[pve-devel] [PATCH pve-storage 4/9] common: add qemu_img_measure

[Alexandre Derumier via pve-devel <pve-devel@lists.proxmox.com>]

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From: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH pve-storage 4/9] common: add qemu_img_measure
Date: Tue,  3 Jun 2025 09:55:44 +0200
Message-ID: <20250603075558.627850-10-alexandre.derumier@groupe-cyllene.com>

Signed-off-by: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
---
 src/PVE/Storage/Common.pm | 40 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/PVE/Storage/Common.pm b/src/PVE/Storage/Common.pm
index 25f5d28..11b5b94 100644
--- a/src/PVE/Storage/Common.pm
+++ b/src/PVE/Storage/Common.pm
@@ -241,4 +241,44 @@ sub qemu_img_info {
     return $json;
 }
 
+=pod
+
+=head3 qemu_img_measure
+
+    qemu_img_measure($size, $fmt, $timeout, $is_backed)
+
+Returns a json with the maximum size including all metadatas overhead for an image with format C<$fmt> and original size C<$size>Kb.
+If the image is backed C<$is_backed>, we use different cluster size informations.
+=cut
+
+sub qemu_img_measure {
+    my ($size, $fmt, $timeout, $is_backed) = @_;
+
+    die "format is missing" if !$fmt;
+
+    my $cmd = ['/usr/bin/qemu-img', 'measure', '--output=json', '--size', "${size}K", '-O', $fmt];
+    if ($is_backed) {
+	my $options = $QCOW2_CLUSTERS->{backed};
+	push $cmd->@*, '-o', join(',', @$options) if @$options > 0;
+    }
+
+    my $json = '';
+    my $err_output = '';
+    eval {
+        run_command($cmd,
+            timeout => $timeout,
+            outfunc => sub { $json .= shift },
+            errfunc => sub { $err_output .= shift . "\n"},
+        );
+    };
+    warn $@ if $@;
+    if ($err_output) {
+        # if qemu did not output anything to stdout we die with stderr as an error
+        die $err_output if !$json;
+        # otherwise we warn about it and try to parse the json
+        warn $err_output;
+    }
+    return $json;
+}
+
 1;
-- 
2.39.5



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