/* fs_read
* inputs: fd : file descriptor
* buf : buffer to write into
* nbytes: number of bytes to write
* outputs: -1 on failure
* otherwise, number of bytes read
* notes: Reads nbytes into a buffer given a file
* descriptor.
*/
int32_t fs_read(int32_t fd, void* buf, int32_t nbytes) {
dentry_t curr_dentry;
int32_t check;
int32_t inum;
int32_t readpos;
int32_t flent;
if(!buf){
return -1;
}
inum = pcb_loc[current_terminal]->file_desc[fd].inode_ptr; // we need to fix this because its a temp fa
readpos = pcb_loc[current_terminal]->file_desc[fd].file_pos;
flent = inode_length(inum);
inode_t* inode_ptr;
inode_ptr = (inode_t*)(&(boot[inum + 1]));
// verify file existence
check = read_dentry_by_index(inum, &curr_dentry);
if (check == -1){
return -1;
}
// read data into buffer
check = read_data(inum, readpos, buf, nbytes);
if(check == -1){
return -1;
}
//update file position
pcb_loc[current_terminal]->file_desc[fd].file_pos += check; // we need to fix this because its a temp fa
//returns number of read bytes
return check;
}
/* dir_read
* inputs: fd : file descriptor
* buf : buffer to write into
* nbytes: number of bytes to write
* outputs: -1 on failure
* 0 signfies that directory has been completely read
* otherwise, number of bytes read
* notes: Same as fs_read, except only file names are read
* into buffer
*/
int32_t dir_read(int32_t fd, void* buf, int32_t nbytes){
dentry_t curr_dentry;
int32_t check;
int32_t readpos;
if(!buf){
return -1;
}
readpos = pcb_loc[current_terminal]->file_desc[fd].file_pos;
check = read_dentry_by_index(readpos, &curr_dentry);
/* if either name is null, or file is not found, return 0
to signal that directory has finished reading*/
if(check == -1){
return 0;
}
if(curr_dentry.name[0] == '\0'){
return 0;
}
// make sure nbytes is size of string length
if(strlen((char *)curr_dentry.name) < nbytes){
nbytes = strlen((char *)curr_dentry.name);
}
if(nbytes>NAME_SIZE){
nbytes = NAME_SIZE;
}
memcpy(buf, &(curr_dentry.name), nbytes);
//update file position
readpos++;
//returns number of read bytes
pcb_loc[current_terminal]->file_desc[fd].file_pos = readpos;
return nbytes;
}
/*
* dir_read
* Description: read directory
* INPUTS:
int32_t fd -- file descriptor
void* buf -- buffer address
int32_t nbytes -- number of bytes
pcb_t* mypcb -- Process control block
* OUTPUTS: None
* RETURN: None
* SIDE EFFECTS: None
*/
extern int32_t dir_read(int32_t fd, void* buf, int32_t nbytes, pcb_t* mypcb)
{
uint32_t offset = mypcb->file_array[fd].file_position;
boot_block_t* bb = (boot_block_t*)mods_addrs;
uint32_t limit = bb->num_dir_entry;
dentry_t dentry;
static uint32_t read_dir_falg = 0;
if (read_dir_falg == 1)
{
read_dir_falg = 0;
return 0;
}
read_dentry_by_index(offset, &dentry);
offset++;
if (offset == limit)
{
offset %= limit;
read_dir_falg = 1;
}
mypcb->file_array[fd].file_position = offset;
uint32_t n = nbytes;
if (nbytes > FIVE_BITS)
n = FIVE_BITS;
// strncpy((int8_t *)buf, dentry.file_name, n);
// ((int8_t *)buf)[n+1] = '\n';
strcpy((int8_t *)buf, dentry.file_name);
return strlen((int8_t *)buf);
return n;
}
/*
* Function: dir_read
* Description: this functions outputs (into buf) the name of the file or directory specified in the
* directoryLoc file variable, which is then incremented (or returned to 0 if it passes the end)
* the inputs fd and nbytes are ignored.
* inputs: fd and nbytes are ignored
* outputs: buf is filled with a c string (not null terminated) containing the name of the file
* returns: number of bytes written (will be 0 if we've reached the end)
*/
int32_t dir_read (int32_t fd, void* buf, int32_t nbytes)
{
dentry_t dentry;
int i;
if (read_dentry_by_index(directoryLoc, &dentry) == 0)
{
//clear buffer
for (i = 0; i < 33; i++)
((int8_t*)(buf))[i] = '\0';
//copy file name into buffer if directory entry can be read
int32_t len = strlen((int8_t*)dentry.fileName);
strncpy((int8_t*)buf, (int8_t*)dentry.fileName, len);
directoryLoc++;
return len;
}
else
{
/*TEMP FIX = directoryLoc needs to be changed for checkpoint 3 */
directoryLoc = 0;
return 0;
}
}
