libc/src/unistd/linux/pathconf_utils.cpp

//===-- Linux implementation of pathconf_utils ----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// This header must go before limits_macros.h otherwise libc header may choose
// to undefine LINK_MAX.
#include <linux/limits.h> // For LINK_MAX and other limits

#include "hdr/limits_macros.h"
#include "hdr/unistd_macros.h"
#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
#include "src/errno/libc_errno.h"
#include "src/sys/statvfs/linux/statfs_utils.h"

// other linux specific includes
#include <linux/bfs_fs.h>
#if __has_include(<linux/ufs_fs.h>)
#include <linux/ufs_fs.h>
#else
// from https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/
#define UFS_MAGIC 0x00011954
#endif
#include <linux/magic.h> // For common FS magics

namespace LIBC_NAMESPACE_DECL {

long filesizebits(const statfs_utils::LinuxStatFs &s) {
  switch (s.f_type) {
  case JFFS2_SUPER_MAGIC:
  case MSDOS_SUPER_MAGIC:
  case NCP_SUPER_MAGIC:
    return 32;
  }
  return 64;
}

long link_max(const statfs_utils::LinuxStatFs &s) {
  switch (s.f_type) {
  case EXT2_SUPER_MAGIC:
    return 32000;
  case MINIX_SUPER_MAGIC:
    return 250;
  case MINIX2_SUPER_MAGIC:
    return 65530;
  case REISERFS_SUPER_MAGIC:
    return 0xffff - 1000;
  case UFS_MAGIC:
    return 32000;
  }
  return LINK_MAX;
}

long symlinks(const statfs_utils::LinuxStatFs &s) {
  switch (s.f_type) {
  case ADFS_SUPER_MAGIC:
  case BFS_MAGIC:
  case CRAMFS_MAGIC:
  case EFS_SUPER_MAGIC:
  case MSDOS_SUPER_MAGIC:
  case QNX4_SUPER_MAGIC:
    return 0;
  }
  return 1;
}

long pathconfig(const statfs_utils::LinuxStatFs &s, int name) {
  switch (name) {
  case _PC_LINK_MAX:
    return link_max(s);

  case _PC_FILESIZEBITS:
    return filesizebits(s);

  case _PC_2_SYMLINKS:
    return symlinks(s);

  case _PC_REC_MIN_XFER_SIZE:
    return s.f_bsize;

  case _PC_ALLOC_SIZE_MIN:
  case _PC_REC_XFER_ALIGN:
    return s.f_frsize;

  case _PC_MAX_CANON:
    return _POSIX_MAX_CANON;

  case _PC_MAX_INPUT:
    return _POSIX_MAX_INPUT;

  case _PC_NAME_MAX:
    return s.f_namelen;

  case _PC_PATH_MAX:
    return _POSIX_PATH_MAX;

  case _PC_PIPE_BUF:
    return _POSIX_PIPE_BUF;

  case _PC_CHOWN_RESTRICTED:
    return _POSIX_CHOWN_RESTRICTED;

  case _PC_NO_TRUNC:
    return _POSIX_NO_TRUNC;

  case _PC_VDISABLE:
    return _POSIX_VDISABLE;

  case _PC_ASYNC_IO:
  case _PC_PRIO_IO:
  case _PC_REC_INCR_XFER_SIZE:
  case _PC_REC_MAX_XFER_SIZE:
  case _PC_SYMLINK_MAX:
  case _PC_SYNC_IO:
    return -1;

  default:
    libc_errno = EINVAL;
    return -1;
  }
}

} // namespace LIBC_NAMESPACE_DECL