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<title>[34740] trunk/src/wp-admin/includes/misc.php: Rewrite `insert_with_markers()` to use `flock()` when available, significant cleanup of the function too.</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/34740">34740</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/34740","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>dd32</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2015-10-01 07:45:35 +0000 (Thu, 01 Oct 2015)</dd>
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<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Rewrite `insert_with_markers()` to use `flock()` when available, significant cleanup of the function too.
The call to `flock()` is an exclusive advisory lock, which in my testing only PHP respects (apache continues to read it).
Not all filesystems support locking (remote NFS mounts for example) so this offers minimal benefit to those platforms, but offers much better protection against file corruption on systems which do support it.
The call is blocking, so a second process will wait for the first to complete before writing if supported.
See <a href="https://core.trac.wordpress.org/ticket/31767">#31767</a></pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpadminincludesmiscphp">trunk/src/wp-admin/includes/misc.php</a></li>
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<h3>Diff</h3>
<a id="trunksrcwpadminincludesmiscphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-admin/includes/misc.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-admin/includes/misc.php 2015-10-01 05:42:20 UTC (rev 34739)
+++ trunk/src/wp-admin/includes/misc.php 2015-10-01 07:45:35 UTC (rev 34740)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -102,50 +102,68 @@
</span><span class="cx" style="display: block; padding: 0 10px"> * @return bool True on write success, false on failure.
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> function insert_with_markers( $filename, $marker, $insertion ) {
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if (!file_exists( $filename ) || is_writeable( $filename ) ) {
- if (!file_exists( $filename ) ) {
- $markerdata = '';
- } else {
- $markerdata = explode( "\n", implode( '', file( $filename ) ) );
- }
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( ! is_writeable( $filename ) ) {
+ return false;
+ }
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( !$f = @fopen( $filename, 'w' ) )
- return false;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( ! is_array( $insertion ) ) {
+ $insertion = array( $insertion );
+ }
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $foundit = false;
- if ( $markerdata ) {
- $state = true;
- foreach ( $markerdata as $n => $markerline ) {
- if (strpos($markerline, '# BEGIN ' . $marker) !== false)
- $state = false;
- if ( $state ) {
- if ( $n + 1 < count( $markerdata ) )
- fwrite( $f, "{$markerline}\n" );
- else
- fwrite( $f, "{$markerline}" );
- }
- if (strpos($markerline, '# END ' . $marker) !== false) {
- fwrite( $f, "# BEGIN {$marker}\n" );
- if ( is_array( $insertion ))
- foreach ( $insertion as $insertline )
- fwrite( $f, "{$insertline}\n" );
- fwrite( $f, "# END {$marker}\n" );
- $state = true;
- $foundit = true;
- }
- }
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $start_marker = "# BEGIN {$marker}";
+ $end_marker = "# END {$marker}";
+
+ $fp = fopen( $filename, 'r+' );
+ if ( ! $fp ) {
+ return false;
+ }
+
+ // Attempt to get a lock. If the filesystem supports locking, this will block until the lock is acquired.
+ flock( $fp, LOCK_EX );
+
+ $lines = array();
+ while ( ! feof( $fp ) ) {
+ $lines[] = rtrim( fgets( $fp ), "\r\n" );
+ }
+
+ // Split out the existing file into the preceeding lines, and those that appear after the marker
+ $pre_lines = $post_lines = array();
+ $found_marker = $found_end_marker = false;
+ foreach ( $lines as $line ) {
+ if ( ! $found_marker && false !== strpos( $line, $start_marker ) ) {
+ $found_marker = true;
+ continue;
+ } elseif ( ! $found_end_marker && false !== strpos( $line, $end_marker ) ) {
+ $found_end_marker = true;
+ continue;
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if (!$foundit) {
- fwrite( $f, "\n# BEGIN {$marker}\n" );
- foreach ( $insertion as $insertline )
- fwrite( $f, "{$insertline}\n" );
- fwrite( $f, "# END {$marker}\n" );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( ! $found_marker ) {
+ $pre_lines[] = $line;
+ } elseif ( $found_marker && $found_end_marker ) {
+ $post_lines[] = $line;
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- fclose( $f );
- return true;
- } else {
- return false;
</del><span class="cx" style="display: block; padding: 0 10px"> }
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+
+ // Generate the new file data
+ $new_file_data = implode( "\n", array_merge(
+ $pre_lines,
+ array( $start_marker ),
+ $insertion,
+ array( $end_marker ),
+ $post_lines
+ ) );
+
+ // Write to the start of the file, and truncate it to that length
+ fseek( $fp, 0 );
+ $bytes = fwrite( $fp, $new_file_data );
+ if ( $bytes ) {
+ ftruncate( $fp, $bytes );
+ }
+
+ flock( $fp, LOCK_UN );
+ fclose( $fp );
+
+ return (bool) $bytes;
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span></span></pre>
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