From 642b5fb0007b64c77d186fcb018d571152ee1d47 Mon Sep 17 00:00:00 2001 From: dzwdz Date: Mon, 14 Aug 2023 18:51:07 +0200 Subject: reorganization: first steps --- src/bootstrap/tar.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 155 insertions(+) create mode 100644 src/bootstrap/tar.c (limited to 'src/bootstrap/tar.c') diff --git a/src/bootstrap/tar.c b/src/bootstrap/tar.c new file mode 100644 index 0000000..2020fe0 --- /dev/null +++ b/src/bootstrap/tar.c @@ -0,0 +1,155 @@ +#include "tar.h" +#include +#include +#include +#include +#include +#include +#include +#include + +#define BUF_SIZE 64 + +static void *tar_open(const char *path, int len, void *base, size_t base_len); +static char tar_type(void *meta); +static void tar_dirbuild(struct dirbuild *db, const char *meta, void *base, size_t base_len); +static void tar_read(struct ufs_request *res, void *base, size_t base_len); +static int tar_size(void *sector); +static int oct_parse(char *str, size_t len); + + +static const char *root_fakemeta = ""; /* see comment in tar_open */ + + +void tar_driver(void *base) { + static char buf[BUF_SIZE]; + struct ufs_request res; + void *ptr; + while (!c0_fs_wait(buf, BUF_SIZE, &res)) { + switch (res.op) { + case VFSOP_OPEN: + ptr = tar_open(buf, res.len, base, ~0); + c0_fs_respond(ptr, ptr ? 0 : -1, 0); + break; + + case VFSOP_READ: + tar_read(&res, base, ~0); + break; + + case VFSOP_GETSIZE: + if (tar_type(res.id) != '5') { + c0_fs_respond(NULL, tar_size(res.id), 0); + } else { + struct dirbuild db; + dir_start(&db, res.offset, NULL, 0); + tar_dirbuild(&db, res.id, base, ~0); + c0_fs_respond(NULL, dir_finish(&db), 0); + } + break; + + default: + c0_fs_respond(NULL, -1, 0); // unsupported + break; + } + } + exit(0); +} + +static char tar_type(void *meta) { + if (meta == root_fakemeta) return '5'; + return *(char*)(meta + 156); +} + +static void *tar_open(const char *path, int len, void *base, size_t base_len) { + if (len <= 0) return NULL; + path += 1; // skip the leading slash + len -= 1; + + /* TAR archives don't (seem to) contain an entry for the root dir, so i'm + * returning a fake one. this isn't a full entry because i'm currently too + * lazy to create a full one - thus, it has to be special cased in tar_read */ + if (len == 0) + return (void*)root_fakemeta; + + return tar_find(path, len, base, base_len); +} + +static void tar_dirbuild(struct dirbuild *db, const char *meta, void *base, size_t base_len) { + size_t meta_len = strlen(meta); + for (size_t off = 0; off < base_len;) { + if (0 != memcmp(base + off + 257, "ustar", 5)) + break; // not a metadata sector + + /* check if prefix matches */ + if (0 == memcmp(base + off, meta, meta_len) + && *(char*)(base + off + meta_len) != '\0') { + char *suffix = base + off + meta_len; + + /* check if the path contains any non-trailing slashes */ + char *slash = strchr(suffix, '/'); + if (!slash || slash[1] == '\0') { + if (dir_append(db, suffix)) break; + } + } + + int size = tar_size(base + off); + off += 512; // skip this metadata sector + off += (size + 511) & ~511; // skip the data sectors + } +} + +static void tar_read(struct ufs_request *res, void *base, size_t base_len) { + void *meta = (void*)res->id; + static char buf[BUF_SIZE]; + // TODO reuse a single buffer for both tar_driver and tar_read + + switch (tar_type(meta)) { + case '\0': + case '0': /* normal files */ + fs_normslice(&res->offset, &res->len, tar_size(meta), false); + c0_fs_respond(meta + 512 + res->offset, res->len, 0); + break; + + case '5': /* directory */ + struct dirbuild db; + dir_start(&db, res->offset, buf, sizeof buf); + tar_dirbuild(&db, meta, base, base_len); + c0_fs_respond(buf, dir_finish(&db), 0); + break; + + default: + c0_fs_respond(NULL, -1, 0); + break; + } +} + +static int tar_size(void *sector) { + return oct_parse(sector + 124, 11); +} + +void *tar_find(const char *path, size_t path_len, void *base, size_t base_len) { + int size; + if (path_len > 100) return NULL; // illegal path + + for (size_t off = 0; off < base_len;) { + if (0 != memcmp(base + off + 257, "ustar", 5)) + break; // not a metadata sector + if (0 == memcmp(base + off, path, path_len) && + *(char*)(base + off + path_len) == '\0') + return base + off; // file found, quit + + size = tar_size(base + off); + off += 512; // skip this metadata sector + off += (size + 511) & ~511; // skip the data sectors + } + return NULL; +} + +static int oct_parse(char *str, size_t len) { + int res = 0; + for (size_t i = 0; i < len; i++) { + res *= 8; + res += str[i] - '0'; // no format checking + } + return res; +} -- cgit v1.2.3