Fix detection of image formats in system gd library

- Use gdFontCacheShutdown() to detect freetype
  Currently we look for gdImageStringFT() to determine whether or not gd
  has freetype support... but that function always exists. This leads
  PHP to believe that gd has freetype support when it does not, and can
  lead to build failures.

  The gdFontCacheShutdown() function, on the other hand, is only present
  when gd was built with freetype support. Let's use that instead.

- Fix GD image format detection
  We currently check for, say, AVIF support by attempting to link a
  program that calls libgd's gdImageCreateFromAvif() function. But
  perversely, that function always exists in libgd; moreover when AVIF
  support is missing it emits a warning and returns normally. Thus
  our straightforward link test becomes not so straightforward.

  This commit adds a new macro PHP_GD_CHECK_FORMAT that compiles, links,
  and runs a test program instead. The test program overrides that "emit
  a warning" handler so that the program actually fails if the format
  we're looking for is not supported. This fixes detection of AVIF and
  the other formats we check for in an external libgd.

- ext/gd/tests/bug77391.phpt: skip if gd lacks BMP support
  I don't actually know how to remove BMP support from libgd, but PHP
  has a ./configure test for it, so we should probably treat it as
  optional.

Closes phpGH-12019

Author: orlitzky

NEWS

@@ -16,6 +16,10 @@ PHP                                                                        NEWS
   . Fixed bug #75712 (getenv in php-fpm should not read $_ENV, $_SERVER).
     (Jakub Zelenka)
 
+- GD:
+  . Fixed bug GH-12019 (detection of image formats in system gd library).
+    (Michael Orlitzky)
+
 - MySQLnd:
   . Fixed bug GH-11950 ([mysqlnd] Fixed not to set CR_MALFORMED_PACKET to error
     if CR_SERVER_GONE_ERROR is already set). (Saki Takamachi)

ext/gd/config.m4

@@ -138,15 +138,60 @@ AC_DEFUN([PHP_GD_JISX0208],[
   fi
 ])
 
+dnl Build and run a program to determine if GD has support for the given
+dnl format. The first argument is the proper-noun-capitalized name of the
+dnl format -- basically the word Foo in gdImageCreateFromFoo -- such as
+dnl Png. If support for format Foo exists, the second argument (the name
+dnl of a constant) will be defined to 1. The reason for this charade is
+dnl that gd defines "junk" versions of each gdImageCreateFromFoo function
+dnl even when it does not support the Foo format. Those junk functions
+dnl display a warning but eventually return normally, making a simple link
+dnl or run test insufficient.
+AC_DEFUN([PHP_GD_CHECK_FORMAT],[
+  old_LIBS="${LIBS}"
+  LIBS="${LIBS} ${GD_SHARED_LIBADD}"
+  AC_MSG_CHECKING([for working gdImageCreateFrom$1 in libgd])
+  AC_LANG_PUSH([C])
+  AC_RUN_IFELSE([AC_LANG_SOURCE([
+#include <stdio.h>
+#include <unistd.h>
+#include <gd.h>
+
+/* A custom gdErrorMethod */
+void exit1(int priority, const char *format, va_list args) {
+  _exit(1);
+}
+
+/* Override the default gd_error_method with one that
+   actually causes the program to return an error. */
+int main(int argc, char** argv) {
+  m4_if([$1],[Xpm],
+  [char* f = "test.xpm"],
+  [FILE* f = NULL]);
+  gdSetErrorMethod(exit1);
+  gdImagePtr p = gdImageCreateFrom$1(f);
+  return 0;
+}])],[
+    AC_MSG_RESULT([yes])
+    AC_DEFINE($2, 1, [Does gdImageCreateFrom$1 work?])
+  ],[
+    AC_MSG_RESULT([no])
+  ],[
+    AC_MSG_RESULT([no])
+  ])
+  AC_LANG_POP([C])
+  LIBS="${old_LIBS}"
+])
+
 AC_DEFUN([PHP_GD_CHECK_VERSION],[
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromPng,          [AC_DEFINE(HAVE_GD_PNG,               1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromAvif,         [AC_DEFINE(HAVE_GD_AVIF,              1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromWebp,         [AC_DEFINE(HAVE_GD_WEBP,              1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromJpeg,         [AC_DEFINE(HAVE_GD_JPG,               1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromXpm,          [AC_DEFINE(HAVE_GD_XPM,               1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromBmp,          [AC_DEFINE(HAVE_GD_BMP,               1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageCreateFromTga,          [AC_DEFINE(HAVE_GD_TGA,               1, [ ])], [], [ $GD_SHARED_LIBADD ])
-  PHP_CHECK_LIBRARY(gd, gdImageStringFT,               [AC_DEFINE(HAVE_GD_FREETYPE,          1, [ ])], [], [ $GD_SHARED_LIBADD ])
+  PHP_GD_CHECK_FORMAT([Png],  [HAVE_GD_PNG])
+  PHP_GD_CHECK_FORMAT([Avif], [HAVE_GD_AVIF])
+  PHP_GD_CHECK_FORMAT([Webp], [HAVE_GD_WEBP])
+  PHP_GD_CHECK_FORMAT([Jpeg], [HAVE_GD_JPG])
+  PHP_GD_CHECK_FORMAT([Xpm],  [HAVE_GD_XPM])
+  PHP_GD_CHECK_FORMAT([Bmp],  [HAVE_GD_BMP])
+  PHP_GD_CHECK_FORMAT([Tga],  [HAVE_GD_TGA])
+  PHP_CHECK_LIBRARY(gd, gdFontCacheShutdown,           [AC_DEFINE(HAVE_GD_FREETYPE,          1, [ ])], [], [ $GD_SHARED_LIBADD ])
   PHP_CHECK_LIBRARY(gd, gdVersionString,               [AC_DEFINE(HAVE_GD_LIBVERSION,        1, [ ])], [], [ $GD_SHARED_LIBADD ])
   PHP_CHECK_LIBRARY(gd, gdImageGetInterpolationMethod, [AC_DEFINE(HAVE_GD_GET_INTERPOLATION, 1, [ ])], [], [ $GD_SHARED_LIBADD ])
 ])