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/*******************************************************************/
/* slibtool: a skinny libtool implementation, written in C */
/* Copyright (C) 2016--2021 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_driver_impl.h"
#include "slibtool_readlink_impl.h"
#ifdef __unix__
#include <sys/syscall.h>
#endif
#ifdef _MIDIPIX_ABI
#include <sys/fs.h>
#endif
#ifndef ENOTSUP
#define ENOTSUP EOPNOTSUPP
#endif
#ifdef SYS___realpathat
extern long syscall(int, ...);
#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
#ifdef SYS___realpathat
return syscall(SYS___realpathat,fdat,path,buf,buflen,0);
#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_readlinkat(fdat,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;
}
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