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stream: add getpos routine

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udf: save last read position.
This commit is contained in:
rocky
2006-04-15 03:05:14 +00:00
parent 80ab1a301c
commit 22608b594e
7 changed files with 179 additions and 143 deletions
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255
lib/driver/_cdio_stream.c
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@@ -1,8 +1,8 @@
/*
$Id: _cdio_stream.c,v 1.7 2005/03/18 12:56:00 rocky Exp $
$Id: _cdio_stream.c,v 1.8 2006/04/15 03:05:14 rocky Exp $
Copyright (C) 2000, 2004, 2005 Herbert Valerio Riedel <hvr@gnu.org>
Copyright (C) 2005 Rocky Bernstein <rocky@panix.com>
Copyright (C) 2005, 2006 Rocky Bernstein <rocky@cpan.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -35,7 +35,7 @@
#include <cdio/util.h>
#include "_cdio_stream.h"
static const char _rcsid[] = "$Id: _cdio_stream.c,v 1.7 2005/03/18 12:56:00 rocky Exp $";
static const char _rcsid[] = "$Id: _cdio_stream.c,v 1.8 2006/04/15 03:05:14 rocky Exp $";
/*
* DataSource implementations
@@ -48,123 +48,6 @@ struct _CdioDataSource {
long position;
};
/*
Open if not already open.
Return false if we hit an error. Errno should be set for that error.
*/
static bool
_cdio_stream_open_if_necessary(CdioDataSource_t *p_obj)
{
if (!p_obj) return false;
if (!p_obj->is_open) {
if (p_obj->op.open(p_obj->user_data)) {
cdio_warn ("could not open input stream...");
return false;
} else {
cdio_debug ("opened source...");
p_obj->is_open = 1;
p_obj->position = 0;
}
}
return true;
}
/*!
Like 3 fseek and in fact may be the same.
This function sets the file position indicator for the stream
pointed to by stream. The new position, measured in bytes, is obtained
by adding offset bytes to the position specified by whence. If whence
is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to
the start of the file, the current position indicator, or end-of-file,
respectively. A successful call to the fseek function clears the end-
of-file indicator for the stream and undoes any effects of the
ungetc(3) function on the same stream.
@return unpon successful completion, DRIVER_OP_SUCCESS, else,
DRIVER_OP_ERROR is returned and the global variable errno is set to
indicate the error.
*/
driver_return_code_t
cdio_stream_seek(CdioDataSource_t* p_obj, long int offset, int whence)
{
if (!p_obj) return DRIVER_OP_UNINIT;
if (!_cdio_stream_open_if_necessary(p_obj))
/* errno is set by _cdio_stream_open_if necessary. */
return DRIVER_OP_ERROR;
if (offset < 0) return DRIVER_OP_ERROR;
if (p_obj->position != offset) {
#ifdef STREAM_DEBUG
cdio_warn("had to reposition DataSource from %ld to %ld!", obj->position, offset);
#endif
p_obj->position = offset;
return p_obj->op.seek(p_obj->user_data, offset, whence);
}
return 0;
}
CdioDataSource_t *
cdio_stream_new(void *user_data, const cdio_stream_io_functions *funcs)
{
CdioDataSource_t *new_obj;
new_obj = calloc (1, sizeof (CdioDataSource_t));
new_obj->user_data = user_data;
memcpy(&(new_obj->op), funcs, sizeof(cdio_stream_io_functions));
return new_obj;
}
/*!
Like fread(3) and in fact may be the same.
DESCRIPTION:
The function fread reads nmemb elements of data, each size bytes long,
from the stream pointed to by stream, storing them at the location
given by ptr.
RETURN VALUE:
return the number of items successfully read or written (i.e.,
not the number of characters). If an error occurs, or the
end-of-file is reached, the return value is a short item count
(or zero).
We do not distinguish between end-of-file and error, and callers
must use feof(3) and ferror(3) to determine which occurred.
*/
long
cdio_stream_read(CdioDataSource_t* p_obj, void *ptr, long size, long nmemb)
{
long read_bytes;
if (!p_obj) return 0;
if (!_cdio_stream_open_if_necessary(p_obj)) return 0;
read_bytes = (p_obj->op.read)(p_obj->user_data, ptr, size*nmemb);
p_obj->position += read_bytes;
return read_bytes;
}
/*!
Return whatever size of stream reports, I guess unit size is bytes.
On error return -1;
*/
long int
cdio_stream_stat(CdioDataSource_t *p_obj)
{
if (!p_obj) return -1;
if (!_cdio_stream_open_if_necessary(p_obj)) return -1;
return p_obj->op.stat(p_obj->user_data);
}
void
cdio_stream_close(CdioDataSource_t *p_obj)
{
@@ -190,6 +73,138 @@ cdio_stream_destroy(CdioDataSource_t *p_obj)
free(p_obj);
}
/**
Like 3 fgetpos.
This function gets the current file position indicator for the stream
pointed to by stream.
@return unpon successful completion, return value is positive, else,
the global variable errno is set to indicate the error.
*/
ssize_t
cdio_stream_getpos(CdioDataSource_t* p_obj, /*out*/ ssize_t *i_offset)
{
if (!p_obj || !p_obj->is_open) return DRIVER_OP_UNINIT;
return *i_offset = p_obj->position;
}
CdioDataSource_t *
cdio_stream_new(void *user_data, const cdio_stream_io_functions *funcs)
{
CdioDataSource_t *new_obj;
new_obj = calloc (1, sizeof (CdioDataSource_t));
new_obj->user_data = user_data;
memcpy(&(new_obj->op), funcs, sizeof(cdio_stream_io_functions));
return new_obj;
}
/*
Open if not already open.
Return false if we hit an error. Errno should be set for that error.
*/
static bool
_cdio_stream_open_if_necessary(CdioDataSource_t *p_obj)
{
if (!p_obj) return false;
if (!p_obj->is_open) {
if (p_obj->op.open(p_obj->user_data)) {
cdio_warn ("could not open input stream...");
return false;
} else {
cdio_debug ("opened source...");
p_obj->is_open = 1;
p_obj->position = 0;
}
}
return true;
}
/**
Like fread(3) and in fact may be the same.
DESCRIPTION:
The function fread reads nmemb elements of data, each size bytes long,
from the stream pointed to by stream, storing them at the location
given by ptr.
RETURN VALUE:
return the number of items successfully read or written (i.e.,
not the number of characters). If an error occurs, or the
end-of-file is reached, the return value is a short item count
(or zero).
We do not distinguish between end-of-file and error, and callers
must use feof(3) and ferror(3) to determine which occurred.
*/
ssize_t
cdio_stream_read(CdioDataSource_t* p_obj, void *ptr, long size, long nmemb)
{
long read_bytes;
if (!p_obj) return 0;
if (!_cdio_stream_open_if_necessary(p_obj)) return 0;
read_bytes = (p_obj->op.read)(p_obj->user_data, ptr, size*nmemb);
p_obj->position += read_bytes;
return read_bytes;
}
/**
Like 3 fseek and in fact may be the same.
This function sets the file position indicator for the stream
pointed to by stream. The new position, measured in bytes, is obtained
by adding offset bytes to the position specified by whence. If whence
is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to
the start of the file, the current position indicator, or end-of-file,
respectively. A successful call to the fseek function clears the end-
of-file indicator for the stream and undoes any effects of the
ungetc(3) function on the same stream.
@return unpon successful completion, return value is positive, else,
the global variable errno is set to indicate the error.
*/
ssize_t
cdio_stream_seek(CdioDataSource_t* p_obj, ssize_t offset, int whence)
{
if (!p_obj) return DRIVER_OP_UNINIT;
if (!_cdio_stream_open_if_necessary(p_obj))
/* errno is set by _cdio_stream_open_if necessary. */
return DRIVER_OP_ERROR;
if (offset < 0) return DRIVER_OP_ERROR;
if (p_obj->position != offset) {
#ifdef STREAM_DEBUG
cdio_warn("had to reposition DataSource from %ld to %ld!", obj->position, offset);
#endif
p_obj->position = offset;
return p_obj->op.seek(p_obj->user_data, offset, whence);
}
return 0;
}
/**
Return whatever size of stream reports, I guess unit size is bytes.
On error return -1;
*/
ssize_t
cdio_stream_stat(CdioDataSource_t *p_obj)
{
if (!p_obj) return -1;
if (!_cdio_stream_open_if_necessary(p_obj)) return -1;
return p_obj->op.stat(p_obj->user_data);
}
/*
* Local variables: