1 /* LBS: An LFS-inspired filesystem backup system
2 * Copyright (C) 2006 Michael Vrable
4 * Backup data is stored in a collection of objects, which are grouped together
5 * into segments for storage purposes. This file provides interfaces for
6 * reading and writing objects and segments. */
15 OutputStream::OutputStream()
20 void OutputStream::write(const void *data, size_t len)
22 write_internal(data, len);
26 void OutputStream::write_u8(uint8_t val)
31 void OutputStream::write_u16(uint16_t val)
36 buf[1] = (val >> 8) & 0xff;
40 void OutputStream::write_u32(uint32_t val)
45 buf[1] = (val >> 8) & 0xff;
46 buf[2] = (val >> 16) & 0xff;
47 buf[3] = (val >> 24) & 0xff;
51 void OutputStream::write_u64(uint64_t val)
56 buf[1] = (val >> 8) & 0xff;
57 buf[2] = (val >> 16) & 0xff;
58 buf[3] = (val >> 24) & 0xff;
59 buf[4] = (val >> 32) & 0xff;
60 buf[5] = (val >> 40) & 0xff;
61 buf[6] = (val >> 48) & 0xff;
62 buf[7] = (val >> 56) & 0xff;
66 /* Writes an integer to an output stream using a variable-sized representation:
67 * seven bits are written at a time (little-endian), and the eigth bit of each
68 * byte is set if more data follows. */
69 void OutputStream::write_varint(uint64_t val)
72 uint8_t remainder = (val & 0x7f);
80 /* Write an arbitrary string by first writing out the length, followed by the
82 void OutputStream::write_string(const string &s)
84 size_t len = s.length();
89 void OutputStream::write_dictionary(const dictionary &d)
91 size_t size = d.size();
96 for (dictionary::const_iterator i = d.begin(); i != d.end(); ++i) {
97 write_string(i->first);
98 write_string(i->second);
102 assert(written == size);
105 StringOutputStream::StringOutputStream()
106 : buf(std::ios_base::out)
110 void StringOutputStream::write_internal(const void *data, size_t len)
112 buf.write((const char *)data, len);
114 throw IOException("error writing to StringOutputStream");
117 FileOutputStream::FileOutputStream(FILE *file)
122 FileOutputStream::~FileOutputStream()
127 void FileOutputStream::write_internal(const void *data, size_t len)
131 res = fwrite(data, 1, len, f);
133 throw IOException("write error");
137 WrapperOutputStream::WrapperOutputStream(OutputStream &o)
142 void WrapperOutputStream::write_internal(const void *data, size_t len)
144 real.write(data, len);
147 /* Utility functions, for encoding data types to strings. */
148 string encode_u16(uint16_t val)
150 StringOutputStream s;
155 string encode_u32(uint32_t val)
157 StringOutputStream s;
162 string encode_u64(uint64_t val)
164 StringOutputStream s;
169 SegmentWriter::SegmentWriter(OutputStream &output, struct uuid u)
174 /* Write out the segment header first. */
175 static const char signature[] = "LBSSEG0\n";
176 out.write(signature, strlen(signature));
177 out.write(id.bytes, sizeof(struct uuid));
180 SegmentWriter::~SegmentWriter()
185 // Write out the object table which gives the sizes and locations of all
186 // objects, and then add the trailing signature, which indicates the end of
187 // the segment and gives the offset of the object table.
188 int64_t index_offset = out.get_pos();
190 for (object_table::const_iterator i = objects.begin();
191 i != objects.end(); ++i) {
192 out.write_s64(i->first);
193 out.write_s64(i->second);
196 static const char signature2[] = "LBSEND";
197 out.write(signature2, strlen(signature2));
198 out.write_s64(index_offset);
199 out.write_u32(objects.size());
202 OutputStream *SegmentWriter::new_object()
207 object_start_offset = out.get_pos();
208 object_stream = new WrapperOutputStream(out);
210 return object_stream;
213 void SegmentWriter::finish_object()
215 assert(object_stream != NULL);
217 // store (start, length) information for locating this object
218 objects.push_back(std::make_pair(object_start_offset,
219 object_stream->get_pos()));
221 delete object_stream;
222 object_stream = NULL;
225 struct uuid SegmentWriter::generate_uuid()
229 uuid_generate(u.bytes);
234 string SegmentWriter::format_uuid(const struct uuid u)
236 // A UUID only takes 36 bytes, plus the trailing '\0', so this is safe.
239 uuid_unparse_lower(u.bytes, buf);