utils/mount_opts.c

/*
 * mount_opts.c, by rmk
 *
 * Decode mount options.
 */
#include <sys/mount.h>
#include <stdlib.h>
#include <string.h>

#include "mount_opts.h"

#define ARRAY_SIZE(x)	(sizeof(x) / sizeof(x[0]))

static const struct mount_opts options[] = {
	/* name		mask		set		noset		*/
	{ "async",	MS_SYNCHRONOUS,	0,		MS_SYNCHRONOUS	},
	{ "atime",	MS_NOATIME,	0,		MS_NOATIME	},
	{ "bind",	MS_TYPE,	MS_BIND,	0,		},
	{ "dev",	MS_NODEV,	0,		MS_NODEV	},
	{ "diratime",	MS_NODIRATIME,	0,		MS_NODIRATIME	},
	{ "dirsync",	MS_DIRSYNC,	MS_DIRSYNC,	0		},
	{ "exec",	MS_NOEXEC,	0,		MS_NOEXEC	},
	{ "move",	MS_TYPE,	MS_MOVE,	0		},
	{ "recurse",	MS_REC,		MS_REC,		0		},
	{ "remount",	MS_TYPE,	MS_REMOUNT,	0		},
	{ "ro",		MS_RDONLY,	MS_RDONLY,	0		},
	{ "rw",		MS_RDONLY,	0,		MS_RDONLY	},
	{ "suid",	MS_NOSUID,	0,		MS_NOSUID	},
	{ "sync",	MS_SYNCHRONOUS,	MS_SYNCHRONOUS,	0		},
	{ "verbose",	MS_VERBOSE,	MS_VERBOSE,	0		},
};

static void add_extra_option(struct extra_opts *extra, char *s)
{
	int len = strlen(s) + 1;			/* +1 for ',' */
	int newlen = extra->used_size + len;

	if (newlen >= extra->alloc_size) {
		char *new;

		new = realloc(extra->str, newlen + 1);	/* +1 for NUL */
		if (!new)
			return;

		extra->end += new - extra->str;
		extra->str = new;
		extra->alloc_size = newlen;
	}

	if (extra->used_size)
		*extra->end = ',';
	strcpy(extra->end, s);
	extra->used_size += len;
}

unsigned long
parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra)
{
	char *s;

	while ((s = strsep(&arg, ",")) != NULL) {
		char *opt = s;
		unsigned int i;
		int res, no = s[0] == 'n' && s[1] == 'o';

		if (no)
			s += 2;

		for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) {
			res = strcmp(s, options[i].str);

			if (res == 0) {
				rwflag &= ~options[i].rwmask;
				if (no)
					rwflag |= options[i].rwnoset;
				else
					rwflag |= options[i].rwset;
			}
			if (res <= 0)
				break;
		}

		if (res != 0 && s[0])
			add_extra_option(extra, opt);
	}

	return rwflag;
}