print errors on mem alloc failure

src/mem.cpp

@@ -61,7 +61,7 @@ Arena *arena_alloc_sized(u64 init_res, u64 init_cmt)
 {
   assert(ARENA_HEADER_SIZE < init_cmt && init_cmt <= init_res);
 
-  u64 page_size = getpagesize();
+  u64 page_size = os_page_size();
   u64 res = align_pow2(init_res, page_size);
   u64 cmt = align_pow2(init_cmt, page_size);
 
@@ -199,6 +199,7 @@ u8 *arena_push_contiguous(Arena *arena, u64 size)
   arena->grow = 0;
   void *mem = arena_push_impl(arena, size);
   arena->grow = restore;
+  if (!mem) fprintf(stderr, "Failed to allocate %lu bytes of contiguous memory\n", size);
   return (u8 *)mem;
 }
 

src/platform_linux.h

@@ -4,6 +4,12 @@
 #include <unistd.h>
 #include <limits.h> // for NAME_MAX
 
+internal
+i32 os_page_size()
+{
+  return getpagesize();
+}
+
 internal
 bool os_open_and_map_file(const char *fname, App_State &app)
 {
@@ -56,7 +62,11 @@ void os_stop_file_watch(App_State &app)
 internal 
 void *os_reserve(u64 size)
 {
-  return mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  void *mem = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  if (UNLIKELY(mem == MAP_FAILED)) {
+    fprintf(stderr, "Error reserving memory: %s (%d)\n", strerror(errno), errno);
+  }
+  return mem;
 }
 
 internal 
@@ -68,6 +78,10 @@ void os_release(void *mem, u64 size)
 internal 
 b32x os_commit(void *addr, u64 size)
 {
-  return mprotect(addr, size, PROT_READ|PROT_WRITE) == 0;
+  b32x err = mprotect(addr, size, PROT_READ|PROT_WRITE);
+  if (UNLIKELY(err)) {
+    fprintf(stderr, "Error committing memory: %s (%d)\n", strerror(errno), errno);
+  }
+  return err == 0;
 }
 

src/types.h

@@ -22,3 +22,6 @@ using i64 = int64_t;
 #define KiB(b) (b * 1024)
 #define MiB(b) (KiB(b) * 1024)
 #define GiB(b) (MiB(b) * 1024)
+
+#define LIKELY(x) __builtin_expect(!!(x), 1)
+#define UNLIKELY(x) __builtin_expect(!!(x), 0)