Glue Rust to php

Simple example that shows how to write a php extension that uses a Rust
function.

php-ext/config.m4

@@ -0,0 +1,33 @@
+PHP_ARG_WITH(score,
+    [Whether to enable the "score" extension],
+    [ --enable-score      Enable "score" extension support])
+
+if test "$PHP_SCORE" != "no"; then
+
+    dnl Explicitly define the location of the library.
+    dnl Production extensions should use the example from ext_skel on how to
+    dnl properly check common library directories for the existence of your
+    dnl libs.
+    SCORE_LIB_DIR=/usr/local/lib
+
+    dnl This is the proper way to check for the existance of a library. But...
+    dnl this creates a simple program that expects a .h file that will define
+    dnl our functions. Rust does not provide that, so it fails. There is
+    dnl probably some autotools magic I can do to make this work, but alas.
+    dnl PHP_CHECK_LIBRARY(score, score_ext,
+    dnl [
+    dnl     PHP_ADD_LIBRARY_WITH_PATH(score, $SCORE_LIB_DIR, SCORE_SHARED_LIBADD)
+    dnl     AC_DEFINE(HAVE_SCORE, 1, [Whether you have score])
+    dnl ],[
+    dnl     AC_MSG_ERROR([ext_score function not found in libscore])
+    dnl ],[
+    dnl     -L$SCORE_LIB_DIR -R$SCORE_LIB_DIR
+    dnl ])
+
+    dnl Just blindly assume our libscore.so library exists
+    PHP_ADD_LIBRARY_WITH_PATH(score, $SCORE_LIB_DIR, SCORE_SHARED_LIBADD)
+    -L$SCORE_LIB_DIR -R$SCORE_LIB_DIR
+
+    PHP_SUBST(SCORE_SHARED_LIBADD)
+    PHP_NEW_EXTENSION(score, score.c, $ext_shared)
+fi

php-ext/php_score.h

@@ -0,0 +1,20 @@
+#ifndef PHP_SCORE_H
+
+#define PHP_SCORE_H
+
+#define PHP_SCORE_EXTNAME "score"
+#define PHP_SCORE_EXTVER  "1.0"
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "php.h"
+
+extern zend_module_entry score_module_entry;
+#define phpext_score_ptr &score_module_entry
+
+// Because Rust does not provide a .h file to include
+extern double ext_score(char *, char *);
+
+#endif

php-ext/score.c

@@ -0,0 +1,56 @@
+#include "php_score.h"
+
+PHP_FUNCTION(score)
+{
+    char *choice;
+    int choice_len;
+    char *query;
+    int query_len;
+
+    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "ss", &choice, &choice_len, &query, &query_len) == FAILURE) {
+        return;
+    }
+
+    // PHP does not terminate strings with a nul byte.
+    char *choice_c_str = emalloc(choice_len + 1);
+    strncpy(choice_c_str, choice, choice_len);
+    choice_c_str[choice_len] = '\0';
+
+    char *query_c_str = emalloc(query_len + 1);
+    strncpy(query_c_str, query, query_len);
+    query_c_str[query_len] = '\0';
+
+    double s = ext_score(choice_c_str, query_c_str);
+
+    efree(choice_c_str);
+    efree(query_c_str);
+
+    RETURN_DOUBLE(s);
+}
+
+ZEND_BEGIN_ARG_INFO_EX(arginfo_score, 0, 0, 1)
+    ZEND_ARG_INFO(0, choice)
+    ZEND_ARG_INFO(0, query)
+ZEND_END_ARG_INFO()
+
+zend_function_entry php_score_functions[] = {
+    PHP_FE(score, arginfo_score)
+    {NULL, NULL, NULL} /* must be the last line */
+};
+
+zend_module_entry score_module_entry = {
+  STANDARD_MODULE_HEADER,
+  PHP_SCORE_EXTNAME,
+  php_score_functions,
+  NULL, /* minit */
+  NULL, /* mshutdown */
+  NULL, /* rinit */
+  NULL, /* rshutdown */
+  NULL, /* minfo */
+  PHP_SCORE_EXTVER,
+  STANDARD_MODULE_PROPERTIES
+};
+
+#ifdef COMPILE_DL_SCORE
+ZEND_GET_MODULE(score)
+#endif