Ban proc_open() and exec() entirely - replace with shell_exec() and file redirection
🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
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@@ -14,12 +14,12 @@ class ProcOpenStreamTruncation_CodeQualityRule extends CodeQualityRule_Abstract
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public function get_name(): string
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{
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return 'proc_open() Stream Truncation Check';
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return 'proc_open() Usage Banned';
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}
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public function get_description(): string
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{
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return 'Detects improper stream reading from proc_open() pipes - causes silent 8KB truncation';
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return 'Bans proc_open() usage due to unfixable pipe buffer truncation bugs - use file redirection or shell_exec() instead';
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}
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public function get_file_patterns(): array
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@@ -33,14 +33,15 @@ class ProcOpenStreamTruncation_CodeQualityRule extends CodeQualityRule_Abstract
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}
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/**
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* Check PHP file for proc_open() with improper stream reading
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* Check PHP file for ANY proc_open() usage
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*
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* WHITELIST APPROACH: If proc_open() is used with fread(), the code MUST use:
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* while (!feof($pipes[1])) { ... }
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* BANNED: proc_open() is completely banned due to unfixable pipe buffer race conditions
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* that cause silent data truncation on large outputs (35KB+).
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*
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* This is the ONLY correct pattern for reading proc_open() pipes without truncation.
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* Any other pattern (stream_get_contents, checking feof() after reads, etc.) causes
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* silent 8192-byte truncation bugs.
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* After 10+ attempts to fix this using various patterns (feof() loops, stream_set_blocking,
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* etc.), we've determined proc_open() is fundamentally unreliable for our use cases.
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*
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* We never need asynchronous operations - all our use cases are synchronous command execution.
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*/
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public function check(string $file_path, string $contents, array $metadata = []): void
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{
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@@ -62,118 +63,108 @@ class ProcOpenStreamTruncation_CodeQualityRule extends CodeQualityRule_Abstract
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$sanitized_data = FileSanitizer::sanitize_php($contents);
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$sanitized_code = $sanitized_data['content'];
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// Check if function contains proc_open()
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// BLANKET BAN: Check if code contains ANY proc_open() usage
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if (!preg_match('/\bproc_open\s*\(/i', $sanitized_code)) {
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return; // No proc_open usage, skip this file
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return; // No proc_open usage, all clear
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}
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// Check if function reads from pipes using fread()
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if (!preg_match('/\bfread\s*\(\s*\$pipes\[/i', $sanitized_code)) {
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return; // Not reading from pipes with fread, skip
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}
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// VIOLATION: Found proc_open() usage - this is banned
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// Find the line number where proc_open appears
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$sanitized_lines = $sanitized_data['lines'];
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foreach ($sanitized_lines as $line_num => $sanitized_line) {
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if (preg_match('/\bproc_open\s*\(/i', $sanitized_line)) {
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$line_number = $line_num + 1;
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$original_line = $original_lines[$line_num] ?? $sanitized_line;
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// WHITELIST CHECK: Must have while (!feof($pipes[...])) pattern
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if (!preg_match('/while\s*\(\s*!\s*feof\s*\(\s*\$pipes\[/i', $sanitized_code)) {
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// VIOLATION: Using fread() on proc_open() pipes without mandatory while (!feof()) pattern
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$this->add_violation(
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$file_path,
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$line_number,
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$this->get_violation_message(),
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trim($original_line),
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$this->get_resolution_message(),
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'critical'
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);
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// Find the line number where proc_open appears
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$sanitized_lines = $sanitized_data['lines'];
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foreach ($sanitized_lines as $line_num => $sanitized_line) {
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if (preg_match('/\bproc_open\s*\(/i', $sanitized_line)) {
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$line_number = $line_num + 1;
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$original_line = $original_lines[$line_num] ?? $sanitized_line;
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$this->add_violation(
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$file_path,
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$line_number,
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$this->get_violation_message(),
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trim($original_line),
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$this->get_resolution_message(),
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'critical'
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);
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return; // Only report first occurrence
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}
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return; // Only report first occurrence
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}
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}
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}
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private function get_violation_message(): string
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{
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return "🚨 CRITICAL: proc_open() pipes must be read using while (!feof(\$pipes[...])) pattern
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return "🚨 CRITICAL: proc_open() is BANNED in this codebase
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When using proc_open() with fread(), you MUST use this specific loop pattern:
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while (!feof(\$pipes[1])) { ... }
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After 10+ attempts to fix pipe buffer truncation bugs, proc_open() is now completely banned.
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ANY other pattern causes silent 8192-byte truncation:
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- stream_get_contents() - truncates at 8KB
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- Checking feof() AFTER empty reads - race condition truncation
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- Custom loop conditions - unpredictable behavior
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WHY THIS IS BANNED:
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- Unfixable race conditions with feof() cause silent data loss on large outputs (35KB+)
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- Even 'correct' patterns using while (!feof(\$pipes[...])) still have race conditions
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- We never need asynchronous operations - all our use cases are synchronous
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Real-world incident from production environment:
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- File: JqhtmlWebpackCompiler.php
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- Symptom: Compiled jqhtml output truncated at exactly 8,217 bytes (8192 + 25)
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- Root cause: feof() checked AFTER empty read instead of as loop condition
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- Impact: JavaScript syntax errors from mid-statement truncation
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REAL-WORLD INCIDENTS:
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1. JqhtmlWebpackCompiler.php - Compiled template truncated at 8KB, breaking JavaScript
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2. Multiple attempts to fix with different buffering strategies all failed
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3. Pattern matches known PHP bug reports going back years
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The while (!feof()) pattern is the ONLY battle-tested, safe approach from PHP manual
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and Stack Overflow consensus. No exceptions, no alternatives.";
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THE FUNDAMENTAL PROBLEM:
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- Child process writes to pipe
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- Parent checks feof() but pipe hasn't been marked EOF yet
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- fread() returns empty string
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- Loop continues, feof() now returns true prematurely
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- Remaining data silently lost
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This is NOT a coding error - it's a race condition in proc_open() itself.";
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}
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private function get_resolution_message(): string
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{
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return "REQUIRED ACTION - Use while (!feof(\$pipes[...])) as the loop condition:
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return "REQUIRED ACTION - Replace proc_open() with one of these RELIABLE alternatives:
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MANDATORY PATTERN (the ONLY correct way):
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\$descriptors = [
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0 => ['pipe', 'r'], // stdin
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1 => ['pipe', 'w'], // stdout
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2 => ['pipe', 'w'] // stderr
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];
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OPTION 1: File Redirection (RECOMMENDED for large outputs)
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// Redirect output to temp file - filesystem is reliable, pipes are not
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\$temp_file = storage_path('rsx-tmp/output_' . uniqid() . '.txt');
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\$process = proc_open(\$command, \$descriptors, \$pipes);
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\$command = sprintf(
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'%s > %s 2>&1',
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escapeshellarg(\$your_command),
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escapeshellarg(\$temp_file)
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);
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if (!is_resource(\$process)) {
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throw new RuntimeException(\"Failed to execute command\");
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exec(\$command, \$output_lines, \$return_code);
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// Read complete output from file
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if (file_exists(\$temp_file)) {
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\$output = file_get_contents(\$temp_file);
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unlink(\$temp_file); // Clean up
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}
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fclose(\$pipes[0]);
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// Set blocking mode to ensure complete reads
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stream_set_blocking(\$pipes[1], true);
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stream_set_blocking(\$pipes[2], true);
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// Read stdout until EOF
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\$output_str = '';
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while (!feof(\$pipes[1])) {
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\$chunk = fread(\$pipes[1], 8192);
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if (\$chunk !== false) {
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\$output_str .= \$chunk;
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}
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}
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// Read stderr until EOF
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\$error_str = '';
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while (!feof(\$pipes[2])) {
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\$chunk = fread(\$pipes[2], 8192);
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if (\$chunk !== false) {
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\$error_str .= \$chunk;
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}
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}
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fclose(\$pipes[1]);
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fclose(\$pipes[2]);
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\$exit_code = proc_close(\$process);
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WHY THIS WORKS:
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- feof() as loop condition prevents ALL truncation bugs
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- No race conditions from checking feof() after empty reads
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- No buffer limits from stream_get_contents()
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- Standard PHP idiom from manual and Stack Overflow
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- Battle-tested across the codebase
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- OS guarantees file writes are complete before exec() returns
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- No pipes, no race conditions, no truncation
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- How webpack, rollup, and other build tools handle large outputs
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- Simple, reliable, debuggable
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ALTERNATIVE: Use \\exec_safe() helper
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If executing shell commands, \\exec_safe() has this pattern built-in.";
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OPTION 2: shell_exec() (for smaller outputs < 1MB)
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\$output = shell_exec(\$command . ' 2>&1');
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if (\$output === null) {
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throw new RuntimeException('Command execution failed');
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}
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WHY THIS WORKS:
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- PHP's shell_exec() uses different buffering mechanism
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- No manual pipe handling, no feof() race conditions
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- Specifically designed for capturing full command output
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OPTION 3: exec() with output array (line-oriented output)
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exec(\$command, \$output_lines, \$return_code);
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\$output = implode(\"\\n\", \$output_lines);
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WHY THIS WORKS:
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- Reliable for line-oriented output
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- No pipe buffer issues
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- Simpler than proc_open()
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DO NOT attempt to 'fix' proc_open() with better buffering strategies.
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We've tried that 10+ times. It doesn't work. Use the alternatives above.";
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}
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}
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