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| author | manuel <manuel@mausz.at> | 2012-03-27 11:51:08 +0200 |
|---|---|---|
| committer | manuel <manuel@mausz.at> | 2012-03-27 11:51:08 +0200 |
| commit | 4f670845ff9ab6c48bcb5f7bf4d4ef6dc3c3064b (patch) | |
| tree | 868c52e06f207b5ec8a3cc141f4b8b2bdfcc165c /pintos-progos/userprog/syscall.c | |
| parent | eae0bd57f0a26314a94785061888d193d186944a (diff) | |
| download | progos-4f670845ff9ab6c48bcb5f7bf4d4ef6dc3c3064b.tar.gz progos-4f670845ff9ab6c48bcb5f7bf4d4ef6dc3c3064b.tar.bz2 progos-4f670845ff9ab6c48bcb5f7bf4d4ef6dc3c3064b.zip | |
reorganize file structure to match the upstream requirements
Diffstat (limited to 'pintos-progos/userprog/syscall.c')
| -rw-r--r-- | pintos-progos/userprog/syscall.c | 563 |
1 files changed, 0 insertions, 563 deletions
diff --git a/pintos-progos/userprog/syscall.c b/pintos-progos/userprog/syscall.c deleted file mode 100644 index f8e0197..0000000 --- a/pintos-progos/userprog/syscall.c +++ /dev/null | |||
| @@ -1,563 +0,0 @@ | |||
| 1 | #include <stdio.h> | ||
| 2 | #include <syscall-nr.h> | ||
| 3 | #include "devices/input.h" | ||
| 4 | #include "devices/shutdown.h" | ||
| 5 | #include "filesys/file.h" | ||
| 6 | #include "filesys/filesys.h" | ||
| 7 | #include "filesys/inode.h" | ||
| 8 | #include "lib/string.h" | ||
| 9 | #include "threads/interrupt.h" | ||
| 10 | #include "threads/palloc.h" | ||
| 11 | #include "threads/synch.h" | ||
| 12 | #include "threads/thread.h" | ||
| 13 | #include "threads/vaddr.h" | ||
| 14 | #include "userprog/pagedir.h" | ||
| 15 | #include "userprog/process.h" | ||
| 16 | #include "userprog/syscall.h" | ||
| 17 | |||
| 18 | #define STACK_SLOT_SIZE sizeof(int) | ||
| 19 | |||
| 20 | /* Prototypes for Utilities */ | ||
| 21 | static int get_user (const uint8_t *uaddr); | ||
| 22 | static bool put_user (uint8_t *udst, uint8_t byte); | ||
| 23 | static void* memcpy_from_user (void *kaddr, void *uaddr, size_t bytes); | ||
| 24 | static void* memcpy_to_user (void *kaddr, void *addr, size_t bytes); | ||
| 25 | static void* copy_string_arg (void *usp, bool *segfault); | ||
| 26 | static void free_string_arg_buf (void *kbuf); | ||
| 27 | |||
| 28 | /* Reads a byte at user virtual address UADDR. | ||
| 29 | UADDR must be below PHYS_BASE. | ||
| 30 | Returns the byte value if successful, -1 if a segfault | ||
| 31 | occurred. */ | ||
| 32 | static int | ||
| 33 | get_user (const uint8_t *uaddr) | ||
| 34 | { | ||
| 35 | int result; | ||
| 36 | asm ("movl $1f, %0; " /* save eip in eax */ | ||
| 37 | "movzbl %1, %0; " /* read byte from user memory into eax */ | ||
| 38 | "1:" /* continue here on page fault, with eax set to -1 */ | ||
| 39 | : "=&a" (result) : "m" (*uaddr)); | ||
| 40 | return result; | ||
| 41 | } | ||
| 42 | |||
| 43 | /* Writes BYTE to user address UDST. | ||
| 44 | UDST must be below PHYS_BASE. | ||
| 45 | Returns true if successful, false if a segfault occurred. */ | ||
| 46 | static bool | ||
| 47 | put_user (uint8_t *udst, uint8_t byte) | ||
| 48 | { | ||
| 49 | int error_code; | ||
| 50 | asm ("movl $1f, %0;" /* save EIP in EAX */ | ||
| 51 | "movb %b2, %1;" /* write byte to user memory */ | ||
| 52 | "1:" /* continue here on page fault, with eax set to -1 */ | ||
| 53 | : "=&a" (error_code), "=m" (*udst) : "q" (byte)); | ||
| 54 | return error_code != -1; | ||
| 55 | } | ||
| 56 | |||
| 57 | /* Copy bytes from user space; returns NULL if a segfault | ||
| 58 | occured, and kaddr otherwise */ | ||
| 59 | static void* | ||
| 60 | memcpy_from_user (void *kaddr, void *uaddr, size_t bytes) | ||
| 61 | { | ||
| 62 | uint8_t* kp = kaddr; | ||
| 63 | size_t i; | ||
| 64 | if (! is_user_vaddr (uaddr) || | ||
| 65 | ! is_user_vaddr (uaddr + bytes - 1)) | ||
| 66 | return false; | ||
| 67 | for (i=0;i<bytes;i++) { | ||
| 68 | int b = get_user (uaddr+i); | ||
| 69 | if (b < 0) | ||
| 70 | break; /* segfault */ | ||
| 71 | else | ||
| 72 | kp[i] = b; | ||
| 73 | } | ||
| 74 | if (i != bytes) | ||
| 75 | return NULL; /* segfault */ | ||
| 76 | return kaddr; | ||
| 77 | } | ||
| 78 | |||
| 79 | /* Copy bytes to user space; returns NULL if a segfault | ||
| 80 | occured, and uaddr otherwise */ | ||
| 81 | static void* | ||
| 82 | memcpy_to_user (void *uaddr, void *kaddr, size_t bytes) | ||
| 83 | { | ||
| 84 | uint8_t* kp = kaddr; | ||
| 85 | size_t i; | ||
| 86 | if (! is_user_vaddr (uaddr) || | ||
| 87 | ! is_user_vaddr (uaddr + bytes - 1)) | ||
| 88 | return false; | ||
| 89 | for (i=0;i<bytes;i++) { | ||
| 90 | if (! put_user (uaddr+i, kp[i])) | ||
| 91 | break; /* segfault */ | ||
| 92 | } | ||
| 93 | if (i != bytes) | ||
| 94 | return NULL; /* segfault */ | ||
| 95 | return uaddr; | ||
| 96 | } | ||
| 97 | |||
| 98 | /* Copy string (at most cnt bytes) from user memory to the kernel address | ||
| 99 | `kaddr`. The number of bytes copied is returned; 0 indicates a segfault. */ | ||
| 100 | static size_t | ||
| 101 | strncpy_from_user (void *kaddr, void *uaddr, size_t cnt) | ||
| 102 | { | ||
| 103 | uint8_t *kp = (uint8_t*) kaddr; | ||
| 104 | size_t i; | ||
| 105 | int c = 1; | ||
| 106 | for (i = 0; i < cnt && c; i++) { | ||
| 107 | if (! is_user_vaddr (uaddr+i)) | ||
| 108 | return 0; /* sefault */ | ||
| 109 | c = get_user (uaddr+i); | ||
| 110 | if (c < 0) | ||
| 111 | return 0; /* segfault */ | ||
| 112 | kp[i] = c; | ||
| 113 | } | ||
| 114 | return i; | ||
| 115 | } | ||
| 116 | |||
| 117 | /* Copy a value of scalar type `typeof(*kdst)` from user space pointer | ||
| 118 | `usrc` to kernel space variable pointed to by `kdst`. Returns | ||
| 119 | false on segfault, and true otherwise. */ | ||
| 120 | #define copy_from_user(kdst, usrc) \ | ||
| 121 | (memcpy_from_user (kdst, usrc, sizeof (*kdst)) != NULL) | ||
| 122 | |||
| 123 | /* Takes user space stack pointer, which points to a string | ||
| 124 | in user space. Copies that string (at most PGSIZE bytes) | ||
| 125 | to a freshly allocated buffer in kernel space. Reurns NULL on | ||
| 126 | error; on a segfault, additionally sets `segfault` to true */ | ||
| 127 | static void* | ||
| 128 | copy_string_arg (void *usp, bool *segfault) | ||
| 129 | { | ||
| 130 | size_t bytes_copied; | ||
| 131 | char *uptr; | ||
| 132 | char *kpage; | ||
| 133 | if (! copy_from_user (&uptr, usp)) { | ||
| 134 | *segfault = true; | ||
| 135 | return NULL; | ||
| 136 | } | ||
| 137 | kpage = palloc_get_page (PAL_ZERO); | ||
| 138 | if (kpage == NULL) | ||
| 139 | return NULL; | ||
| 140 | bytes_copied = strncpy_from_user (kpage, uptr, PGSIZE); | ||
| 141 | if (bytes_copied == 0) { | ||
| 142 | *segfault = true; | ||
| 143 | palloc_free_page (kpage); | ||
| 144 | return NULL; | ||
| 145 | } | ||
| 146 | if (kpage[bytes_copied-1] != '\0') { | ||
| 147 | palloc_free_page (kpage); | ||
| 148 | return NULL; | ||
| 149 | }; | ||
| 150 | return kpage; | ||
| 151 | } | ||
| 152 | |||
| 153 | /* free buffer allocated by `copy_string_arg` */ | ||
| 154 | static void free_string_arg_buf (void *kbuf) | ||
| 155 | { | ||
| 156 | palloc_free_page (kbuf); | ||
| 157 | } | ||
| 158 | |||
| 159 | /* Stack slot address */ | ||
| 160 | #define STACK_ADDR(sp, slot) (sp + STACK_SLOT_SIZE*slot) | ||
| 161 | |||
| 162 | /* syscall handler prototype */ | ||
| 163 | static void syscall_handler (struct intr_frame *); | ||
| 164 | |||
| 165 | typedef int (handler)(void *sp, bool *segfault); | ||
| 166 | |||
| 167 | /* Prototypes for syscall handlers */ | ||
| 168 | static handler | ||
| 169 | syscall_halt, | ||
| 170 | syscall_exit, | ||
| 171 | syscall_write, | ||
| 172 | syscall_wait , | ||
| 173 | syscall_exec, | ||
| 174 | syscall_create, | ||
| 175 | syscall_remove, | ||
| 176 | syscall_open, | ||
| 177 | syscall_filesize, | ||
| 178 | syscall_read, | ||
| 179 | syscall_seek, | ||
| 180 | syscall_tell, | ||
| 181 | syscall_close; | ||
| 182 | |||
| 183 | /* Register syscall_handler for interrupt 0x30 */ | ||
| 184 | void | ||
| 185 | syscall_init (void) | ||
| 186 | { | ||
| 187 | intr_register_int (0x30, 3, INTR_ON, syscall_handler, "syscall"); | ||
| 188 | } | ||
| 189 | |||
| 190 | /* Syscall handler, delegating known syscalls to the respective implementations */ | ||
| 191 | static void | ||
| 192 | syscall_handler (struct intr_frame *f) | ||
| 193 | { | ||
| 194 | int syscall_nr; | ||
| 195 | handler* fp; | ||
| 196 | bool segfault = false; | ||
| 197 | int result; | ||
| 198 | void *sp = f->esp; | ||
| 199 | |||
| 200 | /* The system call number and the arguments are on the stack */ | ||
| 201 | if (! copy_from_user (&syscall_nr,sp)) | ||
| 202 | goto fail; | ||
| 203 | switch (syscall_nr) { | ||
| 204 | case SYS_HALT: fp = syscall_halt; break; | ||
| 205 | case SYS_EXIT: fp = syscall_exit; break; | ||
| 206 | case SYS_EXEC: fp = syscall_exec; break; | ||
| 207 | case SYS_WAIT: fp = syscall_wait; break; | ||
| 208 | case SYS_CREATE: fp = syscall_create; break; | ||
| 209 | case SYS_REMOVE: fp = syscall_remove; break; | ||
| 210 | case SYS_OPEN: fp = syscall_open; break; | ||
| 211 | case SYS_FILESIZE: fp = syscall_filesize; break; | ||
| 212 | case SYS_READ: fp = syscall_read; break; | ||
| 213 | case SYS_WRITE: fp = syscall_write; break; | ||
| 214 | case SYS_SEEK: fp = syscall_seek; break; | ||
| 215 | case SYS_TELL: fp = syscall_tell; break; | ||
| 216 | case SYS_CLOSE: fp = syscall_close; break; | ||
| 217 | default: | ||
| 218 | goto fail; | ||
| 219 | } | ||
| 220 | result = fp (sp, &segfault); | ||
| 221 | if (segfault) | ||
| 222 | goto fail; | ||
| 223 | f->eax = result; | ||
| 224 | return; | ||
| 225 | |||
| 226 | fail: | ||
| 227 | process_current()->exit_status = -1; | ||
| 228 | thread_exit (); | ||
| 229 | } | ||
| 230 | |||
| 231 | /* Shutdown machine */ | ||
| 232 | static int | ||
| 233 | syscall_halt (void *sp UNUSED, bool *segfault UNUSED) | ||
| 234 | { | ||
| 235 | shutdown (); | ||
| 236 | NOT_REACHED (); | ||
| 237 | } | ||
| 238 | |||
| 239 | /* Exit current process with given exit code */ | ||
| 240 | static int | ||
| 241 | syscall_exit (void *sp, bool *segfault) | ||
| 242 | { | ||
| 243 | int exit_status; | ||
| 244 | if (! copy_from_user (&exit_status, STACK_ADDR (sp,1))) { | ||
| 245 | *segfault = true; | ||
| 246 | return -1; | ||
| 247 | } | ||
| 248 | process_current()->exit_status = exit_status; | ||
| 249 | thread_exit (); | ||
| 250 | NOT_REACHED (); | ||
| 251 | } | ||
| 252 | |||
| 253 | /* Spawn new process executing the supplied command */ | ||
| 254 | static int | ||
| 255 | syscall_exec (void *sp, bool *segfault) | ||
| 256 | { | ||
| 257 | char *kbuf; | ||
| 258 | int result = TID_ERROR; | ||
| 259 | if ((kbuf = copy_string_arg (STACK_ADDR (sp, 1), segfault)) != NULL) { | ||
| 260 | result = process_execute (kbuf); | ||
| 261 | free_string_arg_buf (kbuf); | ||
| 262 | } | ||
| 263 | return result; | ||
| 264 | } | ||
| 265 | |||
| 266 | /* Wait until specified process exits */ | ||
| 267 | static int | ||
| 268 | syscall_wait (void *sp, bool *segfault) | ||
| 269 | { | ||
| 270 | tid_t arg; | ||
| 271 | if (! copy_from_user (&arg, STACK_ADDR (sp,1))) { | ||
| 272 | *segfault = true; | ||
| 273 | return 0; | ||
| 274 | } | ||
| 275 | return process_wait (arg); | ||
| 276 | } | ||
| 277 | |||
| 278 | /* Create a new file with given initial size */ | ||
| 279 | static int | ||
| 280 | syscall_create (void *sp, bool *segfault) | ||
| 281 | { | ||
| 282 | bool success = false; | ||
| 283 | char *fname; | ||
| 284 | int initial_size; | ||
| 285 | |||
| 286 | if (! copy_from_user (&initial_size, STACK_ADDR (sp,2))) { | ||
| 287 | *segfault = true; | ||
| 288 | return false; | ||
| 289 | } | ||
| 290 | if ((fname = copy_string_arg (STACK_ADDR (sp, 1), segfault)) == NULL) | ||
| 291 | return false; | ||
| 292 | |||
| 293 | process_lock_filesys (); | ||
| 294 | success = filesys_create (fname, initial_size); | ||
| 295 | process_unlock_filesys (); | ||
| 296 | free_string_arg_buf (fname); | ||
| 297 | return success; | ||
| 298 | } | ||
| 299 | |||
| 300 | /* Remove name file, returns true if successful */ | ||
| 301 | static int | ||
| 302 | syscall_remove (void *sp, bool *segfault) | ||
| 303 | { | ||
| 304 | bool success; | ||
| 305 | char *fname; | ||
| 306 | |||
| 307 | if ((fname = copy_string_arg (STACK_ADDR (sp, 1), segfault)) == NULL) | ||
| 308 | return false; | ||
| 309 | process_lock_filesys (); | ||
| 310 | success = filesys_remove (fname); | ||
| 311 | process_unlock_filesys (); | ||
| 312 | free_string_arg_buf (fname); | ||
| 313 | return (int)success; | ||
| 314 | } | ||
| 315 | |||
| 316 | /* Open file, returning non-negative file descriptor if successful */ | ||
| 317 | static int | ||
| 318 | syscall_open (void *sp, bool *segfault) | ||
| 319 | { | ||
| 320 | char *fname; | ||
| 321 | int fd; | ||
| 322 | if ((fname = copy_string_arg (STACK_ADDR (sp, 1), segfault)) == NULL) | ||
| 323 | return false; | ||
| 324 | fd = process_open_file (fname); | ||
| 325 | free_string_arg_buf (fname); | ||
| 326 | return fd; | ||
| 327 | } | ||
| 328 | |||
| 329 | /* Return size of file described by file descriptor */ | ||
| 330 | static int | ||
| 331 | syscall_filesize (void *sp, bool *segfault) | ||
| 332 | { | ||
| 333 | int fd; | ||
| 334 | struct file *f; | ||
| 335 | int size; | ||
| 336 | |||
| 337 | if (! copy_from_user (&fd, STACK_ADDR (sp,1))) { | ||
| 338 | *segfault = true; | ||
| 339 | return -1; | ||
| 340 | } | ||
| 341 | if ((f = process_get_file (fd)) == NULL) | ||
| 342 | return -1; | ||
| 343 | process_lock_filesys (); | ||
| 344 | size = inode_length (file_get_inode (f)); | ||
| 345 | process_unlock_filesys (); | ||
| 346 | return size; | ||
| 347 | } | ||
| 348 | |||
| 349 | /* Read bytes from the file referenced by the given file | ||
| 350 | descriptor into the supplied user space buffer, returning | ||
| 351 | number of bytes read. */ | ||
| 352 | static int | ||
| 353 | syscall_read (void *sp, bool *segfault) | ||
| 354 | { | ||
| 355 | int fd; | ||
| 356 | uint8_t *user_buffer; | ||
| 357 | size_t size, bytes_to_read; | ||
| 358 | |||
| 359 | /* get arguments */ | ||
| 360 | if (! copy_from_user (&fd, STACK_ADDR (sp,1)) || | ||
| 361 | ! copy_from_user (&user_buffer, STACK_ADDR (sp, 2)) || | ||
| 362 | ! copy_from_user (&size, STACK_ADDR (sp,3))) { | ||
| 363 | *segfault = true; | ||
| 364 | return -1; | ||
| 365 | } | ||
| 366 | |||
| 367 | /* ensure buffer is in user space */ | ||
| 368 | if (! is_user_vaddr (user_buffer) || | ||
| 369 | ! is_user_vaddr (user_buffer + size - 1)) { | ||
| 370 | *segfault = true; | ||
| 371 | return -1; | ||
| 372 | } | ||
| 373 | |||
| 374 | bytes_to_read = size; | ||
| 375 | /* handle stdin */ | ||
| 376 | if (fd == STDIN_FILENO) { | ||
| 377 | char c; | ||
| 378 | while (bytes_to_read--) { | ||
| 379 | c = input_getc (); | ||
| 380 | if (! put_user (user_buffer++, c)) { | ||
| 381 | *segfault = true; | ||
| 382 | return -1; | ||
| 383 | } | ||
| 384 | } | ||
| 385 | return size; | ||
| 386 | } | ||
| 387 | /* get file */ | ||
| 388 | struct file *file = process_get_file (fd); | ||
| 389 | if (file == NULL) | ||
| 390 | return -1; | ||
| 391 | |||
| 392 | char *kbuf = palloc_get_page (0); | ||
| 393 | if (kbuf == NULL) | ||
| 394 | return -1; | ||
| 395 | |||
| 396 | /* read loop */ | ||
| 397 | do { | ||
| 398 | int bytes_read; | ||
| 399 | int blocksize = bytes_to_read; | ||
| 400 | if (bytes_to_read > PGSIZE) | ||
| 401 | blocksize = PGSIZE; | ||
| 402 | |||
| 403 | /* read bytes */ | ||
| 404 | process_lock_filesys (); | ||
| 405 | bytes_read = file_read (file, kbuf, blocksize); | ||
| 406 | process_unlock_filesys (); | ||
| 407 | |||
| 408 | /* Stop when EOF has been reached */ | ||
| 409 | if (bytes_read == 0) | ||
| 410 | break; | ||
| 411 | bytes_to_read -= bytes_read; | ||
| 412 | if (! memcpy_to_user (user_buffer, kbuf, bytes_read)) { | ||
| 413 | *segfault = true; | ||
| 414 | break; | ||
| 415 | } | ||
| 416 | user_buffer += bytes_read; | ||
| 417 | } while (bytes_to_read > 0); | ||
| 418 | |||
| 419 | palloc_free_page (kbuf); | ||
| 420 | return size - bytes_to_read; | ||
| 421 | } | ||
| 422 | |||
| 423 | /* Write bytes from user buffer into the specified | ||
| 424 | file, returning number of bytes written. */ | ||
| 425 | static int | ||
| 426 | syscall_write (void *sp, bool *segfault) | ||
| 427 | { | ||
| 428 | int fd; | ||
| 429 | size_t size, bytes_to_write; | ||
| 430 | char *user_buffer; | ||
| 431 | |||
| 432 | /* get arguments */ | ||
| 433 | if (! copy_from_user (&fd, STACK_ADDR (sp,1)) || | ||
| 434 | ! copy_from_user (&user_buffer, STACK_ADDR (sp, 2)) || | ||
| 435 | ! copy_from_user (&size, STACK_ADDR (sp,3))) { | ||
| 436 | *segfault = true; | ||
| 437 | return -1; | ||
| 438 | } | ||
| 439 | |||
| 440 | /* ensure buffer is in user space */ | ||
| 441 | if (! is_user_vaddr (user_buffer) || | ||
| 442 | ! is_user_vaddr (user_buffer + size - 1)) { | ||
| 443 | *segfault = true; | ||
| 444 | return -1; | ||
| 445 | } | ||
| 446 | |||
| 447 | /* get file handle */ | ||
| 448 | struct file *file = NULL; | ||
| 449 | if (fd != STDOUT_FILENO) { | ||
| 450 | file = process_get_file (fd); | ||
| 451 | if (file == NULL) | ||
| 452 | return -1; | ||
| 453 | } | ||
| 454 | |||
| 455 | /* allocate kernel buffer */ | ||
| 456 | char *kbuf = palloc_get_page (0); | ||
| 457 | if (kbuf == NULL) | ||
| 458 | return -1; | ||
| 459 | |||
| 460 | /* write loop */ | ||
| 461 | bytes_to_write = size; | ||
| 462 | do { | ||
| 463 | int blocksize = bytes_to_write; | ||
| 464 | if (bytes_to_write > PGSIZE) | ||
| 465 | blocksize = PGSIZE; | ||
| 466 | if (memcpy_from_user (kbuf, user_buffer, blocksize) == NULL) { | ||
| 467 | *segfault = true; | ||
| 468 | break; | ||
| 469 | } | ||
| 470 | if (fd == STDOUT_FILENO) { | ||
| 471 | putbuf (kbuf, blocksize); | ||
| 472 | bytes_to_write -= blocksize; | ||
| 473 | } else { | ||
| 474 | int bytes_written = 0; | ||
| 475 | int bytes_left_filesys = blocksize; | ||
| 476 | |||
| 477 | process_lock_filesys (); | ||
| 478 | while (bytes_left_filesys > 0) { | ||
| 479 | bytes_written = file_write (file, kbuf, bytes_left_filesys); | ||
| 480 | if (bytes_written <= 0) { | ||
| 481 | break; | ||
| 482 | } | ||
| 483 | bytes_left_filesys -= bytes_written; | ||
| 484 | } | ||
| 485 | process_unlock_filesys (); | ||
| 486 | |||
| 487 | if (bytes_written <= 0) | ||
| 488 | break; | ||
| 489 | bytes_to_write -= blocksize; | ||
| 490 | } | ||
| 491 | user_buffer += blocksize; | ||
| 492 | } while (bytes_to_write > 0); | ||
| 493 | |||
| 494 | /* return bytes written */ | ||
| 495 | palloc_free_page (kbuf); | ||
| 496 | return size - bytes_to_write; | ||
| 497 | } | ||
| 498 | |||
| 499 | /* Change the position where the next byte will be read or written */ | ||
| 500 | static int | ||
| 501 | syscall_seek (void *sp, bool *segfault) | ||
| 502 | { | ||
| 503 | int fd; | ||
| 504 | off_t new_pos; | ||
| 505 | |||
| 506 | /* get arguments */ | ||
| 507 | if (! copy_from_user (&fd, STACK_ADDR (sp,1)) || | ||
| 508 | ! copy_from_user (&new_pos, STACK_ADDR (sp, 2))) { | ||
| 509 | *segfault = true; | ||
| 510 | return 0; | ||
| 511 | } | ||
| 512 | |||
| 513 | /* no way to return something sensible (void function) */ | ||
| 514 | struct file *file = process_get_file (fd); | ||
| 515 | if (file == NULL) | ||
| 516 | return 0; | ||
| 517 | |||
| 518 | process_lock_filesys (); | ||
| 519 | file_seek (file, new_pos); | ||
| 520 | process_unlock_filesys (); | ||
| 521 | return 0; | ||
| 522 | } | ||
| 523 | |||
| 524 | /* Returns the position of the next byte to be read or written */ | ||
| 525 | static int | ||
| 526 | syscall_tell (void *sp, bool *segfault) | ||
| 527 | { | ||
| 528 | int fd; | ||
| 529 | unsigned r = 0; | ||
| 530 | |||
| 531 | /* get arguments */ | ||
| 532 | if (! copy_from_user (&fd, STACK_ADDR (sp,1))) { | ||
| 533 | *segfault = true; | ||
| 534 | return 0; | ||
| 535 | } | ||
| 536 | |||
| 537 | /* no way to return something sensible function */ | ||
| 538 | struct file *file = process_get_file (fd); | ||
| 539 | if (file == NULL) | ||
| 540 | return 0; | ||
| 541 | |||
| 542 | process_lock_filesys (); | ||
| 543 | r = file_tell (file); | ||
| 544 | process_unlock_filesys (); | ||
| 545 | return r; | ||
| 546 | } | ||
| 547 | |||
| 548 | /* Close the given file */ | ||
| 549 | static int | ||
| 550 | syscall_close (void *sp, bool *segfault) | ||
| 551 | { | ||
| 552 | int fd; | ||
| 553 | |||
| 554 | /* get arguments */ | ||
| 555 | if (! copy_from_user (&fd, STACK_ADDR (sp,1))) { | ||
| 556 | *segfault = true; | ||
| 557 | return 0; | ||
| 558 | } | ||
| 559 | |||
| 560 | /* no way to return something sensible function (void) */ | ||
| 561 | (void) process_close_file (fd); | ||
| 562 | return 0; | ||
| 563 | } | ||
