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@inactive123
inactive123 committed Nov 25, 2017
1 parent ac651b7 commit 395e84e
Showing 1 changed file with 108 additions and 96 deletions.
204 changes: 108 additions & 96 deletions libretro-common/file/nbio/nbio_linux.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,155 +11,167 @@
#include <sys/syscall.h>
#include <linux/aio_abi.h>

/* there's also a Unix AIO thingy, but it's not in glibc and we don't want more dependencies */
struct nbio_t
{
int fd;
bool busy;

aio_context_t ctx;
struct iocb cb;

void* ptr;
size_t len;
};


/* there's also a Unix AIO thingy, but it's not in glibc
* and we don't want more dependencies */

static int io_setup(unsigned nr, aio_context_t * ctxp)
{
return syscall(__NR_io_setup, nr, ctxp);
return syscall(__NR_io_setup, nr, ctxp);
}

static int io_destroy(aio_context_t ctx)
{
return syscall(__NR_io_destroy, ctx);
return syscall(__NR_io_destroy, ctx);
}

static int io_submit(aio_context_t ctx, long nr, struct iocb ** cbp)
{
return syscall(__NR_io_submit, ctx, nr, cbp);
return syscall(__NR_io_submit, ctx, nr, cbp);
}

static int io_cancel(aio_context_t ctx, struct iocb * iocb, struct io_event * result)
{
return syscall(__NR_io_cancel, ctx, iocb, result);
return syscall(__NR_io_cancel, ctx, iocb, result);
}

static int io_getevents(aio_context_t ctx, long min_nr, long nr,
struct io_event * events, struct timespec * timeout)
struct io_event * events, struct timespec * timeout)
{
return syscall(__NR_io_getevents, ctx, min_nr, nr, events, timeout);
return syscall(__NR_io_getevents, ctx, min_nr, nr, events, timeout);
}

struct nbio_t
{
int fd;
bool busy;

aio_context_t ctx;
struct iocb cb;

void* ptr;
size_t len;
};

struct nbio_t* nbio_open(const char * filename, unsigned mode)
{
static const int o_flags[] = { O_RDONLY, O_RDWR|O_CREAT|O_TRUNC, O_RDWR, O_RDONLY, O_RDWR|O_CREAT|O_TRUNC };
aio_context_t ctx = 0;
struct nbio_t* handle;
int fd;
fd = open(filename, o_flags[mode]|O_CLOEXEC, 0644);
if (fd < 0) return NULL;
if (io_setup(128, &ctx) < 0)
{
close(fd);
return NULL;
}
handle = malloc(sizeof(struct nbio_t));
handle->fd = fd;
handle->ctx = ctx;
handle->len = lseek(fd, 0, SEEK_END);
handle->ptr = malloc(handle->len);
handle->busy = false;
return handle;
static const int o_flags[] = { O_RDONLY, O_RDWR|O_CREAT|O_TRUNC, O_RDWR, O_RDONLY, O_RDWR|O_CREAT|O_TRUNC };

aio_context_t ctx = 0;
struct nbio_t* handle = NULL;
int fd = open(filename, o_flags[mode]|O_CLOEXEC, 0644);
if (fd < 0)
return NULL;

if (io_setup(128, &ctx) < 0)
{
close(fd);
return NULL;
}

handle = malloc(sizeof(struct nbio_t));
handle->fd = fd;
handle->ctx = ctx;
handle->len = lseek(fd, 0, SEEK_END);
handle->ptr = malloc(handle->len);
handle->busy = false;

return handle;
}

static void nbio_begin_op(struct nbio_t* handle, uint16_t op)
{
struct iocb * cbp = &handle->cb;
memset(&handle->cb, 0, sizeof(handle->cb));
handle->cb.aio_fildes = handle->fd;
handle->cb.aio_lio_opcode = op;
handle->cb.aio_buf = (uint64_t)(uintptr_t)handle->ptr;
handle->cb.aio_offset = 0;
handle->cb.aio_nbytes = handle->len;
if (io_submit(handle->ctx, 1, &cbp) != 1)
{
puts("ERROR - io_submit() failed");
abort();
}
handle->busy = true;
struct iocb * cbp = &handle->cb;

memset(&handle->cb, 0, sizeof(handle->cb));
handle->cb.aio_fildes = handle->fd;
handle->cb.aio_lio_opcode = op;

handle->cb.aio_buf = (uint64_t)(uintptr_t)handle->ptr;
handle->cb.aio_offset = 0;
handle->cb.aio_nbytes = handle->len;

if (io_submit(handle->ctx, 1, &cbp) != 1)
{
puts("ERROR - io_submit() failed");
abort();
}

handle->busy = true;
}

void nbio_begin_read(struct nbio_t* handle)
{
nbio_begin_op(handle, IOCB_CMD_PREAD);
nbio_begin_op(handle, IOCB_CMD_PREAD);
}

void nbio_begin_write(struct nbio_t* handle)
{
nbio_begin_op(handle, IOCB_CMD_PWRITE);
nbio_begin_op(handle, IOCB_CMD_PWRITE);
}

bool nbio_iterate(struct nbio_t* handle)
{
if (handle->busy)
{
struct io_event ev;
if (io_getevents(handle->ctx, 0, 1, &ev, NULL) == 1)
{
handle->busy = false;
}
}
return !handle->busy;
if (handle->busy)
{
struct io_event ev;
if (io_getevents(handle->ctx, 0, 1, &ev, NULL) == 1)
handle->busy = false;
}
return !handle->busy;
}

void nbio_resize(struct nbio_t* handle, size_t len)
{
if (len < handle->len)
{
/* this works perfectly fine if this check is removed, but it won't work on other nbio implementations */
/* therefore, it's blocked so nobody accidentally relies on it */
puts("ERROR - attempted file shrink operation, not implemented");
abort();
}
if (ftruncate(handle->fd, len) != 0)
{
puts("ERROR - couldn't resize file (ftruncate)");
abort(); /* this one returns void and I can't find any other way for it to report failure */
}
handle->ptr = realloc(handle->ptr, len);
handle->len = len;
if (len < handle->len)
{
/* this works perfectly fine if this check is removed, but it
* won't work on other nbio implementations */
/* therefore, it's blocked so nobody accidentally relies on it */
puts("ERROR - attempted file shrink operation, not implemented");
abort();
}
if (ftruncate(handle->fd, len) != 0)
{
puts("ERROR - couldn't resize file (ftruncate)");
abort(); /* this one returns void and I can't find any other way
for it to report failure */
}
handle->ptr = realloc(handle->ptr, len);
handle->len = len;
}

void* nbio_get_ptr(struct nbio_t* handle, size_t* len)
{
if (len) *len = handle->len;
if (!handle->busy) return handle->ptr;
else return NULL;
if (!handle)
return NULL;
if (len)
*len = handle->len;
if (!handle->busy)
return handle->ptr;
return NULL;
}

void nbio_cancel(struct nbio_t* handle)
{
if (handle->busy)
{
struct io_event ev;
io_cancel(handle->ctx, &handle->cb, &ev);
handle->busy = false;
}
if (!handle)
return;

if (handle->busy)
{
struct io_event ev;
io_cancel(handle->ctx, &handle->cb, &ev);
handle->busy = false;
}
}

void nbio_free(struct nbio_t* handle)
{
io_destroy(handle->ctx);
close(handle->fd);
free(handle->ptr);
free(handle);
if (!handle)
return;

io_destroy(handle->ctx);
close(handle->fd);
free(handle->ptr);
free(handle);
}

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