Re: [libvirt] [PATCH 3/4] Fix QEMU save/restore with block devices

The save process was relying on use of the shell >> append operator to ensure the save data was placed after the libvirt header + XML. This doesn't work for block devices though. Replace this code with use of 'dd' and its 'seek' parameter. The qemuMonitorMigateToCommand() monitor API is used for both save/coredump, and migration via UNIX socket. We can't simply switch this to use 'dd' since this causes problems with the migration usage. Thus, create a dedicated qemuMonitorMigateToFile which can accept an filename + offset, and remove the filename from the current qemuMonitorMigateToCommand() API * src/qemu/qemu_driver.c: Switch to qemuMonitorMigateToFile for save and core dump * src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h, src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h, src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Create a new qemuMonitorMigateToFile, separate from the existing qemuMonitorMigateToCommand to allow handling file offsets --- src/qemu/qemu_driver.c | 172 +++++++++++++++++++++++------------------- src/qemu/qemu_monitor.c | 28 ++++++-- src/qemu/qemu_monitor.h | 9 ++- src/qemu/qemu_monitor_json.c | 35 ++++++++- src/qemu/qemu_monitor_json.h | 9 ++- src/qemu/qemu_monitor_text.c | 35 ++++++++- src/qemu/qemu_monitor_text.h | 9 ++- 7 files changed, 201 insertions(+), 96 deletions(-)

- if (virAsprintf(&dest, "exec:%s >>%s 2>/dev/null", argstr, safe_target) < 0) { + if (virAsprintf(&dest, "exec:%s | dd of=%s seek=%llub", + argstr, safe_target, offset) < 0) {

virReportOOMError(); goto cleanup; }

- if (virAsprintf(&dest, "exec:%s >>%s 2>/dev/null", argstr, safe_target) < 0) { + if (virAsprintf(&dest, "exec:%s | dd of=%s seek=%llub", + argstr, safe_target, offset) < 0) {