kc3-lang/gnulib/lib/at-func.c

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• Hash : 7b089321
  Author :
  Date : 2025-01-01T09:24:36
  

  maint: run 'make update-copyright'
  

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• lib/at-func.c

• /* Define at-style functions like fstatat, unlinkat, fchownat, etc.
     Copyright (C) 2006, 2009-2025 Free Software Foundation, Inc.
  
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  /* written by Jim Meyering */
  
  #include "filename.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
  
  #ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
  # include <errno.h>
  # ifndef ENOTSUP
  #  define ENOTSUP EINVAL
  # endif
  #else
  # include "openat.h"
  # include "openat-priv.h"
  # include "save-cwd.h"
  #endif
  
  #ifdef AT_FUNC_USE_F1_COND
  # define CALL_FUNC(F)                           \
    (flag == AT_FUNC_USE_F1_COND                  \
      ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)     \
      : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
  # define VALIDATE_FLAG(F)                       \
    if (flag & ~AT_FUNC_USE_F1_COND)              \
      {                                           \
        errno = EINVAL;                           \
        return FUNC_FAIL;                         \
      }
  #else
  # define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
  # define VALIDATE_FLAG(F) /* empty */
  #endif
  
  #ifdef AT_FUNC_RESULT
  # define FUNC_RESULT AT_FUNC_RESULT
  #else
  # define FUNC_RESULT int
  #endif
  
  #ifdef AT_FUNC_FAIL
  # define FUNC_FAIL AT_FUNC_FAIL
  #else
  # define FUNC_FAIL -1
  #endif
  
  /* Call AT_FUNC_F1 to operate on FILE, which is in the directory
     open on descriptor FD.  If AT_FUNC_USE_F1_COND is defined to a value,
     AT_FUNC_POST_FILE_PARAM_DECLS must include a parameter named flag;
     call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
     AT_FUNC_USE_F1_COND.  Return int and fail with -1 unless AT_FUNC_RESULT
     or AT_FUNC_FAIL are defined.  If possible, do it without changing the
     working directory.  Otherwise, resort to using save_cwd/fchdir,
     then AT_FUNC_F?/restore_cwd.  If either the save_cwd or the restore_cwd
     fails, then give a diagnostic and exit nonzero.  */
  FUNC_RESULT
  AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
  {
    VALIDATE_FLAG (flag);
  
    if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
      return CALL_FUNC (file);
  
  #ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
    errno = ENOTSUP;
    return FUNC_FAIL;
  #else
    {
    /* Be careful to choose names unlikely to conflict with
       AT_FUNC_POST_FILE_PARAM_DECLS.  */
    struct saved_cwd saved_cwd;
    int saved_errno;
    FUNC_RESULT err;
  
    {
      char proc_buf[OPENAT_BUFFER_SIZE];
      char *proc_file = openat_proc_name (proc_buf, fd, file);
      if (proc_file)
        {
          FUNC_RESULT proc_result = CALL_FUNC (proc_file);
          int proc_errno = errno;
          if (proc_file != proc_buf)
            free (proc_file);
          /* If the syscall succeeds, or if it fails with an unexpected
             errno value, then return right away.  Otherwise, fall through
             and resort to using save_cwd/restore_cwd.  */
          if (FUNC_FAIL != proc_result)
            return proc_result;
          if (! EXPECTED_ERRNO (proc_errno))
            {
              errno = proc_errno;
              return proc_result;
            }
        }
    }
  
    if (save_cwd (&saved_cwd) != 0)
      openat_save_fail (errno);
    if (0 <= fd && fd == saved_cwd.desc)
      {
        /* If saving the working directory collides with the user's
           requested fd, then the user's fd must have been closed to
           begin with.  */
        free_cwd (&saved_cwd);
        errno = EBADF;
        return FUNC_FAIL;
      }
  
    if (fchdir (fd) != 0)
      {
        saved_errno = errno;
        free_cwd (&saved_cwd);
        errno = saved_errno;
        return FUNC_FAIL;
      }
  
    err = CALL_FUNC (file);
    saved_errno = (err == FUNC_FAIL ? errno : 0);
  
    if (restore_cwd (&saved_cwd) != 0)
      openat_restore_fail (errno);
  
    free_cwd (&saved_cwd);
  
    if (saved_errno)
      errno = saved_errno;
    return err;
    }
  #endif
  }
  #undef CALL_FUNC
  #undef FUNC_RESULT
  #undef FUNC_FAIL
  

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