289 lines
7.3 KiB
C
289 lines
7.3 KiB
C
/* Utilities for reading/writing fstab, mtab, etc.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <alloca.h>
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#include <mntent.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdio_ext.h>
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#include <string.h>
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#include <sys/types.h>
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#define flockfile(s) _IO_flockfile (s)
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#define funlockfile(s) _IO_funlockfile (s)
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#undef __setmntent
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#undef __endmntent
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#undef __getmntent_r
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/* Prepare to begin reading and/or writing mount table entries from the
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beginning of FILE. MODE is as for `fopen'. */
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FILE *
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__setmntent (const char *file, const char *mode)
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{
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/* Extend the mode parameter with "c" to disable cancellation in the
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I/O functions and "e" to set FD_CLOEXEC. */
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size_t modelen = strlen (mode);
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char newmode[modelen + 3];
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memcpy (mempcpy (newmode, mode, modelen), "ce", 3);
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FILE *result = fopen (file, newmode);
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if (result != NULL)
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/* We do the locking ourselves. */
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__fsetlocking (result, FSETLOCKING_BYCALLER);
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return result;
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}
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libc_hidden_def (__setmntent)
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weak_alias (__setmntent, setmntent)
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/* Close a stream opened with `setmntent'. */
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int
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__endmntent (FILE *stream)
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{
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if (stream) /* SunOS 4.x allows for NULL stream */
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fclose (stream);
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return 1; /* SunOS 4.x says to always return 1 */
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}
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libc_hidden_def (__endmntent)
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weak_alias (__endmntent, endmntent)
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/* Since the values in a line are separated by spaces, a name cannot
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contain a space. Therefore some programs encode spaces in names
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by the strings "\040". We undo the encoding when reading an entry.
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The decoding happens in place. */
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static char *
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decode_name (char *buf)
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{
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char *rp = buf;
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char *wp = buf;
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do
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if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' && rp[3] == '0')
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{
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/* \040 is a SPACE. */
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*wp++ = ' ';
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rp += 3;
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}
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else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '1')
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{
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/* \011 is a TAB. */
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*wp++ = '\t';
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rp += 3;
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}
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else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '2')
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{
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/* \012 is a NEWLINE. */
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*wp++ = '\n';
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rp += 3;
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}
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else if (rp[0] == '\\' && rp[1] == '\\')
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{
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/* We have to escape \\ to be able to represent all characters. */
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*wp++ = '\\';
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rp += 1;
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}
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else if (rp[0] == '\\' && rp[1] == '1' && rp[2] == '3' && rp[3] == '4')
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{
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/* \134 is also \\. */
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*wp++ = '\\';
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rp += 3;
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}
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else
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*wp++ = *rp;
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while (*rp++ != '\0');
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return buf;
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}
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static bool
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get_mnt_entry (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
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{
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char *cp;
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char *head;
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do
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{
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char *end_ptr;
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if (__fgets_unlocked (buffer, bufsiz, stream) == NULL)
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return false;
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end_ptr = strchr (buffer, '\n');
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if (end_ptr != NULL) /* chop newline */
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{
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/* Do not walk past the start of buffer if it's all whitespace. */
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while (end_ptr != buffer
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&& (end_ptr[-1] == ' ' || end_ptr[-1] == '\t'))
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end_ptr--;
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*end_ptr = '\0';
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}
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else
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{
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/* Not the whole line was read. Do it now but forget it. */
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char tmp[1024];
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while (__fgets_unlocked (tmp, sizeof tmp, stream) != NULL)
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if (strchr (tmp, '\n') != NULL)
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break;
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}
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head = buffer + strspn (buffer, " \t");
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/* skip empty lines and comment lines: */
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}
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while (head[0] == '\0' || head[0] == '#');
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cp = __strsep (&head, " \t");
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mp->mnt_fsname = cp != NULL ? decode_name (cp) : (char *) "";
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if (head)
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head += strspn (head, " \t");
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cp = __strsep (&head, " \t");
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mp->mnt_dir = cp != NULL ? decode_name (cp) : (char *) "";
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if (head)
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head += strspn (head, " \t");
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cp = __strsep (&head, " \t");
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mp->mnt_type = cp != NULL ? decode_name (cp) : (char *) "";
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if (head)
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head += strspn (head, " \t");
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cp = __strsep (&head, " \t");
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mp->mnt_opts = cp != NULL ? decode_name (cp) : (char *) "";
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switch (head ? sscanf (head, " %d %d ", &mp->mnt_freq, &mp->mnt_passno) : 0)
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{
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case 0:
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mp->mnt_freq = 0;
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/* Fall through. */
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case 1:
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mp->mnt_passno = 0;
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/* Fall through. */
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case 2:
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break;
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}
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return true;
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}
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/* Read one mount table entry from STREAM. Returns a pointer to storage
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reused on the next call, or null for EOF or error (use feof/ferror to
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check). */
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struct mntent *
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__getmntent_r (FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
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{
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struct mntent *result;
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flockfile (stream);
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while (true)
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if (get_mnt_entry (stream, mp, buffer, bufsiz))
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{
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/* If the file system is autofs look for a mount option hint
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("ignore") to skip the entry. */
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if (strcmp (mp->mnt_type, "autofs") == 0 && __hasmntopt (mp, "ignore"))
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memset (mp, 0, sizeof (*mp));
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else
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{
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result = mp;
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break;
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}
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}
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else
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{
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result = NULL;
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break;
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}
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funlockfile (stream);
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return result;
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}
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libc_hidden_def (__getmntent_r)
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weak_alias (__getmntent_r, getmntent_r)
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/* Write STR into STREAM, escaping whitespaces as we go. Do not check for
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errors here; we check the stream status in __ADDMNTENT. */
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static void
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write_string (FILE *stream, const char *str)
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{
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char c;
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const char *encode_chars = " \t\n\\";
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while ((c = *str++) != '\0')
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{
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if (strchr (encode_chars, c) == NULL)
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__putc_unlocked (c, stream);
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else
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{
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__putc_unlocked ('\\', stream);
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__putc_unlocked (((c & 0xc0) >> 6) + '0', stream);
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__putc_unlocked (((c & 0x38) >> 3) + '0', stream);
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__putc_unlocked (((c & 0x07) >> 0) + '0', stream);
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}
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}
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__putc_unlocked (' ', stream);
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}
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/* Write the mount table entry described by MNT to STREAM.
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Return zero on success, nonzero on failure. */
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int
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__addmntent (FILE *stream, const struct mntent *mnt)
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{
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int ret = 1;
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if (fseek (stream, 0, SEEK_END))
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return ret;
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flockfile (stream);
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write_string (stream, mnt->mnt_fsname);
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write_string (stream, mnt->mnt_dir);
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write_string (stream, mnt->mnt_type);
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write_string (stream, mnt->mnt_opts);
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fprintf (stream, "%d %d\n", mnt->mnt_freq, mnt->mnt_passno);
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ret = __ferror_unlocked (stream) != 0 || fflush (stream) != 0;
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funlockfile (stream);
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return ret;
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}
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weak_alias (__addmntent, addmntent)
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/* Search MNT->mnt_opts for an option matching OPT.
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Returns the address of the substring, or null if none found. */
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char *
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__hasmntopt (const struct mntent *mnt, const char *opt)
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{
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const size_t optlen = strlen (opt);
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char *rest = mnt->mnt_opts, *p;
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while ((p = strstr (rest, opt)) != NULL)
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{
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if ((p == rest || p[-1] == ',')
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&& (p[optlen] == '\0' || p[optlen] == '=' || p[optlen] == ','))
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return p;
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rest = strchr (p, ',');
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if (rest == NULL)
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break;
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++rest;
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}
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return NULL;
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}
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libc_hidden_def (__hasmntopt)
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weak_alias (__hasmntopt, hasmntopt)
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