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#include <camellia/flags.h>
#include <camellia/fs/dir.h>
#include <camellia/fs/misc.h>
#include <camellia/fsutil.h>
#include <camellia/syscalls.h>
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
struct node {
char *name;
size_t namelen;
bool directory;
char *buf;
size_t size, capacity;
size_t open; /* amount of open handles */
struct node *sibling, *child;
/* Pointer to the sibling/child field referencing the node. NULL for removed
* files. */
struct node **ref;
/* allocated by tmpfs_open
* freed by node_close when (open == 0 && ref == NULL && self != node_root). */
};
static struct node node_root = {
.directory = true,
};
/** Responds to open(), finding an existing node, or creating one when applicable. */
static struct node *tmpfs_open(const char *path, struct ufs_request *req);
/** Finds a direct child with the given name. */
static struct node *node_getchild(struct node *parent, const char *name, size_t len);
/** Corresponds to close(); drops a reference. */
static void node_close(struct node *node);
/** Removes a file. It's kept in memory until all the open handles are closed. */
static long node_remove(struct node *node);
static struct node *node_getchild(struct node *parent, const char *name, size_t len) {
for (struct node *iter = parent->child; iter; iter = iter->sibling) {
if (iter->namelen == len && !memcmp(name, iter->name, len)) {
return iter;
}
}
return NULL;
}
static struct node *tmpfs_open(const char *path, struct ufs_request *req) {
/* *path is not null terminated! */
struct node *node = &node_root;
if (req->len == 0) return NULL;
if (req->len == 1) return node; /* "/" */
path++;
req->len--;
bool more = true;
size_t segpos = 0, seglen; /* segments end with a slash, inclusive */
while (more) {
struct node *parent = node;
char *slash = memchr(path + segpos, '/', req->len - segpos);
seglen = (slash ? (size_t)(slash - path + 1) : req->len) - segpos;
more = segpos + seglen < req->len;
node = node_getchild(parent, path + segpos, seglen);
if (!node) {
if (!more && (req->flags & OPEN_CREATE)) {
node = calloc(1, sizeof *node);
node->name = malloc(seglen + 1);
if (node->name == NULL) {
free(node);
return NULL;
}
memcpy(node->name, path + segpos, seglen);
node->name[seglen] = '\0';
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 node_close(struct node *node) {
node->open--;
if (!node->ref && node != &node_root && node->open == 0) {
free(node->buf);
free(node);
}
}
static long node_remove(struct node *node) {
if (node == &node_root) return -1;
if (!node->ref) return -1;
if (node->child) return -ENOTEMPTY;
*node->ref = node->sibling;
node->ref = NULL;
node_close(node);
return 0;
}
int main(void) {
const size_t buflen = 4096;
char *buf = malloc(buflen);
if (!buf) return -1;
for (;;) {
struct ufs_request req;
hid_t reqh = ufs_wait(buf, buflen, &req);
struct node *ptr = req.id;
if (reqh < 0) break;
switch (req.op) {
case VFSOP_OPEN:
ptr = tmpfs_open(buf, &req);
_sys_fs_respond(reqh, ptr, ptr ? 0 : -ENOENT, 0);
break;
case VFSOP_READ:
if (ptr->directory) {
struct dirbuild db;
dir_start(&db, req.offset, buf, buflen);
for (struct node *iter = ptr->child; iter; iter = iter->sibling) {
dir_appendl(&db, iter->name, iter->namelen);
}
_sys_fs_respond(reqh, buf, dir_finish(&db), 0);
} else {
fs_normslice(&req.offset, &req.len, ptr->size, false);
_sys_fs_respond(reqh, ptr->buf + req.offset, req.len, 0);
}
break;
case VFSOP_WRITE:
if (ptr->directory) {
_sys_fs_respond(reqh, NULL, -ENOSYS, 0);
break;
}
fs_normslice(&req.offset, &req.len, ptr->size, true);
if (ptr->capacity <= req.offset + req.len) {
ptr->capacity = (req.offset + req.len + 511) & ~511;
ptr->buf = realloc(ptr->buf, ptr->capacity);
}
memcpy(ptr->buf + req.offset, buf, req.len);
if ((req.flags & WRITE_TRUNCATE) || ptr->size < req.offset + req.len) {
ptr->size = req.offset + req.len;
}
_sys_fs_respond(reqh, NULL, req.len, 0);
break;
case VFSOP_GETSIZE:
if (ptr->directory) {
// TODO could be cached in ptr->size
struct dirbuild db;
dir_start(&db, req.offset, NULL, buflen);
for (struct node *iter = ptr->child; iter; iter = iter->sibling) {
dir_append(&db, iter->name);
}
_sys_fs_respond(reqh, NULL, dir_finish(&db), 0);
} else {
_sys_fs_respond(reqh, NULL, ptr->size, 0);
}
break;
case VFSOP_REMOVE:
_sys_fs_respond(reqh, NULL, node_remove(ptr), 0);
break;
case VFSOP_CLOSE:
node_close(ptr);
_sys_fs_respond(reqh, NULL, -1, 0);
break;
default:
_sys_fs_respond(reqh, NULL, -1, 0);
break;
}
}
return 1;
}
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