libpwdgrp: use FAST_FUNC to make "matching ABI" optimization more likely to succeed

See bb_internal_get*nam_r size reduction:

function                                             old     new   delta
bb_internal_getpwent_r                               167     176      +9
getXXnam_r                                           204     206      +2
sulogin_main                                         326     325      -1
su_main                                              471     470      -1
read_line_input                                     3832    3831      -1
print_stat                                           865     864      -1
prepare_socket_fd                                    283     282      -1
load_crontab                                         777     776      -1
fork_job                                             456     455      -1
do_shm                                               884     883      -1
do_sem                                               637     636      -1
do_msg                                               783     782      -1
complete_username                                    124     123      -1
bb_internal_getgrouplist                              71      70      -1
xgetpwuid                                             27      25      -2
xgetpwnam                                             27      25      -2
xgetgrnam                                             27      25      -2
xgetgrgid                                             27      25      -2
uid2uname                                             18      16      -2
login_main                                           980     978      -2
gid2group                                             18      16      -2
get_shell_name                                        54      52      -2
change_identity                                       50      48      -2
bb_internal_initgroups                                50      48      -2
argstr                                              1261    1259      -2
print_perms                                          177     174      -3
inetd_main                                          2077    2074      -3
run_applet_no_and_exit                               446     442      -4
fileaction_setowngrp                                  89      85      -4
deluser_main                                         312     308      -4
bb_internal_getpwuid                                  19      15      -4
bb_internal_getpwnam                                  11       7      -4
bb_internal_getgrnam                                  14      10      -4
bb_internal_getgrgid                                  19      15      -4
adduser_main                                         865     861      -4
passwd_main                                          989     984      -5
get_passwd                                            97      92      -5
data_extract_all                                     887     882      -5
check_user_passwd                                    490     485      -5
get_groups                                            81      75      -6
ftpd_main                                           2178    2171      -7
bb_internal_getspnam_r                                42      18     -24
bb_internal_getpwnam_r                                39      15     -24
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/41 up/down: 11/-153)         Total: -142 bytes
   text	   data	    bss	    dec	    hex	filename
 923167	    928	  17676	 941771	  e5ecb	busybox_old
 923023	    928	  17676	 941627	  e5e3b	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 41 insertions, 42 deletions

diff --git a/include/grp_.h b/include/grp_.h
index f7b8d836f..db13ce3b4 100644
--- a/include/grp_.h
+++ b/include/grp_.h
@@ -36,31 +36,30 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 #define getgrouplist bb_internal_getgrouplist
 #define initgroups   bb_internal_initgroups
 
-
 /* All function names below should be remapped by #defines above
  * in order to not collide with libc names. */
 
 /* Close the group-file stream.  */
-extern void endgrent(void);
+void FAST_FUNC endgrent(void);
 
 /* Search for an entry with a matching group ID.  */
-extern struct group *getgrgid(gid_t __gid);
+struct group* FAST_FUNC getgrgid(gid_t __gid);
 
 /* Search for an entry with a matching group name.  */
-extern struct group *getgrnam(const char *__name);
+struct group* FAST_FUNC getgrnam(const char *__name);
 
 /* Reentrant versions of some of the functions above. */
 
 /* Store at most *NGROUPS members of the group set for USER into
    *GROUPS.  Also include GROUP.  The actual number of groups found is
    returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.  */
-extern int getgrouplist(const char *__user, gid_t __group,
+int FAST_FUNC getgrouplist(const char *__user, gid_t __group,
 		gid_t *__groups, int *__ngroups);
 
 /* Initialize the group set for the current user
    by reading the group database and using all groups
    of which USER is a member.  Also include GROUP.  */
-extern int initgroups(const char *__user, gid_t __group);
+int FAST_FUNC initgroups(const char *__user, gid_t __group);
 
 POP_SAVED_FUNCTION_VISIBILITY
 
diff --git a/include/pwd_.h b/include/pwd_.h
index d086f86e3..32b5b366e 100644
--- a/include/pwd_.h
+++ b/include/pwd_.h
@@ -43,21 +43,21 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
  * in order to not collide with libc names. */
 
 /* Rewind the password-file stream.  */
-extern void setpwent(void);
+void FAST_FUNC setpwent(void);
 
 /* Close the password-file stream.  */
-extern void endpwent(void);
+void FAST_FUNC endpwent(void);
 
 #ifdef UNUSED_SINCE_WE_AVOID_STATIC_BUFS
 /* Read an entry from the password-file stream, opening it if necessary.  */
-extern struct passwd *getpwent(void);
+struct passwd* FAST_FUNC getpwent(void);
 #endif
 
 /* Search for an entry with a matching user ID.  */
-extern struct passwd *getpwuid(uid_t __uid);
+struct passwd* FAST_FUNC getpwuid(uid_t __uid);
 
 /* Search for an entry with a matching username.  */
-extern struct passwd *getpwnam(const char *__name);
+struct passwd* FAST_FUNC getpwnam(const char *__name);
 
 /* Reentrant versions of some of the functions above.
 
@@ -67,11 +67,11 @@ extern struct passwd *getpwnam(const char *__name);
    other reentrant functions so the chances are good this is what the
    POSIX people would choose.  */
 
-extern int getpwent_r(struct passwd *__restrict __resultbuf,
+int FAST_FUNC getpwent_r(struct passwd *__restrict __resultbuf,
 		char *__restrict __buffer, size_t __buflen,
 		struct passwd **__restrict __result);
 
-extern int getpwnam_r(const char *__restrict __name,
+int FAST_FUNC getpwnam_r(const char *__restrict __name,
 		struct passwd *__restrict __resultbuf,
 		char *__restrict __buffer, size_t __buflen,
 		struct passwd **__restrict __result);
diff --git a/include/shadow_.h b/include/shadow_.h
index 7babe4f30..8e2581e7c 100644
--- a/include/shadow_.h
+++ b/include/shadow_.h
@@ -57,48 +57,48 @@ struct spwd {
 
 #ifdef UNUSED_FOR_NOW
 /* Open database for reading */
-extern void setspent(void);
+void FAST_FUNC setspent(void);
 
 /* Close database */
-extern void endspent(void);
+void FAST_FUNC endspent(void);
 
 /* Get next entry from database, perhaps after opening the file */
-extern struct spwd *getspent(void);
+struct spwd* FAST_FUNC getspent(void);
 
 /* Get shadow entry matching NAME */
-extern struct spwd *getspnam(const char *__name);
+struct spwd* FAST_FUNC getspnam(const char *__name);
 
 /* Read shadow entry from STRING */
-extern struct spwd *sgetspent(const char *__string);
+struct spwd* FAST_FUNC sgetspent(const char *__string);
 
 /* Read next shadow entry from STREAM */
-extern struct spwd *fgetspent(FILE *__stream);
+struct spwd* FAST_FUNC fgetspent(FILE *__stream);
 
 /* Write line containing shadow password entry to stream */
-extern int putspent(const struct spwd *__p, FILE *__stream);
+int FAST_FUNC putspent(const struct spwd *__p, FILE *__stream);
 
 /* Reentrant versions of some of the functions above */
-extern int getspent_r(struct spwd *__result_buf, char *__buffer,
+int FAST_FUNC getspent_r(struct spwd *__result_buf, char *__buffer,
 		size_t __buflen, struct spwd **__result);
 #endif
 
-extern int getspnam_r(const char *__name, struct spwd *__result_buf,
+int FAST_FUNC getspnam_r(const char *__name, struct spwd *__result_buf,
 		char *__buffer, size_t __buflen,
 		struct spwd **__result);
 
 #ifdef UNUSED_FOR_NOW
-extern int sgetspent_r(const char *__string, struct spwd *__result_buf,
+int FAST_FUNC sgetspent_r(const char *__string, struct spwd *__result_buf,
 		char *__buffer, size_t __buflen,
 		struct spwd **__result);
 
-extern int fgetspent_r(FILE *__stream, struct spwd *__result_buf,
+int FAST_FUNC fgetspent_r(FILE *__stream, struct spwd *__result_buf,
 		char *__buffer, size_t __buflen,
 		struct spwd **__result);
 /* Protect password file against multi writers */
-extern int lckpwdf(void);
+int FAST_FUNC lckpwdf(void);
 
 /* Unlock password file */
-extern int ulckpwdf(void);
+int FAST_FUNC ulckpwdf(void);
 #endif
 
 POP_SAVED_FUNCTION_VISIBILITY
diff --git a/libpwdgrp/pwd_grp.c b/libpwdgrp/pwd_grp.c
index ed8370124..0d8e2bb5c 100644
--- a/libpwdgrp/pwd_grp.c
+++ b/libpwdgrp/pwd_grp.c
@@ -288,7 +288,7 @@ static void *convert_to_struct(const char *def,	const unsigned char *off,
 
 /****** getXXnam/id_r */
 
-static int getXXnam_r(const char *name, uintptr_t db_and_field_pos, char *buffer, size_t buflen,
+static int FAST_FUNC getXXnam_r(const char *name, uintptr_t db_and_field_pos, char *buffer, size_t buflen,
 		void *result)
 {
 	void *struct_buf = *(void**)result;
@@ -316,18 +316,18 @@ static int getXXnam_r(const char *name, uintptr_t db_and_field_pos, char *buffer
 	return errno;
 }
 
-int getpwnam_r(const char *name, struct passwd *struct_buf, char *buffer, size_t buflen,
+int FAST_FUNC getpwnam_r(const char *name, struct passwd *struct_buf, char *buffer, size_t buflen,
 				struct passwd **result)
 {
 	/* Why the "store buffer address in result" trick?
 	 * This way, getXXnam_r has the same ABI signature as getpwnam_r,
-	 * hopefully compiler can optimize tall call better in this case.
+	 * hopefully compiler can optimize tail call better in this case.
 	 */
 	*result = struct_buf;
 	return getXXnam_r(name, (0 << 2) + 0, buffer, buflen, result);
 }
 #if ENABLE_USE_BB_SHADOW
-int getspnam_r(const char *name, struct spwd *struct_buf, char *buffer, size_t buflen,
+int FAST_FUNC getspnam_r(const char *name, struct spwd *struct_buf, char *buffer, size_t buflen,
 			   struct spwd **result)
 {
 	*result = struct_buf;
@@ -337,7 +337,7 @@ int getspnam_r(const char *name, struct spwd *struct_buf, char *buffer, size_t b
 
 /****** getXXent_r */
 
-static int getXXent_r(void *struct_buf, char *buffer, size_t buflen,
+static int FAST_FUNC getXXent_r(void *struct_buf, char *buffer, size_t buflen,
 		void *result,
 		unsigned db_idx)
 {
@@ -374,14 +374,14 @@ static int getXXent_r(void *struct_buf, char *buffer, size_t buflen,
 	return errno;
 }
 
-int getpwent_r(struct passwd *struct_buf, char *buffer, size_t buflen, struct passwd **result)
+int FAST_FUNC getpwent_r(struct passwd *struct_buf, char *buffer, size_t buflen, struct passwd **result)
 {
 	return getXXent_r(struct_buf, buffer, buflen, result, 0);
 }
 
 /****** getXXnam/id */
 
-static void *getXXnam(const char *name, unsigned db_and_field_pos)
+static void* FAST_FUNC getXXnam(const char *name, unsigned db_and_field_pos)
 {
 	char *buf;
 	void *result;
@@ -409,39 +409,39 @@ static void *getXXnam(const char *name, unsigned db_and_field_pos)
 	return result;
 }
 
-struct passwd *getpwnam(const char *name)
+struct passwd* FAST_FUNC getpwnam(const char *name)
 {
 	return getXXnam(name, (0 << 2) + 0);
 }
-struct group *getgrnam(const char *name)
+struct group* FAST_FUNC getgrnam(const char *name)
 {
 	return getXXnam(name, (1 << 2) + 0);
 }
-struct passwd *getpwuid(uid_t id)
+struct passwd* FAST_FUNC getpwuid(uid_t id)
 {
 	return getXXnam(utoa(id), (0 << 2) + 2);
 }
-struct group *getgrgid(gid_t id)
+struct group* FAST_FUNC getgrgid(gid_t id)
 {
 	return getXXnam(utoa(id), (1 << 2) + 2);
 }
 
 /****** end/setXXend */
 
-void endpwent(void)
+void FAST_FUNC endpwent(void)
 {
 	if (has_S && S.db[0].fp) {
 		fclose(S.db[0].fp);
 		S.db[0].fp = NULL;
 	}
 }
-void setpwent(void)
+void FAST_FUNC setpwent(void)
 {
 	if (has_S && S.db[0].fp) {
 		rewind(S.db[0].fp);
 	}
 }
-void endgrent(void)
+void FAST_FUNC endgrent(void)
 {
 	if (has_S && S.db[1].fp) {
 		fclose(S.db[1].fp);
@@ -491,7 +491,7 @@ static gid_t* FAST_FUNC getgrouplist_internal(int *ngroups_ptr,
 	return group_list;
 }
 
-int initgroups(const char *user, gid_t gid)
+int FAST_FUNC initgroups(const char *user, gid_t gid)
 {
 	int ngroups;
 	gid_t *group_list = getgrouplist_internal(&ngroups, user, gid);
@@ -501,7 +501,7 @@ int initgroups(const char *user, gid_t gid)
 	return ngroups;
 }
 
-int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
+int FAST_FUNC getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
 {
 	int ngroups_old = *ngroups;
 	gid_t *group_list = getgrouplist_internal(ngroups, user, gid);