Fix proc_close() to return 128+signal when child is killed by signal

proc_close() previously returned the raw waitpid status when a child
process was killed by a signal, making it impossible to distinguish
a signal death from a normal exit with the same code.

Now follows the bash convention: return 128 + signal_number for
signal-terminated processes (e.g. 139 for SIGSEGV, 143 for SIGTERM).

Closes GH-21292

Author: alies-dev

ext/standard/proc_open.c

@@ -302,11 +302,13 @@ static void proc_open_rsrc_dtor(zend_resource *rsrc)
 
 	if (wait_pid <= 0) {
 		FG(pclose_ret) = -1;
+	} else if (WIFEXITED(wstatus)) {
+		FG(pclose_ret) = WEXITSTATUS(wstatus);
+	} else if (WIFSIGNALED(wstatus)) {
+		/* Follow the bash/shell convention: 128 + signal number */
+		FG(pclose_ret) = 128 + WTERMSIG(wstatus);
 	} else {
-		if (WIFEXITED(wstatus)) {
-			wstatus = WEXITSTATUS(wstatus);
-		}
-		FG(pclose_ret) = wstatus;
+		FG(pclose_ret) = -1;
 	}
 
 #else

ext/standard/tests/general_functions/proc_close_signal_exit_code.phpt

@@ -0,0 +1,48 @@
+--TEST--
+proc_close() returns 128+signal when child is killed by a signal
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY === 'Windows') die('skip Not for Windows');
+if (!function_exists('posix_kill') || !function_exists('posix_getpid')) die('skip posix extension required');
+?>
+--FILE--
+<?php
+
+// Child that kills itself with SIGTERM (15)
+$child = '<?php posix_kill(posix_getpid(), 15);';
+
+$process = proc_open(
+    [PHP_BINARY, '-r', $child],
+    [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']],
+    $pipes
+);
+
+foreach ($pipes as $pipe) {
+    fclose($pipe);
+}
+
+$exitCode = proc_close($process);
+// Should be 128 + 15 = 143
+var_dump($exitCode);
+
+// Child that exits normally with code 42
+$child2 = '<?php exit(42);';
+
+$process2 = proc_open(
+    [PHP_BINARY, '-r', $child2],
+    [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']],
+    $pipes2
+);
+
+foreach ($pipes2 as $pipe) {
+    fclose($pipe);
+}
+
+$exitCode2 = proc_close($process2);
+// Should be 42
+var_dump($exitCode2);
+
+?>
+--EXPECT--
+int(143)
+int(42)