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file: Add 'blocksize' option

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Interruptibility of file operations is strongly desirable in case of
slow storage access, e.g. mounted network share.
This commit introduces possibility to limit data quantity transferred by
'file' protocol at once. By default, old behaviour is preserved and data
is still tried to be transferred without block size limitation.

Note that file I/O operation still may block (or even freeze) inside of
single read(2) or write(2) operation.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Andrey Utkin 2013-07-31 15:22:01 +03:00 committed by Michael Niedermayer
parent 3b3c1ed076
commit a8f171151f
1 changed files with 21 additions and 2 deletions
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23
libavformat/file.c
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@ -49,10 +49,17 @@ typedef struct FileContext {
const AVClass *class;
int fd;
int trunc;
int blocksize;
} FileContext;
static const AVOption file_options[] = {
{ "truncate", "Truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
{ "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 },
{ NULL }
};
static const AVOption pipe_options[] = {
{ "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 },
{ NULL }
};
@ -63,17 +70,28 @@ static const AVClass file_class = {
.version = LIBAVUTIL_VERSION_INT,
};
static const AVClass pipe_class = {
.class_name = "pipe",
.item_name = av_default_item_name,
.option = pipe_options,
.version = LIBAVUTIL_VERSION_INT,
};
static int file_read(URLContext *h, unsigned char *buf, int size)
{
FileContext *c = h->priv_data;
int r = read(c->fd, buf, size);
int r;
size = FFMIN(size, c->blocksize);
r = read(c->fd, buf, size);
return (-1 == r)?AVERROR(errno):r;
}
static int file_write(URLContext *h, const unsigned char *buf, int size)
{
FileContext *c = h->priv_data;
int r = write(c->fd, buf, size);
int r;
size = FFMIN(size, c->blocksize);
r = write(c->fd, buf, size);
return (-1 == r)?AVERROR(errno):r;
}
@ -213,6 +231,7 @@ URLProtocol ff_pipe_protocol = {
.url_get_file_handle = file_get_handle,
.url_check = file_check,
.priv_data_size = sizeof(FileContext),
.priv_data_class = &pipe_class,
};
#endif /* CONFIG_PIPE_PROTOCOL */