6164445cce
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
163 lines
3.0 KiB
C
163 lines
3.0 KiB
C
#include <unistd.h>
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#include <string.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include "../util.h"
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mode_t
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getumask(void)
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{
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mode_t mask = umask(0);
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umask(mask);
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return mask;
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}
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mode_t
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parsemode(const char *str, mode_t mode, mode_t mask)
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{
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char *end;
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const char *p = str;
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int octal, op;
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mode_t who, perm, clear;
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octal = strtol(str, &end, 8);
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if(*end == '\0') {
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if(octal < 0 || octal > 07777) {
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eprintf("%s: invalid mode\n", str);
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return -1;
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}
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mode = 0;
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if(octal & 04000) mode |= S_ISUID;
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if(octal & 02000) mode |= S_ISGID;
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if(octal & 01000) mode |= S_ISVTX;
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if(octal & 00400) mode |= S_IRUSR;
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if(octal & 00200) mode |= S_IWUSR;
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if(octal & 00100) mode |= S_IXUSR;
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if(octal & 00040) mode |= S_IRGRP;
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if(octal & 00020) mode |= S_IWGRP;
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if(octal & 00010) mode |= S_IXGRP;
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if(octal & 00004) mode |= S_IROTH;
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if(octal & 00002) mode |= S_IWOTH;
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if(octal & 00001) mode |= S_IXOTH;
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return mode;
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}
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next:
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/* first, determine which bits we will be modifying */
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for(who = 0; *p; p++) {
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switch(*p) {
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/* masks */
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case 'u':
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who |= S_IRWXU|S_ISUID;
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continue;
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case 'g':
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who |= S_IRWXG|S_ISGID;
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continue;
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case 'o':
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who |= S_IRWXO;
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continue;
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case 'a':
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who |= S_IRWXU|S_ISUID|S_IRWXG|S_ISGID|S_IRWXO;
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continue;
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}
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break;
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}
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if(who) {
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clear = who;
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} else {
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clear = S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO;
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who = ~mask;
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}
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while(*p) {
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switch(*p) {
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/* opers */
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case '=':
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case '+':
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case '-':
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op = (int)*p;
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break;
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default:
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eprintf("%s: invalid mode\n", str);
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return -1;
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}
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perm = 0;
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switch(*++p) {
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/* copy */
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case 'u':
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if(mode & S_IRUSR)
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perm |= S_IRUSR|S_IRGRP|S_IROTH;
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if(mode & S_IWUSR)
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perm |= S_IWUSR|S_IWGRP|S_IWOTH;
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if(mode & S_IXUSR)
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perm |= S_IXUSR|S_IXGRP|S_IXOTH;
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if(mode & S_ISUID)
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perm |= S_ISUID|S_ISGID;
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p++;
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break;
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case 'g':
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if(mode & S_IRGRP)
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perm |= S_IRUSR|S_IRGRP|S_IROTH;
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if(mode & S_IWGRP)
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perm |= S_IWUSR|S_IWGRP|S_IWOTH;
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if(mode & S_IXGRP)
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perm |= S_IXUSR|S_IXGRP|S_IXOTH;
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if(mode & S_ISGID)
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perm |= S_ISUID|S_ISGID;
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p++;
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break;
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case 'o':
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if(mode & S_IROTH)
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perm |= S_IRUSR|S_IRGRP|S_IROTH;
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if(mode & S_IWOTH)
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perm |= S_IWUSR|S_IWGRP|S_IWOTH;
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if(mode & S_IXOTH)
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perm |= S_IXUSR|S_IXGRP|S_IXOTH;
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p++;
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break;
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default:
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for(; *p; p++) {
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switch(*p) {
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/* modes */
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case 'r':
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perm |= S_IRUSR|S_IRGRP|S_IROTH;
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break;
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case 'w':
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perm |= S_IWUSR|S_IWGRP|S_IWOTH;
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break;
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case 'x':
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perm |= S_IXUSR|S_IXGRP|S_IXOTH;
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break;
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case 's':
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perm |= S_ISUID|S_ISGID;
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break;
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case 't':
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perm |= S_ISVTX;
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break;
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default:
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goto apply;
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}
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}
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}
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apply:
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/* apply */
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switch(op) {
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case '=':
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mode &= ~clear;
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/* fallthrough */
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case '+':
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mode |= perm & who;
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break;
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case '-':
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mode &= ~(perm & who);
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break;
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}
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/* if we hit a comma, move on to the next clause */
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if(*p == ',') {
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p++;
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goto next;
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}
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}
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return mode;
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}
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