From 249427ea152227b8c4e0d84fed5277ee67b0efb9 Mon Sep 17 00:00:00 2001
From: m-holger <m.holger@qpdf.org>
Date: Thu, 27 Mar 2025 18:36:01 +0000
Subject: [PATCH] Enhance --rotate usage message (fixes #1410)

---
 libqpdf/QPDFJob.cc                  | 21 ++++++++-------------
 qpdf/qtest/qpdf/invalid-rotated.out |  9 +++++++++
 qpdf/qtest/rotate-pages.test        | 18 +++++++++++++++++-
 3 files changed, 34 insertions(+), 14 deletions(-)
 create mode 100644 qpdf/qtest/qpdf/invalid-rotated.out

diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index bbaf291..efa07d3 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -398,24 +398,19 @@ QPDFJob::parseRotationParameter(std::string const& parameter)
     if (range.empty()) {
         range = "1-z";
     }
-    bool range_valid = false;
     try {
         QUtil::parse_numrange(range.c_str(), 0);
-        range_valid = true;
     } catch (std::runtime_error const&) {
-        // ignore
-    }
-    if (range_valid &&
-        ((angle_str == "0") || (angle_str == "90") || (angle_str == "180") ||
-         (angle_str == "270"))) {
-        int angle = QUtil::string_to_int(angle_str.c_str());
-        if (relative == -1) {
-            angle = -angle;
-        }
-        m->rotations[range] = RotationSpec(angle, (relative != 0));
-    } else {
         usage("invalid parameter to rotate: " + parameter);
     }
+    int angle = QUtil::string_to_int(angle_str.c_str()) % 360;
+    if (angle % 90 != 0) {
+        usage("invalid parameter to rotate (angle must be a multiple of 90): " + parameter);
+    }
+    if (relative == -1) {
+        angle = -angle;
+    }
+    m->rotations[range] = RotationSpec(angle, (relative != 0));
 }
 
 std::vector<int>
diff --git a/qpdf/qtest/qpdf/invalid-rotated.out b/qpdf/qtest/qpdf/invalid-rotated.out
new file mode 100644
index 0000000..7514838
--- /dev/null
+++ b/qpdf/qtest/qpdf/invalid-rotated.out
@@ -0,0 +1,9 @@
+
+qpdf: invalid parameter to rotate (angle must be a multiple of 90): 45:1,4,11,16
+
+For help:
+  qpdf --help=usage       usage information
+  qpdf --help=topic       help on a topic
+  qpdf --help=--option    help on an option
+  qpdf --help             general help and a topic list
+
diff --git a/qpdf/qtest/rotate-pages.test b/qpdf/qtest/rotate-pages.test
index 2f43fed..46527ff 100644
--- a/qpdf/qtest/rotate-pages.test
+++ b/qpdf/qtest/rotate-pages.test
@@ -14,7 +14,7 @@ cleanup();
 
 my $td = new TestDriver('rotate-pages');
 
-my $n_tests = 18;
+my $n_tests = 21;
 
 # Do absolute, positive, and negative on ranges that include
 # inherited and non-inherited.
@@ -32,6 +32,22 @@ $td->runtest("check output",
              {$td->COMMAND => "qpdf-test-compare a.pdf rotated.pdf"},
              {$td->FILE => "rotated.pdf", $td->EXIT_STATUS => 0});
 
+$td->runtest("page rotation (>270)",
+             {$td->COMMAND => "qpdf --static-id to-rotate.pdf a.pdf" .
+                  " --rotate=+450:1,4,11,16" .
+                  " --rotate=900:2,5,12-13" .
+                  " --rotate=-1890:3,15,17,18"},
+             {$td->STRING => "", $td->EXIT_STATUS => 0});
+$td->runtest("check output",
+             {$td->COMMAND => "qpdf-test-compare a.pdf rotated.pdf"},
+             {$td->FILE => "rotated.pdf", $td->EXIT_STATUS => 0});
+
+$td->runtest("invald page rotation",
+             {$td->COMMAND => "qpdf --static-id to-rotate.pdf a.pdf" .
+                  " --rotate=45:1,4,11,16"},
+             {$td->FILE => "invalid-rotated.out", $td->EXIT_STATUS => 2},
+             $td->NORMALIZE_NEWLINES);
+
 $td->runtest("remove rotation",
              {$td->COMMAND => "qpdf --static-id rotated.pdf a.pdf" .
                   " --qdf --no-original-object-ids --rotate=0"},
--
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