Merge pull request #20346 from poettering/strlen-unsigned-fix

CONST_MAX() integer size fix
macro: change DECIMAL_STR_WIDTH() return type to size_t, like strlen() and so on
2026-03-24 15:55:00 +01:00 · 2021-08-03 11:03:29 +09:00 · 2021-07-30 15:59:29 +02:00 · 2021-07-30 15:58:09 +02:00 · 2021-07-30 15:56:56 +02:00
2 changed files with 22 additions and 5 deletions
--- a/src/basic/macro.h
+++ b/src/basic/macro.h
@ -214,7 +214,7 @@ static inline size_t GREEDY_ALLOC_ROUND_UP(size_t l) {
 *          Contrary to strlen(), this is a constant expression.
 * @x: a string literal.
 */
-#define STRLEN(x) ((unsigned) sizeof(""x"") - 1)
+#define STRLEN(x) (sizeof(""x"") - 1U)

 /*
 * container_of - cast a member of a structure out to the containing structure
@ -345,12 +345,12 @@ static inline int __coverity_check_and_return__(int condition) {
        (2U+(sizeof(type) <= 1 ? 3U :                                   \
             sizeof(type) <= 2 ? 5U :                                   \
             sizeof(type) <= 4 ? 10U :                                  \
-             sizeof(type) <= 8 ? 20U : (unsigned) sizeof(int[-2*(sizeof(type) > 8)])))
+             sizeof(type) <= 8 ? 20U : sizeof(int[-2*(sizeof(type) > 8)])))

 #define DECIMAL_STR_WIDTH(x)                            \
        ({                                              \
                typeof(x) _x_ = (x);                    \
-                unsigned ans = 1;                       \
+                size_t ans = 1;                         \
                while ((_x_ /= 10) != 0)                \
                        ans++;                          \
                ans;                                    \
--- a/src/fundamental/macro-fundamental.h
+++ b/src/fundamental/macro-fundamental.h
@ -70,12 +70,29 @@
                UNIQ_T(A, aq) > UNIQ_T(B, bq) ? UNIQ_T(A, aq) : UNIQ_T(B, bq); \
        })

-/* evaluates to (void) if _A or _B are not constant or of different types */
+#define IS_UNSIGNED_INTEGER_TYPE(type) \
+        (__builtin_types_compatible_p(typeof(type), unsigned char) ||   \
+         __builtin_types_compatible_p(typeof(type), unsigned short) ||  \
+         __builtin_types_compatible_p(typeof(type), unsigned) ||        \
+         __builtin_types_compatible_p(typeof(type), unsigned long) ||   \
+         __builtin_types_compatible_p(typeof(type), unsigned long long))
+
+#define IS_SIGNED_INTEGER_TYPE(type) \
+        (__builtin_types_compatible_p(typeof(type), signed char) ||   \
+         __builtin_types_compatible_p(typeof(type), signed short) ||  \
+         __builtin_types_compatible_p(typeof(type), signed) ||        \
+         __builtin_types_compatible_p(typeof(type), signed long) ||   \
+         __builtin_types_compatible_p(typeof(type), signed long long))
+
+/* Evaluates to (void) if _A or _B are not constant or of different types (being integers of different sizes
+ * is also OK as long as the signedness matches) */
 #define CONST_MAX(_A, _B) \
        (__builtin_choose_expr(                                         \
                __builtin_constant_p(_A) &&                             \
                __builtin_constant_p(_B) &&                             \
-                __builtin_types_compatible_p(typeof(_A), typeof(_B)),   \
+                (__builtin_types_compatible_p(typeof(_A), typeof(_B)) || \
+                 (IS_UNSIGNED_INTEGER_TYPE(_A) && IS_UNSIGNED_INTEGER_TYPE(_B)) || \
+                 (IS_SIGNED_INTEGER_TYPE(_A) && IS_SIGNED_INTEGER_TYPE(_B))), \
                ((_A) > (_B)) ? (_A) : (_B),                            \
                VOID_0))
Author	SHA1	Message	Date
Yu Watanabe	c7cfde640d	Merge pull request #20346 from poettering/strlen-unsigned-fix CONST_MAX() integer size fix	2021-08-03 11:03:29 +09:00
Lennart Poettering	d844529dc7	macro: change DECIMAL_STR_WIDTH() return type to size_t, like strlen() and so on	2021-07-30 15:59:29 +02:00
Lennart Poettering	777003365a	macro: sizeof() returns size_t, and that's good Now that CONST_MAX() is a bit more foregiving, let's stick to the native return type of sizeof() everywhere, which is size_t, instead of casting to "unsigned", so that on the common archs we don't unnecessarily lose the upper 32bits. This semi-reverts d3e40294572512810c9329933a488619e7ce22fd.	2021-07-30 15:58:09 +02:00
Lennart Poettering	addae96a1a	macro: relax CONST_MAX() type check a tiny bit This checked for strict type compatibility so far, which mean CONST_MAX() couldn't be used on two differently signed integers, even though conceptually there's nothing wrong with allowing that here, as C correctly picks the larger type in the ternary op. hence, let's explicitly whitelist integer comparisons here, as long as the signedness matches.	2021-07-30 15:56:56 +02:00