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#include "shm.h"
#include <mem/mem.h>
#include <mem/seg.h>
#include <task/task.h>
#include <core/sys.h>
static struct segment_map* shmseg_map(struct segment* seg, struct page_directory *pagedir, size_t offset);
static void shmseg_unmap(struct segment_map*);
static void shmseg_delete(struct segment *seg);
static int shmseg_handleFault(struct segment_map *map, size_t addr, int write);
/* Call this function when creating a new shared memory segment.
Creates the shmseg struct and segment struct, fills them in. */
struct segment* shmseg_make(size_t len, struct process* owner) {
struct shmseg *ss = kmalloc(sizeof(struct shmseg));
struct segment *se = kmalloc(sizeof(struct segment));
unsigned i;
se->seg_data = ss;
se->mappings = 0;
se->map = shmseg_map;
se->unmap = shmseg_unmap;
se->delete = shmseg_delete;
se->handle_fault = shmseg_handleFault;
ss->len = len;
ss->owner = owner;
ss->frames = kmalloc((len / 0x1000) * sizeof(uint32_t));
for (i = 0; i < (len / 0x1000); i++) ss->frames[i] = 0;
return se;
}
/* For internal use only. Called when the shared memory is mapped somewhere.
Creates the segment_map struct and fills it up. */
struct segment_map *shmseg_map(struct segment *seg, struct page_directory *pagedir, size_t offset) {
struct segment_map *sm = kmalloc(sizeof(struct segment_map));
sm->start = offset;
sm->len = ((struct shmseg*)(seg->seg_data))->len;
return sm;
}
/* For internal use only. Called when the shared memory is unmapped from somewhere.
Unmaps all the pages from that place. */
void shmseg_unmap(struct segment_map *sm) {
size_t i;
for (i = 0; i < sm->len; i += 0x1000) {
struct page *page = pagedir_getPage(sm->pagedir, sm->start + i, 0);
if (page != 0) page_unmap(page);
}
}
/* For internal use only. Called when a page fault occurs.
Maps a page at that place, possibly requesting a free frame first. */
int shmseg_handleFault(struct segment_map *sm, size_t addr, int write) {
struct shmseg *ss = sm->seg->seg_data;
addr &= 0xFFFFF000;
struct page *p = pagedir_getPage(sm->pagedir, addr, 1);
if (p->frame != 0) return 1;
int frame_idx = (addr - sm->start) / 0x1000;
if (ss->frames[frame_idx] == 0) {
ss->frames[frame_idx] = frame_alloc();
}
page_map(p, ss->frames[frame_idx], 1, 1);
return 0;
}
/* For internal use only. Called when the shared memory is deleted.
Frees all the frames. */
void shmseg_delete(struct segment *seg) {
struct shmseg *ss = seg->seg_data;
unsigned i;
for (i = 0; i < (ss->len / 0x1000); i++) {
if (ss->frames[i] != 0) frame_free(ss->frames[i]);
}
kfree(ss->frames);
}
/* Looks through the mapped segment for a process, looking for a shared memory segment at given offset. */
struct segment_map* shmseg_getByOff(struct process* pr, size_t offset) {
struct segment_map* m = pr->pagedir->mappedSegs;
while (m != 0) {
if (m->start == offset && m->seg->delete == shmseg_delete) return m;
m = m->next;
}
return 0;
}
// **** **** SHM syscalls **** ****
int shm_create(size_t offset, size_t len) {
if (offset >= 0xE0000000) return -1;
if (len >= 0x10000000) return -1;
if (offset+len >= 0xE0000000) return -1;
seg_map(shmseg_make(len, current_thread->process), current_thread->process->pagedir, offset);
return 0;
}
int shm_delete(size_t offset) {
struct segment_map *s = shmseg_getByOff(current_thread->process, offset);
if (s == 0) return -1;
seg_unmap(s);
return 0;
}
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