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Clarify error callback API, and actually use the return value.

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Improve repair implementation.
This commit is contained in:
Michael R Sweet
2025-04-23 14:43:14 -04:00
parent 1e6bb710e3
commit 278ddb7fa7
7 changed files with 168 additions and 62 deletions
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doc/pdfio.html
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@ -732,7 +732,7 @@ password_cb(<span class="reserved">void</span> *data, <span class="reserved">con
<span class="reserved">return</span> (<span class="string">&quot;Password42&quot;</span>);
}
</code></pre>
<p>The error callback is called for both errors and warnings and accepts the <code>pdfio_file_t</code> pointer, a message string, and the callback pointer value, for example:</p>
<p>The error callback is called for both errors and warnings and accepts the <code>pdfio_file_t</code> pointer, a message string, and the callback pointer value. It returns <code>true</code> to continue processing the file or <code>false</code> to stop, for example:</p>
<pre><code class="language-c"><span class="reserved">bool</span>
error_cb(pdfio_file_t *pdf, <span class="reserved">const</span> <span class="reserved">char</span> *message, <span class="reserved">void</span> *data)
{
@ -740,11 +740,14 @@ error_cb(pdfio_file_t *pdf, <span class="reserved">const</span> <span class="res
fprintf(stderr, <span class="string">&quot;%s: %s\n&quot;</span>, pdfioFileGetName(pdf), message);
<span class="comment">// Return false to treat warnings as errors</span>
<span class="reserved">return</span> (<span class="reserved">false</span>);
<span class="comment">// Return true for warning messages (continue) and false for errors (stop)</span>
<span class="reserved">return</span> (!strncmp(message, <span class="string">&quot;WARNING:&quot;</span>, <span class="number">8</span>));
}
</code></pre>
<p>The default error callback (<code>NULL</code>) does the equivalent of the above.</p>
<blockquote>
<p>Note: Many errors are unrecoverable, so PDFio ignores the return value from the error callback and always stops processing the PDF file. Warning messages start with the prefix &quot;WARNING:&quot; while errors have no prefix.</p>
</blockquote>
<p>Each PDF file contains one or more pages. The <a href="#pdfioFileGetNumPages"><code>pdfioFileGetNumPages</code></a> function returns the number of pages in the file while the <a href="#pdfioFileGetPage"><code>pdfioFileGetPage</code></a> function gets the specified page in the PDF file:</p>
<pre><code class="language-c">pdfio_file_t *pdf; <span class="comment">// PDF file</span>
size_t i; <span class="comment">// Looping var</span>
@ -4129,8 +4132,9 @@ CropBox for pages in the PDF file - if <code>NULL</code> then a default &quot;Un
of 8.27x11in (the intersection of US Letter and ISO A4) is used.<br>
<br>
The &quot;error_cb&quot; and &quot;error_cbdata&quot; arguments specify an error handler callback
and its data pointer - if <code>NULL</code> the default error handler is used that
writes error messages to <code>stderr</code>.</p>
and its data pointer - if <code>NULL</code> then the default error handler is used that
writes error messages to <code>stderr</code>. The error handler callback should return
<code>true</code> to continue writing the PDF file or <code>false</code> to stop.</p>
<h3 class="function"><a id="pdfioFileCreateArrayObj">pdfioFileCreateArrayObj</a></h3>
<p class="description">Create a new object in a PDF file containing an array.</p>
<p class="code">
@ -4434,8 +4438,9 @@ CropBox for pages in the PDF file - if <code>NULL</code> then a default &quot;Un
of 8.27x11in (the intersection of US Letter and ISO A4) is used.<br>
<br>
The &quot;error_cb&quot; and &quot;error_cbdata&quot; arguments specify an error handler callback
and its data pointer - if <code>NULL</code> the default error handler is used that
writes error messages to <code>stderr</code>.<br>
and its data pointer - if <code>NULL</code> then the default error handler is used that
writes error messages to <code>stderr</code>. The error handler callback should return
<code>true</code> to continue writing the PDF file or <code>false</code> to stop.<br>
<br>
</p><blockquote>
<em>Note</em>: Files created using this API are slightly larger than those
@ -4772,8 +4777,15 @@ cancel the open. If <code>NULL</code> is specified for the callback function an
PDF file requires a password, the open will always fail.<br>
<br>
The &quot;error_cb&quot; and &quot;error_cbdata&quot; arguments specify an error handler callback
and its data pointer - if <code>NULL</code> the default error handler is used that
writes error messages to <code>stderr</code>.</p>
and its data pointer - if <code>NULL</code> then the default error handler is used that
writes error messages to <code>stderr</code>. The error handler callback should return
<code>true</code> to continue reading the PDF file or <code>false</code> to stop.<br>
<br>
</p><blockquote>
Note: Error messages starting with &quot;WARNING:&quot; are actually warning
messages - the callback should normally return <code>true</code> to allow PDFio to
try to resolve the issue. In addition, some errors are unrecoverable and
ignore the return value of the error callback.</blockquote>
<h3 class="function"><a id="pdfioFileSetAuthor">pdfioFileSetAuthor</a></h3>
<p class="description">Set the author for a PDF file.</p>
<p class="code">