Fix builds for 32 bit architecture (#15)

* Run tests against 7.1 and 7.0 32 bit architecture.

* Fix segfaults for 32-bit builds.

zend_parse_parameters is not setting optional zval pointers to NULL.
Instead, we need to default the pointer to NULL so we can check for it
and set a default value.

* Fix the generation of span ids to always be positive integers.

php_mt_rand() returns 32 bits of randomness even for 64 bit integers.
In the 64 bit case, a 0 is always right shifted into the 32nd bit.
In the 32 bit case, a right shift is dependent on the compiler
implementation. Generally, negative numbers will remain negative to make
bitshift arthmatic work.

* Fix implicit declaration warnings

* Add comment about why we're casting the php_mt_rand() before bitshifting.

* Fix allocation of default zval for PHP 7.0

Author: chingor13

Dockerfile

@@ -33,7 +33,7 @@ ENV TEST_PHP_ARGS="-q" \
     REPORT_EXIT_STATUS=1
 
 RUN phpize && \
-    ./configure --enable-stackdriver-trace && \
+    ./configure --enable-opencensus && \
     make clean && \
     make && \
     make test && \

cloudbuild.yaml

@@ -12,3 +12,11 @@ steps:
     args: ['build', '--build-arg', 'BASE_IMAGE=gcr.io/php-mvm-a/php72:alpha3', '.']
     waitFor: ['-']
     id: php72
+  - name: gcr.io/cloud-builders/docker
+    args: ['build', '--build-arg', 'BASE_IMAGE=gcr.io/php-stackdriver/php71-32bit', '.']
+    waitFor: ['-']
+    id: php71-32bit
+  - name: gcr.io/cloud-builders/docker
+    args: ['build', '--build-arg', 'BASE_IMAGE=gcr.io/php-stackdriver/php70-32bit', '.']
+    waitFor: ['-']
+    id: php70-32bit

ext/opencensus_trace.c

@@ -16,6 +16,8 @@
 
 #include "php_opencensus.h"
 #include "opencensus_trace.h"
+#include "opencensus_trace_span.h"
+#include "opencensus_trace_context.h"
 #include "Zend/zend_compile.h"
 #include "Zend/zend_closures.h"
 #include "zend_extensions.h"
@@ -250,7 +252,13 @@ static opencensus_trace_span_t *opencensus_trace_begin(zend_string *function_nam
         php_mt_srand(GENERATE_SEED());
     }
 #endif
-    span->span_id = (php_mt_rand() >> 1);
+    /**
+     * Force the random span id to be positive. php_mt_rand() generates 32 bits
+     * of randomness. On 32-bit systems, we must cast to an unsigned int before
+     * bitshifting to force a positive number. We're ok to lose on bit of
+     * randomness because previous versions of mt_rand only generated 31 bits.
+     */
+    span->span_id = ((uint32_t) php_mt_rand()) >> 1;
 
     if (OPENCENSUS_TRACE_G(current_span)) {
         span->parent = OPENCENSUS_TRACE_G(current_span);
@@ -519,14 +527,14 @@ void opencensus_trace_execute_internal(INTERNAL_FUNCTION_PARAMETERS)
 PHP_FUNCTION(opencensus_trace_function)
 {
     zend_string *function_name;
-    zval *handler, *copy;
+    zval *handler = NULL, *copy;
+    zval h;
 
     if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "S|z", &function_name, &handler) == FAILURE) {
         RETURN_FALSE;
     }
 
     if (handler == NULL) {
-        zval h;
         ZVAL_LONG(&h, 1);
         handler = &h;
     }
@@ -550,14 +558,14 @@ PHP_FUNCTION(opencensus_trace_function)
 PHP_FUNCTION(opencensus_trace_method)
 {
     zend_string *class_name, *function_name, *key;
-    zval *handler, *copy;
+    zval *handler = NULL, *copy;
+    zval h;
 
     if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "SS|z", &class_name, &function_name, &handler) == FAILURE) {
         RETURN_FALSE;
     }
 
     if (handler == NULL) {
-        zval h;
         ZVAL_LONG(&h, 1);
         handler = &h;
     }

ext/opencensus_trace_context.h

@@ -21,4 +21,6 @@
 
 extern zend_class_entry* opencensus_trace_context_ce;
 
+int opencensus_trace_context_minit(INIT_FUNC_ARGS);
+
 #endif /* PHP_OPENCENSUS_TRACE_CONTEXT_H */

ext/opencensus_trace_span.h

@@ -39,5 +39,6 @@ int opencensus_trace_span_add_label_str(opencensus_trace_span_t *span, char *k,
 int opencensus_trace_span_apply_span_options(opencensus_trace_span_t *span, zval *span_options);
 opencensus_trace_span_t *opencensus_trace_span_alloc();
 void opencensus_trace_span_free(opencensus_trace_span_t *span);
+int opencensus_trace_span_minit(INIT_FUNC_ARGS);
 
 #endif /* PHP_OPENCENSUS_TRACE_SPAN_H */