FFmpeg
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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/opt.h"
24 #include "avformat.h"
25 #include <fcntl.h>
26 #if HAVE_IO_H
27 #include <io.h>
28 #endif
29 #if HAVE_UNISTD_H
30 #include <unistd.h>
31 #endif
32 #include <sys/stat.h>
33 #include <stdlib.h>
34 #include "os_support.h"
35 #include "url.h"
36 
37 /* Some systems may not have S_ISFIFO */
38 #ifndef S_ISFIFO
39 # ifdef S_IFIFO
40 # define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
41 # else
42 # define S_ISFIFO(m) 0
43 # endif
44 #endif
45 
46 /* standard file protocol */
47 
48 typedef struct FileContext {
49  const AVClass *class;
50  int fd;
51  int trunc;
52 } FileContext;
53 
54 static const AVOption file_options[] = {
55  { "truncate", "Truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
56  { NULL }
57 };
58 
59 static const AVClass file_class = {
60  .class_name = "file",
61  .item_name = av_default_item_name,
62  .option = file_options,
63  .version = LIBAVUTIL_VERSION_INT,
64 };
65 
66 static int file_read(URLContext *h, unsigned char *buf, int size)
67 {
68  FileContext *c = h->priv_data;
69  int r = read(c->fd, buf, size);
70  return (-1 == r)?AVERROR(errno):r;
71 }
72 
73 static int file_write(URLContext *h, const unsigned char *buf, int size)
74 {
75  FileContext *c = h->priv_data;
76  int r = write(c->fd, buf, size);
77  return (-1 == r)?AVERROR(errno):r;
78 }
79 
81 {
82  FileContext *c = h->priv_data;
83  return c->fd;
84 }
85 
86 static int file_check(URLContext *h, int mask)
87 {
88 #if HAVE_ACCESS && defined(R_OK)
89  int ret = 0;
90  if (access(h->filename, F_OK) < 0)
91  return AVERROR(errno);
92  if (mask&AVIO_FLAG_READ)
93  if (access(h->filename, R_OK) >= 0)
94  ret |= AVIO_FLAG_READ;
95  if (mask&AVIO_FLAG_WRITE)
96  if (access(h->filename, W_OK) >= 0)
97  ret |= AVIO_FLAG_WRITE;
98 #else
99  struct stat st;
100  int ret = stat(h->filename, &st);
101  if (ret < 0)
102  return AVERROR(errno);
103 
104  ret |= st.st_mode&S_IRUSR ? mask&AVIO_FLAG_READ : 0;
105  ret |= st.st_mode&S_IWUSR ? mask&AVIO_FLAG_WRITE : 0;
106 #endif
107  return ret;
108 }
109 
110 #if CONFIG_FILE_PROTOCOL
111 
112 static int file_open(URLContext *h, const char *filename, int flags)
113 {
114  FileContext *c = h->priv_data;
115  int access;
116  int fd;
117  struct stat st;
118 
119  av_strstart(filename, "file:", &filename);
120 
121  if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
122  access = O_CREAT | O_RDWR;
123  if (c->trunc)
124  access |= O_TRUNC;
125  } else if (flags & AVIO_FLAG_WRITE) {
126  access = O_CREAT | O_WRONLY;
127  if (c->trunc)
128  access |= O_TRUNC;
129  } else {
130  access = O_RDONLY;
131  }
132 #ifdef O_BINARY
133  access |= O_BINARY;
134 #endif
135  fd = open(filename, access, 0666);
136  if (fd == -1)
137  return AVERROR(errno);
138  c->fd = fd;
139 
140  h->is_streamed = !fstat(fd, &st) && S_ISFIFO(st.st_mode);
141 
142  return 0;
143 }
144 
145 /* XXX: use llseek */
146 static int64_t file_seek(URLContext *h, int64_t pos, int whence)
147 {
148  FileContext *c = h->priv_data;
149  int64_t ret;
150 
151  if (whence == AVSEEK_SIZE) {
152  struct stat st;
153  ret = fstat(c->fd, &st);
154  return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ? 0 : st.st_size);
155  }
156 
157  ret = lseek(c->fd, pos, whence);
158 
159  return ret < 0 ? AVERROR(errno) : ret;
160 }
161 
162 static int file_close(URLContext *h)
163 {
164  FileContext *c = h->priv_data;
165  return close(c->fd);
166 }
167 
168 URLProtocol ff_file_protocol = {
169  .name = "file",
170  .url_open = file_open,
171  .url_read = file_read,
172  .url_write = file_write,
173  .url_seek = file_seek,
174  .url_close = file_close,
175  .url_get_file_handle = file_get_handle,
176  .url_check = file_check,
177  .priv_data_size = sizeof(FileContext),
178  .priv_data_class = &file_class,
179 };
180 
181 #endif /* CONFIG_FILE_PROTOCOL */
182 
183 #if CONFIG_PIPE_PROTOCOL
184 
185 static int pipe_open(URLContext *h, const char *filename, int flags)
186 {
187  FileContext *c = h->priv_data;
188  int fd;
189  char *final;
190  av_strstart(filename, "pipe:", &filename);
191 
192  fd = strtol(filename, &final, 10);
193  if((filename == final) || *final ) {/* No digits found, or something like 10ab */
194  if (flags & AVIO_FLAG_WRITE) {
195  fd = 1;
196  } else {
197  fd = 0;
198  }
199  }
200 #if HAVE_SETMODE
201  setmode(fd, O_BINARY);
202 #endif
203  c->fd = fd;
204  h->is_streamed = 1;
205  return 0;
206 }
207 
208 URLProtocol ff_pipe_protocol = {
209  .name = "pipe",
210  .url_open = pipe_open,
211  .url_read = file_read,
212  .url_write = file_write,
213  .url_get_file_handle = file_get_handle,
214  .url_check = file_check,
215  .priv_data_size = sizeof(FileContext),
216 };
217 
218 #endif /* CONFIG_PIPE_PROTOCOL */