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ef5e4526dcc5e0ad8a33ededb031b55ec1fb604e
rtems/cpukit/libfs/src/imfs/memfile.c
Alex Ivanov ef5e4526dc libfs: Doxygen Enhancement Task #1
2012-12-20 09:45:31 -06:00

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/**
* @file
*
* @brief IMFS Memory File Handlers
* @ingroup IMFS
*/
/*
* COPYRIGHT (c) 1989-2010.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include "imfs.h"
#include <stdlib.h>
#include <string.h>
#define MEMFILE_STATIC
/*
* Prototypes of private routines
*/
MEMFILE_STATIC int IMFS_memfile_extend(
IMFS_jnode_t *the_jnode,
bool zero_fill,
off_t new_length
);
MEMFILE_STATIC int IMFS_memfile_addblock(
IMFS_jnode_t *the_jnode,
unsigned int block
);
MEMFILE_STATIC int IMFS_memfile_remove_block(
IMFS_jnode_t *the_jnode,
unsigned int block
);
MEMFILE_STATIC block_p *IMFS_memfile_get_block_pointer(
IMFS_jnode_t *the_jnode,
unsigned int block,
int malloc_it
);
MEMFILE_STATIC ssize_t IMFS_memfile_read(
IMFS_jnode_t *the_jnode,
off_t start,
unsigned char *destination,
unsigned int length
);
ssize_t IMFS_memfile_write( /* cannot be static as used in imfs_fchmod.c */
IMFS_jnode_t *the_jnode,
off_t start,
const unsigned char *source,
unsigned int length
);
void *memfile_alloc_block(void);
void memfile_free_block(
void *memory
);
int memfile_open(
rtems_libio_t *iop,
const char *pathname,
int oflag,
mode_t mode
)
{
IMFS_jnode_t *the_jnode;
the_jnode = iop->pathinfo.node_access;
/*
* Perform 'copy on write' for linear files
*/
if ((iop->flags & LIBIO_FLAGS_WRITE)
&& (IMFS_type( the_jnode ) == IMFS_LINEAR_FILE)) {
uint32_t count = the_jnode->info.linearfile.size;
const unsigned char *buffer = the_jnode->info.linearfile.direct;
the_jnode->control = &IMFS_node_control_memfile;
the_jnode->info.file.size = 0;
the_jnode->info.file.indirect = 0;
the_jnode->info.file.doubly_indirect = 0;
the_jnode->info.file.triply_indirect = 0;
if ((count != 0)
&& (IMFS_memfile_write(the_jnode, 0, buffer, count) == -1))
return -1;
}
return 0;
}
ssize_t memfile_read(
rtems_libio_t *iop,
void *buffer,
size_t count
)
{
IMFS_jnode_t *the_jnode;
ssize_t status;
the_jnode = iop->pathinfo.node_access;
status = IMFS_memfile_read( the_jnode, iop->offset, buffer, count );
if ( status > 0 )
iop->offset += status;
return status;
}
ssize_t memfile_write(
rtems_libio_t *iop,
const void *buffer,
size_t count
)
{
IMFS_jnode_t *the_jnode;
ssize_t status;
the_jnode = iop->pathinfo.node_access;
if ((iop->flags & LIBIO_FLAGS_APPEND) != 0)
iop->offset = the_jnode->info.file.size;
status = IMFS_memfile_write( the_jnode, iop->offset, buffer, count );
if ( status > 0 )
iop->offset += status;
return status;
}
/*
* memfile_stat
*
* This IMFS_stat() can be used.
*/
int memfile_ftruncate(
rtems_libio_t *iop,
off_t length
)
{
IMFS_jnode_t *the_jnode;
the_jnode = iop->pathinfo.node_access;
/*
* POSIX 1003.1b does not specify what happens if you truncate a file
* and the new length is greater than the current size. We treat this
* as an extend operation.
*/
if ( length > the_jnode->info.file.size )
return IMFS_memfile_extend( the_jnode, true, length );
/*
* The in-memory files do not currently reclaim memory until the file is
* deleted. So we leave the previously allocated blocks in place for
* future use and just set the length.
*/
the_jnode->info.file.size = length;
IMFS_update_atime( the_jnode );
return 0;
}
/*
* IMFS_memfile_extend
*
* This routine insures that the in-memory file is of the length
* specified. If necessary, it will allocate memory blocks to
* extend the file.
*/
MEMFILE_STATIC int IMFS_memfile_extend(
IMFS_jnode_t *the_jnode,
bool zero_fill,
off_t new_length
)
{
unsigned int block;
unsigned int new_blocks;
unsigned int old_blocks;
unsigned int offset;
/*
* Perform internal consistency checks
*/
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE );
/*
* Verify new file size is supported
*/
if ( new_length >= IMFS_MEMFILE_MAXIMUM_SIZE )
rtems_set_errno_and_return_minus_one( EFBIG );
/*
* Verify new file size is actually larger than current size
*/
if ( new_length <= the_jnode->info.file.size )
return 0;
/*
* Calculate the number of range of blocks to allocate
*/
new_blocks = new_length / IMFS_MEMFILE_BYTES_PER_BLOCK;
old_blocks = the_jnode->info.file.size / IMFS_MEMFILE_BYTES_PER_BLOCK;
offset = the_jnode->info.file.size - old_blocks * IMFS_MEMFILE_BYTES_PER_BLOCK;
/*
* Now allocate each of those blocks.
*/
for ( block=old_blocks ; block<=new_blocks ; block++ ) {
if ( !IMFS_memfile_addblock( the_jnode, block ) ) {
if ( zero_fill ) {
size_t count = IMFS_MEMFILE_BYTES_PER_BLOCK - offset;
block_p *block_ptr =
IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
memset( &(*block_ptr) [offset], 0, count);
offset = 0;
}
} else {
for ( ; block>=old_blocks ; block-- ) {
IMFS_memfile_remove_block( the_jnode, block );
}
rtems_set_errno_and_return_minus_one( ENOSPC );
}
}
/*
* Set the new length of the file.
*/
the_jnode->info.file.size = new_length;
IMFS_update_ctime(the_jnode);
IMFS_update_mtime(the_jnode);
return 0;
}
/*
* IMFS_memfile_addblock
*
* This routine adds a single block to the specified in-memory file.
*/
MEMFILE_STATIC int IMFS_memfile_addblock(
IMFS_jnode_t *the_jnode,
unsigned int block
)
{
block_p memory;
block_p *block_entry_ptr;
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE );
/*
* Obtain the pointer for the specified block number
*/
block_entry_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 1 );
if ( *block_entry_ptr )
return 0;
/*
* There is no memory for this block number so allocate it.
*/
memory = memfile_alloc_block();
if ( !memory )
return 1;
*block_entry_ptr = memory;
return 0;
}
/*
* IMFS_memfile_remove_block
*
* This routine removes the specified block from the in-memory file.
*
* NOTE: This is a support routine and is called only to remove
* the last block or set of blocks in a file. Removing a
* block from the middle of a file would be exceptionally
* dangerous and the results unpredictable.
*/
MEMFILE_STATIC int IMFS_memfile_remove_block(
IMFS_jnode_t *the_jnode,
unsigned int block
)
{
block_p *block_ptr;
block_p ptr;
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
IMFS_assert( block_ptr );
ptr = *block_ptr;
*block_ptr = 0;
memfile_free_block( ptr );
return 1;
}
/*
* memfile_free_blocks_in_table
*
* This is a support routine for IMFS_memfile_remove. It frees all the
* blocks in one of the indirection tables.
*/
static void memfile_free_blocks_in_table(
block_p **block_table,
int entries
)
{
int i;
block_p *b;
/*
* Perform internal consistency checks
*/
IMFS_assert( block_table );
/*
* Now go through all the slots in the table and free the memory.
*/
b = *block_table;
for ( i=0 ; i<entries ; i++ ) {
if ( b[i] ) {
memfile_free_block( b[i] );
b[i] = 0;
}
}
/*
* Now that all the blocks in the block table are free, we can
* free the block table itself.
*/
memfile_free_block( *block_table );
*block_table = 0;
}
/*
* IMFS_memfile_remove
*
* This routine frees all memory associated with an in memory file.
*
* NOTE: This is an exceptionally conservative implementation.
* It will check EVERY pointer which is non-NULL and insure
* any child non-NULL pointers are freed. Optimistically, all that
* is necessary is to scan until a NULL pointer is found. There
* should be no allocated data past that point.
*
* In experimentation on the powerpc simulator, it was noted
* that using blocks which held 128 slots versus 16 slots made
* a significant difference in the performance of this routine.
*
* Regardless until the IMFS implementation is proven, it
* is better to stick to simple, easy to understand algorithms.
*/
IMFS_jnode_t *IMFS_memfile_remove(
IMFS_jnode_t *the_jnode
)
{
IMFS_memfile_t *info;
int i;
int j;
unsigned int to_free;
block_p *p;
/*
* Perform internal consistency checks
*/
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE );
/*
* Eventually this could be set smarter at each call to
* memfile_free_blocks_in_table to greatly speed this up.
*/
to_free = IMFS_MEMFILE_BLOCK_SLOTS;
/*
* Now start freeing blocks in this order:
* + indirect
* + doubly indirect
* + triply indirect
*/
info = &the_jnode->info.file;
if ( info->indirect ) {
memfile_free_blocks_in_table( &info->indirect, to_free );
}
if ( info->doubly_indirect ) {
for ( i=0 ; i<IMFS_MEMFILE_BLOCK_SLOTS ; i++ ) {
if ( info->doubly_indirect[i] ) {
memfile_free_blocks_in_table(
(block_p **)&info->doubly_indirect[i], to_free );
}
}
memfile_free_blocks_in_table( &info->doubly_indirect, to_free );
}
if ( info->triply_indirect ) {
for ( i=0 ; i<IMFS_MEMFILE_BLOCK_SLOTS ; i++ ) {
p = (block_p *) info->triply_indirect[i];
if ( !p ) /* ensure we have a valid pointer */
break;
for ( j=0 ; j<IMFS_MEMFILE_BLOCK_SLOTS ; j++ ) {
if ( p[j] ) {
memfile_free_blocks_in_table( (block_p **)&p[j], to_free);
}
}
memfile_free_blocks_in_table(
(block_p **)&info->triply_indirect[i], to_free );
}
memfile_free_blocks_in_table(
(block_p **)&info->triply_indirect, to_free );
}
return the_jnode;
}
/*
* IMFS_memfile_read
*
* This routine read from memory file pointed to by the_jnode into
* the specified data buffer specified by destination. The file
* is NOT extended. An offset greater than the length of the file
* is considered an error. Read from an offset for more bytes than
* are between the offset and the end of the file will result in
* reading the data between offset and the end of the file (truncated
* read).
*/
MEMFILE_STATIC ssize_t IMFS_memfile_read(
IMFS_jnode_t *the_jnode,
off_t start,
unsigned char *destination,
unsigned int length
)
{
block_p *block_ptr;
unsigned int block;
unsigned int my_length;
unsigned int to_copy = 0;
unsigned int last_byte;
unsigned int copied;
unsigned int start_offset;
unsigned char *dest;
dest = destination;
/*
* Perform internal consistency checks
*/
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE ||
IMFS_type( the_jnode ) == IMFS_LINEAR_FILE );
IMFS_assert( dest );
/*
* Linear files (as created from a tar file are easier to handle
* than block files).
*/
my_length = length;
if ( IMFS_type( the_jnode ) == IMFS_LINEAR_FILE ) {
unsigned char *file_ptr;
file_ptr = (unsigned char *)the_jnode->info.linearfile.direct;
if (my_length > (the_jnode->info.linearfile.size - start))
my_length = the_jnode->info.linearfile.size - start;
memcpy(dest, &file_ptr[start], my_length);
IMFS_update_atime( the_jnode );
return my_length;
}
/*
* If the last byte we are supposed to read is past the end of this
* in memory file, then shorten the length to read.
*/
last_byte = start + length;
if ( last_byte > the_jnode->info.file.size )
my_length = the_jnode->info.file.size - start;
copied = 0;
/*
* Three phases to the read:
* + possibly the last part of one block
* + all of zero of more blocks
* + possibly the first part of one block
*/
/*
* Phase 1: possibly the last part of one block
*/
start_offset = start % IMFS_MEMFILE_BYTES_PER_BLOCK;
block = start / IMFS_MEMFILE_BYTES_PER_BLOCK;
if ( start_offset ) {
to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK - start_offset;
if ( to_copy > my_length )
to_copy = my_length;
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
memcpy( dest, &(*block_ptr)[ start_offset ], to_copy );
dest += to_copy;
block++;
my_length -= to_copy;
copied += to_copy;
}
/*
* Phase 2: all of zero of more blocks
*/
to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK;
while ( my_length >= IMFS_MEMFILE_BYTES_PER_BLOCK ) {
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
memcpy( dest, &(*block_ptr)[ 0 ], to_copy );
dest += to_copy;
block++;
my_length -= to_copy;
copied += to_copy;
}
/*
* Phase 3: possibly the first part of one block
*/
IMFS_assert( my_length < IMFS_MEMFILE_BYTES_PER_BLOCK );
if ( my_length ) {
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
memcpy( dest, &(*block_ptr)[ 0 ], my_length );
copied += my_length;
}
IMFS_update_atime( the_jnode );
return copied;
}
/*
* IMFS_memfile_write
*
* This routine writes the specified data buffer into the in memory
* file pointed to by the_jnode. The file is extended as needed.
*/
MEMFILE_STATIC ssize_t IMFS_memfile_write(
IMFS_jnode_t *the_jnode,
off_t start,
const unsigned char *source,
unsigned int length
)
{
block_p *block_ptr;
unsigned int block;
int status;
unsigned int my_length;
unsigned int to_copy = 0;
unsigned int last_byte;
unsigned int start_offset;
int copied;
const unsigned char *src;
src = source;
/*
* Perform internal consistency checks
*/
IMFS_assert( source );
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE );
my_length = length;
/*
* If the last byte we are supposed to write is past the end of this
* in memory file, then extend the length.
*/
last_byte = start + my_length;
if ( last_byte > the_jnode->info.file.size ) {
bool zero_fill = start > the_jnode->info.file.size;
status = IMFS_memfile_extend( the_jnode, zero_fill, last_byte );
if ( status )
return status;
}
copied = 0;
/*
* Three phases to the write:
* + possibly the last part of one block
* + all of zero of more blocks
* + possibly the first part of one block
*/
/*
* Phase 1: possibly the last part of one block
*/
start_offset = start % IMFS_MEMFILE_BYTES_PER_BLOCK;
block = start / IMFS_MEMFILE_BYTES_PER_BLOCK;
if ( start_offset ) {
to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK - start_offset;
if ( to_copy > my_length )
to_copy = my_length;
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
#if 0
fprintf(
stderr,
"write %d at %d in %d: %*s\n",
to_copy,
start_offset,
block,
to_copy,
src
);
#endif
memcpy( &(*block_ptr)[ start_offset ], src, to_copy );
src += to_copy;
block++;
my_length -= to_copy;
copied += to_copy;
}
/*
* Phase 2: all of zero of more blocks
*/
to_copy = IMFS_MEMFILE_BYTES_PER_BLOCK;
while ( my_length >= IMFS_MEMFILE_BYTES_PER_BLOCK ) {
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
#if 0
fprintf(stdout, "write %d in %d: %*s\n", to_copy, block, to_copy, src );
#endif
memcpy( &(*block_ptr)[ 0 ], src, to_copy );
src += to_copy;
block++;
my_length -= to_copy;
copied += to_copy;
}
/*
* Phase 3: possibly the first part of one block
*/
IMFS_assert( my_length < IMFS_MEMFILE_BYTES_PER_BLOCK );
to_copy = my_length;
if ( my_length ) {
block_ptr = IMFS_memfile_get_block_pointer( the_jnode, block, 0 );
if ( !block_ptr )
return copied;
#if 0
fprintf(stdout, "write %d in %d: %*s\n", to_copy, block, to_copy, src );
#endif
memcpy( &(*block_ptr)[ 0 ], src, my_length );
my_length = 0;
copied += to_copy;
}
IMFS_mtime_ctime_update( the_jnode );
return copied;
}
/*
* IMFS_memfile_get_block_pointer
*
* This routine looks up the block pointer associated with the given block
* number. If that block has not been allocated and "malloc_it" is
* TRUE, then the block is allocated. Otherwise, it is an error.
*/
#if 0
block_p *IMFS_memfile_get_block_pointer_DEBUG(
IMFS_jnode_t *the_jnode,
unsigned int block,
int malloc_it
);
block_p *IMFS_memfile_get_block_pointer(
IMFS_jnode_t *the_jnode,
unsigned int block,
int malloc_it
)
{
block_p *p;
p = IMFS_memfile_get_block_pointer_DEBUG( the_jnode, block, malloc_it );
fprintf(stdout, "(%d -> %p) ", block, p );
return p;
}
block_p *IMFS_memfile_get_block_pointer_DEBUG(
#else
block_p *IMFS_memfile_get_block_pointer(
#endif
IMFS_jnode_t *the_jnode,
unsigned int block,
int malloc_it
)
{
unsigned int my_block;
IMFS_memfile_t *info;
unsigned int singly;
unsigned int doubly;
unsigned int triply;
block_p *p;
block_p *p1;
block_p *p2;
/*
* Perform internal consistency checks
*/
IMFS_assert( the_jnode );
IMFS_assert( IMFS_type( the_jnode ) == IMFS_MEMORY_FILE );
info = &the_jnode->info.file;
my_block = block;
/*
* Is the block number in the simple indirect portion?
*/
if ( my_block <= LAST_INDIRECT ) {
p = info->indirect;
if ( malloc_it ) {
if ( !p ) {
p = memfile_alloc_block();
if ( !p )
return 0;
info->indirect = p;
}
return &info->indirect[ my_block ];
}
if ( !p )
return 0;
return &info->indirect[ my_block ];
}
/*
* Is the block number in the doubly indirect portion?
*/
if ( my_block <= LAST_DOUBLY_INDIRECT ) {
my_block -= FIRST_DOUBLY_INDIRECT;
singly = my_block % IMFS_MEMFILE_BLOCK_SLOTS;
doubly = my_block / IMFS_MEMFILE_BLOCK_SLOTS;
p = info->doubly_indirect;
if ( malloc_it ) {
if ( !p ) {
p = memfile_alloc_block();
if ( !p )
return 0;
info->doubly_indirect = p;
}
p1 = (block_p *)p[ doubly ];
if ( !p1 ) {
p1 = memfile_alloc_block();
if ( !p1 )
return 0;
p[ doubly ] = (block_p) p1;
}
return (block_p *)&p1[ singly ];
}
if ( !p )
return 0;
p = (block_p *)p[ doubly ];
if ( !p )
return 0;
return (block_p *)&p[ singly ];
}
/*
* Is the block number in the triply indirect portion?
*/
if ( my_block <= LAST_TRIPLY_INDIRECT ) {
my_block -= FIRST_TRIPLY_INDIRECT;
singly = my_block % IMFS_MEMFILE_BLOCK_SLOTS;
doubly = my_block / IMFS_MEMFILE_BLOCK_SLOTS;
triply = doubly / IMFS_MEMFILE_BLOCK_SLOTS;
doubly %= IMFS_MEMFILE_BLOCK_SLOTS;
p = info->triply_indirect;
if ( malloc_it ) {
if ( !p ) {
p = memfile_alloc_block();
if ( !p )
return 0;
info->triply_indirect = p;
}
p1 = (block_p *) p[ triply ];
if ( !p1 ) {
p1 = memfile_alloc_block();
if ( !p1 )
return 0;
p[ triply ] = (block_p) p1;
}
p2 = (block_p *)p1[ doubly ];
if ( !p2 ) {
p2 = memfile_alloc_block();
if ( !p2 )
return 0;
p1[ doubly ] = (block_p) p2;
}
return (block_p *)&p2[ singly ];
}
if ( !p )
return 0;
p1 = (block_p *) p[ triply ];
if ( !p1 )
return 0;
p2 = (block_p *)p1[ doubly ];
if ( !p2 )
return 0;
return (block_p *)&p2[ singly ];
}
/*
* This means the requested block number is out of range.
*/
return 0;
}
/*
* memfile_alloc_block
*
* Allocate a block for an in-memory file.
*/
int memfile_blocks_allocated = 0;
void *memfile_alloc_block(void)
{
void *memory;
memory = (void *)calloc(1, IMFS_MEMFILE_BYTES_PER_BLOCK);
if ( memory )
memfile_blocks_allocated++;
return memory;
}
/*
* memfile_free_block
*
* Free a block from an in-memory file.
*/
void memfile_free_block(
void *memory
)
{
free(memory);
memfile_blocks_allocated--;
}
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