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Commit 58a9cbaa authored by abinade2's avatar abinade2
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student-distrib/syscall.c
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#include "syscall.h"
/*
*The halt system call
/* The halt system call
*
*DESCRIPTION: This function terminates a process, returning the specified value to its parent process.
*INPUT: status --
*RETURN:
* int32_t halt (uint8_t status)
*
* DESCRIPTION: This function terminates a process, returning the specified value to its parent process.
*
* INPUT: status --
*
* RETURN:
*/
int32_t halt (uint8_t status){
int32_t halt (uint8_t status)
{
int i;
cli();
pcb_t* pcb_cur = terminal[running_terminal].pcb;
//pcb_t* pcb_cur = current_pcb();
// printf("[halt] running_terminal = %d\n", running_terminal);
......@@ -71,20 +73,24 @@ int32_t halt (uint8_t status){
return 0;
}
/*
*The execute system call
*
*DESCRIPTION: This function attempts to load and execute a new program,
* handing off the processor to the new program until it terminates.
*INPUT: command -- a space-separated sequence of words. The first word is the file name
* of the program to be executed, and the rest of the command—stripped
* of leading spaces—should be provided to the new program on request
* via the getargs system call.
*RETURN: -1 if the command cannot be executed. (for example, program does not exist / the file not executable,)
* 256 if the program dies by an exception.
* 0-255 if the program executes a halt system call. (in which case the value returned is that given by the program’s call to halt)
/* The execute system call
*
* int32_t execute(const uint8_t* command)
*
* DESCRIPTION: This function attempts to load and execute a new program,
* handing off the processor to the new program until it terminates.
*
* INPUT: command -- a space-separated sequence of words. The first word is the file name
* of the program to be executed, and the rest of the command—stripped
* of leading spaces—should be provided to the new program on request
* via the getargs system call.
*
* RETURN: -1 -- if the command cannot be executed. (for example, program does not exist / the file not executable,)
* 256 -- if the program dies by an exception.
* 0-255 -- if the program executes a halt system call. (in which case the value returned is that given by the program’s call to halt)
*/
int32_t execute(const uint8_t* command){
int32_t execute(const uint8_t* command)
{
cli();
......@@ -231,41 +237,42 @@ int32_t execute(const uint8_t* command){
return 0;
}
/*
*The read system call
/* The read system call
*
*DISCRIPTION: This function reads data from the keyboard, a file, device (RTC), or directory.
* This function use a jump table referenced by the task’s file array to call
* from a generic handler for this call into a file-type-specific function.
* This jump table is inserted into the file array on the open system call.
* int32_t read(int32_t fd_n, void* buf, int32_t nbytes)
*
* case 1 - keyboard : return data from one line that has been terminated by pressing
* Enter, or as much as fits in the buffer from one such line.
* The line returned should include the line feed character.
* DESCRIPTION: This function reads data from the keyboard, a file, device (RTC), or directory.
* This function use a jump table referenced by the task’s file array to call
* from a generic handler for this call into a file-type-specific function.
* This jump table is inserted into the file array on the open system call.
*
* case 2 - file : data should be read to the end of the file or the end of the
* buffer provided, whichever occurs sooner.
* case 1 - keyboard : return data from one line that has been terminated by pressing
* Enter, or as much as fits in the buffer from one such line.
* The line returned should include the line feed character.
*
* case 3 - device(RTC): this call should always return 0, but only after an interrupt
* has occurred (set a flag and wait until the interrupt handler
* clears it, then return 0).
* case 2 - file : data should be read to the end of the file or the end of the
* buffer provided, whichever occurs sooner.
*
* case 4 - directory : only the filename should be provided (as much as fits, max 32 bytes),
* and subsequent reads should read from successive directory entries
* until the last is reached, at which point read should repeatedly
* return 0.
* case 3 - device(RTC): this call should always return 0, but only after an interrupt
* has occurred (set a flag and wait until the interrupt handler
* clears it, then return 0).
*
*INPUT: fd -- file discriptor
* buf -- buffer that store the file
* nbytes -- the number of bytes that need to read
* case 4 - directory : only the filename should be provided (as much as fits, max 32 bytes),
* and subsequent reads should read from successive directory entries
* until the last is reached, at which point read should repeatedly
* return 0.
*
* INPUT: fd -- file discriptor
* buf -- buffer that store the file
* nbytes -- the number of bytes that need to read
*
*RETURN: 1. the number of bytes read when success
* 2. 0 when the initial file position is at or beyond the end of file,
* for normal files and the directory
* 3. -1 when there fd are out of range or indicate to STDOUT_FD
* RETURN: 1. the number of bytes read when success
* 2. 0 when the initial file position is at or beyond the end of file,
* for normal files and the directory
* 3. -1 when there fd are out of range or indicate to STDOUT_FD
*/
int32_t read (int32_t fd_n, void* buf, int32_t nbytes){
int32_t read(int32_t fd_n, void* buf, int32_t nbytes)
{
int32_t ret;
if (fd_check(fd_n) < 0 || fd_n == STDOUT_FD) return -1; // invalid fd
......@@ -274,15 +281,9 @@ int32_t read (int32_t fd_n, void* buf, int32_t nbytes){
if (nbytes < 0) return -1; // invalid nbytes
//terminal[running_terminal].pcb = current_pcb();
/* Enable for keyboard interrupts */
//sti();
ret = terminal[running_terminal].pcb->fd[fd_n].fileop_ptr.read(fd_n, buf, nbytes);
return ret;
}
/*
......@@ -391,55 +392,55 @@ int32_t open (const uint8_t* filename){
return fd;
}
/*
*The close system call
*
*DISCRIPTION: This function closes the specified file descriptor and makes it available
* for return from later calls to open.
*NOTE: the default descriptors (0 for input and 1 for output) can't be closed
*INPUT: fd -- file discriptor for the file that we want to close
*RETURN: 1. -1 when Trying to close an invalid descriptor
* 2. 0 when successful closes the file.
/* The close system call
*
* int32_t close (int32_t fd)
*
* DESCRIPTION: This function closes the specified file descriptor and makes it available
* for return from later calls to open.
*
* NOTE: the default descriptors (0 for input and 1 for output) can't be closed
*
* INPUT: fd -- file discriptor for the file that we want to close
*
* RETURN: -1 -- when Trying to close an invalid descriptor
* 0 -- when successful closes the file.
*/
int32_t close (int32_t fd){
int32_t close (int32_t fd)
{
if(fd_check(fd) < 0 || fd < USER_FILE_START)
return -1; // invalid fd
if (fd_check(fd) < 0 || fd < USER_FILE_START) return -1; // invalid fd
terminal[running_terminal].pcb->fd[fd].fileop_ptr.close(fd);
//terminal[ running_terminal].pcb = current_pcb();
//sti();
terminal[ running_terminal].pcb->fd[fd].fileop_ptr.close(fd);
fd_clear(fd);
return 0;
}
/*
*The getargs system call
*
*DISCRIPTION: This function reads the program’s command line arguments into a user-level buffer.
* These arguments are stored as part of the task data when a new program is loaded.
* Here they are merely copied into user space.
* DESCRIPTION: This function reads the program’s command line arguments into a user-level buffer.
* These arguments are stored as part of the task data when a new program is loaded.
* Here they are merely copied into user space.
*
*INPUT: buf -- buffer that holds the file
* nbytes -- number of bytes that we want to operate
* INPUT: buf -- buffer that holds the file
* nbytes -- number of bytes that we want to COPY
*
*RETURN: -1 If there are no arguments, or if the arguments and a terminal NULL (0-byte) do not fit in the buffer.
* RETURN: -1 If there are no arguments, or if the arguments and a terminal NULL (0-byte) do not fit in the buffer.
*
*NOTE: The shell does not request arguments, but you should probably still
* initialize the shell task’s argument data to the empty string.
* NOTE: The shell does not request arguments, but you should probably still
* initialize the shell task’s argument data to the empty string.
*/
int32_t getargs (uint8_t* buf, int32_t nbytes){
uint8_t* argument;
//terminal[ running_terminal].pcb = current_pcb();
argument = (uint8_t*) ( terminal[ running_terminal].pcb->argv);
argument = (uint8_t*) (terminal[running_terminal].pcb->argv);
if( terminal[ running_terminal].pcb->arg_num == 0 || nbytes <= 0 )
if( terminal[running_terminal].pcb->arg_num == 0 || nbytes <= 0 )
{
//printf("[getargs] return -1\n");
return -1; //If there are no arguments
......@@ -458,25 +459,26 @@ int32_t getargs (uint8_t* buf, int32_t nbytes){
return 0;
}
/*
*The vidmap system call
/* int32_t vidmap (uint8_t** screen_start)
*
*DESCRIPTION: This function maps the text-mode video memory into user space at a pre-set virtual address.
* Although the address returned is always the same, it should be written into the memory
* location provided by the caller (which must be checked for validity).
* The vidmap system call
*
*INPUT: screen_start --
* DESCRIPTION: This function maps the text-mode video memory into user space at a pre-set virtual address.
* Although the address returned is always the same, it should be written into the memory
* location provided by the caller (which must be checked for validity).
*
*RETURN: -1 If the location is invalid.
* INPUT: screen_start --
*
*NOTE:1. To avoid adding kernel-side exception handling for this sort of check, you can simply
* check whether the address falls within the address range covered by the single user-level page.
* 2. The video memory will require you to add another page mapping for the program, in this case
* a 4 kB page. It is not ok to simply change the permissions of the video page located < 4MB
* and pass that address
* RETURN: -1 If the location is invalid.
*
* NOTE: 1. To avoid adding kernel-side exception handling for this sort of check, you can simply
* check whether the address falls within the address range covered by the single user-level page.
* 2. The video memory will require you to add another page mapping for the program, in this case
* a 4 kB page. It is not ok to simply change the permissions of the video page located < 4MB
* and pass that address
*/
int32_t vidmap (uint8_t** screen_start){
int32_t vidmap (uint8_t** screen_start)
{
/* Check for valid argument */
if ( screen_start == NULL)
return -1;
......@@ -492,27 +494,28 @@ int32_t vidmap (uint8_t** screen_start){
*screen_start = (uint8_t *)(0x8400000);
//screen_start = terminal[ running_terminal].vid_mem;
return 0x8400000;
}
/*
*The set handler system calls
* The set handler system calls
*
* DESCRIPTION: This function are related to signal handling and are discussed in the section Signals below.
*
* INPUT: signum --
* handler_address --
*
*DISCRIPTION: This function are related to signal handling and are discussed in the section Signals below.
*INPUT: signum --
* handler_address --
*RETURN:
* RETURN:
*
*NOTE: Even if your operating system does not support signals, you must support these system calls;
* in such a case, however, you may immediately return failure from these calls.
* NOTE: Even if your operating system does not support signals, you must support these system calls;
* in such a case, however, you may immediately return failure from these calls.
*/
int32_t set_handler (int32_t signum, void* handler_address){
int32_t set_handler (int32_t signum, void* handler_address)
{
return -1;
}
int32_t sigreturn (void){
int32_t sigreturn (void)
{
return -1;
}
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