1 files changed, 143 insertions, 0 deletions
diff --git a/usr/utils/file_mode.c b/usr/utils/file_mode.c
new file mode 100644
index 0000000..48f7f43
--- /dev/null
+++ b/usr/utils/file_mode.c
@@ -0,0 +1,143 @@
+#include <sys/stat.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "file_mode.h"
+
+extern char *progname;
+
+mode_t parse_file_mode(char *arg, mode_t mode, mode_t sumask)
+{
+	char *clause;
+
+	if (isdigit(*arg) && *arg < '8') {
+		unsigned long num;
+
+		num = strtoul(arg, NULL, 8);
+		if ((num == ULONG_MAX && errno == ERANGE) || num > 07777) {
+			fprintf(stderr, "%s: invalid mode `%s'\n", progname,
+				arg);
+			exit(255);
+		}
+		return (mode_t) num;
+	}
+
+	while ((clause = strsep(&arg, ",")) != NULL) {
+		mode_t who = 0;
+		int action;
+		char *p = clause;
+
+		/*
+		 * Parse the who list.  Optional.
+		 */
+		while (1) {
+			switch (*p++) {
+			case 'u':
+				who |= S_IRWXU | S_ISUID;
+				continue;
+			case 'g':
+				who |= S_IRWXG | S_ISGID;
+				continue;
+			case 'o':
+				who |= S_IRWXO | S_ISVTX;
+				continue;
+			case 'a':
+				who =
+				    S_IRWXU | S_IRWXG | S_IRWXO | S_ISUID |
+				    S_ISGID | S_ISVTX;
+				continue;
+			}
+			/* undo the increment above */
+			p--;
+			break;
+		}
+
+		if (who == 0)
+			who = (~sumask) | S_ISVTX;
+
+		/*
+		 * Parse an action list.  Must be at least one action.
+		 */
+		while (*p) {
+			mode_t perm = 0;
+
+			/*
+			 * Parse the action
+			 */
+			action = *p;
+			if (action == '+' || action == '-' || action == '=')
+				p++;
+
+			/*
+			 * Parse perm
+			 */
+			while (*p) {
+				switch (*p++) {
+				case 'r':
+					perm |= S_IRUSR | S_IRGRP | S_IROTH;
+					continue;
+				case 'w':
+					perm |= S_IWUSR | S_IWGRP | S_IWOTH;
+					continue;
+				case 'x':
+					perm |= S_IXUSR | S_IXGRP | S_IXOTH;
+					continue;
+				case 'X':
+					perm |= S_ISVTX;
+					continue;
+				case 's':
+					perm |= S_ISUID | S_ISGID;
+					continue;
+				case 'u':
+					perm = mode & S_IRWXU;
+					perm |= perm >> 3 | perm >> 6;
+					if (mode & S_ISUID)
+						perm |= S_ISGID;
+					continue;
+				case 'g':
+					perm = mode & S_IRWXG;
+					perm |= perm << 3 | perm >> 3;
+					if (mode & S_ISGID)
+						perm |= S_ISUID;
+					continue;
+				case 'o':
+					perm = mode & S_IRWXO;
+					perm |= perm << 6 | perm << 3;
+					continue;
+				}
+				/* undo the increment above */
+				p--;
+				break;
+			}
+
+			perm &= who;
+
+			switch (action) {
+			case '+':
+				mode |= perm;
+				continue;
+
+			case '-':
+				mode &= ~perm;
+				continue;
+
+			case '=':
+				mode &= ~who;
+				mode |= perm;
+				continue;
+			}
+
+			if (!action)
+				break;
+			fprintf(stderr, "%s: invalid mode `%s'\n", progname,
+				clause);
+			exit(255);
+		}
+	}
+
+	return mode;
+}