Fix GH-8563, GH-8564: SplFileObject EOF handling for seek() and next()

spl_filesystem_file_read_ex() treated a NULL buffer from
php_stream_get_line as a successful read of an empty line, creating a
phantom cached line at EOF. This caused seek() to give inconsistent
results between SplFileObject and SplTempFileObject (GH-8563), and
next() to increment the line counter indefinitely past EOF (GH-8564).

Return FAILURE when php_stream_get_line returns NULL, matching the
behavior of the existing php_stream_eof check. In seek(), break out
of the loop on EOF instead of returning, so the post-loop cleanup
runs consistently. In next(), return early at EOF without incrementing.
Make __toString() return empty string at EOF instead of throwing.

Closes GH-8563
Closes GH-8564

Author: iliaal

ext/spl/spl_directory.c

@@ -1813,21 +1813,24 @@ static zend_result spl_filesystem_file_read_ex(spl_filesystem_object *intern, bo
 	}
 
 	if (!buf) {
-		intern->u.file.current_line = ZSTR_EMPTY_ALLOC();
-	} else {
-		if (!csv && SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_DROP_NEW_LINE)) {
-			if (line_len > 0 && buf[line_len - 1] == '\n') {
+		if (!silent) {
+			spl_filesystem_file_cannot_read(intern);
+		}
+		return FAILURE;
+	}
+
+	if (!csv && SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_DROP_NEW_LINE)) {
+		if (line_len > 0 && buf[line_len - 1] == '\n') {
+			line_len--;
+			if (line_len > 0 && buf[line_len - 1] == '\r') {
 				line_len--;
-				if (line_len > 0 && buf[line_len - 1] == '\r') {
-					line_len--;
-				}
-				buf[line_len] = '\0';
 			}
+			buf[line_len] = '\0';
 		}
-
-		intern->u.file.current_line = zend_string_init(buf, line_len, /* persistent */ false);
-		efree(buf);
 	}
+
+	intern->u.file.current_line = zend_string_init(buf, line_len, /* persistent */ false);
+	efree(buf);
 	intern->u.file.current_line_num += line_add;
 
 	return SUCCESS;
@@ -2144,7 +2147,9 @@ PHP_METHOD(SplFileObject, next)
 	ZEND_PARSE_PARAMETERS_NONE();
 
 	if (!intern->u.file.current_line && Z_ISUNDEF(intern->u.file.current_zval)) {
-		spl_filesystem_file_read_line(ZEND_THIS, intern, true);
+		if (spl_filesystem_file_read_line(ZEND_THIS, intern, true) == FAILURE) {
+			return;
+		}
 	}
 
 	spl_filesystem_file_free_line(intern);
@@ -2634,7 +2639,7 @@ PHP_METHOD(SplFileObject, seek)
 
 	for (i = 0; i < line_pos; i++) {
 		if (spl_filesystem_file_read_line(ZEND_THIS, intern, true) == FAILURE) {
-			return;
+			break;
 		}
 	}
 	if (line_pos > 0 && !SPL_HAS_FLAG(intern->flags, SPL_FILE_OBJECT_READ_AHEAD)) {
@@ -2653,9 +2658,8 @@ PHP_METHOD(SplFileObject, __toString)
 
 	if (!intern->u.file.current_line) {
 		ZEND_ASSERT(Z_ISUNDEF(intern->u.file.current_zval));
-		zend_result result = spl_filesystem_file_read_line(ZEND_THIS, intern, false);
-		if (UNEXPECTED(result != SUCCESS)) {
-			RETURN_THROWS();
+		if (spl_filesystem_file_read_line(ZEND_THIS, intern, true) == FAILURE) {
+			RETURN_EMPTY_STRING();
 		}
 	}
 

ext/spl/tests/SplFileObject/SplFileObject_key_error001.phpt

@@ -18,5 +18,5 @@ var_dump($s->key());
 var_dump($s->valid());
 ?>
 --EXPECT--
-int(14)
+int(12)
 bool(false)

ext/spl/tests/SplFileObject/SplFileObject_key_error002.phpt

@@ -18,5 +18,5 @@ var_dump($s->key());
 var_dump($s->valid());
 ?>
 --EXPECT--
-int(13)
+int(12)
 bool(false)

ext/spl/tests/SplFileObject/bug81477.phpt

@@ -21,7 +21,6 @@ string(8) "baz,bat
 "
 string(10) "more,data
 "
-string(0) ""
 --CLEAN--
 <?php
 @unlink(__DIR__ . '/bug81477.csv');

ext/spl/tests/SplFileObject/fgetcsv_blank_file.phpt

@@ -18,8 +18,5 @@ $file->rewind();
 var_dump($file->fgetcsv());
 ?>
 --EXPECT--
-array(1) {
-  [0]=>
-  NULL
-}
+bool(false)
 bool(false)

ext/spl/tests/SplFileObject/gh8563.phpt

@@ -0,0 +1,29 @@
+--TEST--
+GH-8563 (Different results for seek() on SplFileObject and SplTempFileObject)
+--FILE--
+<?php
+$path = __DIR__ . '/gh8563.txt';
+$file_01 = new SplFileObject($path, 'w+');
+$file_02 = new SplTempFileObject();
+
+for ($i = 0; $i < 5; $i++) {
+    $file_01->fwrite("line {$i}" . PHP_EOL);
+    $file_02->fwrite("line {$i}" . PHP_EOL);
+}
+
+$file_01->rewind();
+$file_02->rewind();
+
+$file_01->seek(10);
+$file_02->seek(10);
+
+echo 'SplFileObject: ' . $file_01->key() . "\n";
+echo 'SplTempFileObject: ' . $file_02->key() . "\n";
+?>
+--CLEAN--
+<?php
+unlink(__DIR__ . '/gh8563.txt');
+?>
+--EXPECT--
+SplFileObject: 5
+SplTempFileObject: 5

ext/spl/tests/SplFileObject/gh8564.phpt

@@ -0,0 +1,20 @@
+--TEST--
+GH-8564 (SplFileObject: next() moves to nonexistent indexes)
+--FILE--
+<?php
+$file = new SplTempFileObject();
+for ($i = 0; $i < 5; $i++) {
+    $file->fwrite("line {$i}" . PHP_EOL);
+}
+
+$file->rewind();
+for ($i = 0; $i < 10; $file->next(), $i++);
+echo "next() 10x: key=" . $file->key() . " valid=" . var_export($file->valid(), true) . "\n";
+
+$file->rewind();
+$file->seek(10);
+echo "seek(10): key=" . $file->key() . " valid=" . var_export($file->valid(), true) . "\n";
+?>
+--EXPECT--
+next() 10x: key=5 valid=false
+seek(10): key=5 valid=false

ext/spl/tests/gh13685.phpt

@@ -44,9 +44,9 @@ try {
 string(14) ""A", "B", "C"
 "
 string(13) ""D", "E", "F""
-Cannot read from file php://temp
+string(0) ""
 --- Use csv control ---
 string(14) ""A", "B", "C"
 "
 string(13) ""D", "E", "F""
-Cannot read from file php://temp
+string(0) ""