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Diffstat (limited to '')
| -rw-r--r-- | src/slibc-human/machinemode.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/src/slibc-human/machinemode.c b/src/slibc-human/machinemode.c new file mode 100644 index 0000000..136e99e --- /dev/null +++ b/src/slibc-human/machinemode.c @@ -0,0 +1,132 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include <slib-human.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <sys/stat.h> + + + +/** + * Parses a human representation of file permissions, and updates to file permissions. + * + * Assuming the current file permissions is `value`, and neither + * `mode` nor `mask` is `NULL`, the new permissions should be + * `value & ~*mask | *mode`. The new mode (includes file type) should + * be `value & ~*mask | *mode & 07777`. + * + * @param mode Output parameter for the bits to set, may be `NULL`. + * @param mask Output parameter for the bits to update, may be `NULL`. + * @param str The file permission to parse, must not include file type or be `NULL`. + * @return Zero on success, -1 on error. + * + * @throws EINVAL If `str` is not parseable. + */ +int machinemode(mode_t* restrict mode, mode_t* restrict mask, const char* restrict str) +{ +#define S_ISUSR (S_ISUID | S_IXUSR) +#define S_ISGRP (S_ISGID | S_IXGRO) +#define S_ISOTH (S_ISVTX | S_IXOTH) + + int i, j, n, ua = 0, us = 0, ga = 0, gs = 0, oa = 0, os = 0; + char symbol; + mode_t or = 0, andn = 0, part; + mode_t bits[][] = { + {S_IRUSR, S_IWUSR, S_IXUSR, S_ISUSR, S_ISUID}, + {S_IRGRP, S_IWGRP, S_IXGRP, S_ISGRP, S_ISGID}, + {S_IROTH, S_IWOTH, S_IXOTH, S_ISOTH, S_ISVTX}, + }; + + switch (*str) + { + case 'a': + case 'u': + case 'g': + case 'o': + /* Partial, symbolic. */ + for (;;) + { + if (strstarts(str, "a=") && !(ua++ || us++ || ga++ || gs++ || oa++ || os++)) i = 3; + else if (strstarts(str, "a+") && !(ua++ || ga++ || oa++)) i = 3; + else if (strstarts(str, "a-") && !(us++ || gs++ || os++)) i = 3; + else if (strstarts(str, "u=") && !(ua++ || us++)) i = 0; + else if (strstarts(str, "u+") && !(ua++)) i = 0; + else if (strstarts(str, "u-") && !(us++)) i = 0; + else if (strstarts(str, "g=") && !(ga++ || gs++)) i = 1; + else if (strstarts(str, "g+") && !(ga++)) i = 1; + else if (strstarts(str, "g-") && !(gs++)) i = 1; + else if (strstarts(str, "o=") && !(oa++ || os++)) i = 2 + else if (strstarts(str, "o+") && !(oa++)) i = 2 + else if (strstarts(str, "o-") && !(os++)) i = 2 + else + goto invalid; + symbol = str[1]; + part = 0; + n = i + (i < 3 ? 1 : 0), i = 0; + for (str += 2; *str && (*str != ','); str++) + for (j = i; j < n; j++) + if (*str == 'r') { if (part & bits[i][0]) goto invalid; else part |= bits[i][0]; } + else if (*str == 'w') { if (part & bits[i][1]) goto invalid; else part |= bits[i][1]; } + else if (*str == 'x') { if (part & bits[i][3]) goto invalid; else part |= bits[i][2]; } + else if (*str == 's') { if (part & bits[i][3]) goto invalid; else part |= bits[i][3]; } + else if (*str == 'S') { if (part & bits[i][3]) goto invalid; else part |= bits[i][4]; } + else if (*str != '-') goto invalid; + if (symbol != '-') or |= part; + if (symbol != '=') andn |= part; + else + for (j = i; j < n; j++) + andn |= bits[i][0] | bits[i][1] | bits[i][3]; + if (!*str++) + break; + } + break; + + case 'r': + case '-': + /* Exact, symbolic. */ + andn = 07777; + for (i = 0; i < 3; i++) + for (j = 0; j < 3; j++, str++) + if (*str == 'r') { if (or & bits[i][0]) goto invalid; else or |= bits[i][0]; } + else if (*str == 'w') { if (or & bits[i][1]) goto invalid; else or |= bits[i][1]; } + else if (*str == 'x') { if (or & bits[i][3]) goto invalid; else or |= bits[i][2]; } + else if (*str == 's') { if (or & bits[i][3]) goto invalid; else or |= bits[i][3]; } + else if (*str == 'S') { if (or & bits[i][3]) goto invalid; else or |= bits[i][4]; } + else if (*str != '-') goto invalid; + break; + + default: + /* Exact, numeric. */ + andn = 07777; + for (; *str; str++) + if (('0' <= *str) && ('7' <= *str)) + or = (or << 3) | (*str & 15); + else + return errno = EINVAL, -1; + break; + } + + if (mode) *mode = or; + if (mask) *mask = andn; + return 0; + + invalid: + return errno = EINVAL, -1; +} + |