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-rw-r--r--src/slibc-human/machinemode.c132
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
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+++ 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;
+}
+