[Qemu-devel] [PATCH v2 1/7] qemu-img: add seek option to dd

[Reda Sallahi <fullmanet@gmail.com>]

This patch adds the seek option which allows qemu-img dd to skip a number of
blocks on the output before copying the input.

A test case was added to test the seek option.

Signed-off-by: Reda Sallahi <fullmanet@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qemu-img-cmds.hx           |  4 +--
 qemu-img.c                 | 45 +++++++++++++++++++++++-----
 qemu-img.texi              |  4 ++-
 tests/qemu-iotests/161     | 73 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/161.out | 51 ++++++++++++++++++++++++++++++++
 tests/qemu-iotests/group   |  1 +
 6 files changed, 167 insertions(+), 11 deletions(-)
 create mode 100755 tests/qemu-iotests/161
 create mode 100644 tests/qemu-iotests/161.out

diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 18685ac..e79a577 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -46,9 +46,9 @@ STEXI
 ETEXI
 
 DEF("dd", img_dd,
-    "dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks] [skip=blocks] [conv=notrunc] if=input of=output")
+    "dd [--image-opts] [-f fmt] [-O output_fmt] [bs=block_size] [count=blocks] [skip=blocks] [seek=blocks] [conv=notrunc] if=input of=output")
 STEXI
-@item dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}] [conv=notrunc] if=@var{input} of=@var{output}
+    @item dd [--image-opts] [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}] [seek=@var{blocks}] [conv=notrunc] if=@var{input} of=@var{output}
 ETEXI
 
 DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index 816a406..7d313fd 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -175,6 +175,7 @@ static void QEMU_NORETURN help(void)
            "  'if=FILE' read from FILE\n"
            "  'of=FILE' write to FILE\n"
            "  'skip=N' skip N bs-sized blocks at the start of input\n"
+           "  'seek=N' seek N bs-sized blocks at the start of output\n"
            "  'conv=notrunc' do not truncate the output file\n";
 
     printf("%s\nSupported formats:", help_msg);
@@ -3808,7 +3809,8 @@ out:
 #define C_IF      04
 #define C_OF      010
 #define C_SKIP    020
-#define C_CONV    040
+#define C_SEEK    040
+#define C_CONV    0100
 
 struct DdInfo {
     unsigned int flags;
@@ -3897,6 +3899,22 @@ static int img_dd_skip(const char *arg,
     return 0;
 }
 
+static int img_dd_seek(const char *arg,
+                       struct DdIo *in, struct DdIo *out,
+                       struct DdInfo *dd)
+{
+    char *end;
+
+    out->offset = qemu_strtosz_suffix(arg, &end, QEMU_STRTOSZ_DEFSUFFIX_B);
+
+    if (out->offset < 0 || *end) {
+        error_report("invalid number: '%s'", arg);
+        return 1;
+    }
+
+    return 0;
+}
+
 #define C_NOTRUNC 01
 
 static int img_dd_conv(const char *arg,
@@ -3927,7 +3945,7 @@ static int img_dd(int argc, char **argv)
     const char *out_fmt = "raw";
     const char *fmt = NULL;
     const char *out_filename;
-    int64_t size = 0, out_size;
+    int64_t size = 0, out_size = 0;
     int64_t block_count = 0, out_pos, in_pos;
     struct DdInfo dd = {
         .flags = 0,
@@ -3953,6 +3971,7 @@ static int img_dd(int argc, char **argv)
         { "if", img_dd_if, C_IF },
         { "of", img_dd_of, C_OF },
         { "skip", img_dd_skip, C_SKIP },
+        { "seek", img_dd_seek, C_SEEK },
         { "conv", img_dd_conv, C_CONV },
         { NULL, NULL, 0 }
     };
@@ -4019,6 +4038,14 @@ static int img_dd(int argc, char **argv)
         arg = NULL;
     }
 
+    /* Overflow check for seek */
+    if (out.offset > INT64_MAX / out.bsz) {
+        error_report("seek with the block size specified is too large "
+                     "for data type used");
+        ret = -1;
+        goto out;
+    }
+
     if (!(dd.flags & C_IF && dd.flags & C_OF)) {
         error_report("Must specify both input and output files");
         ret = -1;
@@ -4044,9 +4071,9 @@ static int img_dd(int argc, char **argv)
     }
     /* Overflow means the specified offset is beyond input image's size */
     if (in.offset > INT64_MAX / in.bsz || size < in.offset * in.bsz) {
-        out_size = 0;
+        out_size = out.offset * out.bsz;
     } else {
-        out_size = size - in.offset * in.bsz;
+        out_size = size - in.offset * in.bsz + out.offset * out.bsz;
     }
 
     out_filename = out.filename;
@@ -4132,10 +4159,12 @@ static int img_dd(int argc, char **argv)
             goto out;
         }
 
-        if (in.offset <= INT64_MAX / in.bsz && size >= in.offset * in.bsz) {
-            if (blk2sz < out_size) {
-                blk_truncate(blk2, out_size);
+        if (in.offset > INT64_MAX / in.bsz || size < in.offset * in.bsz) {
+            if (blk2sz < out.offset * out.bsz) {
+                blk_truncate(blk2, out.offset * out.bsz);
             }
+        } else if (blk2sz < out_size) {
+            blk_truncate(blk2, out_size);
         }
     }
 
@@ -4152,7 +4181,7 @@ static int img_dd(int argc, char **argv)
 
     in.buf = g_new(uint8_t, in.bsz);
 
-    for (out_pos = 0; in_pos < size; block_count++) {
+    for (out_pos = out.offset * out.bsz; in_pos < size; block_count++) {
         int in_ret, out_ret;
 
         if (in_pos + in.bsz > size) {
diff --git a/qemu-img.texi b/qemu-img.texi
index 002dde2..95f603b 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -154,6 +154,8 @@ sets the output file. dd truncates the output file to zero if 'conv=notrunc'
 is not specified.
 @item skip=@var{blocks}
 sets the number of input blocks to skip
+@item seek=@var{blocks}
+sets the number of output blocks to skip
 @item conv=notrunc
 makes dd not truncate output file to zero
 @end table
@@ -329,7 +331,7 @@ skipped. This is useful for formats such as @code{rbd} if the target
 volume has already been created with site specific options that cannot
 be supplied through qemu-img.
 
-@item dd [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}] [conv=notrunc] if=@var{input} of=@var{output}
+@item dd [-f @var{fmt}] [-O @var{output_fmt}] [bs=@var{block_size}] [count=@var{blocks}] [skip=@var{blocks}] [seek=@var{blocks}] [conv=notrunc] if=@var{input} of=@var{output}
 
 Dd copies from @var{input} file to @var{output} file converting it from
 @var{fmt} format to @var{output_fmt} format.
diff --git a/tests/qemu-iotests/161 b/tests/qemu-iotests/161
new file mode 100755
index 0000000..bc99102
--- /dev/null
+++ b/tests/qemu-iotests/161
@@ -0,0 +1,73 @@
+#! /bin/bash
+#
+# qemu-img dd test for the seek option
+#
+# Copyright (C) 2016 Reda Sallahi
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+owner=fullmanet@gmail.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+status=1
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm -f "$TEST_IMG.out" "$TEST_IMG.out.dd"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+. ./common.rc
+. ./common.filter
+. ./common.pattern
+
+_supported_fmt raw
+_supported_proto file
+_supported_os Linux
+
+TEST_SEEK_BLOCKS="1 2 30 30K"
+
+for seek in $TEST_SEEK_BLOCKS; do
+    echo
+    echo "== Creating image =="
+
+    size=1M
+    _make_test_img $size
+    _check_test_img
+    $QEMU_IO -c "write -P 0xa 13k 512k" "$TEST_IMG" | _filter_qemu_io
+
+    echo
+    echo "== Converting the image with dd with seek=$seek =="
+
+    $QEMU_IMG dd if="$TEST_IMG" of="$TEST_IMG.out" seek="$seek" conv=notrunc \
+        -O "$IMGFMT" 2> /dev/null
+    TEST_IMG="$TEST_IMG.out" _check_test_img
+    dd if="$TEST_IMG" of="$TEST_IMG.out.dd" seek="$seek" conv=notrunc \
+        status=none
+
+    echo
+    echo "== Compare the images with qemu-img compare =="
+
+    $QEMU_IMG compare "$TEST_IMG.out.dd" "$TEST_IMG.out"
+done
+
+echo
+echo "*** done"
+rm -f "$seq.full"
+status=0
diff --git a/tests/qemu-iotests/161.out b/tests/qemu-iotests/161.out
new file mode 100644
index 0000000..5dfc748
--- /dev/null
+++ b/tests/qemu-iotests/161.out
@@ -0,0 +1,51 @@
+QA output created by 161
+
+== Creating image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
+No errors were found on the image.
+wrote 524288/524288 bytes at offset 13312
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== Converting the image with dd with seek=1 ==
+No errors were found on the image.
+
+== Compare the images with qemu-img compare ==
+Images are identical.
+
+== Creating image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
+No errors were found on the image.
+wrote 524288/524288 bytes at offset 13312
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== Converting the image with dd with seek=2 ==
+No errors were found on the image.
+
+== Compare the images with qemu-img compare ==
+Images are identical.
+
+== Creating image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
+No errors were found on the image.
+wrote 524288/524288 bytes at offset 13312
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== Converting the image with dd with seek=30 ==
+No errors were found on the image.
+
+== Compare the images with qemu-img compare ==
+Images are identical.
+
+== Creating image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576
+No errors were found on the image.
+wrote 524288/524288 bytes at offset 13312
+512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== Converting the image with dd with seek=30K ==
+No errors were found on the image.
+
+== Compare the images with qemu-img compare ==
+Images are identical.
+
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 503eb27..28833ee 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -160,4 +160,5 @@
 158 rw auto quick
 159 rw auto quick
 160 rw auto quick
+161 rw auto quick
 162 auto quick
-- 
2.9.3