1 // Copyright (c) 2016 Google Inc.
2 //
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
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
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.
14
15 #ifndef TOOLS_IO_H_
16 #define TOOLS_IO_H_
17
18 #include <cstdint>
19 #include <cstdio>
20 #include <vector>
21
22 // Appends the content from the file named as |filename| to |data|, assuming
23 // each element in the file is of type |T|. The file is opened with the given
24 // |mode|. If |filename| is nullptr or "-", reads from the standard input, but
25 // reopened with the given mode. If any error occurs, writes error messages to
26 // standard error and returns false.
27 template <typename T>
ReadFile(const char * filename,const char * mode,std::vector<T> * data)28 bool ReadFile(const char* filename, const char* mode, std::vector<T>* data) {
29 const int buf_size = 1024;
30 const bool use_file = filename && strcmp("-", filename);
31 if (FILE* fp =
32 (use_file ? fopen(filename, mode) : freopen(nullptr, mode, stdin))) {
33 T buf[buf_size];
34 while (size_t len = fread(buf, sizeof(T), buf_size, fp)) {
35 data->insert(data->end(), buf, buf + len);
36 }
37 if (ftell(fp) == -1L) {
38 if (ferror(fp)) {
39 fprintf(stderr, "error: error reading file '%s'\n", filename);
40 return false;
41 }
42 } else {
43 if (sizeof(T) != 1 && (ftell(fp) % sizeof(T))) {
44 fprintf(
45 stderr,
46 "error: file size should be a multiple of %zd; file '%s' corrupt\n",
47 sizeof(T), filename);
48 return false;
49 }
50 }
51 if (use_file) fclose(fp);
52 } else {
53 fprintf(stderr, "error: file does not exist '%s'\n", filename);
54 return false;
55 }
56 return true;
57 }
58
59 // Writes the given |data| into the file named as |filename| using the given
60 // |mode|, assuming |data| is an array of |count| elements of type |T|. If
61 // |filename| is nullptr or "-", writes to standard output. If any error occurs,
62 // returns false and outputs error message to standard error.
63 template <typename T>
WriteFile(const char * filename,const char * mode,const T * data,size_t count)64 bool WriteFile(const char* filename, const char* mode, const T* data,
65 size_t count) {
66 const bool use_stdout =
67 !filename || (filename[0] == '-' && filename[1] == '\0');
68 if (FILE* fp = (use_stdout ? stdout : fopen(filename, mode))) {
69 size_t written = fwrite(data, sizeof(T), count, fp);
70 if (count != written) {
71 fprintf(stderr, "error: could not write to file '%s'\n", filename);
72 return false;
73 }
74 if (!use_stdout) fclose(fp);
75 } else {
76 fprintf(stderr, "error: could not open file '%s'\n", filename);
77 return false;
78 }
79 return true;
80 }
81
82 #endif // TOOLS_IO_H_
83