6:29 p.m.
* configure.ac (VIR_WRAPPER_SHELL): Define to a replacement shell,
if /bin/sh is broken on <> redirection.
* src/qemu/qemu_monitor.h (VIR_WRAPPER_SHELL_PREFIX)
(VIR_WRAPPER_SHELL_SUFFIX): New macros.
* src/qemu/qemu_monitor_text.c (qemuMonitorTextMigrateToFile): Use
them.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONMigrateToFile):
Likewise.
---
Took longer than I thought, but this should do the trick with no
overhead on decent systems, and while still avoiding buggy dash ==
/bin/sh with something that works elsewhere.
This passes for me on Fedora, where /bin/sh is bash; testing on
Ubuntu or other debian-based system where /bin/sh is dash 0.5.5
would be appreciated.
configure.ac | 50 ++++++++++++++++++++++++++++++++++++++++++
src/qemu/qemu_monitor.h | 13 +++++++++++
src/qemu/qemu_monitor_json.c | 5 ++-
src/qemu/qemu_monitor_text.c | 5 ++-
4 files changed, 69 insertions(+), 4 deletions(-)
diff --git a/configure.ac b/configure.ac
index e41f2b5..6aa09f7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -583,6 +583,56 @@ if test "$with_lxc" = "yes" ; then
fi
AM_CONDITIONAL([WITH_LXC], [test "$with_lxc" = "yes"])
+dnl
+dnl check for shell that understands <> redirection without truncation,
+dnl needed by src/qemu/qemu_monitor_{text,json}.c.
+dnl
+if test "$with_qemu" = yes; then
+ lv_wrapper_shell=
+ AC_CACHE_CHECK([for shell that supports <> redirection],
+ [lv_cv_wrapper_shell],
+ [
+ # If cross-compiling, guess that /bin/sh is good enough except for
+ # Linux, where it might be dash 0.5.5 which is known broken; and on
+ # Linux, we have a good chance that /bin/bash will exist.
+ # If we guess wrong, a user can override the cache variable.
+ # Going through /bin/bash is a slight slowdown if /bin/sh works.
+ if test "$cross_compiling" = yes; then
+ case $host_os in
+ linux*) lv_cv_wrapper_shell=/bin/bash ;;
+ *) lv_cv_wrapper_shell=/bin/sh ;;
+ esac
+ else
+ for lv_cv_wrapper_shell in /bin/sh bash ksh zsh none; do
+ test $lv_cv_wrapper_shell = none &&
+ AC_MSG_ERROR([could not find decent shell])
+ echo a > conftest.a
+ $lv_cv_wrapper_shell -c ': 1<>conftest.a'
+ case `cat conftest.a`.$lv_cv_wrapper_shell in
+ a./*) break;; dnl /bin/sh is good enough
+ a.*) dnl bash, ksh, and zsh all understand 'command', use that
+ dnl to determine the absolute path of the shell
+ lv_cv_wrapper_shell=`$lv_cv_wrapper_shell -c \
+ 'command -v $lv_cv_wrapper_shell'`
+ case $lv_cv_wrapper_shell in
+ /*) break;;
+ esac
+ ;;
+ esac
+ done
+ rm -f conftest.a
+ fi
+ ])
+ if test "x$lv_cv_wrapper_shell" != x/bin/sh; then
+ lv_wrapper_shell=$lv_cv_wrapper_shell
+ fi
+ if test "x$lv_wrapper_shell" != x; then
+ AC_DEFINE_UNQUOTED([VIR_WRAPPER_SHELL], [$lv_wrapper_shell],
+ [Define to the absolute path of a shell that does not truncate on
+ <> redirection, if /bin/sh does not fit the bill])
+ fi
+fi
+
dnl
dnl check for kernel headers required by src/bridge.c
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 48f4c20..7d09145 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -391,4 +391,17 @@ int qemuMonitorDeleteSnapshot(qemuMonitorPtr mon, const char *name);
int qemuMonitorArbitraryCommand(qemuMonitorPtr mon, const char *cmd, char **reply);
+/**
+ * When running two dd process and using <> redirection, we need a
+ * shell that will not truncate files. These two strings serve that
+ * purpose.
+ */
+# ifdef VIR_WRAPPER_SHELL
+# define VIR_WRAPPER_SHELL_PREFIX VIR_WRAPPER_SHELL " -c '"
+# define VIR_WRAPPER_SHELL_SUFFIX "'"
+# else
+# define VIR_WRAPPER_SHELL_PREFIX /* nothing */
+# define VIR_WRAPPER_SHELL_SUFFIX /* nothing */
+# endif
+
#endif /* QEMU_MONITOR_H */
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index d3ab25f..d2c6f0a 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -1698,8 +1698,9 @@ int qemuMonitorJSONMigrateToFile(qemuMonitorPtr mon,
* allow starting at an alignment of 512, but without wasting
* padding to get to the larger alignment useful for speed. Use
* <> redirection to avoid truncating a regular file. */
- if (virAsprintf(&dest, "exec:%s | { dd bs=%llu seek=%llu if=/dev/null
&& "
- "dd bs=%llu; } 1<>%s",
+ if (virAsprintf(&dest, "exec:" VIR_WRAPPER_SHELL_PREFIX "%s |
"
+ "{ dd bs=%llu seek=%llu if=/dev/null && "
+ "dd bs=%llu; } 1<>%s" VIR_WRAPPER_SHELL_SUFFIX,
argstr, QEMU_MONITOR_MIGRATE_TO_FILE_BS,
offset / QEMU_MONITOR_MIGRATE_TO_FILE_BS,
QEMU_MONITOR_MIGRATE_TO_FILE_TRANSFER_SIZE,
diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c
index 69971a6..d7e128c 100644
--- a/src/qemu/qemu_monitor_text.c
+++ b/src/qemu/qemu_monitor_text.c
@@ -1277,8 +1277,9 @@ int qemuMonitorTextMigrateToFile(qemuMonitorPtr mon,
* allow starting at an alignment of 512, but without wasting
* padding to get to the larger alignment useful for speed. Use
* <> redirection to avoid truncating a regular file. */
- if (virAsprintf(&dest, "exec:%s | { dd bs=%llu seek=%llu if=/dev/null
&& "
- "dd bs=%llu; } 1<>%s",
+ if (virAsprintf(&dest, "exec:" VIR_WRAPPER_SHELL_PREFIX "%s |
"
+ "{ dd bs=%llu seek=%llu if=/dev/null && "
+ "dd bs=%llu; } 1<>%s" VIR_WRAPPER_SHELL_SUFFIX,
argstr, QEMU_MONITOR_MIGRATE_TO_FILE_BS,
offset / QEMU_MONITOR_MIGRATE_TO_FILE_BS,
QEMU_MONITOR_MIGRATE_TO_FILE_TRANSFER_SIZE,
--
1.7.2.3