/* 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_state(transformer_state_t *xstate)
{
        memset(xstate, 0, sizeof(*xstate));
}

int FAST_FUNC check_signature16(transformer_state_t *xstate, unsigned magic16)
{
        if (!xstate->signature_skipped) {
                uint16_t magic2;
                if (full_read(xstate->src_fd, &magic2, 2) != 2 || magic2 != magic16) {
                        bb_error_msg("invalid magic");
                        return -1;
                }
                xstate->signature_skipped = 2;
        }
        return 0;
}

ssize_t FAST_FUNC transformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
{
        ssize_t nwrote;

        if (xstate->mem_output_size_max != 0) {
                size_t pos = xstate->mem_output_size;
                size_t size;

                size = (xstate->mem_output_size += bufsize);
                if (size > xstate->mem_output_size_max) {
                        free(xstate->mem_output_buf);
                        xstate->mem_output_buf = NULL;
                        bb_perror_msg("buffer %u too small", (unsigned)xstate->mem_output_size_max);
                        nwrote = -1;
                        goto ret;
                }
                xstate->mem_output_buf = xrealloc(xstate->mem_output_buf, size + 1);
                memcpy(xstate->mem_output_buf + pos, buf, bufsize);
                xstate->mem_output_buf[size] = '\0';
                nwrote = bufsize;
        } else {
                nwrote = full_write(xstate->dst_fd, buf, bufsize);
                if (nwrote != (ssize_t)bufsize) {
                        bb_perror_msg("write");
                        nwrote = -1;
                        goto ret;
                }
        }
 ret:
        return nwrote;
}

ssize_t FAST_FUNC xtransformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
{
        ssize_t nwrote = transformer_write(xstate, buf, bufsize);
        if (nwrote != (ssize_t)bufsize) {
                xfunc_die();
        }
        return nwrote;
}

void check_errors_in_children(int signo)
{
        int status;

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

        /* Wait for any child without blocking */
        for (;;) {
                if (wait_any_nohang(&status) < 0)
//FIXME: check EINTR?
                        /* wait failed?! I'm confused... */
                        return;
 check_status:
                /*if (WIFEXITED(status) && WEXITSTATUS(status) == 0)*/
                /* On Linux, the above can be checked simply as: */
                if (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 fork_transformer(int fd,
        int signature_skipped,
        IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_state_t *xstate)
)
#else
void FAST_FUNC fork_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
                {
                        IF_DESKTOP(long long) int r;
                        transformer_state_t xstate;
                        init_transformer_state(&xstate);
                        xstate.signature_skipped = signature_skipped;
                        xstate.src_fd = fd;
                        xstate.dst_fd = fd_pipe.wr;
                        r = transformer(&xstate);
                        if (ENABLE_FEATURE_CLEAN_UP) {
                                close(fd_pipe.wr); /* send EOF */
                                close(fd);
                        }
                        /* must be _exit! bug was actually seen here */
                        _exit(/*error if:*/ r < 0);
                }
#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.
 */
static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_compressed)
{
        transformer_state_t *xstate;

        xstate = xzalloc(sizeof(*xstate));
        xstate->src_fd = fd;

        /* .gz and .bz2 both have 2-byte signature, and their
         * unpack_XXX_stream wants this header skipped. */
        xstate->signature_skipped = 2;
        xread(fd, xstate->magic.b16, 2);
        if (ENABLE_FEATURE_SEAMLESS_GZ
         && xstate->magic.b16[0] == GZIP_MAGIC
        ) {
                xstate->xformer = unpack_gz_stream;
                USE_FOR_NOMMU(xstate->xformer_prog = "gunzip";)
                goto found_magic;
        }
        if (ENABLE_FEATURE_SEAMLESS_Z
         && xstate->magic.b16[0] == COMPRESS_MAGIC
        ) {
                xstate->xformer = unpack_Z_stream;
                USE_FOR_NOMMU(xstate->xformer_prog = "uncompress";)
                goto found_magic;
        }
        if (ENABLE_FEATURE_SEAMLESS_BZ2
         && xstate->magic.b16[0] == BZIP2_MAGIC
        ) {
                xstate->xformer = unpack_bz2_stream;
                USE_FOR_NOMMU(xstate->xformer_prog = "bunzip2";)
                goto found_magic;
        }
        if (ENABLE_FEATURE_SEAMLESS_XZ
         && xstate->magic.b16[0] == XZ_MAGIC1
        ) {
                uint32_t v32;
                xstate->signature_skipped = 6;
                xread(fd, &xstate->magic.b16[1], 4);
                move_from_unaligned32(v32, &xstate->magic.b16[1]);
                if (v32 == XZ_MAGIC2) {
                        xstate->xformer = unpack_xz_stream;
                        USE_FOR_NOMMU(xstate->xformer_prog = "unxz";)
                        goto found_magic;
                }
        }

        /* No known magic seen */
        if (fail_if_not_compressed)
                bb_error_msg_and_die("no gzip"
                        IF_FEATURE_SEAMLESS_BZ2("/bzip2")
                        IF_FEATURE_SEAMLESS_XZ("/xz")
                        " magic");

        /* Some callers expect this function to "consume" fd
         * even if data is not compressed. In this case,
         * we return a state with trivial transformer.
         */
//      USE_FOR_MMU(xstate->xformer = copy_stream;)
//      USE_FOR_NOMMU(xstate->xformer_prog = "cat";)

 found_magic:
        return xstate;
}

static void fork_transformer_and_free(transformer_state_t *xstate)
{
# if BB_MMU
        fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
# else
        /* NOMMU version of fork_transformer execs
         * an external unzipper that wants
         * file position at the start of the file.
         */
        xlseek(xstate->src_fd, - xstate->signature_skipped, SEEK_CUR);
        xstate->signature_skipped = 0;
        fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
# endif
        free(xstate);
}

/* 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_compressed)
{
        transformer_state_t *xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);

        if (!xstate->xformer) {
                free(xstate);
                return 1;
        }

        fork_transformer_and_free(xstate);
        return 0;
}
#if ENABLE_FEATURE_SEAMLESS_LZMA
/* ...and custom version for LZMA */
void FAST_FUNC setup_lzma_on_fd(int fd)
{
        transformer_state_t *xstate = xzalloc(sizeof(*xstate));
        xstate->src_fd = fd;
        xstate->xformer = unpack_lzma_stream;
        USE_FOR_NOMMU(xstate->xformer_prog = "unlzma";)
        fork_transformer_and_free(xstate);
}
#endif

static transformer_state_t *open_transformer(const char *fname, int fail_if_not_compressed)
{
        transformer_state_t *xstate;
        int fd;

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

        if (ENABLE_FEATURE_SEAMLESS_LZMA) {
                /* .lzma has no header/signature, can only detect it by extension */
                if (is_suffixed_with(fname, ".lzma")) {
                        xstate = xzalloc(sizeof(*xstate));
                        xstate->src_fd = fd;
                        xstate->xformer = unpack_lzma_stream;
                        USE_FOR_NOMMU(xstate->xformer_prog = "unlzma";)
                        return xstate;
                }
        }

        xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);

        return xstate;
}

int FAST_FUNC open_zipped(const char *fname, int fail_if_not_compressed)
{
        int fd;
        transformer_state_t *xstate;

        xstate = open_transformer(fname, fail_if_not_compressed);
        if (!xstate)
                return -1;

        fd = xstate->src_fd;
# if BB_MMU
        if (xstate->xformer) {
                fork_transformer_with_no_sig(fd, xstate->xformer);
        } else {
                /* the file is not compressed */
                xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
                xstate->signature_skipped = 0;
        }
# else
        /* NOMMU can't avoid the seek :( */
        xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
        xstate->signature_skipped = 0;
        if (xstate->xformer) {
                fork_transformer_with_sig(fd, xstate->xformer, xstate->xformer_prog);
        } /* else: the file is not compressed */
# endif

        free(xstate);
        return fd;
}

void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
{
# if 1
        transformer_state_t *xstate;
        char *image;

        xstate = open_transformer(fname, /*fail_if_not_compressed:*/ 0);
        if (!xstate) /* file open error */
                return NULL;

        image = NULL;
        if (xstate->xformer) {
                /* In-memory decompression */
                xstate->mem_output_size_max = maxsz_p ? *maxsz_p : (size_t)(INT_MAX - 4095);
                xstate->xformer(xstate);
                if (xstate->mem_output_buf) {
                        image = xstate->mem_output_buf;
                        if (maxsz_p)
                                *maxsz_p = xstate->mem_output_size;
                }
        } else {
                /* File is not compressed.
                 * We already read first few bytes, account for that.
                 * Example where it happens:
                 * "modinfo MODULE.ko" (not compressed)
                 *   open("MODULE.ko", O_RDONLY|O_LARGEFILE) = 4
                 *   read(4, "\177E", 2)                     = 2
                 *   fstat64(4, ...)
                 *   mmap(...)
                 *   read(4, "LF\2\1\1\0\0\0\0"...
                 * ...and we avoided seeking on the fd! :)
                 */
                image = xmalloc_read_with_initial_buf(
                        xstate->src_fd,
                        maxsz_p,
                        xmemdup(&xstate->magic, xstate->signature_skipped),
                        xstate->signature_skipped
                );
                xstate->signature_skipped = 0;
        }

        if (!image)
                bb_perror_msg("read error from '%s'", fname);
        close(xstate->src_fd);
        free(xstate);
        return image;
# else
        /* This version forks a subprocess - much more expensive */
        int fd;
        char *image;

        fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
        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;
# endif
}

#endif /* SEAMLESS_COMPRESSION */