Simplify list traversal logic.

3 files changed, 31 insertions, 40 deletions

diff --git a/rainbow/nss/nss-rainbow.c b/rainbow/nss/nss-rainbow.c
index 1f69ac3..6a2125c 100644
--- a/rainbow/nss/nss-rainbow.c
+++ b/rainbow/nss/nss-rainbow.c
@@ -5,6 +5,7 @@
 #include <pwd.h>
 #include <grp.h>
 #include <stdint.h>
+#include <stddef.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <sys/types.h>
@@ -286,7 +287,7 @@ gid_to_members_scanner(const struct dirent* d) {
   bool find_gid(struct gid_row* iter) {
     if (iter->gid == gid) { g_cur_gid = iter; return 0; } else return 1;
   }
-  slist_search(struct gid_row, list, g_gids, found, not_found, &find_gid);
+  slist_search(struct gid_row, list, g_gids, found, not_found, find_gid);
 
 not_found:
   LET(gr = calloc(1, sizeof(struct gid_row)), !gr,
@@ -329,10 +330,10 @@ enum nss_status _nss_rainbow_endgrent(void) {
       free(member_iter->name);
       free(member_iter);
     }
-    slist_for(struct member_row, list, gid_iter->members, &free_member);
+    slist_for(struct member_row, list, gid_iter->members, free_member);
     free(gid_iter);
   }
-  slist_for(struct gid_row, list, g_gids, &free_gid);
+  slist_for(struct gid_row, list, g_gids, free_gid);
 
   return NSS_STATUS_SUCCESS;
 }
@@ -366,8 +367,8 @@ fill_group(struct group* result, char* buf, size_t buflen, struct gid_row* gid_i
 
   /* count the number of members */
   size_t member_count = 0;
-  void count_member(struct member_row* iter) { member_count++; }
-  slist_for(struct member_row, list, gid_iter->members, &count_member);
+  void count_member(struct member_row* iter) { (void) iter; member_count++; }
+  slist_for(struct member_row, list, gid_iter->members, count_member);
 
   /* reserve space for the member-pointers */
   size_t member_size = (member_count+1)* sizeof(char*);
@@ -381,7 +382,7 @@ fill_group(struct group* result, char* buf, size_t buflen, struct gid_row* gid_i
   /* fill in the members and swing the pointers */
   member_count = 0;
   slist_while(struct member_row, list, gid_iter->members, out_error,
-               &fill_member, result, &buf, &buflen, &member_count);
+               fill_member, result, &buf, &buflen, &member_count);
 
   return 0;
 
@@ -432,7 +433,7 @@ _nss_rainbow_getgrgid_r(gid_t gid, struct group *result, char *buf, size_t bufle
   }
 
   slist_search(struct gid_row, list, g_gids, resume, resume,
-               &find_gid, &gid_iter);
+               find_gid, &gid_iter);
 resume:
 
   TST(&gid_iter->list == NULL, ret = NSS_STATUS_NOTFOUND,
diff --git a/rainbow/nss/slist.h b/rainbow/nss/slist.h
index aaccd41..cd031ee 100644
--- a/rainbow/nss/slist.h
+++ b/rainbow/nss/slist.h
@@ -7,44 +7,33 @@ bool slist_non_null(struct slist* self);
 size_t slist_length(struct slist* self);
 void slist_extend(struct slist* self, struct slist* rhs);
 
-/* Definition from kernel/include/list.h */
-#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
-
-/* Definition from kernel/include/list.h */
-#define container_of(ptr, type, member) ({                      \
-        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
-        (type *)( (char *)__mptr - offsetof(type,member) );})
+#define container_of(PTR, TYPE, MEMBER) \
+  (TYPE *)((char *)(PTR) - ((ptrdiff_t) &((TYPE*)0)->MEMBER))
 
 /* FUN should return false to break iteration. */
 /* NB: Comma-swallowing paste of gnu-style named variadic macro argument. */
-#define slist_search(TYPE, MEMBER, PTR, FOUND_LABEL, NOTFOUND_LABEL, FUN, COOKIE...) ({ \
-  struct slist *__slist_iter = ((PTR)->MEMBER).next; \
+#define slist_metafor(TYPE, MEMBER, PTR, BODY) { \
+  struct slist *__slist_head = &((PTR)->MEMBER); \
+  struct slist *__slist_iter = __slist_head->next; \
   struct slist *__slist_next; \
-  while(__slist_iter != &((PTR)->MEMBER)) { \
+  while(__slist_iter != __slist_head) { \
         __slist_next = __slist_iter->next; \
         TYPE* __value_ptr = container_of(__slist_iter, TYPE, MEMBER); \
-        if(!(*(FUN))(__value_ptr, ##COOKIE)) goto FOUND_LABEL; \
+        BODY; \
         __slist_iter = __slist_next; \
-      } \
-  goto NOTFOUND_LABEL; })
+  } \
+}
 
-#define slist_while(TYPE, MEMBER, PTR, ERR_LABEL, FUN, COOKIE...) ({ \
-  struct slist *__slist_iter = ((PTR)->MEMBER).next; \
-  struct slist *__slist_next; \
-  while(__slist_iter != &((PTR)->MEMBER)) { \
-        __slist_next = __slist_iter->next; \
-        TYPE* __value_ptr = container_of(__slist_iter, TYPE, MEMBER); \
-        if((*(FUN))(__value_ptr, ##COOKIE)) goto ERR_LABEL; \
-        __slist_iter = __slist_next; \
-      } \
-  })
+#define slist_search(TYPE, MEMBER, PTR, FOUND_LABEL, NOTFOUND_LABEL, FUN, \
+  COOKIE...) \
+  slist_metafor(TYPE, MEMBER, PTR, \
+    { if(!(FUN)(__value_ptr, ##COOKIE)) goto FOUND_LABEL; } \
+  ) \
+  goto NOTFOUND_LABEL;
 
-#define slist_for(TYPE, MEMBER, PTR, FUN, COOKIE...) ({ \
-  struct slist *__slist_iter = ((PTR)->MEMBER).next; \
-  struct slist *__slist_next; \
-  while(__slist_iter != &((PTR)->MEMBER)) { \
-        __slist_next = __slist_iter->next; \
-        TYPE* __value_ptr = container_of(__slist_iter, TYPE, MEMBER); \
-        (*(FUN))(__value_ptr, ##COOKIE); \
-        __slist_iter = __slist_next; \
-      } })
+#define slist_while(TYPE, MEMBER, PTR, ERR_LABEL, FUN, COOKIE...) \
+  slist_metafor(TYPE, MEMBER, PTR, \
+    { if((FUN)(__value_ptr, ##COOKIE)) goto ERR_LABEL; }) \
+
+#define slist_for(TYPE, MEMBER, PTR, FUN, COOKIE...) \
+  slist_metafor(TYPE, MEMBER, PTR, { (FUN)(__value_ptr, ##COOKIE); })
diff --git a/rainbow/nss/test_slist.c b/rainbow/nss/test_slist.c
index 66be29d..138adf4 100644
--- a/rainbow/nss/test_slist.c
+++ b/rainbow/nss/test_slist.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdint.h>
+#include <stddef.h>
 #include <stdbool.h>
 
 #include "slist.h"
@@ -22,7 +23,7 @@ int find_two(struct node* self) {
   if (self->id == 2) return 0; else return 1;
 }
 
-int main(int argc, char** argv) {
+int main() {
   struct node h, a, b, c;
   node_init(&h); a.id = 0;
   node_init(&a); a.id = 1;