X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fshared%2Fmacro.h;h=daa42c4c68101ce5e70fb773a7fafd5937c417e8;hb=30535c16924a3da7b47ea87190d929d617d95c5a;hp=548294e47b65f5cc4636dbc0776bfece60245ea2;hpb=5f86c1f4c43ee9caa120d130e9b89d3fd25124c0;p=elogind.git

diff --git a/src/shared/macro.h b/src/shared/macro.h
index 548294e47..daa42c4c6 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -197,6 +197,17 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
                                         UNIQ_T(X,xq);                   \
         })
 
+/* [(x + y - 1) / y] suffers from an integer overflow, even though the
+ * computation should be possible in the given type. Therefore, we use
+ * [x / y + !!(x % y)]. Note that on "Real CPUs" a division returns both the
+ * quotient and the remainder, so both should be equally fast. */
+#define DIV_ROUND_UP(_x, _y)                                            \
+        __extension__ ({                                                \
+                const typeof(_x) __x = (_x);                            \
+                const typeof(_y) __y = (_y);                            \
+                (__x / __y + !!(__x % __y));                            \
+        })
+
 #define assert_se(expr)                                                 \
         do {                                                            \
                 if (_unlikely_(!(expr)))                                \
@@ -264,6 +275,14 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
 #define PTR_TO_SIZE(p) ((size_t) ((uintptr_t) (p)))
 #define SIZE_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 
+/* The following macros add 1 when converting things, since UID 0 is a
+ * valid UID, while the pointer NULL is special */
+#define PTR_TO_UID(p) ((uid_t) (((uintptr_t) (p))-1))
+#define UID_TO_PTR(u) ((void*) (((uintptr_t) (u))+1))
+
+#define PTR_TO_GID(p) ((gid_t) (((uintptr_t) (p))-1))
+#define GID_TO_PTR(u) ((void*) (((uintptr_t) (u))+1))
+
 #define memzero(x,l) (memset((x), 0, (l)))
 #define zero(x) (memzero(&(x), sizeof(x)))