Inline GDB scripts in the PHP binary (#13600)

This inlines .gdbinit and php_gdb.py in the .debug_gdb_scripts section of the PHP binary so that GDB can auto-load them regardless of the current directory or the availability of the PHP source code (albeit some functionalities of php_gdb.py currently rely on the source being available).

.gitattributes

@@ -21,6 +21,7 @@
 
 # Collapse generated files within git and pull request diff.
 **/*_arginfo.h linguist-generated -diff
+/main/gdb_inlined_script.c linguist-generated -diff
 /Zend/zend_vm_execute.h linguist-generated -diff
 /Zend/zend_vm_handlers.h linguist-generated -diff
 /Zend/zend_vm_opcodes.[ch] linguist-generated -diff

.github/actions/verify-generated-files/action.yml

@@ -8,6 +8,7 @@ runs:
         [[ "$OSTYPE" == "darwin"* ]] && export PATH="$(brew --prefix)/opt/bison/bin:$PATH"
         scripts/dev/credits
         scripts/dev/genfiles
+        scripts/gdb/debug_gdb_scripts_gen.php
         Zend/zend_vm_gen.php
         ext/tokenizer/tokenizer_data_gen.php
         build/gen_stub.php -f --generate-optimizer-info --verify

configure.ac

@@ -1700,6 +1700,17 @@ PHP_ADD_SOURCES(main, main.c snprintf.c spprintf.c \
        network.c php_open_temporary_file.c php_odbc_utils.c safe_bcmp.c \
        output.c getopt.c php_syslog.c, -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1)
 
+if printf "#if __ELF__\nelf\n#endif\n" | $CC -E - | grep elf > /dev/null; then
+  PHP_ADD_SOURCES(main, debug_gdb_scripts.c)
+
+  cat >> Makefile.objects <<EOF
+$abs_srcdir/main/debug_gdb_scripts.c: $abs_srcdir/scripts/gdb/debug_gdb_scripts_gen.php $abs_srcdir/scripts/gdb/php_gdb.py $abs_srcdir/.gdbinit
+	@if test ! -z "\$(PHP)"; then \\
+		\$(PHP) $abs_srcdir/scripts/gdb/debug_gdb_scripts_gen.php; \\
+	fi;
+EOF
+fi
+
 PHP_ADD_SOURCES_X(main, fastcgi.c, -DZEND_ENABLE_STATIC_TSRMLS_CACHE=1, PHP_FASTCGI_OBJS, no)
 
 PHP_ADD_SOURCES(main/streams, streams.c cast.c memory.c filter.c \

scripts/gdb/debug_gdb_scripts_gen.php

@@ -0,0 +1,53 @@
+#!/usr/bin/env php
+<?php
+
+$rootDir = dirname(__DIR__, 2);
+$mainDir = sprintf('%s/main', $rootDir);
+$outputFile = sprintf('%s/debug_gdb_scripts.c', $mainDir);
+
+printf("Generating %s\n", $outputFile);
+
+$gdbscript = file_get_contents(sprintf("%s/.gdbinit", $rootDir));
+$pyscript = file_get_contents(sprintf("%s/php_gdb.py", __DIR__));
+
+// We can not inline .gdbinit, but we can embed it in the python script.
+$pyscript = sprintf(
+    "gdb.execute('''\n%s\n''')\n%s",
+    addcslashes($gdbscript, '\'\\'),
+    $pyscript,
+);
+
+$ccode = sprintf(
+    <<<'C'
+    /*
+     * Generated by %s.
+     *
+     * This inlines .gdbinit and php_gdb.py into the .debug_gdb_scripts
+     * section of the binary, so that they can be found by gdb.
+     *
+     * See https://sourceware.org/gdb/current/onlinedocs/gdb.html/dotdebug_005fgdb_005fscripts-section.html#dotdebug_005fgdb_005fscripts-section
+     */
+    asm(
+        ".pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n"
+        ".byte 4 /* Python Text */\n"
+        ".ascii \"gdb.inlined-script\\n\"\n"
+        %s
+        ".byte 0\n"
+        ".popsection\n"
+    );
+
+    C,
+    basename(__FILE__),
+    implode("\n    ", array_map(function ($line) {
+        $escapedPy = addcslashes($line."\n", "\"\n\\");
+        $escapedAsm = addcslashes(sprintf(".ascii \"%s\"\n", $escapedPy), "\"\n\\");
+        return sprintf('"%s"', $escapedAsm);
+    }, explode("\n", $pyscript))),
+);
+
+$len = file_put_contents($outputFile, $ccode);
+
+if ($len !== strlen($ccode)) {
+    printf("Failed\n");
+    exit(1);
+}

scripts/gdb/php_gdb.py

@@ -1,9 +1,14 @@
 
 """GDB support for PHP types
 
-Add this to your gdb by amending your ~/.gdbinit as follows:
+This is auto-loaded by GDB if Python Auto-loading is enabled (the default), and
+the PHP binary is in the auto load safe path:
 
-    source .gdb.py
+    # ~/.config/gdb/gdbinit (not ~/.gdbinit)
+    add-auto-load-safe-path /path/to/php-src
+
+See https://sourceware.org/gdb/current/onlinedocs/gdb.html/Python-Auto_002dloading.html
+See https://sourceware.org/gdb/current/onlinedocs/gdb.html/Auto_002dloading-safe-path.html#Auto_002dloading-safe-path
 
 If needed, pretty printers can be by-passed by using the /r flag:
   (gdb) p /r any_variable