Limit each image to 1 MB.

UPLOAD_MAX_MB changes the limit, and UPLOAD_MAX_MB=none removes it.

.env.example

@@ -25,6 +25,10 @@ GOOGLE_ANALYTICS_ID=
 # web root. The default is xxx-uploads in the system temporary directory.
 UPLOAD_DIR=
 
+# The largest image a story can have, in megabytes (default 1). Set it
+# to none for no limit. PHP's upload_max_filesize still applies.
+UPLOAD_MAX_MB=
+
 # The most that the upload directory holds, in megabytes (default 100).
 # Past this, previews do not keep new images. Abandoned uploads are
 # removed after a day.

get_data.lib.php

@@ -373,6 +373,24 @@ function upload_dir() {
   return $dir;
 }
 
+/*
+ * The largest image a story can have, in bytes, from UPLOAD_MAX_MB (1 MB
+ * by default). NULL means no limit, which UPLOAD_MAX_MB=none gives.
+ */
+function upload_max_bytes() {
+  $value = strtolower(trim((string)config('UPLOAD_MAX_MB', '')));
+  if ($value === 'none')
+    return NULL;
+  if (!is_numeric($value) || (float)$value <= 0)
+    $value = 1;
+  return (int)((float)$value * 1024 * 1024);
+}
+
+// The same in megabytes for a message, such as "1" or "2.5"
+function upload_max_mb() {
+  return rtrim(rtrim(number_format(upload_max_bytes() / 1048576, 2, '.', ''), '0'), '.');
+}
+
 function is_upload_name($name) {
   return is_string($name) && preg_match('/^[0-9a-f]{32}\z/', $name);
 }

publish/post.lib.php

@@ -206,10 +206,18 @@ function validate_data() {
     $validate['story'] = "You've tried to remove an image without replacing it with text.";
   }
 
+  $upload_max = upload_max_bytes();
+  $too_large = htmlspecialchars((string)($_FILES['upload']['name'] ?? '')) .
+               ($upload_max === NULL ? ' is larger than the server accepts.' : ' is larger than '.upload_max_mb().' MB.') .
+               ' Please choose a smaller image.';
   // 0 == no error; 4 == no file; all others are errors.
-  if ($upload_error > 0 &&
+  if ($upload_error === UPLOAD_ERR_INI_SIZE || $upload_error === UPLOAD_ERR_FORM_SIZE) {
+    $validate['upload'] = $too_large;
+  } else if ($upload_error > 0 &&
       $upload_error !== 4) {
     $validate['upload'] = 'There was an error uploading the file ('.$upload_error.')';
+  } else if ($upload_tmp && $upload_max !== NULL && (int)@filesize($upload_tmp) > $upload_max) {
+    $validate['upload'] = $too_large;
   } else if ($upload_tmp) {
     $upload = getimagesize($upload_tmp);
     if (!$upload)

tests/php/Pages/SubmitTest.php

@@ -112,6 +112,12 @@ class SubmitTest extends PageTestCase {
     $this->assertSame(array(), $this->queries('/^INSERT/'));
   }
 
+  public function testATooLargeImageIsRefused(): void {
+    $page = $this->previewImage(array(), str_pad(TestCase::png(), 1024 * 1024 + 1, "\0"));
+    $this->assertStringContainsString('a.png is larger than 1 MB. Please choose a smaller image.', $page['body']);
+    $this->assertSame(array(), $this->uploads());
+  }
+
   public function testAnArrayActionIsIgnored(): void {
     $page = $this->post('/publish', array('action' => array('post')));
     $this->assertSame(200, $page['status']);
@@ -128,10 +134,10 @@ class SubmitTest extends PageTestCase {
   }
 
   // Preview the story with an image; returns the answer
-  private function previewImage(array $fields = array()): array {
+  private function previewImage(array $fields = array(), ?string $image = NULL): array {
     $token = $this->csrfToken($this->get('/publish')['body']);
     return $this->postFiles('/publish', $this->story($fields + array('action' => 'preview', 'csrf_token' => $token, 'g-recaptcha-response' => 'pass')),
-                            array('upload' => array('a.png', TestCase::png())));
+                            array('upload' => array('a.png', $image ?? TestCase::png())));
   }
 
   public function testAPreviewKeepsTheImageForTheSession(): void {

tests/php/Unit/ValidateDataTest.php

@@ -59,8 +59,53 @@ class ValidateDataTest extends TestCase {
   }
 
   public function testUploadErrorsAreReported(): void {
-    $_FILES['upload'] = array('name' => 'a.png', 'tmp_name' => '', 'error' => UPLOAD_ERR_INI_SIZE);
+    $_FILES['upload'] = array('name' => 'a.png', 'tmp_name' => '', 'error' => UPLOAD_ERR_PARTIAL);
-    $this->assertSame(array('upload' => 'There was an error uploading the file (1)'), $this->validate(array()));
+    $this->assertSame(array('upload' => 'There was an error uploading the file (3)'), $this->validate(array()));
+  }
+
+  public function testAFileThatPhpRefusedAsTooLargeIsReported(): void {
+    foreach (array(UPLOAD_ERR_INI_SIZE, UPLOAD_ERR_FORM_SIZE) as $error) {
+      $_FILES['upload'] = array('name' => 'big.png', 'tmp_name' => '', 'error' => $error);
+      $this->assertSame(array('upload' => 'big.png is larger than 1 MB. Please choose a smaller image.'), $this->validate(array()));
+    }
+  }
+
+  // An image of $bytes bytes: a PNG with padding after its end
+  private function imageOf(int $bytes): void {
+    $file = $this->tmp . '/upload';
+    file_put_contents($file, str_pad(self::png(), $bytes, "\0"));
+    $_FILES['upload'] = array('name' => '<b>big</b>.png', 'tmp_name' => $file, 'error' => UPLOAD_ERR_OK);
+  }
+
+  public function testImagesCanBeOneMegabyte(): void {
+    $this->imageOf(1024 * 1024);
+    $this->assertSame(array(), $this->validate(array()));
+    $this->imageOf(1024 * 1024 + 1);
+    $this->assertSame(array('upload' => '&lt;b&gt;big&lt;/b&gt;.png is larger than 1 MB. Please choose a smaller image.'), $this->validate(array()));
+  }
+
+  public function testTheImageLimitComesFromTheConfiguration(): void {
+    $this->setEnv('UPLOAD_MAX_MB', '2.5');
+    $this->imageOf(2 * 1024 * 1024);
+    $this->assertSame(array(), $this->validate(array()));
+    $this->imageOf((int)(2.5 * 1024 * 1024) + 1);
+    $this->assertSame(array('upload' => '&lt;b&gt;big&lt;/b&gt;.png is larger than 2.5 MB. Please choose a smaller image.'), $this->validate(array()));
+  }
+
+  public function testNoneMeansNoImageLimit(): void {
+    $this->setEnv('UPLOAD_MAX_MB', 'None');
+    $this->assertNull(upload_max_bytes());
+    $this->imageOf(3 * 1024 * 1024);
+    $this->assertSame(array(), $this->validate(array()));
+    $_FILES['upload'] = array('name' => 'big.png', 'tmp_name' => '', 'error' => UPLOAD_ERR_INI_SIZE);
+    $this->assertSame(array('upload' => 'big.png is larger than the server accepts. Please choose a smaller image.'), $this->validate(array()));
+  }
+
+  public function testABadImageLimitMeansTheDefault(): void {
+    foreach (array('', 'lots', '0', '-2') as $value) {
+      $this->setEnv('UPLOAD_MAX_MB', $value);
+      $this->assertSame(1024 * 1024, upload_max_bytes(), $value);
+    }
   }
 
   public function testNoFileIsNotAnError(): void {