[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * parse_mode implementation for busybox
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| 4 | *
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| 5 | * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 8 | */
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| 9 |
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| 10 | /* http://www.opengroup.org/onlinepubs/007904975/utilities/chmod.html */
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| 11 |
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| 12 | #include "libbb.h"
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| 13 |
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| 14 | /* This function is used from NOFORK applets. It must not allocate anything */
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| 15 |
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| 16 | #define FILEMODEBITS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
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| 17 |
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| 18 | int FAST_FUNC bb_parse_mode(const char *s, mode_t *current_mode)
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| 19 | {
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| 20 | static const mode_t who_mask[] = {
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| 21 | S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO, /* a */
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| 22 | S_ISUID | S_IRWXU, /* u */
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| 23 | S_ISGID | S_IRWXG, /* g */
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| 24 | S_IRWXO /* o */
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| 25 | };
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| 26 | static const mode_t perm_mask[] = {
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| 27 | S_IRUSR | S_IRGRP | S_IROTH, /* r */
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| 28 | S_IWUSR | S_IWGRP | S_IWOTH, /* w */
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| 29 | S_IXUSR | S_IXGRP | S_IXOTH, /* x */
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| 30 | S_IXUSR | S_IXGRP | S_IXOTH, /* X -- special -- see below */
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| 31 | S_ISUID | S_ISGID, /* s */
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| 32 | S_ISVTX /* t */
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| 33 | };
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| 34 | static const char who_chars[] ALIGN1 = "augo";
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| 35 | static const char perm_chars[] ALIGN1 = "rwxXst";
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| 36 |
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| 37 | const char *p;
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| 38 | mode_t wholist;
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| 39 | mode_t permlist;
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| 40 | mode_t new_mode;
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| 41 | char op;
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| 42 |
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| 43 | if ((unsigned char)(*s - '0') < 8) {
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| 44 | unsigned long tmp;
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| 45 | char *e;
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| 46 |
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| 47 | tmp = strtoul(s, &e, 8);
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| 48 | if (*e || (tmp > 07777U)) { /* Check range and trailing chars. */
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| 49 | return 0;
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| 50 | }
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| 51 | *current_mode = tmp;
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| 52 | return 1;
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| 53 | }
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| 54 |
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| 55 | new_mode = *current_mode;
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| 56 |
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| 57 | /* Note: we allow empty clauses, and hence empty modes.
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| 58 | * We treat an empty mode as no change to perms. */
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| 59 |
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| 60 | while (*s) { /* Process clauses. */
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| 61 | if (*s == ',') { /* We allow empty clauses. */
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| 62 | ++s;
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| 63 | continue;
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| 64 | }
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| 65 |
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| 66 | /* Get a wholist. */
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| 67 | wholist = 0;
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| 68 | WHO_LIST:
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| 69 | p = who_chars;
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| 70 | do {
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| 71 | if (*p == *s) {
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| 72 | wholist |= who_mask[(int)(p-who_chars)];
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| 73 | if (!*++s) {
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| 74 | return 0;
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| 75 | }
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| 76 | goto WHO_LIST;
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| 77 | }
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| 78 | } while (*++p);
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| 79 |
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| 80 | do { /* Process action list. */
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| 81 | if ((*s != '+') && (*s != '-')) {
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| 82 | if (*s != '=') {
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| 83 | return 0;
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| 84 | }
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| 85 | /* Since op is '=', clear all bits corresponding to the
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| 86 | * wholist, or all file bits if wholist is empty. */
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| 87 | permlist = ~FILEMODEBITS;
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| 88 | if (wholist) {
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| 89 | permlist = ~wholist;
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| 90 | }
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| 91 | new_mode &= permlist;
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| 92 | }
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| 93 | op = *s++;
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| 94 |
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| 95 | /* Check for permcopy. */
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| 96 | p = who_chars + 1; /* Skip 'a' entry. */
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| 97 | do {
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| 98 | if (*p == *s) {
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| 99 | int i = 0;
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| 100 | permlist = who_mask[(int)(p-who_chars)]
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| 101 | & (S_IRWXU | S_IRWXG | S_IRWXO)
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| 102 | & new_mode;
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| 103 | do {
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| 104 | if (permlist & perm_mask[i]) {
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| 105 | permlist |= perm_mask[i];
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| 106 | }
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| 107 | } while (++i < 3);
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| 108 | ++s;
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| 109 | goto GOT_ACTION;
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| 110 | }
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| 111 | } while (*++p);
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| 112 |
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| 113 | /* It was not a permcopy, so get a permlist. */
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| 114 | permlist = 0;
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| 115 | PERM_LIST:
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| 116 | p = perm_chars;
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| 117 | do {
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| 118 | if (*p == *s) {
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| 119 | if ((*p != 'X')
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| 120 | || (new_mode & (S_IFDIR | S_IXUSR | S_IXGRP | S_IXOTH))
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| 121 | ) {
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| 122 | permlist |= perm_mask[(int)(p-perm_chars)];
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| 123 | }
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| 124 | if (!*++s) {
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| 125 | break;
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| 126 | }
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| 127 | goto PERM_LIST;
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| 128 | }
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| 129 | } while (*++p);
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| 130 | GOT_ACTION:
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| 131 | if (permlist) { /* The permlist was nonempty. */
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| 132 | mode_t tmp = wholist;
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| 133 | if (!wholist) {
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| 134 | mode_t u_mask = umask(0);
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| 135 | umask(u_mask);
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| 136 | tmp = ~u_mask;
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| 137 | }
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| 138 | permlist &= tmp;
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| 139 | if (op == '-') {
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| 140 | new_mode &= ~permlist;
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| 141 | } else {
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| 142 | new_mode |= permlist;
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| 143 | }
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| 144 | }
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| 145 | } while (*s && (*s != ','));
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| 146 | }
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| 147 |
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| 148 | *current_mode = new_mode;
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| 149 | return 1;
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| 150 | }
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