1 /* Copyright (c) 2003-2018 Dovecot authors, see the included COPYING file */
2
3 #include "lib.h"
4 #include "istream-private.h"
5 #include "istream-sized.h"
6
7 struct sized_istream {
8 struct istream_private istream;
9
10 istream_sized_callback_t *error_callback;
11 void *error_context;
12
13 uoff_t size;
14 bool min_size_only;
15 };
16
i_stream_sized_destroy(struct iostream_private * stream)17 static void i_stream_sized_destroy(struct iostream_private *stream)
18 {
19 struct sized_istream *sstream =
20 container_of(stream, struct sized_istream, istream.iostream);
21 uoff_t v_offset;
22
23 v_offset = sstream->istream.parent_start_offset +
24 sstream->istream.istream.v_offset;
25 if (sstream->istream.parent->seekable ||
26 v_offset > sstream->istream.parent->v_offset) {
27 /* get to same position in parent stream */
28 i_stream_seek(sstream->istream.parent, v_offset);
29 }
30 }
31
32 static const char *
i_stream_create_sized_default_error_callback(const struct istream_sized_error_data * data,void * context ATTR_UNUSED)33 i_stream_create_sized_default_error_callback(
34 const struct istream_sized_error_data *data, void *context ATTR_UNUSED)
35 {
36 if (data->v_offset + data->new_bytes < data->wanted_size) {
37 return t_strdup_printf("Stream is smaller than expected "
38 "(%"PRIuUOFF_T" < %"PRIuUOFF_T")",
39 data->v_offset + data->new_bytes, data->wanted_size);
40 } else {
41 return t_strdup_printf("Stream is larger than expected "
42 "(%"PRIuUOFF_T" > %"PRIuUOFF_T", eof=%d)",
43 data->v_offset + data->new_bytes, data->wanted_size,
44 data->eof ? 1 : 0);
45 }
46 }
47
48 static ssize_t
i_stream_sized_parent_read(struct istream_private * stream,size_t * pos_r)49 i_stream_sized_parent_read(struct istream_private *stream, size_t *pos_r)
50 {
51 ssize_t ret;
52
53 do {
54 ret = i_stream_read_memarea(stream->parent);
55 stream->istream.stream_errno = stream->parent->stream_errno;
56 stream->istream.eof = stream->parent->eof;
57 stream->buffer = i_stream_get_data(stream->parent, pos_r);
58 } while (*pos_r <= stream->pos && ret > 0);
59 return ret;
60 }
61
i_stream_sized_read(struct istream_private * stream)62 static ssize_t i_stream_sized_read(struct istream_private *stream)
63 {
64 struct sized_istream *sstream =
65 container_of(stream, struct sized_istream, istream);
66 struct istream_sized_error_data data;
67 const char *error;
68 uoff_t left;
69 ssize_t ret;
70 size_t pos;
71
72 i_stream_seek(stream->parent, sstream->istream.parent_start_offset +
73 stream->istream.v_offset);
74
75 stream->pos -= stream->skip;
76 stream->skip = 0;
77
78 stream->buffer = i_stream_get_data(stream->parent, &pos);
79 if (pos > stream->pos)
80 ret = 0;
81 else {
82 if ((ret = i_stream_sized_parent_read(stream, &pos)) == -2)
83 return -2;
84 }
85
86 left = sstream->size - stream->istream.v_offset;
87 if (pos == left && ret != -1) {
88 /* we have exactly the wanted amount of data left, but we
89 don't know yet if there is more data in parent. */
90 ret = i_stream_sized_parent_read(stream, &pos);
91 }
92
93 i_zero(&data);
94 data.v_offset = stream->istream.v_offset;
95 data.new_bytes = pos;
96 data.wanted_size = sstream->size;
97 data.eof = stream->istream.eof;
98
99 if (pos == left) {
100 /* we may or may not be finished, depending on whether
101 parent is at EOF. */
102 } else if (pos > left) {
103 /* parent has more data available than expected */
104 if (!sstream->min_size_only) {
105 error = sstream->error_callback(&data, sstream->error_context);
106 io_stream_set_error(&stream->iostream, "%s", error);
107 stream->istream.stream_errno = EINVAL;
108 return -1;
109 }
110 pos = left;
111 if (pos <= stream->pos) {
112 stream->istream.eof = TRUE;
113 ret = -1;
114 }
115 } else if (!stream->istream.eof) {
116 /* still more to read */
117 } else if (stream->istream.stream_errno == ENOENT) {
118 /* lost the file */
119 } else {
120 /* EOF before we reached the wanted size */
121 error = sstream->error_callback(&data, sstream->error_context);
122 io_stream_set_error(&stream->iostream, "%s", error);
123 stream->istream.stream_errno = EPIPE;
124 }
125
126 ret = pos > stream->pos ? (ssize_t)(pos - stream->pos) :
127 (ret == 0 ? 0 : -1);
128 stream->pos = pos;
129 i_assert(ret != -1 || stream->istream.eof ||
130 stream->istream.stream_errno != 0);
131 return ret;
132 }
133
134 static int
i_stream_sized_stat(struct istream_private * stream,bool exact ATTR_UNUSED)135 i_stream_sized_stat(struct istream_private *stream, bool exact ATTR_UNUSED)
136 {
137 struct sized_istream *sstream =
138 container_of(stream, struct sized_istream, istream);
139 const struct stat *st;
140
141 /* parent stream may be base64-decoder. don't waste time decoding the
142 entire stream, since we already know what the size is supposed
143 to be. */
144 if (i_stream_stat(stream->parent, FALSE, &st) < 0) {
145 stream->istream.stream_errno = stream->parent->stream_errno;
146 return -1;
147 }
148
149 stream->statbuf = *st;
150 stream->statbuf.st_size = sstream->size;
151 return 0;
152 }
153
154 static struct sized_istream *
i_stream_create_sized_common(struct istream * input,uoff_t size)155 i_stream_create_sized_common(struct istream *input, uoff_t size)
156 {
157 struct sized_istream *sstream;
158
159 sstream = i_new(struct sized_istream, 1);
160 sstream->size = size;
161 sstream->istream.max_buffer_size = input->real_stream->max_buffer_size;
162
163 sstream->istream.iostream.destroy = i_stream_sized_destroy;
164 sstream->istream.read = i_stream_sized_read;
165 sstream->istream.stat = i_stream_sized_stat;
166
167 sstream->istream.istream.readable_fd = input->readable_fd;
168 sstream->istream.istream.blocking = input->blocking;
169 sstream->istream.istream.seekable = input->seekable;
170 (void)i_stream_create(&sstream->istream, input,
171 i_stream_get_fd(input), 0);
172 return sstream;
173 }
174
i_stream_create_sized(struct istream * input,uoff_t size)175 struct istream *i_stream_create_sized(struct istream *input, uoff_t size)
176 {
177 struct sized_istream *sstream;
178
179 sstream = i_stream_create_sized_common(input, size);
180 sstream->error_callback = i_stream_create_sized_default_error_callback;
181 sstream->error_context = sstream;
182 return &sstream->istream.istream;
183 }
184
i_stream_create_sized_range(struct istream * input,uoff_t offset,uoff_t size)185 struct istream *i_stream_create_sized_range(struct istream *input,
186 uoff_t offset, uoff_t size)
187 {
188 uoff_t orig_offset = input->v_offset;
189 struct istream *ret;
190
191 input->v_offset = offset;
192 ret = i_stream_create_sized(input, size);
193 input->v_offset = orig_offset;
194 return ret;
195 }
196
i_stream_create_min_sized(struct istream * input,uoff_t min_size)197 struct istream *i_stream_create_min_sized(struct istream *input, uoff_t min_size)
198 {
199 struct istream *ret;
200
201 ret= i_stream_create_sized(input, min_size);
202 struct sized_istream *ret_sstream =
203 container_of(ret->real_stream, struct sized_istream, istream);
204 ret_sstream->min_size_only = TRUE;
205 return ret;
206 }
207
i_stream_create_min_sized_range(struct istream * input,uoff_t offset,uoff_t min_size)208 struct istream *i_stream_create_min_sized_range(struct istream *input,
209 uoff_t offset, uoff_t min_size)
210 {
211 struct istream *ret;
212
213 ret = i_stream_create_sized_range(input, offset, min_size);
214 struct sized_istream *ret_sstream =
215 container_of(ret->real_stream, struct sized_istream, istream);
216 ret_sstream->min_size_only = TRUE;
217 return ret;
218 }
219
220 #undef i_stream_create_sized_with_callback
221 struct istream *
i_stream_create_sized_with_callback(struct istream * input,uoff_t size,istream_sized_callback_t * error_callback,void * context)222 i_stream_create_sized_with_callback(struct istream *input, uoff_t size,
223 istream_sized_callback_t *error_callback,
224 void *context)
225 {
226 struct sized_istream *sstream;
227
228 sstream = i_stream_create_sized_common(input, size);
229 sstream->error_callback = error_callback;
230 sstream->error_context = context;
231 return &sstream->istream.istream;
232 }
233