sbase/libutil/mode.c
Michael Forney f3d05ffd0a chmod: Implement X perm symbol
Instead of clearing the format bits before calling parsemode, leave
them in so we can differentiate between directories and other files,
then clear the format bits in the result.
2020-01-06 13:47:26 -08:00

153 lines
2.7 KiB
C

/* See LICENSE file for copyright and license details. */
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include "../util.h"
mode_t
getumask(void)
{
mode_t mask = umask(0);
umask(mask);
return mask;
}
mode_t
parsemode(const char *str, mode_t mode, mode_t mask)
{
char *end;
const char *p = str;
int octal, op;
mode_t who, perm, clear;
octal = strtol(str, &end, 8);
if (*end == '\0') {
if (octal < 0 || octal > 07777)
eprintf("%s: invalid mode\n", str);
return octal;
}
next:
/* first, determine which bits we will be modifying */
for (who = 0; *p; p++) {
switch (*p) {
/* masks */
case 'u':
who |= S_IRWXU|S_ISUID;
continue;
case 'g':
who |= S_IRWXG|S_ISGID;
continue;
case 'o':
who |= S_IRWXO;
continue;
case 'a':
who |= S_IRWXU|S_ISUID|S_IRWXG|S_ISGID|S_IRWXO;
continue;
}
break;
}
if (who) {
clear = who;
} else {
clear = S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO;
who = ~mask;
}
while (*p) {
switch (*p) {
/* opers */
case '=':
case '+':
case '-':
op = (int)*p;
break;
default:
eprintf("%s: invalid mode\n", str);
}
perm = 0;
switch (*++p) {
/* copy */
case 'u':
if (mode & S_IRUSR)
perm |= S_IRUSR|S_IRGRP|S_IROTH;
if (mode & S_IWUSR)
perm |= S_IWUSR|S_IWGRP|S_IWOTH;
if (mode & S_IXUSR)
perm |= S_IXUSR|S_IXGRP|S_IXOTH;
if (mode & S_ISUID)
perm |= S_ISUID|S_ISGID;
p++;
break;
case 'g':
if (mode & S_IRGRP)
perm |= S_IRUSR|S_IRGRP|S_IROTH;
if (mode & S_IWGRP)
perm |= S_IWUSR|S_IWGRP|S_IWOTH;
if (mode & S_IXGRP)
perm |= S_IXUSR|S_IXGRP|S_IXOTH;
if (mode & S_ISGID)
perm |= S_ISUID|S_ISGID;
p++;
break;
case 'o':
if (mode & S_IROTH)
perm |= S_IRUSR|S_IRGRP|S_IROTH;
if (mode & S_IWOTH)
perm |= S_IWUSR|S_IWGRP|S_IWOTH;
if (mode & S_IXOTH)
perm |= S_IXUSR|S_IXGRP|S_IXOTH;
p++;
break;
default:
for (; *p; p++) {
switch (*p) {
/* modes */
case 'r':
perm |= S_IRUSR|S_IRGRP|S_IROTH;
break;
case 'w':
perm |= S_IWUSR|S_IWGRP|S_IWOTH;
break;
case 'x':
perm |= S_IXUSR|S_IXGRP|S_IXOTH;
break;
case 'X':
if (S_ISDIR(mode) || mode & (S_IXUSR|S_IXGRP|S_IXOTH))
perm |= S_IXUSR|S_IXGRP|S_IXOTH;
break;
case 's':
perm |= S_ISUID|S_ISGID;
break;
case 't':
perm |= S_ISVTX;
break;
default:
goto apply;
}
}
}
apply:
/* apply */
switch (op) {
case '=':
mode &= ~clear;
/* fallthrough */
case '+':
mode |= perm & who;
break;
case '-':
mode &= ~(perm & who);
break;
}
/* if we hit a comma, move on to the next clause */
if (*p == ',') {
p++;
goto next;
}
}
return mode & ~S_IFMT;
}