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-rw-r--r--src/helper/slbt_realpath.c89
1 files changed, 89 insertions, 0 deletions
diff --git a/src/helper/slbt_realpath.c b/src/helper/slbt_realpath.c
new file mode 100644
index 0000000..4c7446e
--- /dev/null
+++ b/src/helper/slbt_realpath.c
@@ -0,0 +1,89 @@
+
+/*******************************************************************/
+/* slibtool: a skinny libtool implementation, written in C */
+/* Copyright (C) 2016--2020 Z. Gilboa */
+/* Released under the Standard MIT License; see COPYING.SLIBTOOL. */
+/*******************************************************************/
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <slibtool/slibtool.h>
+
+#include "slibtool_readlink_impl.h"
+
+#ifdef _MIDIPIX_ABI
+#include <sys/fs.h>
+#endif
+
+#ifndef ENOTSUP
+#define ENOTSUP EOPNOTSUPP
+#endif
+
+int slbt_realpath(
+ int fdat,
+ const char * path,
+ int options,
+ char * buf,
+ size_t buflen)
+{
+ int ret;
+ int fd;
+ int fdproc;
+ struct stat st;
+ struct stat stproc;
+ char procfspath[36];
+
+ /* common validation */
+ if (!buf || (options & O_CREAT)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* framework-based wrapper */
+#ifdef _MIDIPIX_ABI
+ return __fs_rpath(fdat,path,options,buf,buflen);
+#endif
+
+ /* buflen */
+ if (buflen < PATH_MAX) {
+ errno = ENOBUFS;
+ return -1;
+ }
+
+ /* AT_FDCWD */
+ if (fdat == AT_FDCWD) {
+ return realpath(path,buf) ? 0 : -1;
+ }
+
+ /* /proc/self/fd */
+ if ((fd = openat(fdat,path,options,0)) < 0)
+ return -1;
+
+ sprintf(procfspath,"/proc/self/fd/%d",fd);
+
+ if (slbt_readlink(procfspath,buf,buflen)) {
+ close(fd);
+ return -1;
+ }
+
+ if ((fdproc = openat(AT_FDCWD,buf,options|O_NOFOLLOW,0)) < 0) {
+ close(fd);
+ errno = ELOOP;
+ return -1;
+ }
+
+ ret = fstat(fd,&st) || fstat(fdproc,&stproc);
+
+ close(fd);
+ close(fdproc);
+
+ if (ret || (st.st_dev != stproc.st_dev) || (st.st_ino != stproc.st_ino)) {
+ errno = ENOTSUP;
+ return -1;
+ }
+
+ return 0;
+}