diff options
| -rw-r--r-- | src/userprog/syscall.c | 44 |
1 files changed, 41 insertions, 3 deletions
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c index 8e5593f..e72ee0b 100644 --- a/src/userprog/syscall.c +++ b/src/userprog/syscall.c @@ -4,9 +4,10 @@ #include "threads/interrupt.h" #include "threads/thread.h" -#include "threads/init.h" #include "filesys/filesys.h" #include "filesys/off_t.h" +#include "threads/init.h" +#include "threads/malloc.h" static void syscall_handler (struct intr_frame *); @@ -28,6 +29,42 @@ create (const char *filename, off_t initial_size) return filesys_create (filename, initial_size); } +static int +open (const char *filename) +{ + struct thread *t = thread_current (); + + if (t->max_files == 0) { + t->max_files = 128; + printf("[%s] open: allocating %d file descriptors\n", t->name, t->max_files); + t->files = (struct fd *) calloc (t->max_files, sizeof (struct fd)); + } + + if (t->num_files == t->max_files) { + // not enough space for more file descriptors + printf("[%s] open: too many file descriptors\n", t->name); + return -1; + } + + struct file *file = filesys_open(filename); + if (!file) { + printf("[%s] open: couldn't find file %s\n", t->name, filename); + return -1; + } + + for (int i = 0; i < t->max_files; i++) { + struct fd *fd = t->files + i; + if (!fd->active) { + fd->active = true; + fd->file = file; + return i + 2; // 0 and 1 are reserved for stdin and stdout + } + } + free(file); + printf("[%s] open: unable to find empty file descriptor\n", t->name); + return -1; +} + static void write (const char *buf) { @@ -40,7 +77,7 @@ write (const char *buf) static void syscall_handler (struct intr_frame *f UNUSED) { - int syscall_number = INTR_ESP(0, int); + int syscall_number = INTR_ESP (0, int); switch (syscall_number) { case 0: // halt @@ -51,10 +88,11 @@ syscall_handler (struct intr_frame *f UNUSED) break; case 4: // create - f->eax = create(INTR_ESP(1, char *), INTR_ESP(2, off_t)); + f->eax = create (INTR_ESP (1, char *), INTR_ESP (2, off_t)); break; case 6: // open + f->eax = open (INTR_ESP (1, char *)); break; case 8: // read |