ref: zero-initialize SENTRY_MAKE allocations (#1546)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jpnurmi

src/backends/native/sentry_crash_ipc.c

@@ -23,7 +23,6 @@ sentry__crash_ipc_init_app(sem_t *init_sem)
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = false;
     ipc->init_sem = init_sem; // Use provided semaphore (managed by backend)
 
@@ -179,7 +178,6 @@ sentry__crash_ipc_init_daemon(
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = true;
 
     // Open existing shared memory created by app (using PID and thread ID)
@@ -316,7 +314,6 @@ sentry__crash_ipc_init_app(sem_t *init_sem)
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = false;
     ipc->init_sem = init_sem; // Use provided semaphore (managed by backend)
 
@@ -474,7 +471,6 @@ sentry__crash_ipc_init_daemon(
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = true;
 
     // Open existing shared memory created by app (using PID and thread ID)
@@ -608,7 +604,6 @@ sentry__crash_ipc_init_app(HANDLE init_mutex)
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = false;
     ipc->init_mutex = init_mutex; // Use provided mutex (managed by backend)
 
@@ -738,7 +733,6 @@ sentry__crash_ipc_init_daemon(pid_t app_pid, uint64_t app_tid,
     if (!ipc) {
         return NULL;
     }
-    memset(ipc, 0, sizeof(sentry_crash_ipc_t));
     ipc->is_daemon = true;
 
     // Open existing shared memory (using PID and thread ID)

src/backends/sentry_backend_breakpad.cpp

@@ -335,7 +335,6 @@ sentry__backend_new(void)
     if (!backend) {
         return nullptr;
     }
-    memset(backend, 0, sizeof(sentry_backend_t));
 
     backend->startup_func = breakpad_backend_startup;
     backend->shutdown_func = breakpad_backend_shutdown;

src/backends/sentry_backend_crashpad.cpp

@@ -1041,7 +1041,6 @@ sentry__backend_new(void)
     if (!backend) {
         return nullptr;
     }
-    memset(backend, 0, sizeof(sentry_backend_t));
 
     auto *data = new (std::nothrow) crashpad_state_t {};
     if (!data) {

src/backends/sentry_backend_inproc.c

@@ -1814,7 +1814,6 @@ sentry__backend_new(void)
     if (!backend) {
         return NULL;
     }
-    memset(backend, 0, sizeof(sentry_backend_t));
 
     backend->startup_func = startup_inproc_backend;
     backend->shutdown_func = shutdown_inproc_backend;

src/backends/sentry_backend_native.c

@@ -121,7 +121,6 @@ native_backend_startup(
     if (!state) {
         return 1;
     }
-    memset(state, 0, sizeof(native_backend_state_t));
     backend->data = state;
 
     // Initialize IPC (protected by global synchronization for concurrent
@@ -935,8 +934,6 @@ sentry__backend_new(void)
         return NULL;
     }
 
-    memset(backend, 0, sizeof(sentry_backend_t));
-
     backend->startup_func = native_backend_startup;
     backend->shutdown_func = native_backend_shutdown;
     backend->free_func = native_backend_free;

src/sentry_alloc.c

@@ -21,6 +21,23 @@ sentry_malloc(size_t size)
     return malloc(size);
 }
 
+void *
+sentry__calloc(size_t count, size_t size)
+{
+    if (count && size > SIZE_MAX / count) {
+        return NULL;
+    }
+#ifdef WITH_PAGE_ALLOCATOR
+    if (sentry__page_allocator_enabled()) {
+        // the page allocator is a bump allocator backed by mmap(MAP_ANONYMOUS),
+        // which the OS guarantees to be zeroed on first use, and the page
+        // allocator never reuses freed allocations
+        return sentry__page_allocator_alloc(count * size);
+    }
+#endif
+    return calloc(count, size);
+}
+
 void
 sentry_free(void *ptr)
 {

src/sentry_alloc.h

@@ -3,9 +3,11 @@
 
 #include "sentry_boot.h"
 
+void *sentry__calloc(size_t count, size_t size);
+
 /**
- * This is a shortcut for a typed `malloc`.
+ * This is a shortcut for a typed `calloc` that zero-initializes the allocation.
  */
-#define SENTRY_MAKE(Type) (Type *)sentry_malloc(sizeof(Type))
+#define SENTRY_MAKE(Type) (Type *)sentry__calloc(1, sizeof(Type))
 
 #endif

src/sentry_attachment.c

@@ -79,7 +79,6 @@ sentry__attachment_from_path(sentry_path_t *path)
         sentry__path_free(path);
         return NULL;
     }
-    memset(attachment, 0, sizeof(sentry_attachment_t));
     attachment->path = path;
     return attachment;
 }
@@ -100,7 +99,6 @@ sentry__attachment_from_buffer(
         sentry__path_free(filename);
         return NULL;
     }
-    memset(attachment, 0, sizeof(sentry_attachment_t));
     attachment->filename = filename;
     attachment->buf = sentry_malloc(buf_len * sizeof(char));
     memcpy(attachment->buf, buf, buf_len * sizeof(char));
@@ -220,7 +218,6 @@ attachment_clone(const sentry_attachment_t *attachment)
     if (!clone) {
         return NULL;
     }
-    memset(clone, 0, sizeof(sentry_attachment_t));
 
     if (attachment->path) {
         clone->path = sentry__path_clone(attachment->path);

src/sentry_batcher.c

@@ -3,7 +3,6 @@
 #include "sentry_cpu_relax.h"
 #include "sentry_options.h"
 #include "sentry_utils.h"
-#include <string.h>
 
 // The batcher thread sleeps for this interval between flush cycles.
 // When the timer fires and there are items in the buffer, they are flushed
@@ -28,7 +27,6 @@ sentry__batcher_new(
     if (!batcher) {
         return NULL;
     }
-    memset(batcher, 0, sizeof(sentry_batcher_t));
     batcher->refcount = 1;
     batcher->batch_func = batch_func;
     batcher->data_category = data_category;

src/sentry_hint.c

@@ -14,7 +14,6 @@ sentry_hint_new(void)
     if (!hint) {
         return NULL;
     }
-    memset(hint, 0, sizeof(sentry_hint_t));
     return hint;
 }