Add support for loading bzip2-compressed filesystems. Among other things

this would allow to load bzip2-compressed kernels/modules from the loader(8)
(support for that will be committer separately).

MFC after:	1 month

1 files changed, 297 insertions, 0 deletions

diff --git a/lib/libstand/bzipfs.c b/lib/libstand/bzipfs.c
new file mode 100644
index 0000000..749ea9d
--- /dev/null
+++ b/lib/libstand/bzipfs.c
@@ -0,0 +1,297 @@
+/* 
+ * Copyright (c) 1998 Michael Smith.
+ * Copyright (c) 2000 Maxim Sobolev
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ *
+ */
+
+#include "stand.h"
+
+#include <sys/stat.h>
+#include <string.h>
+#include <bzlib.h>
+
+#define BZ_BUFSIZE 2048	/* XXX larger? */
+
+struct bz_file
+{
+    int			bzf_rawfd;
+    bz_stream		bzf_bzstream;
+    char		bzf_buf[BZ_BUFSIZE];
+};
+
+static int	bzf_fill(struct bz_file *z);
+static int	bzf_open(const char *path, struct open_file *f);
+static int	bzf_close(struct open_file *f);
+static int	bzf_read(struct open_file *f, void *buf, size_t size, size_t *resid);
+static off_t	bzf_seek(struct open_file *f, off_t offset, int where);
+static int	bzf_stat(struct open_file *f, struct stat *sb);
+
+struct fs_ops bzipfs_fsops = {
+    "bzip",
+    bzf_open, 
+    bzf_close, 
+    bzf_read,
+    null_write,
+    bzf_seek,
+    bzf_stat,
+    null_readdir
+};
+
+#if 0
+void *
+calloc(int items, size_t size)
+{
+    return(malloc(items * size));
+}
+#endif
+
+static int
+bzf_fill(struct bz_file *bzf)
+{
+    int		result;
+    int		req;
+    
+    req = BZ_BUFSIZE - bzf->bzf_bzstream.avail_in;
+    result = 0;
+    
+    /* If we need more */
+    if (req > 0) {
+	/* move old data to bottom of buffer */
+	if (req < BZ_BUFSIZE)
+	    bcopy(bzf->bzf_buf + req, bzf->bzf_buf, BZ_BUFSIZE - req);
+	
+	/* read to fill buffer and update availibility data */
+	result = read(bzf->bzf_rawfd, bzf->bzf_buf + bzf->bzf_bzstream.avail_in, req);
+	bzf->bzf_bzstream.next_in = bzf->bzf_buf;
+	if (result >= 0)
+	    bzf->bzf_bzstream.avail_in += result;
+    }
+    return(result);
+}
+
+/*
+ * Adapted from get_byte/check_header in libz
+ *
+ * Returns 0 if the header is OK, nonzero if not.
+ */
+static int
+get_byte(struct bz_file *bzf)
+{
+    if ((bzf->bzf_bzstream.avail_in == 0) && (bzf_fill(bzf) == -1))
+	return(-1);
+    bzf->bzf_bzstream.avail_in--;
+    return(*(bzf->bzf_bzstream.next_in)++);
+}
+
+static int bz_magic[3] = {'B', 'Z', 'h'}; /* bzip2 magic header */
+
+static int
+check_header(struct bz_file *bzf)
+{
+    unsigned int len;
+    int		 c;
+
+    /* Check the bzip2 magic header */
+    for (len = 0; len < 3; len++) {
+	c = get_byte(bzf);
+	if (c != bz_magic[len]) {
+	    return(1);
+	}
+    }
+    /* Check that the block size is valid */
+    c = get_byte(bzf);
+    if (c < '1' || c > '9')
+	return(1);
+
+    /* Put back bytes that we've took from the input stream */
+    bzf->bzf_bzstream.next_in -= 4;
+    bzf->bzf_bzstream.avail_in += 4;
+
+    return(0);
+}
+	
+static int
+bzf_open(const char *fname, struct open_file *f)
+{
+    static char		*bzfname;
+    int			rawfd;
+    struct bz_file	*bzf;
+    char		*cp;
+    int			error;
+    struct stat		sb;
+
+    /* Have to be in "just read it" mode */
+    if (f->f_flags != F_READ)
+	return(EPERM);
+
+    /* If the name already ends in .gz or .bz2, ignore it */
+    if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".gz")
+	    || !strcmp(cp, ".bz2")))
+	return(ENOENT);
+
+    /* Construct new name */
+    bzfname = malloc(strlen(fname) + 5);
+    sprintf(bzfname, "%s.bz2", fname);
+
+    /* Try to open the compressed datafile */
+    rawfd = open(bzfname, O_RDONLY);
+    free(bzfname);
+    if (rawfd == -1)
+	return(ENOENT);
+
+    if (fstat(rawfd, &sb) < 0) {
+	printf("bzf_open: stat failed\n");
+	close(rawfd);
+	return(ENOENT);
+    }
+    if (!S_ISREG(sb.st_mode)) {
+	printf("bzf_open: not a file\n");
+	close(rawfd);
+	return(EISDIR);			/* best guess */
+    }
+
+    /* Allocate a bz_file structure, populate it */
+    bzf = malloc(sizeof(struct bz_file));
+    bzero(bzf, sizeof(struct bz_file));
+    bzf->bzf_rawfd = rawfd;
+
+    /* Verify that the file is bzipped (XXX why do this afterwards?) */
+    if (check_header(bzf)) {
+	close(bzf->bzf_rawfd);
+	BZ2_bzDecompressEnd(&(bzf->bzf_bzstream));
+	free(bzf);
+	return(EFTYPE);
+    }
+
+    /* Initialise the inflation engine */
+    if ((error = BZ2_bzDecompressInit(&(bzf->bzf_bzstream), 0, 1)) != BZ_OK) {
+	printf("bzf_open: BZ2_bzDecompressInit returned %d\n", error);
+	close(bzf->bzf_rawfd);
+	free(bzf);
+	return(EIO);
+    }
+
+    /* Looks OK, we'll take it */
+    f->f_fsdata = bzf;
+    return(0);
+}
+
+static int
+bzf_close(struct open_file *f)
+{
+    struct bz_file	*bzf = (struct bz_file *)f->f_fsdata;
+    
+    BZ2_bzDecompressEnd(&(bzf->bzf_bzstream));
+    close(bzf->bzf_rawfd);
+    free(bzf);
+    return(0);
+}
+ 
+static int 
+bzf_read(struct open_file *f, void *buf, size_t size, size_t *resid)
+{
+    struct bz_file	*bzf = (struct bz_file *)f->f_fsdata;
+    int			error;
+
+    bzf->bzf_bzstream.next_out = buf;			/* where and how much */
+    bzf->bzf_bzstream.avail_out = size;
+
+    while (bzf->bzf_bzstream.avail_out) {
+	if ((bzf->bzf_bzstream.avail_in == 0) && (bzf_fill(bzf) == -1)) {
+	    printf("bzf_read: fill error\n");
+	    return(-1);
+	}
+	if (bzf->bzf_bzstream.avail_in == 0) {		/* oops, unexpected EOF */
+	    printf("bzf_read: unexpected EOF\n");
+	    break;
+	}
+
+	error = BZ2_bzDecompress(&bzf->bzf_bzstream);	/* decompression pass */
+	if (error == BZ_STREAM_END) {			/* EOF, all done */
+	    break;
+	}
+	if (error != BZ_OK) {				/* argh, decompression error */
+	    printf("bzf_read: BZ2_bzDecompress returned %d\n", error);
+	    errno = EIO;
+	    return(-1);
+	}
+    }
+    if (resid != NULL)
+	*resid = bzf->bzf_bzstream.avail_out;
+    return(0);
+}
+
+static off_t
+bzf_seek(struct open_file *f, off_t offset, int where)
+{
+    struct bz_file	*bzf = (struct bz_file *)f->f_fsdata;
+    off_t		target;
+    char		discard[16];
+    
+    switch (where) {
+    case SEEK_SET:
+	target = offset;
+	break;
+    case SEEK_CUR:
+	target = offset + bzf->bzf_bzstream.total_out_lo32;
+	break;
+    default:
+	target = -1;
+    }
+
+    /* Can we get there from here? */
+    if (target < bzf->bzf_bzstream.total_out_lo32) {
+	errno = EOFFSET;
+	return -1;
+    } 
+
+    /* skip forwards if required */
+    while (target > bzf->bzf_bzstream.total_out_lo32) {
+	if (bzf_read(f, discard, min(sizeof(discard), target - bzf->bzf_bzstream.total_out_lo32), NULL) == -1)
+	    return(-1);
+    }
+    /* This is where we are (be honest if we overshot) */
+    return (bzf->bzf_bzstream.total_out_lo32);
+}
+
+static int
+bzf_stat(struct open_file *f, struct stat *sb)
+{
+    struct bz_file	*bzf = (struct bz_file *)f->f_fsdata;
+    int			result;
+
+    /* stat as normal, but indicate that size is unknown */
+    if ((result = fstat(bzf->bzf_rawfd, sb)) == 0)
+	sb->st_size = -1;
+    return(result);
+}
+
+void
+bz_internal_error(int errorcode)
+{
+    panic("bzipfs: critical error %d in bzip2 library occured\n", errorcode);
+}