--- /dev/null
+From 70bc584282901ee2a8954559393f305377016249 Mon Sep 17 00:00:00 2001
+From: Wolfgang Bumiller <w.bumiller@proxmox.com>
+Date: Fri, 23 Jun 2017 12:01:43 +0200
+Subject: [PATCH 50/50] qemu-img dd: add osize and read from/to stdin/stdout
+
+Neither convert nor dd were previously able to write to or
+read from a pipe. Particularly serializing an image file
+into a raw stream or vice versa can be useful, but using
+`qemu-img convert -f qcow2 -O raw foo.qcow2 /dev/stdout` in
+a pipe will fail trying to seek.
+
+While dd and convert have overlapping use cases, `dd` is a
+simple read/write loop while convert is much more
+sophisticated and has ways to dealing with holes and blocks
+of zeroes.
+Since these typically can't be detected in pipes via
+SEEK_DATA/HOLE or skipped while writing, dd seems to be the
+better choice for implementing stdin/stdout streams.
+
+This patch causes "if" and "of" to default to stdin and
+stdout respectively, allowing only the "raw" format to be
+used in these cases.
+Since the input can now be a pipe we have no way of
+detecting the size of the output image to create. Since we
+also want to support images with a size not matching the
+dd command's "bs" parameter (which, together with "count"
+could be used to calculate the desired size, and is already
+used to limit it), the "osize" option is added to explicitly
+override the output file's size.
+
+Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
+---
+ qemu-img.c | 176 +++++++++++++++++++++++++++++++++++++++----------------------
+ 1 file changed, 113 insertions(+), 63 deletions(-)
+
+diff --git a/qemu-img.c b/qemu-img.c
+index 4f7f458dd2..b9d1ef7bb8 100644
+--- a/qemu-img.c
++++ b/qemu-img.c
+@@ -4035,10 +4035,12 @@ out:
+ #define C_IF 04
+ #define C_OF 010
+ #define C_SKIP 020
++#define C_OSIZE 040
+
+ struct DdInfo {
+ unsigned int flags;
+ int64_t count;
++ int64_t osize;
+ };
+
+ struct DdIo {
+@@ -4117,6 +4119,20 @@ static int img_dd_skip(const char *arg,
+ return 0;
+ }
+
++static int img_dd_osize(const char *arg,
++ struct DdIo *in, struct DdIo *out,
++ struct DdInfo *dd)
++{
++ dd->osize = cvtnum(arg);
++
++ if (dd->osize < 0) {
++ error_report("invalid number: '%s'", arg);
++ return 1;
++ }
++
++ return 0;
++}
++
+ static int img_dd(int argc, char **argv)
+ {
+ int ret = 0;
+@@ -4156,6 +4172,7 @@ 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 },
++ { "osize", img_dd_osize, C_OSIZE },
+ { NULL, NULL, 0 }
+ };
+ const struct option long_options[] = {
+@@ -4223,84 +4240,106 @@ static int img_dd(int argc, char **argv)
+ arg = NULL;
+ }
+
+- if (!(dd.flags & C_IF && dd.flags & C_OF)) {
+- error_report("Must specify both input and output files");
++ if (!(dd.flags & C_IF) && (!fmt || strcmp(fmt, "raw") != 0)) {
++ error_report("Input format must be raw when readin from stdin");
+ ret = -1;
+ goto out;
+ }
+- blk1 = img_open(image_opts, in.filename, fmt, 0, false, false);
+-
+- if (!blk1) {
++ if (!(dd.flags & C_OF) && strcmp(out_fmt, "raw") != 0) {
++ error_report("Output format must be raw when writing to stdout");
+ ret = -1;
+ goto out;
+ }
++ if (dd.flags & C_IF) {
++ blk1 = img_open(image_opts, in.filename, fmt, 0, false, false);
+
+- drv = bdrv_find_format(out_fmt);
+- if (!drv) {
+- error_report("Unknown file format");
+- ret = -1;
+- goto out;
+- }
+- proto_drv = bdrv_find_protocol(out.filename, true, &local_err);
+-
+- if (!proto_drv) {
+- error_report_err(local_err);
+- ret = -1;
+- goto out;
+- }
+- if (!drv->create_opts) {
+- error_report("Format driver '%s' does not support image creation",
+- drv->format_name);
+- ret = -1;
+- goto out;
+- }
+- if (!proto_drv->create_opts) {
+- error_report("Protocol driver '%s' does not support image creation",
+- proto_drv->format_name);
+- ret = -1;
+- goto out;
++ if (!blk1) {
++ ret = -1;
++ goto out;
++ }
+ }
+- create_opts = qemu_opts_append(create_opts, drv->create_opts);
+- create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
+-
+- opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
+
+- size = blk_getlength(blk1);
+- if (size < 0) {
+- error_report("Failed to get size for '%s'", in.filename);
++ if (dd.flags & C_OSIZE) {
++ size = dd.osize;
++ } else if (dd.flags & C_IF) {
++ size = blk_getlength(blk1);
++ if (size < 0) {
++ error_report("Failed to get size for '%s'", in.filename);
++ ret = -1;
++ goto out;
++ }
++ } else if (dd.flags & C_COUNT) {
++ size = dd.count * in.bsz;
++ } else {
++ error_report("Output size must be known when reading from stdin");
+ ret = -1;
+ goto out;
+ }
+
+- if (dd.flags & C_COUNT && dd.count <= INT64_MAX / in.bsz &&
++ if (!(dd.flags & C_OSIZE) && dd.flags & C_COUNT && dd.count <= INT64_MAX / in.bsz &&
+ dd.count * in.bsz < size) {
+ size = dd.count * in.bsz;
+ }
+
+- /* Overflow means the specified offset is beyond input image's size */
+- if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
+- size < in.bsz * in.offset)) {
+- qemu_opt_set_number(opts, BLOCK_OPT_SIZE, 0, &error_abort);
+- } else {
+- qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
+- size - in.bsz * in.offset, &error_abort);
+- }
+
+- ret = bdrv_create(drv, out.filename, opts, &local_err);
+- if (ret < 0) {
+- error_reportf_err(local_err,
+- "%s: error while creating output image: ",
+- out.filename);
+- ret = -1;
+- goto out;
+- }
++ if (dd.flags & C_OF) {
++ drv = bdrv_find_format(out_fmt);
++ if (!drv) {
++ error_report("Unknown file format");
++ ret = -1;
++ goto out;
++ }
++ proto_drv = bdrv_find_protocol(out.filename, true, &local_err);
++
++ if (!proto_drv) {
++ error_report_err(local_err);
++ ret = -1;
++ goto out;
++ }
++ if (!drv->create_opts) {
++ error_report("Format driver '%s' does not support image creation",
++ drv->format_name);
++ ret = -1;
++ goto out;
++ }
++ if (!proto_drv->create_opts) {
++ error_report("Protocol driver '%s' does not support image creation",
++ proto_drv->format_name);
++ ret = -1;
++ goto out;
++ }
++ create_opts = qemu_opts_append(create_opts, drv->create_opts);
++ create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
+
+- blk2 = img_open(image_opts, out.filename, out_fmt, BDRV_O_RDWR,
+- false, false);
++ opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
+
+- if (!blk2) {
+- ret = -1;
+- goto out;
++ /* Overflow means the specified offset is beyond input image's size */
++ if (dd.flags & C_OSIZE) {
++ qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
++ } else if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
++ size < in.bsz * in.offset)) {
++ qemu_opt_set_number(opts, BLOCK_OPT_SIZE, 0, &error_abort);
++ } else {
++ qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
++ size - in.bsz * in.offset, &error_abort);
++ }
++
++ ret = bdrv_create(drv, out.filename, opts, &local_err);
++ if (ret < 0) {
++ error_reportf_err(local_err,
++ "%s: error while creating output image: ",
++ out.filename);
++ ret = -1;
++ goto out;
++ }
++
++ blk2 = img_open(image_opts, out.filename, out_fmt, BDRV_O_RDWR,
++ false, false);
++
++ if (!blk2) {
++ ret = -1;
++ goto out;
++ }
+ }
+
+ if (dd.flags & C_SKIP && (in.offset > INT64_MAX / in.bsz ||
+@@ -4318,11 +4357,18 @@ static int img_dd(int argc, char **argv)
+
+ for (out_pos = 0; in_pos < size; block_count++) {
+ int in_ret, out_ret;
++ size_t in_bsz = in_pos + in.bsz > size ? size - in_pos : in.bsz;
+
+- if (in_pos + in.bsz > size) {
+- in_ret = blk_pread(blk1, in_pos, in.buf, size - in_pos);
++ if (blk1) {
++ in_ret = blk_pread(blk1, in_pos, in.buf, in_bsz);
+ } else {
+- in_ret = blk_pread(blk1, in_pos, in.buf, in.bsz);
++ in_ret = read(STDIN_FILENO, in.buf, in_bsz);
++ if (in_ret == 0) {
++ /* early EOF is considered an error */
++ error_report("Input ended unexpectedly");
++ ret = -1;
++ goto out;
++ }
+ }
+ if (in_ret < 0) {
+ error_report("error while reading from input image file: %s",
+@@ -4332,9 +4378,13 @@ static int img_dd(int argc, char **argv)
+ }
+ in_pos += in_ret;
+
+- out_ret = blk_pwrite(blk2, out_pos, in.buf, in_ret, 0);
++ if (blk2) {
++ out_ret = blk_pwrite(blk2, out_pos, in.buf, in_ret, 0);
++ } else {
++ out_ret = write(STDOUT_FILENO, in.buf, in_ret);
++ }
+
+- if (out_ret < 0) {
++ if (out_ret != in_ret) {
+ error_report("error while writing to output image file: %s",
+ strerror(-out_ret));
+ ret = -1;
+--
+2.11.0
+
projects / pve-qemu.git / commitdiff