Add an INI setting to control uint64_t -> zend_long overflow behavior

Author: jbboehr

.github/workflows/ci.yml

@@ -57,13 +57,18 @@ jobs:
 
     test:
         runs-on: ubuntu-latest
-        name: "Test | PHP ${{ matrix.php-version }}"
+        name: "Test | PHP ${{ matrix.php-version }} ${{ matrix.debug }}"
         strategy:
             matrix:
                 php-version:
                     - "8.1"
                     - "8.2"
                     - "8.3"
+                debug:
+                    - ""
+                include:
+                    - php-version: "8.1"
+                      debug: "debug"
         steps:
             -   uses: actions/checkout@v4
 
@@ -84,7 +89,9 @@ jobs:
 
             -   run: phpize
 
-            -   run: ./configure --enable-compile-warnings=error
+            -   run: ./configure --enable-compile-warnings=error "${EXTRA_FLAGS}"
+                env:
+                    EXTRA_FLAGS: ${{ matrix.debug == 'debug' && '--enable-perfidious-debug' || '' }}
 
             -   run: make
 

README.md

@@ -115,6 +115,7 @@ Some notable generic perf events are:
 
 | Name | Default | Changeable | Description  |
 | --------------------- | -------- | ----------- | ------------ |
+| `perfidious.overflow_mode` | `0` | `PHP_INI_SYSTEM` | Sets the overflow behavior when casting counters from `uint64_t` to `zend_long`. See the constants `Perfidious\OVERFLOW_*` for other values. Note that when set to `Perfidious\OVERFLOW_WARN`, `read` and `readArray` may return `NULL`, despite their type signatures indicating otherwise. |
 | `perfidious.global.enable` | `0` | `PHP_INI_SYSTEM` | Set to `1` to enable the global handle. This handle is kept open between requests. You can read from this handle via e.g. `var_dump(Perfidious\global_handle()?->read());`. |
 | `perfidious.global.metrics` | `perf::PERF_COUNT_HW_CPU_CYCLES:u`, `perf::PERF_COUNT_HW_INSTRUCTIONS:u`  | `PHP_INI_SYSTEM` | The metrics to monitor with the global handle. |
 | `perfidious.request.enable` | `0` | `PHP_INI_SYSTEM` | Set to `1` to enable the per-request handle. This handle is kept open between requests, but reset before and after. You can read from this handle via e.g. `var_dump(Perfidious\request_handle()?->read());` |

flake.nix

@@ -79,10 +79,12 @@
           stdenv ? pkgs.stdenv,
           php ? pkgs.php,
           libpfm ? pkgs.libpfm,
+          debugSupport ? false,
         }:
           pkgs.callPackage ./nix/derivation.nix {
             inherit src;
             inherit stdenv php libpfm;
+            inherit debugSupport;
             buildPecl = pkgs.callPackage (nixpkgs + "/pkgs/build-support/php/build-pecl.nix") {
               inherit php stdenv;
             };
@@ -146,7 +148,7 @@
               # in opcache and relies on mkWrapper to load extensions
               export TEST_PHP_ARGS='-c ${package.php.phpIni}'
               # php.unwrapped from the buildDeps is overwriting php
-              export PATH="${package.php}/bin:$PATH"
+              export PATH="${package.php}/bin:./vendor/bin:$PATH"
             '';
           };
 
@@ -200,21 +202,31 @@
         };
 
         # @see https://github.com/NixOS/nixpkgs/pull/110787
-        buildConfs = lib.cartesianProductOfSets {
-          php = ["php81" "php82" "php83"];
-          stdenv = [
-            "gcc"
-            "clang"
-            # totally broken
-            # "musl"
+        buildConfs =
+          (lib.cartesianProductOfSets {
+            php = ["php81" "php82" "php83"];
+            stdenv = [
+              "gcc"
+              "clang"
+              # totally broken
+              # "musl"
+            ];
+            libpfm = ["libpfm" "libpfm-unstable"];
+          })
+          ++ [
+            {
+              php = "php81";
+              stdenv = "gcc";
+              libpfm = "libpfm";
+              debugSupport = true;
+            }
           ];
-          libpfm = ["libpfm" "libpfm-unstable"];
-        };
 
         buildFn = {
           php,
           libpfm,
           stdenv,
+          debugSupport ? false,
         }:
           lib.nameValuePair
           (lib.concatStringsSep "-" (lib.filter (v: v != "") [
@@ -226,12 +238,18 @@
               then ""
               else "${libpfm}"
             )
+            (
+              if debugSupport
+              then "debug"
+              else ""
+            )
           ]))
           (
             makePackage {
               php = matrix.php.${php};
               libpfm = matrix.libpfm.${libpfm};
               stdenv = matrix.stdenv.${stdenv};
+              inherit debugSupport;
             }
           );
 

nix/derivation.nix

@@ -10,6 +10,7 @@
   buildPecl,
   src,
   checkSupport ? false,
+  debugSupport ? false,
   WerrorSupport ? checkSupport,
   valgrindSupport ? true,
 }:
@@ -32,7 +33,8 @@ buildPecl rec {
   configureFlags =
     []
     ++ lib.optional WerrorSupport "--enable-compile-warnings=error"
-    ++ lib.optionals (!WerrorSupport) ["--enable-compile-warnings=yes" "--disable-Werror"];
+    ++ lib.optionals (!WerrorSupport) ["--enable-compile-warnings=yes" "--disable-Werror"]
+    ++ lib.optional debugSupport "--enable-perfidious-debug";
 
   makeFlags = ["phpincludedir=$(dev)/include"];
   outputs = ["out" "dev"];

perfidious.stub.php

@@ -4,6 +4,10 @@
 
 const VERSION = "0.1.0";
 
+const OVERFLOW_THROW = 0;
+const OVERFLOW_WARN = 1;
+const OVERFLOW_SATURATE = 2;
+const OVERFLOW_WRAP = 3;
 
 /**
  * @throws PmuNotFoundException
@@ -99,6 +103,7 @@ final public function disable(): self
 
     /**
      * Get a raw byte stream from the handle's file descriptor
+     *
      * @note closing this resource will cause subsequent calls to read to fail
      * @return resource
      */
@@ -107,6 +112,11 @@ final public function rawStream()
     }
 
     /**
+     * @note If perfidious.overflow_mode is set to Perfidious\OVERFLOW_WARN, this method can return null, despite its
+     *       typehint. If perfidious.overflow_mode is set to any value other than Perfidious\OVERFLOW_THROW, this
+     *       method will *not* throw an OverflowException.
+     *
+     * @return ReadResult
      * @throws OverflowException|IOException
      *
      * @phpstan-return ReadResult<T>
@@ -116,7 +126,11 @@ final public function read(): ReadResult
     }
 
     /**
-     * @return array<string, int>
+     * @note If perfidious.overflow_mode is set to Perfidious\OVERFLOW_WARN, this method can return null, despite its
+     *       typehint. If perfidious.overflow_mode is set to any value other than Perfidious\OVERFLOW_THROW, this
+     *       method will *not* throw an OverflowException.
+     *
+     * @return array
      * @throws OverflowException|IOException
      *
      * @phpstan-return array<value-of<T>, int>

php_perfidious.h

@@ -83,6 +83,15 @@ enum perfidious_error_mode
     PERFIDIOUS_ERROR_MODE_WARNING = 1,
 };
 
+enum perfidious_overflow_mode
+{
+    PERFIDIOUS_OVERFLOW_THROW = 0,
+    PERFIDIOUS_OVERFLOW_WARN = 1,
+    PERFIDIOUS_OVERFLOW_SATURATE = 2,
+    PERFIDIOUS_OVERFLOW_WRAP = 3,
+    PERFIDIOUS_OVERFLOW_MAX = 3,
+};
+
 PERFIDIOUS_PUBLIC extern zend_class_entry *perfidious_exception_interface_ce;
 PERFIDIOUS_PUBLIC extern zend_class_entry *perfidious_pmu_not_found_exception_ce;
 PERFIDIOUS_PUBLIC extern zend_class_entry *perfidious_pmu_event_not_found_exception_ce;
@@ -103,6 +112,7 @@ ZEND_BEGIN_MODULE_GLOBALS(perfidious)
     struct perfidious_handle *request_handle;
 
     enum perfidious_error_mode error_mode;
+    enum perfidious_overflow_mode overflow_mode;
 ZEND_END_MODULE_GLOBALS(perfidious)
 
 ZEND_EXTERN_MODULE_GLOBALS(perfidious);
@@ -171,6 +181,7 @@ zend_result perfidious_handle_read_to_array_with_times(
 ZEND_HOT
 PERFIDIOUS_PUBLIC
 PERFIDIOUS_ATTR_NONNULL_ALL
+PERFIDIOUS_ATTR_WARN_UNUSED_RESULT
 zend_result
 perfidious_handle_read_to_result(const struct perfidious_handle *restrict handle, zval *restrict return_value);
 

src/extension.c

@@ -38,7 +38,6 @@
 #include "ext/standard/php_string.h"
 
 #include "php_perfidious.h"
-#include "functions.h"
 #include "handle.h"
 #include "private.h"
 
@@ -63,6 +62,7 @@ static ZEND_INI_MH(OnUpdateStr)
 
 // clang-format off
 PHP_INI_BEGIN()
+    STD_PHP_INI_ENTRY(PHP_PERFIDIOUS_NAME ".overflow_mode", "0", PHP_INI_SYSTEM, OnUpdateLong, overflow_mode, zend_perfidious_globals, perfidious_globals)
     STD_PHP_INI_ENTRY(PHP_PERFIDIOUS_NAME ".global.enable", "0", PHP_INI_SYSTEM, OnUpdateBool, global_enable, zend_perfidious_globals, perfidious_globals)
     STD_PHP_INI_ENTRY(PHP_PERFIDIOUS_NAME ".global.metrics", DEFAULT_METRICS, PHP_INI_SYSTEM, OnUpdateStr, global_metrics, zend_perfidious_globals, perfidious_globals)
     STD_PHP_INI_ENTRY(PHP_PERFIDIOUS_NAME ".request.enable", "0", PHP_INI_SYSTEM, OnUpdateBool, request_enable, zend_perfidious_globals, perfidious_globals)
@@ -152,10 +152,28 @@ static PHP_MINIT_FUNCTION(perfidious)
         return FAILURE;
     }
 
-    REGISTER_INI_ENTRIES();
-
+#ifdef PERFIDIOUS_DEBUG
+    REGISTER_BOOL_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\DEBUG", (zend_bool) PERFIDIOUS_DEBUG, flags);
+#else
+    REGISTER_BOOL_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\DEBUG", false, flags);
+#endif
     REGISTER_STRING_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\VERSION", (char *) PHP_PERFIDIOUS_VERSION, flags);
 
+    REGISTER_LONG_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\OVERFLOW_THROW", PERFIDIOUS_OVERFLOW_THROW, flags);
+    REGISTER_LONG_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\OVERFLOW_WARN", PERFIDIOUS_OVERFLOW_WARN, flags);
+    REGISTER_LONG_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\OVERFLOW_SATURATE", PERFIDIOUS_OVERFLOW_SATURATE, flags);
+    REGISTER_LONG_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\OVERFLOW_WRAP", PERFIDIOUS_OVERFLOW_WRAP, flags);
+
+#ifdef PERFIDIOUS_DEBUG
+    do {
+        char buf[128];
+        snprintf(buf, sizeof(buf), "%" PRIu64, UINT64_MAX);
+        REGISTER_STRING_CONSTANT(PHP_PERFIDIOUS_NAMESPACE "\\UINT64_MAX", buf, flags);
+    } while (false);
+#endif
+
+    REGISTER_INI_ENTRIES();
+
     perfidious_exceptions_minit();
     perfidious_handle_minit();
     perfidious_pmu_event_info_minit();
@@ -284,25 +302,15 @@ static PHP_GINIT_FUNCTION(perfidious)
     perfidious_globals->error_mode = PERFIDIOUS_ERROR_MODE_THROW;
 }
 
-// clang-format off
-PERFIDIOUS_LOCAL
-const zend_function_entry perfidious_functions[] = {
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\get_pmu_info", ZEND_FN(perfidious_get_pmu_info), perfidious_get_pmu_info_arginfo, 0)
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\global_handle", ZEND_FN(perfidious_global_handle), perfidious_global_handle_arginfo, 0)
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\list_pmus", ZEND_FN(perfidious_list_pmus), perfidious_list_pmus_arginfo, 0)
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\list_pmu_events", ZEND_FN(perfidious_list_pmu_events), perfidious_list_pmu_events_arginfo, 0)
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\open", ZEND_FN(perfidious_open), perfidious_open_arginfo, 0)
-    ZEND_RAW_FENTRY(PHP_PERFIDIOUS_NAMESPACE "\\request_handle", ZEND_FN(perfidious_request_handle), perfidious_request_handle_arginfo, 0)
-    PHP_FE_END
-};
-// clang-format on
-
 static const zend_module_dep perfidious_deps[] = {
     {"spl",     NULL, NULL, MODULE_DEP_REQUIRED},
     {"opcache", NULL, NULL, MODULE_DEP_OPTIONAL},
     ZEND_MOD_END,
 };
 
+PERFIDIOUS_LOCAL
+extern const zend_function_entry perfidious_functions[];
+
 zend_module_entry perfidious_module_entry = {
     STANDARD_MODULE_HEADER_EX,
     NULL,