diff options
Diffstat (limited to 'kernel/fs/tar.c')
| -rw-r--r-- | kernel/fs/tar.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/kernel/fs/tar.c b/kernel/fs/tar.c new file mode 100644 index 0000000..7f34107 --- /dev/null +++ b/kernel/fs/tar.c @@ -0,0 +1,262 @@ +#include <comus/fs.h> +#include <lib.h> + +struct tar_hdr { + char name[100]; + char mode[8]; + char uid[8]; + char gid[8]; + char size[12]; + char mtime[12]; + char chksum[8]; + char typeflag; + char linkname[100]; + char magic[6]; + char version[2]; + char uname[32]; + char gname[32]; + char devmajor[8]; + char devminor[8]; + char prefix[155]; + char unused[12]; +}; + +struct tar_file { + struct file file; + struct file_system *fs; + size_t len; + size_t offset; + size_t sect; +}; + +#define TAR_SECT_SIZE 512 + +#define TMAGIC "ustar" +#define TMAGLEN 6 +#define TVERSION "00" +#define TVERSLEN 2 + +#define REGTYPE '0' +#define DIRTYPE '5' + +static int read_tar_hdr(struct disk *disk, uint32_t sect, struct tar_hdr *hdr) +{ + if (disk_read(disk, sect * TAR_SECT_SIZE, TAR_SECT_SIZE, hdr) < + TAR_SECT_SIZE) + return 1; + + // check magic + if (memcmp(hdr->magic, TMAGIC, TMAGLEN) != 0) + return 1; + + // check version + if (memcmp(hdr->version, TVERSION, TVERSLEN) != 0) + return 1; + + return 0; +} + +static int tar_to_fs_type(char typeflag) +{ + switch (typeflag) { + case REGTYPE: + return F_REG; + case DIRTYPE: + return F_DIR; + default: + return -1; + } +} + +static int tar_locate(struct file_system *fs, const char *path, + struct tar_hdr *out_hdr, size_t *out_sect, + size_t *in_sect, bool partial) +{ + struct tar_hdr hdr; + size_t sect = 0; + + if (in_sect != NULL) + sect = *in_sect; + + while (1) { + size_t filesize, sects; + int cmp; + + if (read_tar_hdr(fs->fs_disk, sect, &hdr)) + return 1; + + filesize = strtoull(hdr.size, NULL, 8); + sects = (filesize + TAR_SECT_SIZE - 1) / TAR_SECT_SIZE; + + if (partial) { + size_t len = MIN(strlen(path), strlen(hdr.name)); + cmp = memcmp(hdr.name, path, len); + } else { + cmp = memcmp(hdr.name, path, strlen(path) + 1); + } + + if (cmp) { + // not our file, goto next + sect += sects + 1; + continue; + } + + // we found our file! + *out_hdr = hdr; + *out_sect = sect; + if (in_sect != NULL) + *in_sect = sect + sects + 1; + return 0; + } + + return 1; +} + +int tar_read(struct file *in, char *buf, size_t len) +{ + struct tar_file *file = (struct tar_file *)in; + size_t max_bytes = file->len - file->offset; + long bytes = MIN(max_bytes, len); + + if (file->file.f_type != F_REG) + return 1; + + if (bytes < 1) + return 0; + + bytes = disk_read(file->fs->fs_disk, + (file->sect + 1) * TAR_SECT_SIZE + file->offset, bytes, + buf); + if (bytes < 0) + return bytes; // return err code + + file->offset += bytes; + return bytes; +} + +int tar_write(struct file *in, const char *buf, size_t len) +{ + (void)in; + (void)buf; + (void)len; + + // cannot write to tar balls + return -1; +} + +int tar_seek(struct file *in, long int off, int whence) +{ + struct tar_file *file = (struct tar_file *)in; + switch (whence) { + case SEEK_SET: + file->offset = off; + return 0; + case SEEK_CUR: + file->offset += off; + return 0; + case SEEK_END: + file->offset = file->len + off; + return 0; + default: + return 1; + } +} + +int tar_ents(struct file *in, struct dirent *ent, size_t entry) +{ + struct tar_file *file; + struct tar_hdr dir, hdr; + size_t sect; + size_t sect_off = 0; + size_t idx = 0; + + file = (struct tar_file *)in; + sect = 0; + + if (file->file.f_type != F_DIR) + return -1; + + if (read_tar_hdr(file->fs->fs_disk, sect, &dir)) + return 1; + + while (1) { + if (tar_locate(file->fs, dir.name, &hdr, §, §_off, true)) + return 1; + + if (idx != entry) { + idx++; + continue; + } + + ent->d_offset = entry; + ent->d_namelen = strlen(hdr.name); + memcpy(ent->d_name, hdr.name, ent->d_namelen + 1); + return 0; + } + + return 1; +} + +void tar_close(struct file *file) +{ + kfree(file); +} + +int tar_open(struct file_system *fs, const char *path, struct file **out) +{ + struct tar_file *file; + struct tar_hdr hdr; + size_t sect; + + if (tar_locate(fs, path, &hdr, §, NULL, false)) + return 1; + + file = kalloc(sizeof(struct tar_file)); + if (file == NULL) + return 1; + + file->file.f_type = tar_to_fs_type(hdr.typeflag); + file->file.read = tar_read; + file->file.write = tar_write; + file->file.seek = tar_seek; + file->file.ents = tar_ents; + file->file.close = tar_close; + file->fs = fs; + file->len = strtoull(hdr.size, NULL, 8); + file->offset = 0; + file->sect = sect; + *out = (struct file *)file; + + return 0; +} + +int tar_stat(struct file_system *fs, const char *path, struct stat *stat) +{ + struct tar_hdr hdr; + size_t sect; + + if (tar_locate(fs, path, &hdr, §, NULL, false)) + return 1; + + stat->s_length = strtoull(hdr.size, NULL, 8); + stat->s_type = tar_to_fs_type(hdr.typeflag); + + return 0; +} + +int tar_mount(struct file_system *fs) +{ + struct tar_hdr hdr; + + // if first tar hdr is valid, assume valid tarball + if (read_tar_hdr(fs->fs_disk, 0, &hdr)) + return 1; + + fs->fs_present = true; + fs->fs_name = "tar"; + fs->open = tar_open; + fs->stat = tar_stat; + + INFO("loaded tarfs on disk %d", fs->fs_disk->d_id); + return 0; +} |