[systemd-devel] [PATCH] util: Use a shared lookup function for string tables

[Bruno Bottazzini]

Macro DEFINE_STRING_TABLE_LOOKUP expands to a new function for each
of the almost 120 tables throghout the code.
Move the its implementation to a function (guaranteed to never be inlined),
and make the macro expand to an inlined function that calls this function.
This saves a few kilobytes from the systemd binary
---
 src/shared/util.c |  9 +++++++++
 src/shared/util.h | 15 ++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/shared/util.c b/src/shared/util.c
index 891182a..5c8e698 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -8080,3 +8080,12 @@ int syslog_parse_priority(const char **p, int *priority, bool with_facility) {
         *p += k;
         return 1;
 }
+
+size_t _string_table_lookup(const char *const *table, size_t len, const char *key){
+        size_t i;
+        if (key)
+            for (i = 0; i < len; i++)
+                    if (table[i] && streq(table[i], key))
+                            return i;
+        return (size_t) -1;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index ca0c2e5..caa960d 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -334,6 +334,8 @@ int make_console_stdio(void);
 int dev_urandom(void *p, size_t n);
 void random_bytes(void *p, size_t n);
 void initialize_srand(void);
+size_t _string_table_lookup(const char *const *table, size_t len, const char *key)
+                            __attribute__((noinline));
 
 static inline uint64_t random_u64(void) {
         uint64_t u;
@@ -355,16 +357,11 @@ static inline uint32_t random_u32(void) {
                 return name##_table[i];                                 \
         }
 
+
 #define _DEFINE_STRING_TABLE_LOOKUP_FROM_STRING(name,type,scope)        \
-        scope type name##_from_string(const char *s) {                  \
-                type i;                                                 \
-                if (!s)                                                 \
-                        return (type) -1;                               \
-                for (i = 0; i < (type)ELEMENTSOF(name##_table); i++)    \
-                        if (name##_table[i] &&                          \
-                            streq(name##_table[i], s))                  \
-                                return i;                               \
-                return (type) -1;                                       \
+        scope inline type name##_from_string(const char *s) {           \
+                return (type)_string_table_lookup(name##_table,         \
+                        ELEMENTSOF(name##_table), s);                   \
         }
 
 #define _DEFINE_STRING_TABLE_LOOKUP(name,type,scope)                    \
-- 
1.9.1