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#include <camellia/fsutil.h>
#include <camellia/syscalls.h>
#include <errno.h>
#include <shared/mem.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <user/lib/fs/dir.h>
struct node {
const char *name;
bool directory;
size_t namelen;
char *buf;
size_t size, capacity;
size_t open; /* amount of open handles */
struct node *sibling, *child;
/* each node except special_root has exacly one sibling or child reference to it
* on remove(), it gets replaced with *sibling. */
struct node **ref;
};
static struct node special_root = {
.directory = true,
.size = 0,
};
static struct node *lookup(struct node *parent, const char *path, size_t len) {
for (struct node *iter = parent->child; iter; iter = iter->sibling) {
if (iter->namelen == len && !memcmp(path, iter->name, len))
return iter;
}
return NULL;
}
static struct node *tmpfs_open(const char *path, struct fs_wait_response *res) {
struct node *node = &special_root;
if (res->len == 0) return NULL;
if (res->len == 1) return node;
path++;
res->len--;
bool more = true;
size_t segpos = 0, seglen; /* segments end with a slash, inclusive */
while (more) {
struct node *const parent = node;
char *slash = memchr(path + segpos, '/', res->len);
seglen = (slash ? (size_t)(slash - path + 1) : res->len) - segpos;
more = segpos + seglen < res->len;
node = lookup(parent, path + segpos, seglen);
if (!node) {
if (!more && (res->flags & OPEN_CREATE)) {
node = malloc(sizeof *node);
memset(node, 0, sizeof *node);
char *namebuf = malloc(seglen + 1);
memcpy(namebuf, path + segpos, seglen);
namebuf[seglen] = '\0';
node->name = namebuf;
node->directory = slash;
node->namelen = seglen;
if (parent->child) {
parent->child->ref = &node->sibling;
*parent->child->ref = parent->child;
}
node->ref = &parent->child;
*node->ref = node;
} else {
return NULL;
}
}
segpos += seglen;
}
node->open++;
return node;
}
static void handle_down(struct node *node) {
node->open--;
if (!node->ref && node != &special_root && node->open == 0) {
free(node->buf);
free(node);
}
}
static long remove_node(struct node *node) {
if (node == &special_root) return -1;
if (!node->ref) return -1;
if (node->child) return -ENOTEMPTY;
*node->ref = node->sibling;
node->ref = NULL;
handle_down(node);
return 0;
}
int main(void) {
const size_t buflen = 4096;
char *buf = malloc(buflen);
struct fs_wait_response res;
struct node *ptr;
while (!_syscall_fs_wait(buf, buflen, &res)) {
switch (res.op) {
case VFSOP_OPEN:
ptr = tmpfs_open(buf, &res);
_syscall_fs_respond(ptr, ptr ? 0 : -1, 0);
break;
case VFSOP_READ:
ptr = (void*)res.id;
if (ptr->directory) {
struct dirbuild db;
dir_start(&db, res.offset, buf, buflen);
for (struct node *iter = ptr->child; iter; iter = iter->sibling)
dir_append(&db, iter->name);
_syscall_fs_respond(buf, dir_finish(&db), 0);
} else {
fs_normslice(&res.offset, &res.len, ptr->size, false);
_syscall_fs_respond(ptr->buf + res.offset, res.len, 0);
}
break;
case VFSOP_WRITE:
ptr = (void*)res.id;
if (ptr == &special_root) {
_syscall_fs_respond(NULL, -1, 0);
break;
}
if (res.len > 0 && !ptr->buf) {
ptr->buf = malloc(256);
if (!ptr->buf) {
_syscall_fs_respond(NULL, -1, 0);
break;
}
memset(ptr->buf, 0, 256);
ptr->capacity = 256;
}
fs_normslice(&res.offset, &res.len, ptr->size, true);
if (ptr->capacity <= res.offset + res.len) {
size_t newcap = 1;
while (newcap && newcap <= res.offset + res.len)
newcap *= 2;
if (!newcap) { /* overflow */
_syscall_fs_respond(NULL, -1, 0);
break;
}
ptr->capacity = newcap;
ptr->buf = realloc(ptr->buf, ptr->capacity);
}
memcpy(ptr->buf + res.offset, buf, res.len);
if ((res.flags & WRITE_TRUNCATE) || ptr->size < res.offset + res.len) {
ptr->size = res.offset + res.len;
}
_syscall_fs_respond(NULL, res.len, 0);
break;
case VFSOP_GETSIZE:
ptr = (void*)res.id;
if (ptr->directory) {
// TODO could be cached in ptr->size
struct dirbuild db;
dir_start(&db, res.offset, NULL, buflen);
for (struct node *iter = ptr->child; iter; iter = iter->sibling)
dir_append(&db, iter->name);
_syscall_fs_respond(NULL, dir_finish(&db), 0);
} else {
_syscall_fs_respond(NULL, ptr->size, 0);
}
break;
case VFSOP_REMOVE:
ptr = (void*)res.id;
_syscall_fs_respond(NULL, remove_node(ptr), 0);
break;
case VFSOP_CLOSE:
ptr = (void*)res.id;
handle_down(ptr);
_syscall_fs_respond(NULL, -1, 0);
break;
default:
_syscall_fs_respond(NULL, -1, 0);
break;
}
}
return 1;
}
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