lib/libstand/pkgfs.c

	pkgfs.c revision 199767f8919635c4928607450d9e0abb932109ce
/*-
 * Copyright (c) 2007-2014, Juniper Networks, Inc.
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "stand.h"

#include <sys/stat.h>
#include <sys/stdint.h>
#include <string.h>
#include <zlib.h>

#ifdef PKGFS_DEBUG
#define DBG(x)  printf x
#else
#define DBG(x)
#endif

static int   pkg_open(const char *, struct open_file *);
static int   pkg_close(struct open_file *);
static int   pkg_read(struct open_file *, void *, size_t, size_t *);
static off_t pkg_seek(struct open_file *, off_t, int);
static int   pkg_stat(struct open_file *, struct stat *);
static int   pkg_readdir(struct open_file *, struct dirent *);

struct fs_ops pkgfs_fsops = {
    "pkg",
    pkg_open,
    pkg_close,
    pkg_read,
    null_write,
    pkg_seek,
    pkg_stat,
    pkg_readdir
};

#define PKG_BUFSIZE 512
#define PKG_MAXCACHESZ  4096

#define PKG_FILEEXT ".tgz"

/*
 * Layout of POSIX 'ustar' header.
 */
struct ustar_hdr {
    char    ut_name[100];
    char    ut_mode[8];
    char    ut_uid[8];
    char    ut_gid[8];
    char    ut_size[12];
    char    ut_mtime[12];
    char    ut_checksum[8];
    char    ut_typeflag[1];
    char    ut_linkname[100];
    char    ut_magic[6];        /* For POSIX: "ustar\0" */
    char    ut_version[2];      /* For POSIX: "00" */
    char    ut_uname[32];
    char    ut_gname[32];
    char    ut_rdevmajor[8];
    char    ut_rdevminor[8];
    union {
        struct {
            char    prefix[155];
        } posix;
        struct {
            char    atime[12];
            char    ctime[12];
            char    offset[12];
            char    longnames[4];
            char    unused[1];
            struct gnu_sparse {
                char    offset[12];
                char    numbytes[12];
            } sparse[4];
            char    isextended[1];
            char    realsize[12];
        } gnu;
    } u;
    u_char __padding[12];
};

struct package;

struct tarfile
{
    struct package *tf_pkg;
    struct tarfile *tf_next;
    struct ustar_hdr tf_hdr;
    off_t   tf_ofs;
    off_t   tf_size;
    off_t   tf_fp;
    size_t  tf_cachesz;
    void    *tf_cache;
};

struct package
{
    struct package *pkg_chain;
    int pkg_fd;
    off_t   pkg_ofs;
    z_stream pkg_zs;
    struct tarfile *pkg_first;
    struct tarfile *pkg_last;
    u_char  pkg_buf[PKG_BUFSIZE];
};

static struct package *package = NULL;

static int new_package(int, struct package **);

void
pkgfs_cleanup(void)
{
    struct package *chain;
    struct tarfile *tf, *tfn;

    while (package != NULL) {
        inflateEnd(&package->pkg_zs);
        close(package->pkg_fd);

        tf = package->pkg_first;
        while (tf != NULL) {
            tfn = tf->tf_next;
            if (tf->tf_cachesz > 0)
                free(tf->tf_cache);
            free(tf);
            tf = tfn;
        }

        chain = package->pkg_chain;
        free(package);
        package = chain;
    }
}

int
pkgfs_init(const char *pkgname, struct fs_ops *proto)
{
    struct package *pkg;
    int error, fd;

    if (proto != &pkgfs_fsops)
        pkgfs_cleanup();

    exclusive_file_system = proto;

    fd = open(pkgname, O_RDONLY);

    exclusive_file_system = NULL;

    if (fd == -1)
        return (errno);

    error = new_package(fd, &pkg);
    if (error) {
        close(fd);
        return (error);
    }

    if (pkg == NULL)
        return (EDOOFUS);

    pkg->pkg_chain = package;
    package = pkg;
    exclusive_file_system = &pkgfs_fsops;
    return (0);
}

static int get_mode(struct tarfile *);
static int get_zipped(struct package *, void *, size_t);
static int new_package(int, struct package **);
static struct tarfile *scan_tarfile(struct package *, struct tarfile *);

static int
pkg_open(const char *fn, struct open_file *f)
{
    struct tarfile *tf;

    if (fn == NULL || f == NULL)
        return (EINVAL);

    if (package == NULL)
        return (ENXIO);

    /*
     * We can only read from a package, so reject request to open
     * for write-only or read-write.
     */
    if (f->f_flags != F_READ)
        return (EPERM);

    /*
     * Scan the file headers for the named file. We stop scanning
     * at the first filename that has the .pkg extension. This is
     * a package within a package. We assume we have all the files
     * we need up-front and without having to dig within nested
     * packages.
     *
     * Note that we preserve streaming properties as much as possible.
     */
    while (*fn == '/')
        fn++;

    /*
     * Allow opening of the root directory for use by readdir()
     * to support listing files in the package.
     */
    if (*fn == '\0') {
        f->f_fsdata = NULL;
        return (0);
    }

    tf = scan_tarfile(package, NULL);
    while (tf != NULL) {
        if (strcmp(fn, tf->tf_hdr.ut_name) == 0) {
            f->f_fsdata = tf;
            tf->tf_fp = 0;  /* Reset the file pointer. */
            return (0);
        }
        tf = scan_tarfile(package, tf);
    }
    return (errno);
}

static int
pkg_close(struct open_file *f)
{
    struct tarfile *tf;

    tf = (struct tarfile *)f->f_fsdata;
    if (tf == NULL)
        return (0);

    /*
     * Free up the cache if we read all of the file.
     */
    if (tf->tf_fp == tf->tf_size && tf->tf_cachesz > 0) {
        free(tf->tf_cache);
        tf->tf_cachesz = 0;
    }
    return (0);
}

static int
pkg_read(struct open_file *f, void *buf, size_t size, size_t *res)
{
    struct tarfile *tf;
    char *p;
    off_t fp;
    size_t sz;

    tf = (struct tarfile *)f->f_fsdata;
    if (tf == NULL) {
        if (res != NULL)
            *res = size;
        return (EBADF);
    }

    fp = tf->tf_fp;
    p = buf;
    sz = 0;
    while (size > 0) {
        sz = tf->tf_size - fp;
        if (fp < tf->tf_cachesz && tf->tf_cachesz < tf->tf_size)
            sz = tf->tf_cachesz - fp;
        if (size < sz)
            sz = size;
        if (sz == 0)
            break;

        if (fp < tf->tf_cachesz) {
            /* Satisfy the request from cache. */
            memcpy(p, tf->tf_cache + fp, sz);
            fp += sz;
            p += sz;
            size -= sz;
            continue;
        }

        if (get_zipped(tf->tf_pkg, p, sz) == -1) {
            sz = -1;
            break;
        }

        fp += sz;
        p += sz;
        size -= sz;

        if (tf->tf_cachesz != 0)
            continue;

        tf->tf_cachesz = (sz <= PKG_MAXCACHESZ) ? sz : PKG_MAXCACHESZ;
        tf->tf_cache = malloc(tf->tf_cachesz);
        if (tf->tf_cache != NULL)
            memcpy(tf->tf_cache, buf, tf->tf_cachesz);
        else
            tf->tf_cachesz = 0;
    }

    tf->tf_fp = fp;
    if (res != NULL)
        *res = size;
    return ((sz == -1) ? errno : 0);
}

static off_t
pkg_seek(struct open_file *f, off_t ofs, int whence)
{
    char buf[512];
    struct tarfile *tf;
    off_t delta;
    size_t sz, res;
    int error;

    tf = (struct tarfile *)f->f_fsdata;
    if (tf == NULL) {
        errno = EBADF;
        return (-1);
    }

    switch (whence) {
    case SEEK_SET:
        delta = ofs - tf->tf_fp;
        break;
    case SEEK_CUR:
        delta = ofs;
        break;
    case SEEK_END:
        delta = tf->tf_size - tf->tf_fp + ofs;
        break;
    default:
        errno = EINVAL;
        return (-1);
    }

    if (delta < 0) {
        DBG(("%s: negative file seek (%jd)\n", __func__,
            (intmax_t)delta));
        errno = ESPIPE;
        return (-1);
    }

    while (delta > 0 && tf->tf_fp < tf->tf_size) {
        sz = (delta > sizeof(buf)) ? sizeof(buf) : delta;
        error = pkg_read(f, buf, sz, &res);
        if (error != 0) {
            errno = error;
            return (-1);
        }
        delta -= sz - res;
    }

    return (tf->tf_fp);
}

static int
pkg_stat(struct open_file *f, struct stat *sb)
{
    struct tarfile *tf;

    tf = (struct tarfile *)f->f_fsdata;
    if (tf == NULL)
        return (EBADF);
    memset(sb, 0, sizeof(*sb));
    sb->st_mode = get_mode(tf);
    sb->st_size = tf->tf_size;
    sb->st_blocks = (tf->tf_size + 511) / 512;
    return (0);
}

static int
pkg_readdir(struct open_file *f, struct dirent *d)
{
    struct tarfile *tf;

    tf = (struct tarfile *)f->f_fsdata;
    if (tf != NULL)
        return (EBADF);

    tf = scan_tarfile(package, NULL);
    if (tf == NULL)
        return (ENOENT);

    d->d_fileno = 0;
    d->d_reclen = sizeof(*d);
    d->d_type = DT_REG;
    memcpy(d->d_name, tf->tf_hdr.ut_name, sizeof(d->d_name));
    return (0);
}

/*
 * Low-level support functions.
 */

static int
get_byte(struct package *pkg, off_t *op)
{
    int c;

    if (pkg->pkg_zs.avail_in == 0) {
        c = read(pkg->pkg_fd, pkg->pkg_buf, PKG_BUFSIZE);
        if (c <= 0)
            return (-1);
        pkg->pkg_zs.avail_in = c;
        pkg->pkg_zs.next_in = pkg->pkg_buf;
    }

    c = *pkg->pkg_zs.next_in;
    pkg->pkg_zs.next_in++;
    pkg->pkg_zs.avail_in--;
    (*op)++;
    return (c);
}

static int
get_zipped(struct package *pkg, void *buf, size_t bufsz)
{
    int c;

    pkg->pkg_zs.next_out = buf;
    pkg->pkg_zs.avail_out = bufsz;

    while (pkg->pkg_zs.avail_out) {
        if (pkg->pkg_zs.avail_in == 0) {
            c = read(pkg->pkg_fd, pkg->pkg_buf, PKG_BUFSIZE);
            if (c <= 0) {
                errno = EIO;
                return (-1);
            }
            pkg->pkg_zs.avail_in = c;
            pkg->pkg_zs.next_in = pkg->pkg_buf;
        }

        c = inflate(&pkg->pkg_zs, Z_SYNC_FLUSH);
        if (c != Z_OK && c != Z_STREAM_END) {
            errno = EIO;
            return (-1);
        }
    }

    pkg->pkg_ofs += bufsz;
    return (0);
}

static int
cache_data(struct tarfile *tf)
{
    struct package *pkg;
    size_t sz;

    if (tf == NULL) {
        DBG(("%s: no file to cache data for?\n", __func__));
        errno = EINVAL;
        return (-1);
    }

    pkg = tf->tf_pkg;
    if (pkg == NULL) {
        DBG(("%s: no package associated with file?\n", __func__));
        errno = EINVAL;
        return (-1);
    }

    if (tf->tf_ofs != pkg->pkg_ofs) {
        DBG(("%s: caching after partial read of file %s?\n",
            __func__, tf->tf_hdr.ut_name));
        errno = EINVAL;
        return (-1);
    }

    /* We don't cache everything... */
    if (tf->tf_size > PKG_MAXCACHESZ) {
        errno = ENOMEM;
        return (-1);
    }

    /* All files are padded to a multiple of 512 bytes. */
    sz = (tf->tf_size + 0x1ff) & ~0x1ff;

    tf->tf_cache = malloc(sz);
    if (tf->tf_cache == NULL) {
        DBG(("%s: could not allocate %d bytes\n", __func__, (int)sz));
        errno = ENOMEM;
        return (-1);
    }

    tf->tf_cachesz = sz;
    return (get_zipped(pkg, tf->tf_cache, sz));
}

/*
 * Note that this implementation does not (and should not!) obey
 * locale settings; you cannot simply substitute strtol here, since
 * it does obey locale.
 */
static off_t
pkg_atol8(const char *p, unsigned char_cnt)
{
        int64_t l, limit, last_digit_limit;
        int digit, sign, base;

        base = 8;
        limit = INT64_MAX / base;
        last_digit_limit = INT64_MAX % base;

        while (*p == ' ' || *p == '\t')
                p++;
        if (*p == '-') {
                sign = -1;
                p++;
        } else
                sign = 1;

        l = 0;
        digit = *p - '0';
        while (digit >= 0 && digit < base  && char_cnt-- > 0) {
                if (l>limit || (l == limit && digit > last_digit_limit)) {
                        l = UINT64_MAX; /* Truncate on overflow. */
                        break;
                }
                l = (l * base) + digit;
                digit = *++p - '0';
        }
        return (sign < 0) ? -l : l;
}

/*
 * Parse a base-256 integer.  This is just a straight signed binary
 * value in big-endian order, except that the high-order bit is
 * ignored.  Remember that "int64_t" may or may not be exactly 64
 * bits; the implementation here tries to avoid making any assumptions
 * about the actual size of an int64_t.  It does assume we're using
 * twos-complement arithmetic, though.
 */
static int64_t
pkg_atol256(const char *_p, unsigned char_cnt)
{
        int64_t l, upper_limit, lower_limit;
        const unsigned char *p = (const unsigned char *)_p;

        upper_limit = INT64_MAX / 256;
        lower_limit = INT64_MIN / 256;

        /* Pad with 1 or 0 bits, depending on sign. */
        if ((0x40 & *p) == 0x40)
                l = (int64_t)-1;
        else
                l = 0;
        l = (l << 6) | (0x3f & *p++);
        while (--char_cnt > 0) {
                if (l > upper_limit) {
                        l = INT64_MAX; /* Truncate on overflow */
                        break;
                } else if (l < lower_limit) {
                        l = INT64_MIN;
                        break;
                }
                l = (l << 8) | (0xff & (int64_t)*p++);
        }
        return (l);
}

static off_t
pkg_atol(const char *p, unsigned char_cnt)
{
    /*
     * Technically, GNU pkg considers a field to be in base-256
     * only if the first byte is 0xff or 0x80.
     */
    if (*p & 0x80)
        return (pkg_atol256(p, char_cnt));
    return (pkg_atol8(p, char_cnt));
}

static int
get_mode(struct tarfile *tf)
{
    return (pkg_atol(tf->tf_hdr.ut_mode, sizeof(tf->tf_hdr.ut_mode)));
}

/* GZip flag byte */
#define ASCII_FLAG  0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC    0x02 /* bit 1 set: header CRC present */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME   0x08 /* bit 3 set: original file name present */
#define COMMENT     0x10 /* bit 4 set: file comment present */
#define RESERVED    0xE0 /* bits 5..7: reserved */

static int
new_package(int fd, struct package **pp)
{
    struct package *pkg;
    off_t ofs;
    int flags, i, error;

    pkg = malloc(sizeof(*pkg));
    if (pkg == NULL)
        return (ENOMEM);

    bzero(pkg, sizeof(*pkg));
    pkg->pkg_fd = fd;

    /*
     * Parse the header.
     */
    error = EFTYPE;
    ofs = 0;

    /* Check megic. */
    if (get_byte(pkg, &ofs) != 0x1f || get_byte(pkg, &ofs) != 0x8b)
        goto fail;
    /* Check method. */
    if (get_byte(pkg, &ofs) != Z_DEFLATED)
        goto fail;
    /* Check flags. */
    flags = get_byte(pkg, &ofs);
    if (flags & RESERVED)
        goto fail;

    /* Skip time, xflags and OS code. */
    for (i = 0; i < 6; i++) {
        if (get_byte(pkg, &ofs) == -1)
            goto fail;
    }

    /* Skip extra field. */
    if (flags & EXTRA_FIELD) {
        i = (get_byte(pkg, &ofs) & 0xff) |
            ((get_byte(pkg, &ofs) << 8) & 0xff);
        while (i-- > 0) {
            if (get_byte(pkg, &ofs) == -1)
                goto fail;
        }
    }

    /* Skip original file name. */
    if (flags & ORIG_NAME) {
        do {
            i = get_byte(pkg, &ofs);
        } while (i != 0 && i != -1);
        if (i == -1)
            goto fail;
    }

    /* Print the comment if it's there. */
    if (flags & COMMENT) {
        while (1) {
            i = get_byte(pkg, &ofs);
            if (i == -1)
                goto fail;
            if (i == 0)
                break;
            putchar(i);
        }
    }

    /* Skip the CRC. */
    if (flags & HEAD_CRC) {
        if (get_byte(pkg, &ofs) == -1)
            goto fail;
        if (get_byte(pkg, &ofs) == -1)
            goto fail;
    }

    /*
     * Done parsing the ZIP header. Spkgt the inflation engine.
     */
    error = inflateInit2(&pkg->pkg_zs, -15);
    if (error != Z_OK)
        goto fail;

    *pp = pkg;
    return (0);

 fail:
    free(pkg);
    return (error);
}

static struct tarfile *
scan_tarfile(struct package *pkg, struct tarfile *last)
{
    char buf[512];
    struct tarfile *cur;
    off_t ofs;
    size_t sz;

    cur = (last != NULL) ? last->tf_next : pkg->pkg_first;
    if (cur == NULL) {
        ofs = (last != NULL) ? last->tf_ofs + last->tf_size :
            pkg->pkg_ofs;
        ofs = (ofs + 0x1ff) & ~0x1ff;

        /* Check if we've reached EOF. */
        if (ofs < pkg->pkg_ofs) {
            errno = ENOSPC;
            return (NULL);
        }

        if (ofs != pkg->pkg_ofs) {
            if (last != NULL && pkg->pkg_ofs == last->tf_ofs) {
                if (cache_data(last) == -1)
                    return (NULL);
            } else {
                sz = ofs - pkg->pkg_ofs;
                while (sz != 0) {
                    if (sz > sizeof(buf))
                        sz = sizeof(buf);
                    if (get_zipped(pkg, buf, sz) == -1)
                        return (NULL);
                    sz = ofs - pkg->pkg_ofs;
                }
            }
        }

        cur = malloc(sizeof(*cur));
        if (cur == NULL)
            return (NULL);
        memset(cur, 0, sizeof(*cur));
        cur->tf_pkg = pkg;

        while (1) {
            if (get_zipped(pkg, &cur->tf_hdr,
                sizeof(cur->tf_hdr)) == -1) {
                free(cur);
                return (NULL);
            }

            /*
             * There are always 2 empty blocks appended to
             * a PKG. It marks the end of the archive.
             */
            if (strncmp(cur->tf_hdr.ut_magic, "ustar", 5) != 0) {
                free(cur);
                errno = ENOSPC;
                return (NULL);
            }

            cur->tf_ofs = pkg->pkg_ofs;
            cur->tf_size = pkg_atol(cur->tf_hdr.ut_size,
                sizeof(cur->tf_hdr.ut_size));

            if (cur->tf_hdr.ut_name[0] != '+')
                break;

            /*
             * Skip package meta-files.
             */
            ofs = cur->tf_ofs + cur->tf_size;
            ofs = (ofs + 0x1ff) & ~0x1ff;
            while (pkg->pkg_ofs < ofs) {
                if (get_zipped(pkg, buf, sizeof(buf)) == -1) {
                    free(cur);
                    return (NULL);
                }
            }
        }

        if (last != NULL)
            last->tf_next = cur;
        else
            pkg->pkg_first = cur;
        pkg->pkg_last = cur;
    }

    return (cur);
}