archival/libarchive/open_transformer.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   4  */
   5
   6 #include "libbb.h"
   7 #include "bb_archive.h"
   8
   9 void FAST_FUNC init_transformer_state(transformer_state_t *xstate)
  10 {
  11         memset(xstate, 0, sizeof(*xstate));
  12 }
  13
  14 int FAST_FUNC check_signature16(transformer_state_t *xstate, unsigned magic16)
  15 {
  16         if (!xstate->signature_skipped) {
  17                 uint16_t magic2;
  18                 if (full_read(xstate->src_fd, &magic2, 2) != 2 || magic2 != magic16) {
  19                         bb_error_msg("invalid magic");
  20                         return -1;
  21                 }
  22                 xstate->signature_skipped = 2;
  23         }
  24         return 0;
  25 }
  26
  27 ssize_t FAST_FUNC transformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
  28 {
  29         ssize_t nwrote;
  30
  31         if (xstate->mem_output_size_max != 0) {
  32                 size_t pos = xstate->mem_output_size;
  33                 size_t size;
  34
  35                 size = (xstate->mem_output_size += bufsize);
  36                 if (size > xstate->mem_output_size_max) {
  37                         free(xstate->mem_output_buf);
  38                         xstate->mem_output_buf = NULL;
  39                         bb_perror_msg("buffer %u too small", (unsigned)xstate->mem_output_size_max);
  40                         nwrote = -1;
  41                         goto ret;
  42                 }
  43                 xstate->mem_output_buf = xrealloc(xstate->mem_output_buf, size + 1);
  44                 memcpy(xstate->mem_output_buf + pos, buf, bufsize);
  45                 xstate->mem_output_buf[size] = '\0';
  46                 nwrote = bufsize;
  47         } else {
  48                 nwrote = full_write(xstate->dst_fd, buf, bufsize);
  49                 if (nwrote != (ssize_t)bufsize) {
  50                         bb_perror_msg("write");
  51                         nwrote = -1;
  52                         goto ret;
  53                 }
  54         }
  55  ret:
  56         return nwrote;
  57 }
  58
  59 ssize_t FAST_FUNC xtransformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
  60 {
  61         ssize_t nwrote = transformer_write(xstate, buf, bufsize);
  62         if (nwrote != (ssize_t)bufsize) {
  63                 xfunc_die();
  64         }
  65         return nwrote;
  66 }
  67
  68 void check_errors_in_children(int signo)
  69 {
  70         int status;
  71
  72         if (!signo) {
  73                 /* block waiting for any child */
  74                 if (wait(&status) < 0)
  75 //FIXME: check EINTR?
  76                         return; /* probably there are no children */
  77                 goto check_status;
  78         }
  79
  80         /* Wait for any child without blocking */
  81         for (;;) {
  82                 if (wait_any_nohang(&status) < 0)
  83 //FIXME: check EINTR?
  84                         /* wait failed?! I'm confused... */
  85                         return;
  86  check_status:
  87                 /*if (WIFEXITED(status) && WEXITSTATUS(status) == 0)*/
  88                 /* On Linux, the above can be checked simply as: */
  89                 if (status == 0)
  90                         /* this child exited with 0 */
  91                         continue;
  92                 /* Cannot happen:
  93                 if (!WIFSIGNALED(status) && !WIFEXITED(status)) ???;
  94                  */
  95                 bb_got_signal = 1;
  96         }
  97 }
  98
  99 /* transformer(), more than meets the eye */
 100 #if BB_MMU
 101 void FAST_FUNC fork_transformer(int fd,
 102         int signature_skipped,
 103         IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_state_t *xstate)
 104 )
 105 #else
 106 void FAST_FUNC fork_transformer(int fd, const char *transform_prog)
 107 #endif
 108 {
 109         struct fd_pair fd_pipe;
 110         int pid;
 111
 112         xpiped_pair(fd_pipe);
 113         pid = BB_MMU ? xfork() : xvfork();
 114         if (pid == 0) {
 115                 /* Child */
 116                 close(fd_pipe.rd); /* we don't want to read from the parent */
 117                 // FIXME: error check?
 118 #if BB_MMU
 119                 {
 120                         IF_DESKTOP(long long) int r;
 121                         transformer_state_t xstate;
 122                         init_transformer_state(&xstate);
 123                         xstate.signature_skipped = signature_skipped;
 124                         xstate.src_fd = fd;
 125                         xstate.dst_fd = fd_pipe.wr;
 126                         r = transformer(&xstate);
 127                         if (ENABLE_FEATURE_CLEAN_UP) {
 128                                 close(fd_pipe.wr); /* send EOF */
 129                                 close(fd);
 130                         }
 131                         /* must be _exit! bug was actually seen here */
 132                         _exit(/*error if:*/ r < 0);
 133                 }
 134 #else
 135                 {
 136                         char *argv[4];
 137                         xmove_fd(fd, 0);
 138                         xmove_fd(fd_pipe.wr, 1);
 139                         argv[0] = (char*)transform_prog;
 140                         argv[1] = (char*)"-cf";
 141                         argv[2] = (char*)"-";
 142                         argv[3] = NULL;
 143                         BB_EXECVP(transform_prog, argv);
 144                         bb_perror_msg_and_die("can't execute '%s'", transform_prog);
 145                 }
 146 #endif
 147                 /* notreached */
 148         }
 149
 150         /* parent process */
 151         close(fd_pipe.wr); /* don't want to write to the child */
 152         xmove_fd(fd_pipe.rd, fd);
 153 }
 154
 155
 156 #if SEAMLESS_COMPRESSION
 157
 158 /* Used by e.g. rpm which gives us a fd without filename,
 159  * thus we can't guess the format from filename's extension.
 160  */
 161 static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_compressed)
 162 {
 163         union {
 164                 uint8_t b[4];
 165                 uint16_t b16[2];
 166                 uint32_t b32[1];
 167         } magic;
 168         transformer_state_t *xstate;
 169
 170         xstate = xzalloc(sizeof(*xstate));
 171         xstate->src_fd = fd;
 172         xstate->signature_skipped = 2;
 173
 174         /* .gz and .bz2 both have 2-byte signature, and their
 175          * unpack_XXX_stream wants this header skipped. */
 176         xread(fd, magic.b16, sizeof(magic.b16[0]));
 177         if (ENABLE_FEATURE_SEAMLESS_GZ
 178          && magic.b16[0] == GZIP_MAGIC
 179         ) {
 180                 xstate->xformer = unpack_gz_stream;
 181                 USE_FOR_NOMMU(xstate->xformer_prog = "gunzip";)
 182                 goto found_magic;
 183         }
 184         if (ENABLE_FEATURE_SEAMLESS_Z
 185          && magic.b16[0] == COMPRESS_MAGIC
 186         ) {
 187                 xstate->xformer = unpack_Z_stream;
 188                 USE_FOR_NOMMU(xstate->xformer_prog = "uncompress";)
 189                 goto found_magic;
 190         }
 191         if (ENABLE_FEATURE_SEAMLESS_BZ2
 192          && magic.b16[0] == BZIP2_MAGIC
 193         ) {
 194                 xstate->xformer = unpack_bz2_stream;
 195                 USE_FOR_NOMMU(xstate->xformer_prog = "bunzip2";)
 196                 goto found_magic;
 197         }
 198         if (ENABLE_FEATURE_SEAMLESS_XZ
 199          && magic.b16[0] == XZ_MAGIC1
 200         ) {
 201                 xstate->signature_skipped = 6;
 202                 xread(fd, magic.b32, sizeof(magic.b32[0]));
 203                 if (magic.b32[0] == XZ_MAGIC2) {
 204                         xstate->xformer = unpack_xz_stream;
 205                         USE_FOR_NOMMU(xstate->xformer_prog = "unxz";)
 206                         goto found_magic;
 207                 }
 208         }
 209
 210         /* No known magic seen */
 211         if (fail_if_not_compressed)
 212                 bb_error_msg_and_die("no gzip"
 213                         IF_FEATURE_SEAMLESS_BZ2("/bzip2")
 214                         IF_FEATURE_SEAMLESS_XZ("/xz")
 215                         " magic");
 216
 217         /* Some callers expect this function to "consume" fd
 218          * even if data is not compressed. In this case,
 219          * we return a state with trivial transformer.
 220          */
 221 //      USE_FOR_MMU(xstate->xformer = copy_stream;)
 222 //      USE_FOR_NOMMU(xstate->xformer_prog = "cat";)
 223
 224  found_magic:
 225         return xstate;
 226 }
 227
 228 /* Used by e.g. rpm which gives us a fd without filename,
 229  * thus we can't guess the format from filename's extension.
 230  */
 231 int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_compressed)
 232 {
 233         transformer_state_t *xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);
 234
 235         if (!xstate || !xstate->xformer) {
 236                 free(xstate);
 237                 return 1;
 238         }
 239
 240 # if BB_MMU
 241         fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
 242 # else
 243         /* NOMMU version of fork_transformer execs
 244          * an external unzipper that wants
 245          * file position at the start of the file.
 246          */
 247         xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
 248         xstate->signature_skipped = 0;
 249         fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
 250 # endif
 251         free(xstate);
 252         return 0;
 253 }
 254
 255 static transformer_state_t *open_transformer(const char *fname, int fail_if_not_compressed)
 256 {
 257         transformer_state_t *xstate;
 258         int fd;
 259
 260         fd = open(fname, O_RDONLY);
 261         if (fd < 0)
 262                 return NULL;
 263
 264         if (ENABLE_FEATURE_SEAMLESS_LZMA) {
 265                 /* .lzma has no header/signature, can only detect it by extension */
 266                 char *sfx = strrchr(fname, '.');
 267                 if (sfx && strcmp(sfx+1, "lzma") == 0) {
 268                         xstate = xzalloc(sizeof(*xstate));
 269                         xstate->src_fd = fd;
 270                         xstate->xformer = unpack_lzma_stream;
 271                         USE_FOR_NOMMU(xstate->xformer_prog = "unlzma";)
 272                         return xstate;
 273                 }
 274         }
 275
 276         xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);
 277
 278         return xstate;
 279 }
 280
 281 int FAST_FUNC open_zipped(const char *fname, int fail_if_not_compressed)
 282 {
 283         int fd;
 284         transformer_state_t *xstate;
 285
 286         xstate = open_transformer(fname, fail_if_not_compressed);
 287         if (!xstate)
 288                 return -1;
 289
 290         fd = xstate->src_fd;
 291 # if BB_MMU
 292         if (xstate->xformer) {
 293                 fork_transformer_with_no_sig(fd, xstate->xformer);
 294         } else {
 295                 /* the file is not compressed */
 296                 xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
 297                 xstate->signature_skipped = 0;
 298         }
 299 # else
 300         /* NOMMU can't avoid the seek :( */
 301         xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
 302         xstate->signature_skipped = 0;
 303         if (xstate->xformer) {
 304                 fork_transformer_with_sig(fd, xstate->xformer, xstate->xformer_prog);
 305         } /* else: the file is not compressed */
 306 # endif
 307
 308         free(xstate);
 309         return fd;
 310 }
 311
 312 void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
 313 {
 314 # if 1
 315         transformer_state_t *xstate;
 316         char *image;
 317
 318         xstate = open_transformer(fname, /*fail_if_not_compressed:*/ 0);
 319         if (!xstate) /* file open error */
 320                 return NULL;
 321
 322         image = NULL;
 323         if (xstate->xformer) {
 324                 /* In-memory decompression */
 325                 xstate->mem_output_size_max = maxsz_p ? *maxsz_p : (size_t)(INT_MAX - 4095);
 326                 xstate->xformer(xstate);
 327                 if (xstate->mem_output_buf) {
 328                         image = xstate->mem_output_buf;
 329                         if (maxsz_p)
 330                                 *maxsz_p = xstate->mem_output_size;
 331                 }
 332         } else {
 333                 /* File is not compressed */
 334                 image = xmalloc_read(xstate->src_fd, maxsz_p);
 335         }
 336
 337         if (!image)
 338                 bb_perror_msg("read error from '%s'", fname);
 339         close(xstate->src_fd);
 340         free(xstate);
 341         return image;
 342 # else
 343         /* This version forks a subprocess - much more expensive */
 344         int fd;
 345         char *image;
 346
 347         fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
 348         if (fd < 0)
 349                 return NULL;
 350
 351         image = xmalloc_read(fd, maxsz_p);
 352         if (!image)
 353                 bb_perror_msg("read error from '%s'", fname);
 354         close(fd);
 355         return image;
 356 # endif
 357 }
 358
 359 #endif /* SEAMLESS_COMPRESSION */