libbb: new function bb_getgroups() - allocating wrapper around getgroups()
function old new delta bb_getgroups - 111 +111 nexpr 843 757 -86 ------------------------------------------------------------------------------ (add/remove: 2/0 grow/shrink: 0/1 up/down: 111/-86) Total: 25 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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@ -563,26 +563,11 @@ static int binop(void)
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/*return 1; - NOTREACHED */
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}
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static void initialize_group_array(void)
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{
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int n;
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/* getgroups may be expensive, try to use it only once */
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ngroups = 32;
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do {
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/* FIXME: ash tries so hard to not die on OOM,
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* and we spoil it with just one xrealloc here */
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/* We realloc, because test_main can be entered repeatedly by shell.
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* Testcase (ash): 'while true; do test -x some_file; done'
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* and watch top. (some_file must have owner != you) */
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n = ngroups;
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group_array = xrealloc(group_array, n * sizeof(gid_t));
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ngroups = getgroups(n, group_array);
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} while (ngroups > n);
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group_array = bb_getgroups(&ngroups, NULL);
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}
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/* Return non-zero if GID is one that we have in our groups list. */
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//XXX: FIXME: duplicate of existing libbb function?
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// see toplevel TODO file:
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@ -610,14 +595,10 @@ static int is_a_group_member(gid_t gid)
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/* Do the same thing access(2) does, but use the effective uid and gid,
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and don't make the mistake of telling root that any file is
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executable. */
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static int test_eaccess(char *path, int mode)
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static int test_eaccess(struct stat *st, int mode)
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{
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struct stat st;
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unsigned int euid = geteuid();
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if (stat(path, &st) < 0)
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return -1;
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if (euid == 0) {
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/* Root can read or write any file. */
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if (mode != X_OK)
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@ -625,16 +606,16 @@ static int test_eaccess(char *path, int mode)
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/* Root can execute any file that has any one of the execute
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* bits set. */
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if (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
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if (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
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return 0;
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}
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if (st.st_uid == euid) /* owner */
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if (st->st_uid == euid) /* owner */
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mode <<= 6;
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else if (is_a_group_member(st.st_gid))
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else if (is_a_group_member(st->st_gid))
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mode <<= 3;
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if (st.st_mode & mode)
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if (st->st_mode & mode)
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return 0;
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return -1;
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@ -667,7 +648,7 @@ static int filstat(char *nm, enum token mode)
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i = W_OK;
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if (mode == FILEX)
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i = X_OK;
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return test_eaccess(nm, i) == 0;
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return test_eaccess(&s, i) == 0;
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}
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if (is_file_type(mode)) {
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if (mode == FILREG)
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@ -1033,6 +1033,15 @@ void die_if_bad_username(const char* name) FAST_FUNC;
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#else
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#define die_if_bad_username(name) ((void)(name))
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#endif
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/*
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* Returns (-1) terminated malloced result of getgroups().
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* Reallocs group_array (useful for repeated calls).
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* ngroups is an initial size of array. It is rounded up to 32 for realloc.
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* ngroups is updated on return.
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* ngroups can be NULL: bb_getgroups(NULL, NULL) is valid usage.
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* Dies on errors (on Linux, only xrealloc can cause this, not internal getgroups call).
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*/
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gid_t *bb_getgroups(int *ngroups, gid_t *group_array) FAST_FUNC;
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#if ENABLE_FEATURE_UTMP
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void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname);
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47
libbb/bb_getgroups.c
Normal file
47
libbb/bb_getgroups.c
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@ -0,0 +1,47 @@
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/*
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* Utility routines.
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*
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* Copyright (C) 2017 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//kbuild:lib-y += bb_getgroups.o
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#include "libbb.h"
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gid_t* FAST_FUNC bb_getgroups(int *ngroups, gid_t *group_array)
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{
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int n = ngroups ? *ngroups : 0;
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/* getgroups may be a bit expensive, try to use it only once */
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if (n < 32)
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n = 32;
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for (;;) {
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// FIXME: ash tries so hard to not die on OOM (when we are called from test),
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// and we spoil it with just one xrealloc here
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group_array = xrealloc(group_array, (n+1) * sizeof(group_array[0]));
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n = getgroups(n, group_array);
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/*
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* If buffer is too small, kernel does not return new_n > n.
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* It returns -1 and EINVAL:
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*/
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if (n >= 0) {
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/* Terminator for bb_getgroups(NULL, NULL) usage */
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group_array[n] = (gid_t) -1;
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break;
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}
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if (errno == EINVAL) { /* too small? */
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/* This is the way to ask kernel how big the array is */
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n = getgroups(0, group_array);
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continue;
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}
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/* Some other error (should never happen on Linux) */
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bb_perror_msg_and_die("getgroups");
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}
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if (ngroups)
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*ngroups = n;
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return group_array;
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}
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