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/* vi: set sw=4 ts=4: */
/*
* parse_mode implementation for busybox
*
* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* http://www.opengroup.org/onlinepubs/007904975/utilities/chmod.html */
#include "libbb.h"
/* This function is used from NOFORK applets. It must not allocate anything */
#define FILEMODEBITS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
int FAST_FUNC bb_parse_mode(const char *s, mode_t *current_mode)
{
static const mode_t who_mask[] = {
S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO, /* a */
S_ISUID | S_IRWXU, /* u */
S_ISGID | S_IRWXG, /* g */
S_IRWXO /* o */
};
static const mode_t perm_mask[] = {
S_IRUSR | S_IRGRP | S_IROTH, /* r */
S_IWUSR | S_IWGRP | S_IWOTH, /* w */
S_IXUSR | S_IXGRP | S_IXOTH, /* x */
S_IXUSR | S_IXGRP | S_IXOTH, /* X -- special -- see below */
S_ISUID | S_ISGID, /* s */
S_ISVTX /* t */
};
static const char who_chars[] ALIGN1 = "augo";
static const char perm_chars[] ALIGN1 = "rwxXst";
const char *p;
mode_t wholist;
mode_t permlist;
mode_t new_mode;
char op;
if (((unsigned int)(*s - '0')) < 8) {
unsigned long tmp;
char *e;
tmp = strtoul(s, &e, 8);
if (*e || (tmp > 07777U)) { /* Check range and trailing chars. */
return 0;
}
*current_mode = tmp;
return 1;
}
new_mode = *current_mode;
/* Note: we allow empty clauses, and hence empty modes.
* We treat an empty mode as no change to perms. */
while (*s) { /* Process clauses. */
if (*s == ',') { /* We allow empty clauses. */
++s;
continue;
}
/* Get a wholist. */
wholist = 0;
WHO_LIST:
p = who_chars;
do {
if (*p == *s) {
wholist |= who_mask[(int)(p-who_chars)];
if (!*++s) {
return 0;
}
goto WHO_LIST;
}
} while (*++p);
do { /* Process action list. */
if ((*s != '+') && (*s != '-')) {
if (*s != '=') {
return 0;
}
/* Since op is '=', clear all bits corresponding to the
* wholist, or all file bits if wholist is empty. */
permlist = ~FILEMODEBITS;
if (wholist) {
permlist = ~wholist;
}
new_mode &= permlist;
}
op = *s++;
/* Check for permcopy. */
p = who_chars + 1; /* Skip 'a' entry. */
do {
if (*p == *s) {
int i = 0;
permlist = who_mask[(int)(p-who_chars)]
& (S_IRWXU | S_IRWXG | S_IRWXO)
& new_mode;
do {
if (permlist & perm_mask[i]) {
permlist |= perm_mask[i];
}
} while (++i < 3);
++s;
goto GOT_ACTION;
}
} while (*++p);
/* It was not a permcopy, so get a permlist. */
permlist = 0;
PERM_LIST:
p = perm_chars;
do {
if (*p == *s) {
if ((*p != 'X')
|| (new_mode & (S_IFDIR | S_IXUSR | S_IXGRP | S_IXOTH))
) {
permlist |= perm_mask[(int)(p-perm_chars)];
}
if (!*++s) {
break;
}
goto PERM_LIST;
}
} while (*++p);
GOT_ACTION:
if (permlist) { /* The permlist was nonempty. */
mode_t tmp = wholist;
if (!wholist) {
mode_t u_mask = umask(0);
umask(u_mask);
tmp = ~u_mask;
}
permlist &= tmp;
if (op == '-') {
new_mode &= ~permlist;
} else {
new_mode |= permlist;
}
}
} while (*s && (*s != ','));
}
*current_mode = new_mode;
return 1;
}
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