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iolayer.c
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iolayer.c
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#include "imager.h"
#include "iolayer.h"
#include "imerror.h"
#include "log.h"
#include <stdlib.h>
#include <stdio.h>
#ifdef _MSC_VER
#include <io.h>
#endif
#include <string.h>
#include <errno.h>
#include "imageri.h"
#define IOL_DEB(x)
#define IOL_DEBs stderr
#define IO_BUF_SIZE 8192
char *io_type_names[] = { "FDSEEK", "FDNOSEEK", "BUFFER", "CBSEEK", "CBNOSEEK", "BUFCHAIN" };
typedef struct io_blink {
char buf[BBSIZ];
/* size_t cnt; */
size_t len; /* How large is this buffer = BBZIS for now */
struct io_blink *next;
struct io_blink *prev;
} io_blink;
typedef struct {
i_io_glue_t base;
int fd;
} io_fdseek;
typedef struct {
i_io_glue_t base;
const char *data;
size_t len;
i_io_closebufp_t closecb; /* free memory mapped segment or decrement refcount */
void *closedata;
off_t cpos;
} io_buffer;
typedef struct {
i_io_glue_t base;
void *p; /* Callback data */
i_io_readl_t readcb;
i_io_writel_t writecb;
i_io_seekl_t seekcb;
i_io_closel_t closecb;
i_io_destroyl_t destroycb;
} io_cb;
typedef struct {
off_t offset; /* Offset of the source - not used */
off_t length; /* Total length of chain in bytes */
io_blink *head; /* Start of chain */
io_blink *tail; /* End of chain */
off_t tfill; /* End of stream in last link */
io_blink *cp; /* Current element of list */
off_t cpos; /* Offset within the current */
off_t gpos; /* Global position in stream */
} io_ex_bchain;
/* turn current offset, file length, whence and offset into a new offset */
#define calc_seek_offset(curr_off, length, offset, whence) \
(((whence) == SEEK_SET) ? (offset) : \
((whence) == SEEK_CUR) ? (curr_off) + (offset) : \
((whence) == SEEK_END) ? (length) + (offset) : -1)
/*
=head1 NAME
iolayer.c - encapsulates different source of data into a single framework.
=head1 SYNOPSIS
io_glue *ig = io_new_fd( fileno(stdin) );
method = io_reqmeth( IOL_NOSEEK | IOL_MMAP ); // not implemented yet
switch (method) {
case IOL_NOSEEK:
code that uses ig->readcb()
to read data goes here.
break;
case IOL_MMAP:
code that uses ig->readcb()
to read data goes here.
break;
}
io_glue_destroy(ig);
// and much more
=head1 DESCRIPTION
iolayer.c implements the basic functions to create and destroy io_glue
objects for Imager. The typical usage pattern for data sources is:
1. Create the source (io_new_fd)
2. Define how you want to get data from it (io_reqmeth)
3. read from it using the interface requested (ig->readdb, ig->mmapcb)
4. Close the source, which
shouldn't really close the underlying source. (io_glue DESTROY)
=head1 FUNCTION REFERENCE
Some of these functions are internal.
=over
=cut
*/
static void
i_io_init(io_glue *ig, int type, i_io_readp_t readcb, i_io_writep_t writecb,
i_io_seekp_t seekcb);
static ssize_t fd_read(io_glue *ig, void *buf, size_t count);
static ssize_t fd_write(io_glue *ig, const void *buf, size_t count);
static off_t fd_seek(io_glue *ig, off_t offset, int whence);
static int fd_close(io_glue *ig);
static ssize_t fd_size(io_glue *ig);
static const char *my_strerror(int err);
static void i_io_setup_buffer(io_glue *ig);
static void
i_io_start_write(io_glue *ig);
static int
i_io_read_fill(io_glue *ig, ssize_t needed);
static void
dump_data(unsigned char *start, unsigned char *end, int bias);
static ssize_t realseek_read(io_glue *igo, void *buf, size_t count);
static ssize_t realseek_write(io_glue *igo, const void *buf, size_t count);
static int realseek_close(io_glue *igo);
static off_t realseek_seek(io_glue *igo, off_t offset, int whence);
static void realseek_destroy(io_glue *igo);
static ssize_t buffer_read(io_glue *igo, void *buf, size_t count);
static ssize_t buffer_write(io_glue *ig, const void *buf, size_t count);
static int buffer_close(io_glue *ig);
static off_t buffer_seek(io_glue *igo, off_t offset, int whence);
static void buffer_destroy(io_glue *igo);
static io_blink*io_blink_new(void);
static void io_bchain_advance(io_ex_bchain *ieb);
static void io_destroy_bufchain(io_ex_bchain *ieb);
static ssize_t bufchain_read(io_glue *ig, void *buf, size_t count);
static ssize_t bufchain_write(io_glue *ig, const void *buf, size_t count);
static int bufchain_close(io_glue *ig);
static off_t bufchain_seek(io_glue *ig, off_t offset, int whence);
static void bufchain_destroy(io_glue *ig);
/*
* Methods for setting up data source
*/
/*
=item io_new_bufchain()
=order 10
=category I/O Layers
returns a new io_glue object that has the 'empty' source and but can
be written to and read from later (like a pseudo file).
=cut
*/
io_glue *
io_new_bufchain() {
io_glue *ig;
io_ex_bchain *ieb = mymalloc(sizeof(io_ex_bchain));
mm_log((1, "io_new_bufchain()\n"));
ig = mymalloc(sizeof(io_glue));
memset(ig, 0, sizeof(*ig));
i_io_init(ig, BUFCHAIN, bufchain_read, bufchain_write, bufchain_seek);
ieb->offset = 0;
ieb->length = 0;
ieb->cpos = 0;
ieb->gpos = 0;
ieb->tfill = 0;
ieb->head = io_blink_new();
ieb->cp = ieb->head;
ieb->tail = ieb->head;
ig->exdata = ieb;
ig->closecb = bufchain_close;
ig->destroycb = bufchain_destroy;
return ig;
}
/*
=item io_new_buffer(data, length)
=order 10
=category I/O Layers
Returns a new io_glue object that has the source defined as reading
from specified buffer. Note that the buffer is not copied.
data - buffer to read from
length - length of buffer
=cut
*/
io_glue *
io_new_buffer(const char *data, size_t len, i_io_closebufp_t closecb, void *closedata) {
io_buffer *ig;
mm_log((1, "io_new_buffer(data %p, len %ld, closecb %p, closedata %p)\n", data, (long)len, closecb, closedata));
ig = mymalloc(sizeof(io_buffer));
memset(ig, 0, sizeof(*ig));
i_io_init(&ig->base, BUFFER, buffer_read, buffer_write, buffer_seek);
ig->data = data;
ig->len = len;
ig->closecb = closecb;
ig->closedata = closedata;
ig->cpos = 0;
ig->base.closecb = buffer_close;
ig->base.destroycb = buffer_destroy;
return (io_glue *)ig;
}
/*
=item io_new_fd(fd)
=order 10
=category I/O Layers
returns a new io_glue object that has the source defined as reading
from specified file descriptor. Note that the the interface to receiving
data from the io_glue callbacks hasn't been done yet.
fd - file descriptor to read/write from
=cut
*/
io_glue *
io_new_fd(int fd) {
io_fdseek *ig;
mm_log((1, "io_new_fd(fd %d)\n", fd));
ig = mymalloc(sizeof(io_fdseek));
memset(ig, 0, sizeof(*ig));
i_io_init(&ig->base, FDSEEK, fd_read, fd_write, fd_seek);
ig->fd = fd;
ig->base.closecb = fd_close;
ig->base.sizecb = fd_size;
ig->base.destroycb = NULL;
mm_log((1, "(%p) <- io_new_fd\n", ig));
return (io_glue *)ig;
}
/*
=item io_new_cb(p, read_cb, write_cb, seek_cb, close_cb, destroy_cb)
=category I/O Layers
=order 10
Create a new I/O layer object that calls your supplied callbacks.
In general the callbacks should behave like the corresponding POSIX
primitives.
=over
=item *
C<read_cb>(p, buffer, length) should read up to C<length> bytes into
C<buffer> and return the number of bytes read. At end of file, return
0. On error, return -1.
=item *
C<write_cb>(p, buffer, length) should write up to C<length> bytes from
C<buffer> and return the number of bytes written. A return value <= 0
will be treated as an error.
=item *
C<seekcb>(p, offset, whence) should seek and return the new offset.
=item *
C<close_cb>(p) should return 0 on success, -1 on failure.
=item *
C<destroy_cb>(p) should release any memory specific to your callback
handlers.
=back
=cut
*/
io_glue *
io_new_cb(void *p, i_io_readl_t readcb, i_io_writel_t writecb,
i_io_seekl_t seekcb, i_io_closel_t closecb,
i_io_destroyl_t destroycb) {
io_cb *ig;
mm_log((1, "io_new_cb(p %p, readcb %p, writecb %p, seekcb %p, closecb %p, "
"destroycb %p)\n", p, readcb, writecb, seekcb, closecb, destroycb));
ig = mymalloc(sizeof(io_cb));
memset(ig, 0, sizeof(*ig));
i_io_init(&ig->base, CBSEEK, realseek_read, realseek_write, realseek_seek);
mm_log((1, "(%p) <- io_new_cb\n", ig));
ig->base.closecb = realseek_close;
ig->base.destroycb = realseek_destroy;
ig->p = p;
ig->readcb = readcb;
ig->writecb = writecb;
ig->seekcb = seekcb;
ig->closecb = closecb;
ig->destroycb = destroycb;
return (io_glue *)ig;
}
/*
=item io_slurp(ig, c)
=category I/O Layers
Takes the source that the io_glue is bound to and allocates space for
a return buffer and returns the entire content in a single buffer.
Note: This only works for io_glue objects created by
io_new_bufchain(). It is useful for saving to scalars and such.
ig - io_glue object
c - pointer to a pointer to where data should be copied to
char *data;
size_t size = io_slurp(ig, &data);
... do something with the data ...
myfree(data);
io_slurp() will abort the program if the supplied I/O layer is not
from io_new_bufchain().
=cut
*/
size_t
io_slurp(io_glue *ig, unsigned char **c) {
ssize_t rc;
off_t orgoff;
io_ex_bchain *ieb;
unsigned char *cc;
io_type inn = ig->type;
if ( inn != BUFCHAIN ) {
i_fatal(0, "io_slurp: called on a source that is not from a bufchain\n");
}
ieb = ig->exdata;
cc = *c = mymalloc( ieb->length );
orgoff = ieb->gpos;
bufchain_seek(ig, 0, SEEK_SET);
rc = bufchain_read(ig, cc, ieb->length);
if (rc != ieb->length)
i_fatal(1, "io_slurp: bufchain_read returned an incomplete read: rc = %d, request was %d\n", rc, ieb->length);
return rc;
}
/*
=item io_glue_destroy(ig)
=category I/O Layers
=order 90
=synopsis io_glue_destroy(ig);
Destroy an io_glue objects. Should clean up all related buffers.
ig - io_glue object to destroy.
=cut
*/
void
io_glue_destroy(io_glue *ig) {
mm_log((1, "io_glue_DESTROY(ig %p)\n", ig));
if (ig->destroycb)
ig->destroycb(ig);
if (ig->buffer)
myfree(ig->buffer);
myfree(ig);
}
/*
=item i_io_getc(ig)
=category I/O Layers
A macro to read a single byte from a buffered I/O glue object.
Returns EOF on failure, or a byte.
=cut
*/
int
i_io_getc_imp(io_glue *ig) {
if (ig->write_ptr)
return EOF;
if (ig->error || ig->buf_eof)
return EOF;
if (!ig->buffered) {
unsigned char buf;
ssize_t rc = i_io_raw_read(ig, &buf, 1);
if (rc > 0) {
return buf;
}
else if (rc == 0) {
ig->buf_eof = 1;
return EOF;
}
else {
ig->error = 1;
return EOF;
}
}
if (!ig->buffer)
i_io_setup_buffer(ig);
if (!ig->read_ptr || ig->read_ptr == ig->read_end) {
if (!i_io_read_fill(ig, 1))
return EOF;
}
return *(ig->read_ptr++);
}
/*
=item i_io_peekc(ig)
=category I/O Layers
Read the next character from the stream without advancing the stream.
On error or end of file, return EOF.
For unbuffered streams a single character buffer will be setup.
=cut
*/
int
i_io_peekc_imp(io_glue *ig) {
if (ig->write_ptr)
return EOF;
if (!ig->buffer)
i_io_setup_buffer(ig);
if (!ig->buffered) {
ssize_t rc = i_io_raw_read(ig, ig->buffer, 1);
if (rc > 0) {
ig->read_ptr = ig->buffer;
ig->read_end = ig->buffer + 1;
return *(ig->buffer);
}
else if (rc == 0) {
ig->buf_eof = 1;
return EOF;
}
else {
ig->error = 1;
return EOF;
}
}
if (!ig->read_ptr || ig->read_ptr == ig->read_end) {
if (ig->error || ig->buf_eof)
return EOF;
if (!i_io_read_fill(ig, 1))
return EOF;
}
return *(ig->read_ptr);
}
/*
=item i_io_peekn(ig, buffer, size)
=category I/O Layers
=synopsis ssize_t count = i_io_peekn(ig, buffer, sizeof(buffer));
Buffer at least C<size> (at most C<< ig->buf_size >> bytes of data
from the stream and return C<size> bytes of it to the caller in
C<buffer>.
This ignores the buffered state of the stream, and will always setup
buffering if needed.
If no C<type> parameter is provided to Imager::read() or
Imager::read_multi(), Imager will call C<i_io_peekn()> when probing
for the file format.
Returns -1 on error, 0 if there is no data before EOF, or the number
of bytes read into C<buffer>.
=cut
*/
ssize_t
i_io_peekn(io_glue *ig, void *buf, size_t size) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn(%p, %p, %d)\n", ig, buf, (int)size));
if (size == 0) {
i_push_error(0, "peekn size must be positive");
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() => -1 (zero size)\n"));
return -1;
}
if (ig->write_ptr) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() => -1 (write_ptr set)\n"));
return -1;
}
if (!ig->buffer)
i_io_setup_buffer(ig);
if ((!ig->read_ptr || size > ig->read_end - ig->read_ptr)
&& !(ig->buf_eof || ig->error)) {
i_io_read_fill(ig, size);
}
if (size > ig->read_end - ig->read_ptr)
size = ig->read_end - ig->read_ptr;
if (size)
memcpy(buf, ig->read_ptr, size);
else if (ig->buf_eof) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() => 0 (eof)\n"));
return 0;
}
else if (ig->error) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() => -1 (error)\n"));
return -1;
}
else {
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() - size 0 but not eof or error!\n"));
return -1;
}
IOL_DEB(fprintf(IOL_DEBs, "i_io_peekn() => %d\n", (int)size));
return size;
}
/*
=item i_io_putc(ig, c)
=category I/O Layers
Write a single character to the stream.
On success return c, on error returns EOF
=cut
*/
int
i_io_putc_imp(io_glue *ig, int c) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_putc_imp(%p, %d)\n", ig, c));
if (!ig->buffered) {
char buf = c;
ssize_t write_result;
int result = c;
if (ig->error)
return EOF;
write_result = i_io_raw_write(ig, &buf, 1);
if (write_result != 1) {
ig->error = 1;
result = EOF;
IOL_DEB(fprintf(IOL_DEBs, " unbuffered putc() failed, setting error mode\n"));
}
IOL_DEB(fprintf(IOL_DEBs, " unbuffered: result %d\n", result));
return result;
}
if (ig->read_ptr)
return EOF;
if (ig->error)
return EOF;
if (!ig->buffer)
i_io_setup_buffer(ig);
if (ig->write_ptr && ig->write_ptr == ig->write_end) {
if (!i_io_flush(ig))
return EOF;
}
i_io_start_write(ig);
*(ig->write_ptr)++ = c;
return (unsigned char)c;
}
/*
=item i_io_read(io, buffer, size)
=category I/O Layers
Read up to C<size> bytes from the stream C<io> into C<buffer>.
Returns the number of bytes read. Returns 0 on end of file. Returns
-1 on error.
=cut
*/
ssize_t
i_io_read(io_glue *ig, void *buf, size_t size) {
unsigned char *pbuf = buf;
ssize_t read_total = 0;
IOL_DEB(fprintf(IOL_DEBs, "i_io_read(%p, %p, %u)\n", ig, buf, (unsigned)size));
if (ig->write_ptr) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_read() => -1 (write_ptr set)\n"));
return -1;
}
if (!ig->buffer && ig->buffered)
i_io_setup_buffer(ig);
if (ig->read_ptr && ig->read_ptr < ig->read_end) {
size_t alloc = ig->read_end - ig->read_ptr;
if (alloc > size)
alloc = size;
memcpy(pbuf, ig->read_ptr, alloc);
ig->read_ptr += alloc;
pbuf += alloc;
size -= alloc;
read_total += alloc;
}
if (size > 0 && !(ig->error || ig->buf_eof)) {
if (!ig->buffered || size > ig->buf_size) {
ssize_t rc;
while (size > 0 && (rc = i_io_raw_read(ig, pbuf, size)) > 0) {
size -= rc;
pbuf += rc;
read_total += rc;
}
IOL_DEB(fprintf(IOL_DEBs, "i_io_read() => %d (raw read)\n", (int)read_total));
if (rc < 0)
ig->error = 1;
else if (rc == 0)
ig->buf_eof = 1;
if (!read_total)
return rc;
}
else {
if (i_io_read_fill(ig, size)) {
size_t alloc = ig->read_end - ig->read_ptr;
if (alloc > size)
alloc = size;
memcpy(pbuf, ig->read_ptr, alloc);
ig->read_ptr += alloc;
pbuf += alloc;
size -= alloc;
read_total += alloc;
}
else {
if (!read_total && ig->error) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_read() => -1 (fill failure)\n"));
return -1;
}
}
}
}
if (!read_total && ig->error)
read_total = -1;
IOL_DEB(fprintf(IOL_DEBs, "i_io_read() => %d\n", (int)read_total));
return read_total;
}
/*
=item i_io_write(io, buffer, size)
=category I/O Layers
=synopsis ssize_t result = i_io_write(io, buffer, size)
Write to the given I/O stream.
Returns the number of bytes written.
=cut
*/
ssize_t
i_io_write(io_glue *ig, const void *buf, size_t size) {
const unsigned char *pbuf = buf;
size_t write_count = 0;
IOL_DEB(fprintf(IOL_DEBs, "i_io_write(%p, %p, %u)\n", ig, buf, (unsigned)size));
if (!ig->buffered) {
ssize_t result;
if (ig->error) {
IOL_DEB(fprintf(IOL_DEBs, " unbuffered, error state\n"));
return -1;
}
result = i_io_raw_write(ig, buf, size);
if (result != size) {
ig->error = 1;
IOL_DEB(fprintf(IOL_DEBs, " unbuffered, setting error flag\n"));
}
IOL_DEB(fprintf(IOL_DEBs, " unbuffered, result: %d\n", (int)result));
return result;
}
if (ig->read_ptr) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_write() => -1 (read_ptr set)\n"));
return -1;
}
if (ig->error) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_write() => -1 (error)\n"));
return -1;
}
if (!ig->buffer)
i_io_setup_buffer(ig);
if (!ig->write_ptr)
i_io_start_write(ig);
if (ig->write_ptr && ig->write_ptr + size <= ig->write_end) {
size_t alloc = ig->write_end - ig->write_ptr;
if (alloc > size)
alloc = size;
memcpy(ig->write_ptr, pbuf, alloc);
write_count += alloc;
size -= alloc;
pbuf += alloc;
ig->write_ptr += alloc;
}
if (size) {
if (!i_io_flush(ig)) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_write() => %d (i_io_flush failure)\n", (int)write_count));
return write_count ? write_count : -1;
}
i_io_start_write(ig);
if (size > ig->buf_size) {
ssize_t rc;
while (size > 0 && (rc = i_io_raw_write(ig, pbuf, size)) > 0) {
write_count += rc;
pbuf += rc;
size -= rc;
}
if (rc <= 0) {
ig->error = 1;
if (!write_count) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_write() => -1 (direct write failure)\n"));
return -1;
}
}
}
else {
memcpy(ig->write_ptr, pbuf, size);
write_count += size;
ig->write_ptr += size;
}
}
IOL_DEB(fprintf(IOL_DEBs, "i_io_write() => %d\n", (int)write_count));
return write_count;
}
/*
=item i_io_seek(io, offset, whence)
=category I/O Layers
Seek within the stream.
Acts like perl's seek.
=cut
*/
off_t
i_io_seek(io_glue *ig, off_t offset, int whence) {
off_t new_off;
IOL_DEB(fprintf(IOL_DEBs, "i_io_seek(%p, %ld, %d)\n", ig, (long)offset, whence));
if (ig->write_ptr && ig->write_ptr != ig->write_end) {
if (!i_io_flush(ig))
return (off_t)(-1);
}
if (whence == SEEK_CUR && ig->read_ptr && ig->read_ptr != ig->read_end)
offset -= ig->read_end - ig->read_ptr;
ig->read_ptr = ig->read_end = NULL;
ig->write_ptr = ig->write_end = NULL;
ig->error = 0;
ig->buf_eof = 0;
new_off = i_io_raw_seek(ig, offset, whence);
if (new_off < 0)
ig->error = 1;
IOL_DEB(fprintf(IOL_DEBs, "i_io_seek() => %ld\n", (long)new_off));
return new_off;
}
/*
=item i_io_flush(io)
=category I/O Layers
Flush any buffered output.
Returns true on success,
=cut
*/
int
i_io_flush(io_glue *ig) {
unsigned char *bufp;
IOL_DEB(fprintf(IOL_DEBs, "i_io_flush(%p)\n", ig));
if (ig->error) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_flush() => 0 (error set)\n", ig));
return 0;
}
/* nothing to do */
if (!ig->write_ptr)
return 1;
bufp = ig->buffer;
while (bufp < ig->write_ptr) {
ssize_t rc = i_io_raw_write(ig, bufp, ig->write_ptr - bufp);
if (rc <= 0) {
IOL_DEB(fprintf(IOL_DEBs, "i_io_flush() => 0 (write error)\n", ig));
ig->error = 1;
return 0;
}
bufp += rc;
}
ig->write_ptr = ig->write_end = NULL;
IOL_DEB(fprintf(IOL_DEBs, "i_io_flush() => 1\n", ig));
return 1;
}
/*
=item i_io_close(io)
=category I/O Layers
Flush any pending output and perform the close action for the stream.
Returns 0 on success.
=cut
*/
int
i_io_close(io_glue *ig) {
int result = 0;
IOL_DEB(fprintf(IOL_DEBs, "i_io_close(%p)\n", ig));
if (ig->error)
result = -1;
if (ig->write_ptr && !i_io_flush(ig))
result = -1;
if (i_io_raw_close(ig))
result = -1;
IOL_DEB(fprintf(IOL_DEBs, "i_io_close() => %d\n", result));
return result;
}
/*
=item i_io_gets(ig, buffer, size, end_of_line)
=category I/O Layers
=synopsis char buffer[BUFSIZ]
=synopsis ssize_t len = i_io_gets(buffer, sizeof(buffer), '\n');
Read up to C<size>-1 bytes from the stream C<ig> into C<buffer>.
If the byte C<end_of_line> is seen then no further bytes will be read.
Returns the number of bytes read.
Always C<NUL> terminates the buffer.
=cut
*/
ssize_t
i_io_gets(io_glue *ig, char *buffer, size_t size, int eol) {
ssize_t read_count = 0;
if (size < 2)
return 0;
--size; /* room for nul */
while (size > 0) {
int byte = i_io_getc(ig);
if (byte == EOF)
break;
*buffer++ = byte;
++read_count;
if (byte == eol)
break;
--size;
}
*buffer++ = '\0';
return read_count;
}
/*
=item i_io_init(ig, readcb, writecb, seekcb)
Do common initialization for io_glue objects.
=cut
*/
static void
i_io_init(io_glue *ig, int type, i_io_readp_t readcb, i_io_writep_t writecb,
i_io_seekp_t seekcb) {
ig->type = type;
ig->exdata = NULL;
ig->readcb = readcb;
ig->writecb = writecb;
ig->seekcb = seekcb;
ig->closecb = NULL;
ig->sizecb = NULL;
ig->destroycb = NULL;
ig->buffer = NULL;
ig->read_ptr = NULL;
ig->read_end = NULL;
ig->write_ptr = NULL;
ig->write_end = NULL;
ig->buf_size = IO_BUF_SIZE;
ig->buf_eof = 0;
ig->error = 0;
ig->buffered = 1;
}
/*
=item i_io_set_buffered(io, buffered)