1 // Copyright 2017 Google Inc.
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
7 // http://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
15 #include "internal/stack_line_reader.h"
16 #include "internal/filesystem.h"
22 void StackLineReader_Initialize(StackLineReader* reader, int fd) {
23 reader->view.ptr = reader->buffer;
24 reader->view.size = 0;
25 reader->skip_mode = false;
29 // Replaces the content of buffer with bytes from the file.
30 static int LoadFullBuffer(StackLineReader* reader) {
31 const int read = CpuFeatures_ReadFile(reader->fd, reader->buffer,
32 STACK_LINE_READER_BUFFER_SIZE);
34 reader->view.ptr = reader->buffer;
35 reader->view.size = read;
39 // Appends with bytes from the file to buffer, filling the remaining space.
40 static int LoadMore(StackLineReader* reader) {
41 char* const ptr = reader->buffer + reader->view.size;
42 const size_t size_to_read = STACK_LINE_READER_BUFFER_SIZE - reader->view.size;
43 const int read = CpuFeatures_ReadFile(reader->fd, ptr, size_to_read);
45 assert(read <= (int)size_to_read);
46 reader->view.size += read;
50 static int IndexOfEol(StackLineReader* reader) {
51 return CpuFeatures_StringView_IndexOfChar(reader->view, '\n');
54 // Relocate buffer's pending bytes at the beginning of the array and fills the
55 // remaining space with bytes from the file.
56 static int BringToFrontAndLoadMore(StackLineReader* reader) {
57 if (reader->view.size && reader->view.ptr != reader->buffer) {
58 memmove(reader->buffer, reader->view.ptr, reader->view.size);
60 reader->view.ptr = reader->buffer;
61 return LoadMore(reader);
64 // Loads chunks of buffer size from disks until it contains a newline character
66 static void SkipToNextLine(StackLineReader* reader) {
68 const int read = LoadFullBuffer(reader);
72 const int eol_index = IndexOfEol(reader);
75 CpuFeatures_StringView_PopFront(reader->view, eol_index + 1);
82 static LineResult CreateLineResult(bool eof, bool full_line, StringView view) {
85 result.full_line = full_line;
90 // Helper methods to provide clearer semantic in StackLineReader_NextLine.
91 static LineResult CreateEOFLineResult(StringView view) {
92 return CreateLineResult(true, true, view);
95 static LineResult CreateTruncatedLineResult(StringView view) {
96 return CreateLineResult(false, false, view);
99 static LineResult CreateValidLineResult(StringView view) {
100 return CreateLineResult(false, true, view);
103 LineResult StackLineReader_NextLine(StackLineReader* reader) {
104 if (reader->skip_mode) {
105 SkipToNextLine(reader);
106 reader->skip_mode = false;
109 const bool can_load_more =
110 reader->view.size < STACK_LINE_READER_BUFFER_SIZE;
111 int eol_index = IndexOfEol(reader);
112 if (eol_index < 0 && can_load_more) {
113 const int read = BringToFrontAndLoadMore(reader);
115 return CreateEOFLineResult(reader->view);
117 eol_index = IndexOfEol(reader);
120 reader->skip_mode = true;
121 return CreateTruncatedLineResult(reader->view);
125 CpuFeatures_StringView_KeepFront(reader->view, eol_index);
127 CpuFeatures_StringView_PopFront(reader->view, eol_index + 1);
128 return CreateValidLineResult(line);