/
vfs.c
executable file
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/
vfs.c
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/*
* @file: futil.c
*
* @author: Kevin Allison
*
* Utility Program for FAT32 Filesystems
*/
#include "vfs.h"
file_t filetable[FILE_LIMIT];
dir_t *dirtable[FILE_LIMIT];
int next_file_pos = 0;
fs_table_t fs_table[] = {
{fat32_init, fat32_createfile, fat32_openfile, fat32_deletefile, fat32_readfile, fat32_write, fat32_readdir, fat32_teardown},
{fat32_init, fat32_createfile, fat32_openfile, fat32_deletefile, fat32_readfile, fat32_write, fat32_readdir, fat32_teardown}
};
mount_t *mount_table[MOUNT_LIMIT];
void mount_fs(const char *device_name, const char *path) {
int mount_pos;
for (mount_pos = 0; mount_pos < MOUNT_LIMIT; mount_pos++) {
if (mount_table[mount_pos] == NULL) { break; }
}
if (mount_pos == MOUNT_LIMIT) { fprintf(stderr, "Could not mount device. No room left in table\n"); return; }
mount_t *newmount = calloc(1, sizeof(mount_t));
newmount->device_name = calloc(strlen(device_name)+1, sizeof(char));
strncpy(newmount->device_name, device_name, strlen(device_name));
newmount->path = calloc(strlen(path)+1, sizeof(char));
strncpy(newmount->path, path, strlen(path));
newmount->fs_type = FAT32;
mount_table[mount_pos] = newmount;
fs_table[newmount->fs_type].init(mount_pos);
}
void unmount_fs(const char *mount_point) {
int mount_pos;
for (mount_pos = 0; mount_pos < MOUNT_LIMIT; mount_pos++) {
if (mount_table[mount_pos] != NULL) {
if (strcmp(mount_table[mount_pos]->path, mount_point) == 0) {
fs_table[mount_table[mount_pos]->fs_type].teardown();
free(mount_table[mount_pos]->device_name);
free(mount_table[mount_pos]->path);
free(mount_table[mount_pos]);
mount_table[mount_pos] = NULL;
break;
}
}
}
}
/*
* Matches the path name to the actual mount point
*
* @param path Absolute path to the file
*
* @return Integer cooresponding to the position in the
* file mount table
*/
int get_device(const char *path) {
int best_match = -1;
int highest_char_match = -1;
for (int i = 0; i < MOUNT_LIMIT; i++) {
if (mount_table[i] != NULL) {
int match_count = 0;
for (int j = 0; j < strlen(mount_table[i]->path); j++) {
if (mount_table[i]->path[j] == path[j]) ++match_count;
}
if (match_count > highest_char_match) {highest_char_match = match_count; best_match = i;};
}
}
return best_match;
}
/*
* Insert a file/directory entry into the filetable
*/
int get_next_table_pos(void *table, int limit) {
for (int fpos = 0; fpos < FILE_LIMIT; fpos++) {
if (filetable[fpos].name == NULL) return fpos;
}
return -1;
}
void init_file(file_t *file, const char *name) {
char *npos = strrchr(name, '/'); int sz = strlen(++npos);
file->name = calloc(sz, sizeof(char));
strncpy(file->name, npos, sz);
file->path = calloc(strlen(name), sizeof(char));
strncpy(file->path, name, strlen(name));
file->device = get_device(name);
// byte offset in file
file->offset = 0;
file->size = 0;
}
void close_file(int pos) {
free(filetable[pos].name);
free(filetable[pos].path);
filetable[pos].device = 0;
filetable[pos].offset = 0;
filetable[pos].size = 0;
}
int opendir(const char *path) {
dir_t *dir = calloc(1, sizeof(dir_t));
dir->path = calloc(strlen(path), sizeof(char));
strncpy(dir->path, path, strlen(path));
dir->device = get_device(path);
dir->offset = 0;
int pos = get_next_table_pos(dirtable, FILE_LIMIT);
//printf("pos: %d\n", pos);
if (pos != -1) dirtable[pos] = dir;
return pos;
}
dir_entry_t readdir(int dir) {
dir_t *dir_info = dirtable[dir];
return fs_table[mount_table[dir_info->device]->fs_type].readdir(dir_info);
}
void changedir(char *dirname) {
file_t file;
file.name = strrchr(dirname, '/');
if (file.name == NULL) file.name = dirname;
else file.name++; // Increase 1 past the last /
file.path = dirname;
file.device = get_device(dirname);
file.offset = 0;
file.size = 0;
fs_table[mount_table[file.device]->fs_type].openfile(-1, &file, 1);
}
void closedir(int dir) {
if (dir > FILE_LIMIT) { return; }
// Flush All Changes Here
dir_t *directory = dirtable[dir];
dirtable[dir] = NULL;
if (directory->path != NULL) free(directory->path);
if (directory != NULL) free(directory);
}
int filecreate(const char *name) {
int pos = get_next_table_pos(filetable, FILE_LIMIT);
init_file(&filetable[pos], name);
mount_t *mp = mount_table[filetable[pos].device];
fs_table[mp->fs_type].createfile(pos, &filetable[pos]);
return 0;
}
int fileopen(const char *fname, int mode) {
int pos = get_next_table_pos(filetable, FILE_LIMIT);
init_file(&filetable[pos], fname);
mount_t *mp = mount_table[filetable[pos].device];
int npos = fs_table[mp->fs_type].openfile(pos, &filetable[pos], 0);
if (npos == -1) close_file(pos);
if (mode == APPEND) filetable[pos].offset += filetable[pos].size;
return npos;
}
int filewrite(int file, const char *buffer, int count) {
if (file > FILE_LIMIT) { return -1; }
file_t *fp = &(filetable[file]);
mount_t *mp = mount_table[fp->device];
return fs_table[mp->fs_type].write(file, buffer, count);
}
int fileread(int file, char *buffer, int count) {
if (file > FILE_LIMIT) { return -1; }
file_t *fp = &(filetable[file]);
mount_t *mp = mount_table[fp->device];
int num_read = fs_table[mp->fs_type].read(file, buffer, count);
if (num_read < count) buffer[num_read] = '\0';
return num_read;
}
int deletefile(char *file) {
/* Find file, set dir entry to 0xE5 */
/* Do NOT clear data/cluster */
file_t f;
f.name = file;
f.device = get_device(file);
fs_table[mount_table[f.device]->fs_type].deletefile(&f);
return 0;
}
void fileclose(int file) {
if (file > FILE_LIMIT) { return; }
// Flush All Changes Here
file_t *fp = &(filetable[file]);
//filetable[file] = NULL;
if (fp->name != NULL) free(fp->name);
}