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Make read_user() non-blocking, and add select() call.

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This commit is contained in:
Michael Brown
2007-08-04 01:22:52 +01:00
parent 218651e125
commit 07f84566d5
3 changed files with 151 additions and 50 deletions
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94
src/core/posix_io.c
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@@ -60,12 +60,6 @@ struct posix_file {
/** List of open files */
static LIST_HEAD ( posix_files );
/** Minimum file descriptor that will ever be allocated */
#define POSIX_FD_MIN ( 1 )
/** Maximum file descriptor that will ever be allocated */
#define POSIX_FD_MAX ( 255 )
/**
* Free open file
*
@@ -251,6 +245,38 @@ int open ( const char *uri_string ) {
return rc;
}
/**
* Check file descriptors for readiness
*
* @v readfds File descriptors to check
* @v wait Wait until data is ready
* @ret nready Number of ready file descriptors
*/
int select ( fd_set *readfds, int wait ) {
struct posix_file *file;
int fd;
do {
for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) {
if ( ! FD_ISSET ( fd, readfds ) )
continue;
file = posix_fd_to_file ( fd );
if ( ! file )
return -EBADF;
if ( ( list_empty ( &file->data ) ) &&
( file->rc != -EINPROGRESS ) )
continue;
/* Data is available or status has changed */
FD_ZERO ( readfds );
FD_SET ( fd, readfds );
return 1;
}
step();
} while ( wait );
return 0;
}
/**
* Read data from file
*
@@ -258,47 +284,45 @@ int open ( const char *uri_string ) {
* @v offset Starting offset within data buffer
* @v len Maximum length to read
* @ret len Actual length read, or negative error number
*
* This call is non-blocking; if no data is available to read then
* -EWOULDBLOCK will be returned.
*/
ssize_t read_user ( int fd, userptr_t buffer, off_t offset, size_t max_len ) {
struct posix_file *file;
struct io_buffer *iobuf;
size_t frag_len;
ssize_t len = 0;
size_t len;
/* Identify file */
file = posix_fd_to_file ( fd );
if ( ! file )
return -EBADF;
while ( 1 ) {
/* Try to fetch more data if none available */
if ( list_empty ( &file->data ) )
step();
/* Dequeue at most one received I/O buffer into user buffer */
list_for_each_entry ( iobuf, &file->data, list ) {
frag_len = iob_len ( iobuf );
if ( frag_len > max_len )
frag_len = max_len;
copy_to_user ( buffer, offset, iobuf->data,
frag_len );
iob_pull ( iobuf, frag_len );
if ( ! iob_len ( iobuf ) ) {
list_del ( &iobuf-> list );
free_iob ( iobuf );
}
file->pos += frag_len;
len += frag_len;
offset += frag_len;
max_len -= frag_len;
break;
/* Try to fetch more data if none available */
if ( list_empty ( &file->data ) )
step();
/* Dequeue at most one received I/O buffer into user buffer */
list_for_each_entry ( iobuf, &file->data, list ) {
len = iob_len ( iobuf );
if ( len > max_len )
len = max_len;
copy_to_user ( buffer, offset, iobuf->data, len );
iob_pull ( iobuf, len );
if ( ! iob_len ( iobuf ) ) {
list_del ( &iobuf->list );
free_iob ( iobuf );
}
/* If buffer is full, return */
if ( ! max_len )
return len;
/* If file has completed, return */
if ( file->rc != -EINPROGRESS )
return ( file->rc ? file->rc : len );
file->pos += len;
return len;
}
/* If file has completed, return (after returning all data) */
if ( file->rc != -EINPROGRESS )
return file->rc;
/* No data ready and file still in progress; return -WOULDBLOCK */
return -EWOULDBLOCK;
}
/**