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lxcmntent.c
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lxcmntent.c
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/* Utilities for reading/writing fstab, mtab, etc.
* Copyright (C) 1995-2000, 2001, 2002, 2003, 2006
* Free Software Foundation, Inc.
* This file is part of the GNU C Library.
*
* The GNU C Library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* The GNU C Library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif
#include <alloca.h>
#include <macro.h>
#include <mntent.h>
#include <stdio.h>
#include <string.h>
/* Since the values in a line are separated by spaces, a name cannot
* contain a space. Therefore some programs encode spaces in names
* by the strings "\040". We undo the encoding when reading an entry.
* The decoding happens in place.
*/
static char *decode_name(char *buf)
{
char *rp = buf;
char *wp = buf;
do {
if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' &&
rp[3] == '0') {
/* \040 is a SPACE. */
*wp++ = ' ';
rp += 3;
} else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' &&
rp[3] == '1') {
/* \011 is a TAB. */
*wp++ = '\t';
rp += 3;
} else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' &&
rp[3] == '2') {
/* \012 is a NEWLINE. */
*wp++ = '\n';
rp += 3;
} else if (rp[0] == '\\' && rp[1] == '\\') {
/* We have to escape \\ to be able to represent all characters. */
*wp++ = '\\';
rp += 1;
} else if (rp[0] == '\\' && rp[1] == '1' && rp[2] == '3' &&
rp[3] == '4') {
/* \134 is also \\. */
*wp++ = '\\';
rp += 3;
} else {
*wp++ = *rp;
}
} while (*rp++ != '\0');
return buf;
}
/* Read one mount table entry from STREAM. Returns a pointer to storage
* reused on the next call, or null for EOF or error (use feof/ferror to check).
*/
struct mntent *getmntent_r(FILE *stream, struct mntent *mp, char *buffer, int bufsiz)
{
char *cp;
char *head;
do {
char *end_ptr;
if (!fgets(buffer, bufsiz, stream))
return NULL;
end_ptr = strchr(buffer, '\n');
if (end_ptr != NULL) {
/* chop newline */
*end_ptr = '\0';
} else {
/* Not the whole line was read. Do it now but forget it. */
char tmp[1024] = {0};
while (fgets(tmp, sizeof tmp, stream))
if (strchr(tmp, '\n') != NULL)
break;
}
head = buffer + strspn(buffer, " \t");
/* skip empty lines and comment lines: */
} while (head[0] == '\0' || head[0] == '#');
cp = strsep(&head, " \t");
mp->mnt_fsname = cp ? decode_name(cp) : (char *)"";
if (head)
head += strspn(head, " \t");
cp = strsep(&head, " \t");
mp->mnt_dir = cp ? decode_name(cp) : (char *)"";
if (head)
head += strspn(head, " \t");
cp = strsep(&head, " \t");
mp->mnt_type = cp ? decode_name(cp) : (char *)"";
if (head)
head += strspn(head, " \t");
cp = strsep(&head, " \t");
mp->mnt_opts = cp ? decode_name(cp) : (char *)"";
if (head) {
int ret = sscanf(head, " %d %d ", &mp->mnt_freq, &mp->mnt_passno);
switch (ret) {
case 0:
mp->mnt_freq = 0;
case 1:
mp->mnt_passno = 0;
case 2:
break;
}
} else {
mp->mnt_freq = 0;
}
return mp;
}
struct mntent *getmntent(FILE *stream)
{
static struct mntent m;
static char *getmntent_buffer;
if (!getmntent_buffer) {
getmntent_buffer = (char *)malloc(LXC_MAX_BUFFER);
if (!getmntent_buffer)
return NULL;
}
return getmntent_r(stream, &m, getmntent_buffer, LXC_MAX_BUFFER);
}
/* Prepare to begin reading and/or writing mount table entries from the
* beginning of FILE. MODE is as for `fopen'.
*/
FILE *setmntent(const char *file, const char *mode)
{
/* Extend the mode parameter with "c" to disable cancellation in the
* I/O functions and "e" to set FD_CLOEXEC.
*/
size_t modelen = strlen(mode);
char *newmode;
newmode = alloca(modelen + 3);
memcpy(newmode, mode, modelen);
memcpy(newmode + modelen, "ce", 3);
return fopen (file, newmode);
}
/* Close a stream opened with `setmntent'. */
int endmntent(FILE *stream)
{
/* SunOS 4.x allows for NULL stream */
if (stream)
fclose(stream);
/* SunOS 4.x says to always return 1 */
return 1;
}
/* Search MNT->mnt_opts for an option matching OPT.
* Returns the address of the substring, or null if none found.
*/
char *hasmntopt(const struct mntent *mnt, const char *opt)
{
const size_t optlen = strlen(opt);
char *rest = mnt->mnt_opts, *p;
while ((p = strstr(rest, opt))) {
if ((p == rest || p[-1] == ',') &&
(p[optlen] == '\0' || p[optlen] == '=' || p[optlen] == ','))
return p;
rest = strchr(p, ',');
if (!rest)
break;
++rest;
}
return NULL;
}