libc: Remove readdir_r(3)

This function was never safe to use.  We marked it deprecated in the
manual page in 2016, and it is marked obsolete in POSIX 2024.  We
previously added a linker warning and annotated the prototype; now that
stable/15 has been branched, we can remove it from main.

Relnotes:	yes
Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D52474

lib/libc/gen/Makefile.inc

@@ -342,7 +342,6 @@ MLINKS+=directory.3 closedir.3 \
 	directory.3 fdopendir.3 \
 	directory.3 opendir.3 \
 	directory.3 readdir.3 \
-	directory.3 readdir_r.3 \
 	directory.3 rewinddir.3 \
 	directory.3 seekdir.3 \
 	directory.3 telldir.3

lib/libc/gen/Symbol.map

@@ -418,7 +418,6 @@ FBSD_1.5 {
 	globfree;
 	nftw;
 	readdir;
-	readdir_r;
 	scandir;
 	sem_clockwait_np;
 	setproctitle_fast;

lib/libc/gen/directory.3

@@ -25,14 +25,13 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 1, 2020
+.Dd September 5, 2025
 .Dt DIRECTORY 3
 .Os
 .Sh NAME
 .Nm opendir ,
 .Nm fdopendir ,
 .Nm readdir ,
-.Nm readdir_r ,
 .Nm telldir ,
 .Nm seekdir ,
 .Nm rewinddir ,
@@ -50,8 +49,6 @@
 .Fn fdopendir "int fd"
 .Ft struct dirent *
 .Fn readdir "DIR *dirp"
-.Ft int
-.Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
 .Ft long
 .Fn telldir "DIR *dirp"
 .Ft void
@@ -65,15 +62,6 @@
 .Ft int
 .Fn dirfd "DIR *dirp"
 .Sh DESCRIPTION
-.Bf -symbolic
-The
-.Fn readdir_r
-interface is deprecated
-because it cannot be used correctly unless
-.Brq Va NAME_MAX
-is a fixed value.
-.Ef
-.Pp
 The
 .Fn opendir
 function
@@ -112,7 +100,6 @@ or to modify the state of the associated description other than by means
 of
 .Fn closedir ,
 .Fn readdir ,
-.Fn readdir_r ,
 or
 .Fn rewinddir ,
 the behavior is undefined.
@@ -144,34 +131,6 @@ may be set to any of the values documented for the
 system call.
 .Pp
 The
-.Fn readdir_r
-function
-provides the same functionality as
-.Fn readdir ,
-but the caller must provide a directory
-.Fa entry
-buffer to store the results in.
-The buffer must be large enough for a
-.Vt struct dirent
-with a
-.Va d_name
-array with
-.Brq Va NAME_MAX
-+ 1 elements.
-If the read succeeds,
-.Fa result
-is pointed at the
-.Fa entry ;
-upon reaching the end of the directory
-.Fa result
-is set to
-.Dv NULL .
-The
-.Fn readdir_r
-function
-returns 0 on success or an error number to indicate failure.
-.Pp
-The
 .Fn telldir
 function
 returns a token representing the current location associated with the named
@@ -305,9 +264,7 @@ is not associated with a directory.
 .Pp
 The
 .Fn readdir
-and
-.Fn readdir_r
-functions may also fail and set
+function may also fail and set
 .Va errno
 for any of the errors specified for the routine
 .Xr getdents 2 .
@@ -338,7 +295,6 @@ The
 .Fn fdopendir ,
 .Fn opendir ,
 .Fn readdir ,
-.Fn readdir_r ,
 .Fn rewinddir ,
 .Fn seekdir
 and
@@ -391,7 +347,8 @@ will always set the correct location to return the same value as that last
 .Fn readdir
 performed.
 This is enough for some applications which want to
-"push back the last entry read", e.g., Samba.
+.Dq push back the last entry read ,
+e.g. Samba.
 Seeks back to any other location,
 other than the beginning of the directory,
 may result in unexpected behaviour if deletes are present.

lib/libc/gen/gen-compat.h

@@ -37,6 +37,7 @@ struct freebsd11_dirent;
 struct freebsd11_stat;
 struct freebsd11_statfs;
 
+int	freebsd15_readdir_r(DIR *, struct dirent *, struct dirent **);
 struct freebsd11_dirent *freebsd11_readdir(DIR *);
 int	freebsd11_readdir_r(DIR *, struct freebsd11_dirent *,
 	    struct freebsd11_dirent **);

lib/libc/gen/gen-private.h

@@ -60,7 +60,4 @@ struct _dirdesc {
 
 #define	_dirfd(dirp)	((dirp)->dd_fd)
 
-struct dirent;
-int __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
-
 #endif /* !_GEN_PRIVATE_H_ */

lib/libc/gen/readdir-compat11.c

@@ -95,7 +95,7 @@ freebsd11_readdir_r(DIR *dirp, struct freebsd11_dirent *entry,
 	struct dirent xentry, *xresult;
 	int error;
 
-	error = __readdir_r(dirp, &xentry, &xresult);
+	error = freebsd15_readdir_r(dirp, &xentry, &xresult);
 	if (error != 0)
 		return (error);
 	if (xresult != NULL) {

lib/libc/gen/readdir.c

@@ -41,6 +41,8 @@
 #include "gen-private.h"
 #include "telldir.h"
 
+#include "gen-compat.h"
+
 /*
  * get next entry in a directory.
  */
@@ -104,7 +106,7 @@ readdir(DIR *dirp)
 }
 
 int
-__readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
+freebsd15_readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
 {
 	struct dirent *dp;
 	int saved_errno;
@@ -133,6 +135,4 @@ __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
 	return (0);
 }
 
-__strong_reference(__readdir_r, readdir_r);
-__warn_references(readdir_r,
-    "warning: this program uses readdir_r(), which is unsafe.");
+__sym_compat(readdir_r, freebsd15_readdir_r, FBSD_1.5);