[wip] add read and write
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parent
4f610340f5
commit
87f3239c52
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@ -3,6 +3,8 @@
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#include <stdio.h>
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#include <unistd.h>
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#include "config.h"
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#include "color.h"
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@ -15,8 +17,10 @@
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#if ENABLE_STDOUT == 1
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#define pr_stdout(...) { printf(__VA_ARGS__); }
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#define write_stdout(data, size) { write(1, (data), (size)); }
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#else
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#define pr_stdout(...) {}
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#define write_stdout(data, size) {}
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#endif
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306
src/fs.c
306
src/fs.c
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@ -587,6 +587,312 @@ int fs_open(void *d)
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return 0;
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}
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int fs_seek(void *d)
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{
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int fd = ((int *) d)[0];
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int offset = ((int *) d)[1];
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if (!fs_file_descriptions[fd].inode) {
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pr_err("fd %d is not open\n", fd);
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return 0;
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}
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struct fs_inode f;
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read_block(fs_file_descriptions[fd].inode, (void *) &f);
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if (offset > f.size) {
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pr_err("offset is larger than file (%d > %d)\n", offset, f.size);
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return 0;
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}
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pr("Moving rw_offset of fd %d: %d -> %d\n",
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fd, fs_file_descriptions[fd].rw_offset, offset);
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fs_file_descriptions[fd].rw_offset = offset;
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return 0;
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}
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static void read_fd_block(unsigned int fd, unsigned int block_index, unsigned char *buf)
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{
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struct fs_inode f;
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read_block(fs_file_descriptions[fd].inode, (void *) &f);
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if (block_index < BLOCK_ADDRESSES_PER_INODE) {
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if (f.blocks[block_index])
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read_block(f.blocks[block_index], (void *) buf);
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else
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memset(buf, 0, FS_BLOCK_SIZE);
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} else {
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int ext_no = (block_index - BLOCK_ADDRESSES_PER_INODE) / BLOCK_ADDRESSES_PER_INODE_EXTENSION;
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int ext_offset = (block_index - BLOCK_ADDRESSES_PER_INODE) % BLOCK_ADDRESSES_PER_INODE_EXTENSION;
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unsigned int target_extension_address;
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unsigned int i;
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// seek to target extension address
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for (
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target_extension_address = f.next_extension, i = 0;
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(i < ext_no) && target_extension_address;
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i++
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) {
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struct fs_inode_extension ext;
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read_block(target_extension_address, (void *) &ext);
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target_extension_address = ext.next_extension;
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}
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if (!target_extension_address) {
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memset(buf, 0, FS_BLOCK_SIZE);
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} else {
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struct fs_inode_extension ext;
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read_block(target_extension_address, (void *) &ext);
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if (!ext.blocks[ext_offset])
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memset(buf, 0, FS_BLOCK_SIZE);
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else
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read_block(ext.blocks[ext_offset], (void *) buf);
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}
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}
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}
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static int write_fd_block(unsigned int fd, unsigned int block_index, unsigned char *buf)
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{
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struct fs_inode f;
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read_block(fs_file_descriptions[fd].inode, (void *) &f);
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if (block_index < BLOCK_ADDRESSES_PER_INODE) {
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if (!f.blocks[block_index]) {
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int new_block = find_free_block();
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if (!new_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for writing file data\n",
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fd, block_index);
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return -1;
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}
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mark_used(new_block);
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f.blocks[block_index] = new_block;
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write_block(fs_file_descriptions[fd].inode, (void *) &f);
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}
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write_block(f.blocks[block_index], (void *) buf);
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} else {
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int ext_no = (block_index - BLOCK_ADDRESSES_PER_INODE) / BLOCK_ADDRESSES_PER_INODE_EXTENSION;
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int ext_offset = (block_index - BLOCK_ADDRESSES_PER_INODE) % BLOCK_ADDRESSES_PER_INODE_EXTENSION;
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// treat switch from base inode to inode extension as special case
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if (!f.next_extension) {
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int new_block = find_free_block();
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if (!new_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for inode extension\n",
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fd, block_index);
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return -1;
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}
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mark_used(new_block);
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struct fs_inode_extension ext;
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memset(&ext, 0, sizeof(struct fs_inode_extension));
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f.next_extension = new_block;
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write_block(fs_file_descriptions[fd].inode, (void *) &f);
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}
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unsigned int target_extension_address;
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unsigned int previous_extension_address = f.next_extension;
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unsigned int i;
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// seek to target extension address
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for (
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target_extension_address = previous_extension_address, i = 0;
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(i < ext_no);
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i++
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) {
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if (!target_extension_address) {
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int new_block = find_free_block();
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if (!new_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for inode extension\n",
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fd, block_index);
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return -1;
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}
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mark_used(new_block);
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// updating previous inode extension
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struct fs_inode_extension prev_ext;
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read_block(previous_extension_address, (void *) &prev_ext); // read
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prev_ext.next_extension = new_block; // modify
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write_block(previous_extension_address, (void *) &prev_ext); // write
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// writing new inode extension
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struct fs_inode_extension ext;
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memset(&ext, 0, sizeof(struct fs_inode_extension));
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write_block(target_extension_address, (void *) &ext);
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}
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struct fs_inode_extension ext;
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read_block(target_extension_address, (void *) &ext);
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previous_extension_address = target_extension_address;
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target_extension_address = ext.next_extension;
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}
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if (!target_extension_address) {
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int new_block = find_free_block();
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if (!new_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for inode extension\n",
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fd, block_index);
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return -1;
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}
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struct fs_inode_extension prev_ext;
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read_block(previous_extension_address, (void *) &prev_ext); // read
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prev_ext.next_extension = new_block; // modify
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write_block(previous_extension_address, (void *) &prev_ext); // write
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int new_data_block = find_free_block();
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if (!new_data_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for data\n",
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fd, block_index);
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return -1;
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}
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mark_used(new_block);
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mark_used(new_data_block);
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// writing new inode extension
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struct fs_inode_extension ext;
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memset(&ext, 0, sizeof(struct fs_inode_extension));
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ext.blocks[ext_offset] = new_data_block;
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write_block(target_extension_address, (void *) &ext);
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// writing new data block
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write_block(new_data_block, (void *) buf);
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} else {
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struct fs_inode_extension ext;
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read_block(target_extension_address, (void *) &ext);
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if (!ext.blocks[ext_offset]) {
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int new_data_block = find_free_block();
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if (!new_data_block) {
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pr_err("failed to write to fd=%d block=%d: can't allocate block for data\n",
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fd, block_index);
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return -1;
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}
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mark_used(new_data_block);
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ext.blocks[ext_offset] = new_data_block;
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write_block(target_extension_address, (void *) &ext);
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}
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write_block(ext.blocks[ext_offset], (void *) buf);
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}
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}
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}
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int fs_read(void *d)
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{
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int fd = ((int *) d)[0];
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int amount = ((int *) d)[1];
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if (!fs_file_descriptions[fd].inode) {
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pr_err("fd %d is not open\n", fd);
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return 0;
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}
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if (amount <= 0)
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return 0;
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struct fs_inode f;
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read_block(fs_file_descriptions[fd].inode, (void *) &f);
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if (fs_file_descriptions[fd].rw_offset + amount > f.size) {
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pr_err("can not read outside of a file (offset %d + amount %d > f.size %d)\n",
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fs_file_descriptions[fd].rw_offset, amount, f.size);
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return 0;
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}
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pr("Reading %d bytes from fd %d (offset %d)\n",
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amount, fd, fs_file_descriptions[fd].rw_offset);
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unsigned char *read_data = malloc(amount);
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unsigned int total_read_data_amount = 0;
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// read from first block
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unsigned char block_buffer[FS_BLOCK_SIZE];
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int block_index = fs_file_descriptions[fd].rw_offset / FS_BLOCK_SIZE;
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int block_offset = fs_file_descriptions[fd].rw_offset % FS_BLOCK_SIZE;
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read_fd_block(fd, block_index, block_buffer);
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if (block_offset + amount <= FS_BLOCK_SIZE) {
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memcpy(read_data, &(block_buffer[block_offset]), amount);
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goto print_read_data;
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} else {
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memcpy(read_data, &(block_buffer[block_offset]), FS_BLOCK_SIZE - block_offset);
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total_read_data_amount += FS_BLOCK_SIZE - block_offset;
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}
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// read from all next blocks
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while (amount - total_read_data_amount > 0) {
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block_index++;
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read_fd_block(fd, block_index, block_buffer);
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int bytes_to_read = (amount - total_read_data_amount > FS_BLOCK_SIZE)
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? FS_BLOCK_SIZE : amount - total_read_data_amount;
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memcpy(&(read_data[total_read_data_amount]), block_buffer, bytes_to_read);
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total_read_data_amount += bytes_to_read;
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}
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print_read_data:
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pr("Updating fd %d offset: %d -> %d\n",
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fd, fs_file_descriptions[fd].rw_offset, fs_file_descriptions[fd].rw_offset+amount);
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fs_file_descriptions[fd].rw_offset += amount;
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write_stdout(read_data, amount);
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pr_stdout("\n");
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free(read_data);
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return 0;
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}
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int fs_write(void *d)
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{
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int fd = ((int *) d)[0];
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char *str = *((char **) d+4);
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int str_len = strlen(str);
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if (!fs_file_descriptions[fd].inode) {
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pr_err("fd %d is not open\n", fd);
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return 0;
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}
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if (str_len == 0)
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return 0;
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int block_index = fs_file_descriptions[fd].rw_offset / FS_BLOCK_SIZE;
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int block_offset = fs_file_descriptions[fd].rw_offset % FS_BLOCK_SIZE;
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unsigned char data_buffer[FS_BLOCK_SIZE];
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if (block_offset + str_len <= FS_BLOCK_SIZE) {
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read_fd_block(fd, block_index, data_buffer);
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memcpy(&(data_buffer[block_offset]), str, str_len);
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write_fd_block(fd, block_index, data_buffer);
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} else {
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read_fd_block(fd, block_index, data_buffer);
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memcpy(&(data_buffer[block_offset]), str, FS_BLOCK_SIZE - block_offset);
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write_fd_block(fd, block_index, data_buffer);
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read_fd_block(fd, block_index+1, data_buffer);
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memcpy(data_buffer, &(str[FS_BLOCK_SIZE - block_offset]), str_len - block_offset);
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write_fd_block(fd, block_index+1, data_buffer);
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}
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pr("Moving fd %d offset: %d -> %d\n",
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fd, fs_file_descriptions[fd].rw_offset, fs_file_descriptions[fd].rw_offset + str_len);
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fs_file_descriptions[fd].rw_offset += str_len;
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return 0;
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}
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int fs_close(void *d)
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{
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int fd = *((int *) d);
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