Re: [Qemu-devel] [PATCH v8 3/4] qemu-img: Add compare subcommand

[Miroslav Rezanina]

See response inline, if no response that comment will be handled in next 
version.

----- Original Message -----
> From: "Kevin Wolf" <address@hidden>
> To: "Miroslav Rezanina" <address@hidden>
> Cc: address@hidden
> Sent: Tuesday, January 29, 2013 12:28:22 PM
> Subject: Re: [Qemu-devel] [PATCH v8 3/4] qemu-img: Add compare subcommand
> 
> Am 14.01.2013 11:26, schrieb Miroslav Rezanina:
> > This patch adds new qemu-img subcommand that compares content of
> > two disk
> > images.
> > 
> > Signed-off-by: Miroslav Rezanina <address@hidden>
> > ---
> >  qemu-img-cmds.hx |    6 ++
> >  qemu-img.c       |  266
> >  ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 272 insertions(+), 0 deletions(-)
> 
> You also need to add documentation to qemu-img.texi. A description of
> the exit codes should probably go there.
> 

As you found out documentation is in patch 4. This code here is needed for
proper working so it's not part of patch 4. I put documentation in separate
patch to have one patch with execution code only. I will add the result codes 
in texi file, I forgot them.

> > diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> > index 90b93e0..bc1ccfa 100644
> > --- a/qemu-img-cmds.hx
> > +++ b/qemu-img-cmds.hx
> > @@ -27,6 +27,12 @@ STEXI
> >  @item commit [-q] [-f @var{fmt}] [-t @var{cache}] @var{filename}
> >  ETEXI
> >  
> > +DEF("compare", img_compare,
> > +    "compare [-f fmt] [-F fmt] [-p] [-q] [-s] filename1
> > filename2")
> > +STEXI
> > address@hidden compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-q] [-s]
> > @var{filename1} @var{filename2}
> > +ETEXI
> > +
> >  DEF("convert", img_convert,
> >      "convert [-c] [-p] [-q] [-f fmt] [-t cache] [-O output_fmt]
> >      [-o options] [-s snapshot_name] [-S sparse_size] filename
> >      [filename2 [...]] output_filename")
> >  STEXI
> > diff --git a/qemu-img.c b/qemu-img.c
> > index 8d55829..0c12692 100644
> > --- a/qemu-img.c
> > +++ b/qemu-img.c
> > @@ -693,6 +693,272 @@ static int compare_sectors(const uint8_t
> > *buf1, const uint8_t *buf2, int n,
> >  
> >  #define IO_BUF_SIZE (2 * 1024 * 1024)
> >  
> > +static int64_t sectors_to_bytes(int64_t sectors)
> > +{
> > +    return sectors << BDRV_SECTOR_BITS;
> > +}
> > +
> > +static int64_t sectors_to_process(int64_t total, int64_t from)
> > +{
> > +    int64_t ret = total - from;
> > +
> > +    if (ret > (IO_BUF_SIZE >> BDRV_SECTOR_BITS)) {
> > +        return IO_BUF_SIZE >> BDRV_SECTOR_BITS;
> > +    }
> > +
> > +    return ret;
> > +}
> 
> return MIN(total - from, IO_BUF_SIZE >> BDRV_SECTOR_BITS) would be a
> bit
> simpler.
> 
> > +
> > +/*
> > + * Check if passed sectors are empty (not allocated or contain
> > only 0 bytes)
> > + *
> > + * Returns 0 in case sectors are filled with 0, 1 if sectors
> > contain non-zero
> > + * data and negative value on error.
> > + *
> > + * @param bs:  Driver used for accessing file
> > + * @param sect_num: Number of first sector to check
> > + * @param sect_count: Number of sectors to check
> > + * @param filename: Name of disk file we are checking (logging
> > purpose)
> > + * @param buffer: Allocated buffer for storing read data
> > + * @param quiet: Flag for quiet mode
> > + */
> > +static int check_empty_sectors(BlockDriverState *bs, int64_t
> > sect_num,
> > +                               int sect_count, const char
> > *filename,
> > +                               uint8_t *buffer, bool quiet)
> > +{
> > +    int pnum, ret = 0;
> > +    ret = bdrv_read(bs, sect_num, buffer, sect_count);
> > +    if (ret < 0) {
> > +        error_report("Error while reading offset %" PRId64 " of
> > %s: %s",
> > +                     sectors_to_bytes(sect_num), filename,
> > strerror(-ret));
> > +        return ret;
> > +    }
> > +    ret = is_allocated_sectors(buffer, sect_count, &pnum);
> > +    if (ret || pnum != sect_count) {
> > +        qprintf(quiet, "Content mismatch at offset %" PRId64
> > "!\n",
> > +                sectors_to_bytes(ret ? sect_num : sect_num +
> > pnum));
> > +        return 1;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > +/*
> > + * Compares two images. Exit codes:
> > + *
> > + * 0 - Images are identical
> > + * 1 - Images differ
> > + * 2 - Error occurred
> > + */
> > +static int img_compare(int argc, char **argv)
> > +{
> > +    const char *fmt1 = NULL, *fmt2 = NULL, *filename1, *filename2;
> > +    BlockDriverState *bs1, *bs2;
> > +    int64_t total_sectors1, total_sectors2;
> > +    uint8_t *buf1 = NULL, *buf2 = NULL;
> > +    int pnum1, pnum2;
> > +    int allocated1, allocated2;
> > +    int ret = 0; /* return value - 0 Ident, 1 Different, 2 Error
> > */
> > +    int progress = 0, quiet = 0, strict = 0;
> 
> Please use bool instead.
> 
> > +    int64_t total_sectors;
> > +    int64_t sector_num = 0;
> > +    int64_t nb_sectors;
> > +    int c, pnum;
> > +    uint64_t bs_sectors;
> > +    uint64_t progress_base;
> > +
> > +    for (;;) {
> > +        c = getopt(argc, argv, "hpf:F:sq");
> > +        if (c == -1) {
> > +            break;
> > +        }
> > +        switch (c) {
> > +        case '?':
> > +        case 'h':
> > +            help();
> > +            break;
> > +        case 'f':
> > +            fmt1 = optarg;
> > +            break;
> > +        case 'F':
> > +            fmt2 = optarg;
> > +            break;
> > +        case 'p':
> > +            progress = 1;
> > +            break;
> > +        case 'q':
> > +            quiet = 1;
> > +            break;
> > +        case 's':
> > +            strict = 1;
> > +            break;
> > +        }
> > +    }
> > +
> > +    /* Progress is not shown in Quiet mode */
> > +    if (quiet) {
> > +        progress = 0;
> > +    }
> > +
> > +
> > +    if (optind > argc - 2) {
> > +        help();
> > +    }
> > +    filename1 = argv[optind++];
> > +    filename2 = argv[optind++];
> > +
> > +    /* Initialize before goto out */
> > +    qemu_progress_init(progress, 2.0);
> > +
> > +    bs1 = bdrv_new_open(filename1, fmt1, BDRV_O_FLAGS, true,
> > quiet);
> > +    if (!bs1) {
> > +        error_report("Can't open file %s", filename1);
> > +        ret = 2;
> > +        goto out3;
> > +    }
> > +
> > +    bs2 = bdrv_new_open(filename2, fmt2, BDRV_O_FLAGS, true,
> > quiet);
> > +    if (!bs2) {
> > +        error_report("Can't open file %s", filename2);
> > +        ret = 2;
> > +        goto out2;
> > +    }
> > +
> > +    buf1 = qemu_blockalign(bs1, IO_BUF_SIZE);
> > +    buf2 = qemu_blockalign(bs2, IO_BUF_SIZE);
> > +    bdrv_get_geometry(bs1, &bs_sectors);
> > +    total_sectors1 = bs_sectors;
> > +    bdrv_get_geometry(bs2, &bs_sectors);
> > +    total_sectors2 = bs_sectors;
> > +    total_sectors = MIN(total_sectors1, total_sectors2);
> > +    progress_base = MAX(total_sectors1, total_sectors2);
> > +
> > +    qemu_progress_print(0, 100);
> > +
> > +    if (strict && total_sectors1 != total_sectors2) {
> > +        ret = 1;
> > +        qprintf(quiet, "Strict mode: Image size mismatch!\n");
> > +        goto out;
> > +    }
> > +
> > +    for (;;) {
> > +        nb_sectors = sectors_to_process(total_sectors,
> > sector_num);
> > +        if (nb_sectors <= 0) {
> > +            break;
> > +        }
> > +        allocated1 = bdrv_is_allocated_above(bs1, NULL,
> > sector_num, nb_sectors,
> > +                                             &pnum1);
> > +        allocated2 = bdrv_is_allocated_above(bs2, NULL,
> > sector_num, nb_sectors,
> > +                                             &pnum2);
> 
> bdrv_is_allocated_above() can return errors, which need to be
> checked.
> 

Right, they have to be checked and respond properly.

> > +        nb_sectors = MIN(pnum1, pnum2);
> > +
> > +        if (allocated1 == allocated2) {
> > +            if (allocated1) {
> > +                ret = bdrv_read(bs1, sector_num, buf1,
> > nb_sectors);
> > +                if (ret < 0) {
> > +                    error_report("error while reading offset %"
> > PRId64 " of %s:"
> > +                                 " %s",
> > sectors_to_bytes(sector_num), filename1,
> > +                                  strerror(-ret));
> > +                    ret = 2;
> > +                    goto out;
> > +                }
> > +                ret = bdrv_read(bs2, sector_num, buf2,
> > nb_sectors);
> > +                if (ret < 0) {
> > +                    error_report("error while reading offset %"
> > PRId64
> > +                                 " of %s: %s",
> > sectors_to_bytes(sector_num),
> > +                                 filename2, strerror(-ret));
> > +                    ret = 2;
> > +                    goto out;
> > +                }
> > +                ret = compare_sectors(buf1, buf2, nb_sectors,
> > &pnum);
> > +                if (ret || pnum != nb_sectors) {
> > +                    ret = 1;
> > +                    qprintf(quiet, "Content mismatch at offset %"
> > PRId64 "!\n",
> > +                            sectors_to_bytes(
> > +                                ret ? sector_num : sector_num +
> > pnum));
> > +                    goto out;
> > +                }
> > +            }
> > +        } else {
> > +            if (strict) {
> > +                ret = 1;
> > +                qprintf(quiet, "Strict mode: Offset %" PRId64
> > +                        " allocation mismatch!\n",
> > +                        sectors_to_bytes(sector_num));
> > +                goto out;
> > +            }
> > +
> > +            if (allocated1) {
> > +                ret = check_empty_sectors(bs1, sector_num,
> > nb_sectors,
> > +                                         filename1, buf1, quiet);
> > +            } else {
> > +                ret = check_empty_sectors(bs2, sector_num,
> > nb_sectors,
> > +                                         filename2, buf1, quiet);
> > +            }
> > +            if (ret) {
> > +                if (ret < 0) {
> > +                    ret = 2;
> > +                }
> > +                goto out;
> > +            }
> > +        }
> > +        sector_num += nb_sectors;
> > +        qemu_progress_print(((float) nb_sectors /
> > progress_base)*100, 100);
> > +    }
> > +
> > +    if (total_sectors1 != total_sectors2) {
> > +        BlockDriverState *bs_over;
> > +        int64_t total_sectors_over;
> > +        const char *filename_over;
> > +
> > +        qprintf(quiet, "Warning: Image size mismatch!\n");
> > +        if (total_sectors1 > total_sectors2) {
> > +            total_sectors_over = total_sectors1;
> > +            bs_over = bs1;
> > +            filename_over = filename1;
> > +        } else {
> > +            total_sectors_over = total_sectors2;
> > +            bs_over = bs2;
> > +            filename_over = filename2;
> > +        }
> > +
> > +        for (;;) {
> > +            nb_sectors = sectors_to_process(total_sectors_over,
> > sector_num);
> > +            if (nb_sectors <= 0) {
> > +                break;
> > +            }
> > +            ret = bdrv_is_allocated_above(bs_over, NULL,
> > sector_num,
> > +                                          nb_sectors, &pnum);
> 
> Error checking again.
> 
> > +            nb_sectors = pnum;
> > +            if (ret) {
> > +                ret = check_empty_sectors(bs_over, sector_num,
> > nb_sectors,
> > +                                          filename_over, buf1,
> > quiet);
> > +                if (ret) {
> > +                    if (ret < 0) {
> > +                        ret = 2;
> > +                    }
> > +                    goto out;
> > +                }
> > +            }
> > +            sector_num += nb_sectors;
> > +            qemu_progress_print(((float) nb_sectors /
> > progress_base)*100, 100);
> > +        }
> > +    }
> > +
> > +    qprintf(quiet, "Images are identical.\n");
> > +    ret = 0;
> > +
> > +out:
> > +    bdrv_delete(bs2);
> > +    qemu_vfree(buf1);
> > +    qemu_vfree(buf2);
> > +out2:
> > +    bdrv_delete(bs1);
> > +out3:
> > +    qemu_progress_end();
> > +    return ret;
> > +}
> > +
> >  static int img_convert(int argc, char **argv)
> >  {
> >      int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size,
> >      cluster_sectors;
> > 
> 
> Kevin
> 

Mirek

-- 
Miroslav Rezanina
Software Engineer - Virtualization Team