[Libguestfs] [PATCH] lib: Pick up qemu-img path at build time.

[Richard W.M. Jones]

The main purpose of this change is two-fold:

(1) Ensure that we run the same version of qemu-img that we are
built against.

(2) Allow the qemu-img path to be overridden at build time in case
it's on a nonstandard path or (like RHV) has a nonstandard name.
---
 docs/guestfs-building.pod | 6 ++++++
 lib/command.c             | 4 ++--
 lib/create.c              | 4 ++--
 lib/info.c                | 2 +-
 m4/guestfs-qemu.m4        | 4 ++++
 5 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/docs/guestfs-building.pod b/docs/guestfs-building.pod
index d85483a0b..94df49158 100644
--- a/docs/guestfs-building.pod
+++ b/docs/guestfs-building.pod
@@ -716,6 +716,12 @@ binary to find the version of Python, the location of Python libraries
 and so on.  See
 L</BUILDING PYTHON 2 AND PYTHON 3 BINDINGS> below.
 
+=item B<QEMU_IMG>
+
+This environment variable may be set to point to the full path of the
+L<qemu-img(1)> program, in case it is on a nonstandard path or has a
+nonstandard name.
+
 =item B<SUPERMIN>
 
 This environment variable can be set to choose an alternative
diff --git a/lib/command.c b/lib/command.c
index bfec76f19..3d8bc7dbf 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -35,7 +35,7 @@
  *
  * I<Either> add arguments:
  *
- *  guestfs_int_cmd_add_arg (cmd, "qemu-img");
+ *  guestfs_int_cmd_add_arg (cmd, QEMU_IMG);
  *  guestfs_int_cmd_add_arg (cmd, "info");
  *  guestfs_int_cmd_add_arg (cmd, filename);
  *
@@ -48,7 +48,7 @@
  * shell commands, with the added safety of allowing args to be quoted
  * properly).
  *
- *  guestfs_int_cmd_add_string_unquoted (cmd, "qemu-img info ");
+ *  guestfs_int_cmd_add_string_unquoted (cmd, "file info ");
  *  guestfs_int_cmd_add_string_quoted (cmd, filename);
  *
  * =item 4.
diff --git a/lib/create.c b/lib/create.c
index fff5cf332..b4865172c 100644
--- a/lib/create.c
+++ b/lib/create.c
@@ -314,7 +314,7 @@ disk_create_qcow2 (guestfs_h *g, const char *orig_filename, int64_t size,
   }
 
   /* Assemble the qemu-img command line. */
-  guestfs_int_cmd_add_arg (cmd, "qemu-img");
+  guestfs_int_cmd_add_arg (cmd, QEMU_IMG);
   guestfs_int_cmd_add_arg (cmd, "create");
   guestfs_int_cmd_add_arg (cmd, "-f");
   guestfs_int_cmd_add_arg (cmd, "qcow2");
@@ -347,7 +347,7 @@ disk_create_qcow2 (guestfs_h *g, const char *orig_filename, int64_t size,
 
   r = guestfs_int_cmd_run (cmd);
   if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
-    guestfs_int_external_command_failed (g, r, "qemu-img", orig_filename);
+    guestfs_int_external_command_failed (g, r, QEMU_IMG, orig_filename);
     return -1;
   }
 
diff --git a/lib/info.c b/lib/info.c
index f7378adfd..4464df994 100644
--- a/lib/info.c
+++ b/lib/info.c
@@ -191,7 +191,7 @@ get_json_output (guestfs_h *g, const char *filename)
   snprintf (fdpath, sizeof fdpath, "/dev/fd/%d", fd);
   guestfs_int_cmd_clear_close_files (cmd);
 
-  guestfs_int_cmd_add_arg (cmd, "qemu-img");
+  guestfs_int_cmd_add_arg (cmd, QEMU_IMG);
   guestfs_int_cmd_add_arg (cmd, "info");
   guestfs_int_cmd_add_arg (cmd, "--output");
   guestfs_int_cmd_add_arg (cmd, "json");
diff --git a/m4/guestfs-qemu.m4 b/m4/guestfs-qemu.m4
index 350bb980d..6ea7ef3d7 100644
--- a/m4/guestfs-qemu.m4
+++ b/m4/guestfs-qemu.m4
@@ -100,3 +100,7 @@ working.
     esac
     AC_DEFINE_UNQUOTED([QEMU],["$QEMU"],[Location of qemu binary.])
 ])
+
+dnl qemu-img (required).
+AC_PATH_PROGS([QEMU_IMG],[qemu-img],[no])
+AC_DEFINE_UNQUOTED([QEMU_IMG],["$QEMU_IMG"],[Path to qemu-img program])
-- 
2.13.2