FFmpeg: libavformat/file.c Source File

FFmpeg
file.c
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1 /*
2  * buffered file I/O
3  * Copyright (c) 2001 Fabrice Bellard
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/avstring.h"
23 #include "libavutil/internal.h"
24 #include "libavutil/opt.h"
25 #include "avformat.h"
26 #include <fcntl.h>
27 #if HAVE_IO_H
28 #include <io.h>
29 #endif
30 #if HAVE_UNISTD_H
31 #include <unistd.h>
32 #endif
33 #include <sys/stat.h>
34 #include <stdlib.h>
35 #include "os_support.h"
36 #include "url.h"
37 
38 /* Some systems may not have S_ISFIFO */
39 #ifndef S_ISFIFO
40 # ifdef S_IFIFO
41 # define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
42 # else
43  # define S_ISFIFO(m) 0
44 # endif
45 #endif
46 
47 /* standard file protocol */
48 
49  typedef struct FileContext {
50   const AVClass *class;
51   int fd;
52   int trunc;
53   int blocksize;
54 } FileContext;
55 
56  static const AVOption file_options[] = {
57  { "truncate", "Truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
58  { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
59  { NULL }
60 };
61 
62  static const AVOption pipe_options[] = {
63  { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
64  { NULL }
65 };
66 
67  static const AVClass file_class = {
68  .class_name = "file",
69  .item_name = av_default_item_name,
70  .option = file_options,
71  .version = LIBAVUTIL_VERSION_INT,
72 };
73 
74  static const AVClass pipe_class = {
75  .class_name = "pipe",
76  .item_name = av_default_item_name,
77  .option = pipe_options,
78  .version = LIBAVUTIL_VERSION_INT,
79 };
80 
81  static int file_read(URLContext *h, unsigned char *buf, int size)
82 {
83  FileContext *c = h->priv_data;
84  int r;
85  size = FFMIN(size, c->blocksize);
86  r = read(c->fd, buf, size);
87  return (-1 == r)?AVERROR(errno):r;
88 }
89 
90  static int file_write(URLContext *h, const unsigned char *buf, int size)
91 {
92  FileContext *c = h->priv_data;
93  int r;
94  size = FFMIN(size, c->blocksize);
95  r = write(c->fd, buf, size);
96  return (-1 == r)?AVERROR(errno):r;
97 }
98 
99  static int file_get_handle(URLContext *h)
100 {
101  FileContext *c = h->priv_data;
102  return c->fd;
103 }
104 
105  static int file_check(URLContext *h, int mask)
106 {
107 #if HAVE_ACCESS && defined(R_OK)
108  int ret = 0;
109  if (access(h->filename, F_OK) < 0)
110  return AVERROR(errno);
111  if (mask&AVIO_FLAG_READ)
112  if (access(h->filename, R_OK) >= 0)
113  ret |= AVIO_FLAG_READ;
114  if (mask&AVIO_FLAG_WRITE)
115  if (access(h->filename, W_OK) >= 0)
116  ret |= AVIO_FLAG_WRITE;
117 #else
118  struct stat st;
119  int ret = stat(h->filename, &st);
120  if (ret < 0)
121  return AVERROR(errno);
122 
123  ret |= st.st_mode&S_IRUSR ? mask&AVIO_FLAG_READ : 0;
124  ret |= st.st_mode&S_IWUSR ? mask&AVIO_FLAG_WRITE : 0;
125 #endif
126  return ret;
127 }
128 
129 #if CONFIG_FILE_PROTOCOL
130 
131 static int file_open(URLContext *h, const char *filename, int flags)
132 {
133  FileContext *c = h->priv_data;
134  int access;
135  int fd;
136  struct stat st;
137 
138  av_strstart(filename, "file:", &filename);
139 
140  if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
141  access = O_CREAT | O_RDWR;
142  if (c->trunc)
143  access |= O_TRUNC;
144  } else if (flags & AVIO_FLAG_WRITE) {
145  access = O_CREAT | O_WRONLY;
146  if (c->trunc)
147  access |= O_TRUNC;
148  } else {
149  access = O_RDONLY;
150  }
151 #ifdef O_BINARY
152  access |= O_BINARY;
153 #endif
154  fd = avpriv_open(filename, access, 0666);
155  if (fd == -1)
156  return AVERROR(errno);
157  c->fd = fd;
158 
159  h->is_streamed = !fstat(fd, &st) && S_ISFIFO(st.st_mode);
160 
161  return 0;
162 }
163 
164 /* XXX: use llseek */
165 static int64_t file_seek(URLContext *h, int64_t pos, int whence)
166 {
167  FileContext *c = h->priv_data;
168  int64_t ret;
169 
170  if (whence == AVSEEK_SIZE) {
171  struct stat st;
172  ret = fstat(c->fd, &st);
173  return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ? 0 : st.st_size);
174  }
175 
176  ret = lseek(c->fd, pos, whence);
177 
178  return ret < 0 ? AVERROR(errno) : ret;
179 }
180 
181 static int file_close(URLContext *h)
182 {
183  FileContext *c = h->priv_data;
184  return close(c->fd);
185 }
186 
187 URLProtocol ff_file_protocol = {
188  .name = "file",
189  .url_open = file_open,
190  .url_read = file_read,
191  .url_write = file_write,
192  .url_seek = file_seek,
193  .url_close = file_close,
194  .url_get_file_handle = file_get_handle,
195  .url_check = file_check,
196  .priv_data_size = sizeof(FileContext),
197  .priv_data_class = &file_class,
198 };
199 
200 #endif /* CONFIG_FILE_PROTOCOL */
201 
202 #if CONFIG_PIPE_PROTOCOL
203 
204 static int pipe_open(URLContext *h, const char *filename, int flags)
205 {
206  FileContext *c = h->priv_data;
207  int fd;
208  char *final;
209  av_strstart(filename, "pipe:", &filename);
210 
211  fd = strtol(filename, &final, 10);
212  if((filename == final) || *final ) {/* No digits found, or something like 10ab */
213  if (flags & AVIO_FLAG_WRITE) {
214  fd = 1;
215  } else {
216  fd = 0;
217  }
218  }
219 #if HAVE_SETMODE
220  setmode(fd, O_BINARY);
221 #endif
222  c->fd = fd;
223  h->is_streamed = 1;
224  return 0;
225 }
226 
227 URLProtocol ff_pipe_protocol = {
228  .name = "pipe",
229  .url_open = pipe_open,
230  .url_read = file_read,
231  .url_write = file_write,
232  .url_get_file_handle = file_get_handle,
233  .url_check = file_check,
234  .priv_data_size = sizeof(FileContext),
235  .priv_data_class = &pipe_class,
236 };
237 
238 #endif /* CONFIG_PIPE_PROTOCOL */
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