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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 
38 /* standard file protocol */
39 
40 typedef struct FileContext {
41  const AVClass *class;
42  int fd;
43  int trunc;
44 } FileContext;
45 
46 static const AVOption file_options[] = {
47  { "truncate", "Truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
48  { NULL }
49 };
50 
51 static const AVClass file_class = {
52  .class_name = "file",
53  .item_name = av_default_item_name,
54  .option = file_options,
55  .version = LIBAVUTIL_VERSION_INT,
56 };
57 
58 static int file_read(URLContext *h, unsigned char *buf, int size)
59 {
60  FileContext *c = h->priv_data;
61  return read(c->fd, buf, size);
62 }
63 
64 static int file_write(URLContext *h, const unsigned char *buf, int size)
65 {
66  FileContext *c = h->priv_data;
67  return write(c->fd, buf, size);
68 }
69 
71 {
72  FileContext *c = h->priv_data;
73  return c->fd;
74 }
75 
76 static int file_check(URLContext *h, int mask)
77 {
78  struct stat st;
79  int ret = stat(h->filename, &st);
80  if (ret < 0)
81  return AVERROR(errno);
82 
83  ret |= st.st_mode&S_IRUSR ? mask&AVIO_FLAG_READ : 0;
84  ret |= st.st_mode&S_IWUSR ? mask&AVIO_FLAG_WRITE : 0;
85 
86  return ret;
87 }
88 
89 #if CONFIG_FILE_PROTOCOL
90 
91 static int file_open(URLContext *h, const char *filename, int flags)
92 {
93  FileContext *c = h->priv_data;
94  int access;
95  int fd;
96 
97  av_strstart(filename, "file:", &filename);
98 
99  if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
100  access = O_CREAT | O_RDWR;
101  if (c->trunc)
102  access |= O_TRUNC;
103  } else if (flags & AVIO_FLAG_WRITE) {
104  access = O_CREAT | O_WRONLY;
105  if (c->trunc)
106  access |= O_TRUNC;
107  } else {
108  access = O_RDONLY;
109  }
110 #ifdef O_BINARY
111  access |= O_BINARY;
112 #endif
113  fd = open(filename, access, 0666);
114  if (fd == -1)
115  return AVERROR(errno);
116  c->fd = fd;
117  return 0;
118 }
119 
120 /* XXX: use llseek */
121 static int64_t file_seek(URLContext *h, int64_t pos, int whence)
122 {
123  FileContext *c = h->priv_data;
124  int64_t ret;
125 
126  if (whence == AVSEEK_SIZE) {
127  struct stat st;
128 
129  ret = fstat(c->fd, &st);
130  return ret < 0 ? AVERROR(errno) : st.st_size;
131  }
132 
133  ret = lseek(c->fd, pos, whence);
134 
135  return ret < 0 ? AVERROR(errno) : ret;
136 }
137 
138 static int file_close(URLContext *h)
139 {
140  FileContext *c = h->priv_data;
141  return close(c->fd);
142 }
143 
144 URLProtocol ff_file_protocol = {
145  .name = "file",
146  .url_open = file_open,
147  .url_read = file_read,
148  .url_write = file_write,
149  .url_seek = file_seek,
150  .url_close = file_close,
151  .url_get_file_handle = file_get_handle,
152  .url_check = file_check,
153  .priv_data_size = sizeof(FileContext),
154  .priv_data_class = &file_class,
155 };
156 
157 #endif /* CONFIG_FILE_PROTOCOL */
158 
159 #if CONFIG_PIPE_PROTOCOL
160 
161 static int pipe_open(URLContext *h, const char *filename, int flags)
162 {
163  FileContext *c = h->priv_data;
164  int fd;
165  char *final;
166  av_strstart(filename, "pipe:", &filename);
167 
168  fd = strtol(filename, &final, 10);
169  if((filename == final) || *final ) {/* No digits found, or something like 10ab */
170  if (flags & AVIO_FLAG_WRITE) {
171  fd = 1;
172  } else {
173  fd = 0;
174  }
175  }
176 #if HAVE_SETMODE
177  setmode(fd, O_BINARY);
178 #endif
179  c->fd = fd;
180  h->is_streamed = 1;
181  return 0;
182 }
183 
184 URLProtocol ff_pipe_protocol = {
185  .name = "pipe",
186  .url_open = pipe_open,
187  .url_read = file_read,
188  .url_write = file_write,
189  .url_get_file_handle = file_get_handle,
190  .url_check = file_check,
191  .priv_data_size = sizeof(FileContext),
192 };
193 
194 #endif /* CONFIG_PIPE_PROTOCOL */
static int file_read(URLContext *h, unsigned char *buf, int size)
Definition: file.c:58
int size
AVOption.
Definition: opt.h:233
int is_streamed
true if streamed (no seek possible), default = false
Definition: url.h:48
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:38
AVOptions.
miscellaneous OS support macros and functions.
static int flags
Definition: log.c:42
static int file_check(URLContext *h, int mask)
Definition: file.c:76
int trunc
Definition: file.c:43
static const uint16_t mask[17]
Definition: lzw.c:38
struct FileContext FileContext
static av_always_inline av_const double trunc(double x)
Definition: libm.h:165
LIBAVUTIL_VERSION_INT
Definition: eval.c:52
NULL
Definition: eval.c:52
av_default_item_name
Definition: dnxhdenc.c:43
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:326
Definition: url.h:41
Describe the class of an AVClass context structure.
Definition: log.h:33
void * priv_data
Definition: url.h:44
static const AVClass file_class
Definition: file.c:51
static const AVOption file_options[]
Definition: file.c:46
const char * name
Definition: url.h:54
int fd
Definition: file.c:42
int av_strstart(const char *str, const char *pfx, const char **ptr)
Return non-zero if pfx is a prefix of str.
Definition: avstring.c:32
Main libavformat public API header.
static int file_get_handle(URLContext *h)
Definition: file.c:70
char * filename
specified URL
Definition: url.h:45
unbuffered private I/O API
static int file_write(URLContext *h, const unsigned char *buf, int size)
Definition: file.c:64