I found quite a lot of bugs, so I ended up pretty much rewriting as I
followed the spec¹.
Now, it works as follows:
- Determine a mask (who) of bits that can be modified for the subsequent
operations. If none are specified, select all file mode bits.
- In a loop, determine which operation (+, -, =) to apply.
- If the next character is a permcopy (u, g, o), set the new permissions
(perm) corresponding to the bits set in the user, group or other parts
of the existing mode.
- Otherwise, set the new permissions by looping through the next r, w,
x, s, t characters.
- Now, the set of bits we want to add or remove is (who & perm). Set or
remove these bits according the the operation (first clearing the
appropriate bits if the operation is =).
- Continue from the top if the next character is a comma, otherwise,
process the next operation.
I tested this on some made up inputs, and I believe it is working
correctly now:
parsemode("g+w", 0644, 0), before: 0606, now: 0664, fixed
parsemode("u+rx", 0222, 0), before: 0077, now: 0722, fixed
parsemode("+x", 0644, 023), before: 0754, now: 0754, still works
parsemode("+w", 0444, 022), before: 0644, now: 0644, still works
parsemode("+w", 0444, 0), before: 0666, now: 0666, still works
parsemode("+s", 0755, 0), before: 0755, now: 6755, fixed
parsemode("u+s", 0755, 0), before: 0055, now: 4755, fixed
parsemode("g+s", 0755, 0), before: 0705, now: 2755, fixed
parsemode("g=u", 0700, 0), before: 0000, now: 0770, fixed
parsemode("go=u-w", 0700, 0), before: 0000, now: 0755, fixed
parsemode("o+u-g", 0641, 0), before: 0000, now: 0643, fixed
parsemode("u=rx,o+w,g-r", 0654, 0) before: error, now: 0516, fixed
parsemode(",", 0654, 0), before: error, now: error, still works
¹ http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chmod.html
---
util/mode.c | 129 ++++++++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 95 insertions(+), 34 deletions(-)
diff --git a/util/mode.c b/util/mode.c
index 4506023..c022e8d 100644
--- a/util/mode.c
+++ b/util/mode.c
@@ -16,9 +16,9 @@ mode_t
parsemode(const char *str, mode_t mode, mode_t mask)
{
char *end;
- const char *p;
- int octal, op = '+';
- mode_t gmask = 0, m = 0;
+ const char *p = str;
+ int octal, op;
+ mode_t who, perm, clear;
octal = strtol(str, &end, 8);
if(*end == '\0') {
@@ -41,61 +41,122 @@ parsemode(const char *str, mode_t mode, mode_t mask)
if(octal & 00001) mode |= S_IXOTH;
return mode;
}
- for(p = str; *p; p++) {
+next:
+ /* first, determine which bits we will be modifying */
+ for(who = 0; *p; p++) {
switch(*p) {
/* masks */
case 'u':
- gmask |= S_IRWXU;
- break;
+ who |= S_IRWXU|S_ISUID;
+ continue;
case 'g':
- gmask |= S_IRWXG;
- break;
+ who |= S_IRWXG|S_ISGID;
+ continue;
case 'o':
- gmask |= S_IRWXO;
- break;
+ who |= S_IRWXO;
+ continue;
case 'a':
- gmask |= S_IRWXU|S_IRWXG|S_IRWXO;
- break;
+ 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;
- /* modes */
- case 'r':
- m |= S_IRUSR|S_IRGRP|S_IROTH;
- break;
- case 'w':
- m |= S_IWUSR|S_IWGRP|S_IWOTH;
- break;
- case 'x':
- m |= S_IXUSR|S_IXGRP|S_IXOTH;
+ default:
+ eprintf("%s: invalid mode\n", str);
+ return -1;
+ }
+
+ 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 's':
- m |= S_ISUID|S_ISGID;
+ 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 't':
- m |= S_ISVTX;
+ 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:
- eprintf("%s: invalid mode\n", str);
- return -1;
+ 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 '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 |= (m & ((~mask) & 0777));
+ mode |= perm & who;
break;
case '-':
- mode &= (~(m & ((~mask) & 0777)));
- break;
- case '=':
- mode = (m & ((~mask) & 0777));
+ mode &= ~(perm & who);
break;
}
+ /* if we hit a comma, move on to the next clause */
+ if(*p == ',') {
+ p++;
+ goto next;
+ }
}
- if(gmask && op != '=')
- mode &= ~gmask;
return mode;
}
--
2.1.3.1.g339ec9c
