From 159c3d0606f8c68712cee6009efc6feb650292ee Mon Sep 17 00:00:00 2001
From: Benjamin Lamowski <benjamin.lamowski@genode-labs.com>
Date: Wed, 16 Aug 2023 18:04:59 +0200
Subject: [PATCH] compat_libc: add versioned symbols for lstat and readdir_r

Ref #4997
---
 repos/libports/src/lib/compat-libc/compat.cc | 94 +++++++++++++++++++-
 1 file changed, 90 insertions(+), 4 deletions(-)

diff --git a/repos/libports/src/lib/compat-libc/compat.cc b/repos/libports/src/lib/compat-libc/compat.cc
index ba9779513a..97ac29ec5d 100644
--- a/repos/libports/src/lib/compat-libc/compat.cc
+++ b/repos/libports/src/lib/compat-libc/compat.cc
@@ -1,6 +1,7 @@
 /*
  * \brief  FreeBSD-11 function versions
  * \author Sebastian Sumpf
+ * \author Benjamin Lamowski
  * \date   2023-06-12
  */
 
@@ -12,15 +13,22 @@
  */
 
 #include <stdio.h>
-#define _WANT_FREEBSD11_STAT /* enable freebsd11_stat */
+#define _WANT_FREEBSD11_STAT /* enable freebsd11_stat and freebsd11_dirent */
 #define _KERNEL              /* disable 'stat' */
 #include <sys/stat.h>
+
+#include <string.h>  /* needed for memset() in dirent.h */
+#include <dirent.h>
 #include <dlfcn.h>
+#include <errno.h>
 
 extern "C" int libc_stat(const char *, struct stat*);
 extern "C" int libc_fstat(int, struct stat *);
+extern "C" int libc_lstat(const char *, struct stat*);
 
-static void _to_freebsd11(struct stat *libc_buf, struct freebsd11_stat *buf)
+extern "C" int libc_readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
+
+static void _to_freebsd11_stat(struct stat *libc_buf, struct freebsd11_stat *buf)
 {
 	buf->st_dev      = libc_buf->st_dev;
 	buf->st_ino      = libc_buf->st_ino;
@@ -38,6 +46,25 @@ static void _to_freebsd11(struct stat *libc_buf, struct freebsd11_stat *buf)
 	buf->st_birthtim = libc_buf->st_birthtim;
 }
 
+
+static bool _to_freebsd11_dirent(struct dirent *libc_buf, struct freebsd11_dirent *buf)
+{
+	buf->d_fileno = libc_buf->d_fileno;
+	buf->d_type   = libc_buf->d_type;
+	buf->d_namlen = libc_buf->d_namlen;
+	/* Calculation taken from FreeBSD's FREEBSD11_DIRSIZ macro */
+	buf->d_reclen = sizeof(struct freebsd11_dirent)
+		        - sizeof(buf->d_name)
+			+ ((buf->d_namlen + 1 + 3) &~ 3);
+	if (libc_buf->d_namlen >= sizeof(buf->d_name))
+		return false;
+
+	strncpy(buf->d_name, libc_buf->d_name, sizeof(buf->d_name));
+
+	return true;
+}
+
+
 static void* libc_handle(void)
 {
 	static void *handle = NULL;
@@ -48,6 +75,9 @@ static void* libc_handle(void)
 
 int (*_stat)(char const*, struct stat*);
 int (*_fstat)(int, struct stat *);
+int (*_lstat)(char const*, struct stat*);
+int (*_readdir_r)(DIR *dirp, struct dirent *entry, struct dirent **result);
+
 
 int libc_stat(const char *path, struct stat *buf)
 {
@@ -66,6 +96,24 @@ int libc_fstat(int fd, struct stat *buf)
 	return _fstat(fd, buf);
 }
 
+
+int libc_lstat(const char *path, struct stat *buf)
+{
+	if (!_lstat)
+		_lstat = (int (*)(const char*, struct stat*)) dlsym(libc_handle(), "lstat");
+
+	return _lstat(path, buf);
+}
+
+int libc_readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
+{
+	if (!_readdir_r)
+		_readdir_r = (int (*)(DIR *dirp, struct dirent *entry, struct dirent **result)) dlsym(libc_handle(), "readdir_r");
+
+	return _readdir_r(dirp, entry, result);
+}
+
+
 extern "C" int freebsd11_stat(const char *path, struct freebsd11_stat *buf)
 {
 	struct stat libc_buf { };
@@ -73,7 +121,7 @@ extern "C" int freebsd11_stat(const char *path, struct freebsd11_stat *buf)
 	int err = libc_stat(path, &libc_buf);
 	if (err) return err;
 
-	_to_freebsd11(&libc_buf, buf);
+	_to_freebsd11_stat(&libc_buf, buf);
 
 	return 0;
 }
@@ -86,10 +134,48 @@ extern "C" int freebsd11_fstat(int fd, struct freebsd11_stat *buf)
 	int err = libc_fstat(fd, &libc_buf);
 	if (err) return err;
 
-	_to_freebsd11(&libc_buf, buf);
+	_to_freebsd11_stat(&libc_buf, buf);
 
 	return 0;
 }
 
+extern "C" int freebsd11_lstat(const char *path, struct freebsd11_stat *buf)
+{
+	struct stat libc_buf { };
+
+	int err = libc_lstat(path, &libc_buf);
+	if (err) return err;
+
+	_to_freebsd11_stat(&libc_buf, buf);
+
+	return 0;
+}
+
+
+extern "C" int freebsd11_readdir_r(DIR *dirp,
+                                   struct freebsd11_dirent *entry,
+                                   struct freebsd11_dirent**result)
+{
+	struct dirent libc_entry { };
+	struct dirent * libc_result;
+
+	int err = libc_readdir_r(dirp, &libc_entry, &libc_result);
+	if (err) return err;
+
+	if (libc_result != NULL) {
+		if (!_to_freebsd11_dirent(&libc_entry, entry)) {
+			*result = NULL;
+			return ENAMETOOLONG;
+		} else {
+			*result = entry;
+		}
+	}
+
+	return 0;
+}
+
+
 __sym_compat(fstat, freebsd11_fstat, FBSD_1.0);
 __sym_compat(stat, freebsd11_stat, FBSD_1.0);
+__sym_compat(lstat, freebsd11_lstat, FBSD_1.0);
+__sym_compat(readdir_r, freebsd11_readdir_r, FBSD_1.0);