source: MondoRescue/branches/3.2/mindi-busybox/archival/libarchive/open_transformer.c@ 3232

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include "libbb.h"
#include "bb_archive.h"

void FAST_FUNC init_transformer_aux_data(transformer_aux_data_t *aux)
{
    memset(aux, 0, sizeof(*aux));
}

int FAST_FUNC check_signature16(transformer_aux_data_t *aux, int src_fd, unsigned magic16)
{
    if (aux && aux->check_signature) {
        uint16_t magic2;
        if (full_read(src_fd, &magic2, 2) != 2 || magic2 != magic16) {
            bb_error_msg("invalid magic");
#if 0 /* possible future extension */
            if (aux->check_signature > 1)
                xfunc_die();
#endif
            return -1;
        }
    }
    return 0;
}

void check_errors_in_children(int signo)
{
    int status;

    if (!signo) {
        /* block waiting for any child */
        if (wait(&status) < 0)
            return; /* probably there are no children */
        goto check_status;
    }

    /* Wait for any child without blocking */
    for (;;) {
        if (wait_any_nohang(&status) < 0)
            /* wait failed?! I'm confused... */
            return;
 check_status:
        if (WIFEXITED(status) && WEXITSTATUS(status) == 0)
            /* this child exited with 0 */
            continue;
        /* Cannot happen?
        if (!WIFSIGNALED(status) && !WIFEXITED(status)) ???; */
        bb_got_signal = 1;
    }
}

/* transformer(), more than meets the eye */
#if BB_MMU
void FAST_FUNC open_transformer(int fd,
    int check_signature,
    IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_aux_data_t *aux, int src_fd, int dst_fd)
)
#else
void FAST_FUNC open_transformer(int fd, const char *transform_prog)
#endif
{
    struct fd_pair fd_pipe;
    int pid;

    xpiped_pair(fd_pipe);
    pid = BB_MMU ? xfork() : xvfork();
    if (pid == 0) {
        /* Child */
        close(fd_pipe.rd); /* we don't want to read from the parent */
        // FIXME: error check?
#if BB_MMU
        {
            transformer_aux_data_t aux;
            init_transformer_aux_data(&aux);
            aux.check_signature = check_signature;
            transformer(&aux, fd, fd_pipe.wr);
            if (ENABLE_FEATURE_CLEAN_UP) {
                close(fd_pipe.wr); /* send EOF */
                close(fd);
            }
            /* must be _exit! bug was actually seen here */
            _exit(EXIT_SUCCESS);
        }
#else
        {
            char *argv[4];
            xmove_fd(fd, 0);
            xmove_fd(fd_pipe.wr, 1);
            argv[0] = (char*)transform_prog;
            argv[1] = (char*)"-cf";
            argv[2] = (char*)"-";
            argv[3] = NULL;
            BB_EXECVP(transform_prog, argv);
            bb_perror_msg_and_die("can't execute '%s'", transform_prog);
        }
#endif
        /* notreached */
    }

    /* parent process */
    close(fd_pipe.wr); /* don't want to write to the child */
    xmove_fd(fd_pipe.rd, fd);
}


#if SEAMLESS_COMPRESSION

/* Used by e.g. rpm which gives us a fd without filename,
 * thus we can't guess the format from filename's extension.
 */
int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_detected)
{
    union {
        uint8_t b[4];
        uint16_t b16[2];
        uint32_t b32[1];
    } magic;
    int offset = -2;
    USE_FOR_MMU(IF_DESKTOP(long long) int FAST_FUNC (*xformer)(transformer_aux_data_t *aux, int src_fd, int dst_fd);)
    USE_FOR_NOMMU(const char *xformer_prog;)

    /* .gz and .bz2 both have 2-byte signature, and their
     * unpack_XXX_stream wants this header skipped. */
    xread(fd, magic.b16, sizeof(magic.b16[0]));
    if (ENABLE_FEATURE_SEAMLESS_GZ
     && magic.b16[0] == GZIP_MAGIC
    ) {
        USE_FOR_MMU(xformer = unpack_gz_stream;)
        USE_FOR_NOMMU(xformer_prog = "gunzip";)
        goto found_magic;
    }
    if (ENABLE_FEATURE_SEAMLESS_BZ2
     && magic.b16[0] == BZIP2_MAGIC
    ) {
        USE_FOR_MMU(xformer = unpack_bz2_stream;)
        USE_FOR_NOMMU(xformer_prog = "bunzip2";)
        goto found_magic;
    }
    if (ENABLE_FEATURE_SEAMLESS_XZ
     && magic.b16[0] == XZ_MAGIC1
    ) {
        offset = -6;
        xread(fd, magic.b32, sizeof(magic.b32[0]));
        if (magic.b32[0] == XZ_MAGIC2) {
            USE_FOR_MMU(xformer = unpack_xz_stream;)
            USE_FOR_NOMMU(xformer_prog = "unxz";)
            goto found_magic;
        }
    }

    /* No known magic seen */
    if (fail_if_not_detected)
        bb_error_msg_and_die("no gzip"
            IF_FEATURE_SEAMLESS_BZ2("/bzip2")
            IF_FEATURE_SEAMLESS_XZ("/xz")
            " magic");
    xlseek(fd, offset, SEEK_CUR);
    return 1;

 found_magic:
# if BB_MMU
    open_transformer_with_no_sig(fd, xformer);
# else
    /* NOMMU version of open_transformer execs
     * an external unzipper that wants
     * file position at the start of the file */
    xlseek(fd, offset, SEEK_CUR);
    open_transformer_with_sig(fd, xformer, xformer_prog);
# endif
    return 0;
}

int FAST_FUNC open_zipped(const char *fname)
{
    char *sfx;
    int fd;

    fd = open(fname, O_RDONLY);
    if (fd < 0)
        return fd;

    sfx = strrchr(fname, '.');
    if (sfx) {
        sfx++;
        if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0)
            /* .lzma has no header/signature, just trust it */
            open_transformer_with_sig(fd, unpack_lzma_stream, "unlzma");
        else
        if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0)
         || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0)
         || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0)
        ) {
            setup_unzip_on_fd(fd, /*fail_if_not_detected:*/ 1);
        }
    }

    return fd;
}

#endif /* SEAMLESS_COMPRESSION */

void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
{
    int fd;
    char *image;

    fd = open_zipped(fname);
    if (fd < 0)
        return NULL;

    image = xmalloc_read(fd, maxsz_p);
    if (!image)
        bb_perror_msg("read error from '%s'", fname);
    close(fd);

    return image;
}