sbase

suckless unix tools
git clone git://git.2f30.org/sbase.git
Log | Files | Refs | README | LICENSE

commit 6164445cceb24fa691595d856c763e278428e68f
parent 6327290cf273766b6ebef9af750951844fef4942
Author: Michael Forney <mforney@mforney.org>
Date:   Sun Nov  2 22:24:52 +0000

Fix symbolic mode parsing in parsemode

I found quite a lot of bugs, so I ended up pretty much rewriting as I
followed the spec┬╣.

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

┬╣ http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chmod.html

Diffstat:
util/mode.c | 129++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------
1 file changed, 95 insertions(+), 34 deletions(-)
diff --git 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; }