %s "Matches a sequence of non-white-space characters" 23 24 // %c "Matches a sequence of characters of exactly the number specified by the 25 // field width (1 if no field width is present in the directive)" 26 27 // %[ "Matches a nonempty sequence of characters from a set of expected 28 // characters (the scanset)." 29 size_t max_width = 0; 30 if (to_conv.max_width > 0) { 31 max_width = to_conv.max_width; 32 } else { 33 if (to_conv.conv_name == 'c') { 34 max_width = 1; 35 } else { 36 max_width = cpp::numeric_limits<size_t>::max(); 37 } 38 } 39 40 char *output = reinterpret_cast<char *>(to_conv.output_ptr); 41 42 char cur_char = reader->getc(); 43 size_t i = 0; 44 for (; i < max_width && cur_char != '\0'; ++i) { 45 // If this is %s and we've hit a space, or if this is %[] and we've found 46 // something not in the scanset. 47 if ((to_conv.conv_name == 's' && internal::isspace(cur_char)) || 48 (to_conv.conv_name == '[' && !to_conv.scan_set.test(cur_char))) { 49 break; 50 } 51 // if the NO_WRITE flag is not set, write to the output. 52 if ((to_conv.flags & NO_WRITE) == 0) 53 output[i] = cur_char; 54 cur_char = reader->getc(); 55 } 56 57 // We always read one more character than will be used, so we have to put the 58 // last one back. 59 reader->ungetc(cur_char); 60 61 // If this is %s or %[] 62 if (to_conv.conv_name != 'c' && (to_conv.flags & NO_WRITE) == 0) { 63 // Always null terminate the string. This may cause a write to the 64 // (max_width + 1) byte, which is correct. The max width describes the max 65 // number of characters read from the input string, and doesn't necessarily 66 // correspond to the output. 67 output[i] = '\0'; 68 } 69 70 if (i == 0) 71 return MATCHING_FAILURE; 72 return READ_OK; 73 } 74 75 } // namespace scanf_core 76 } // namespace LIBC_NAMESPACE 77