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