/* portability.c - code to workaround the deficiencies of various platforms.
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*
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* Copyright 2012 Rob Landley <rob@landley.net>
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* Copyright 2012 Georgi Chorbadzhiyski <gf@unixsol.org>
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*/
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#include "toys.h"
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// We can't fork() on nommu systems, and vfork() requires an exec() or exit()
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// before resuming the parent (because they share a heap until then). And no,
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// we can't implement our own clone() call that does the equivalent of fork()
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// because nommu heaps use physical addresses so if we copy the heap all our
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// pointers are wrong. (You need an mmu in order to map two heaps to the same
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// address range without interfering with each other.) In the absence of
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// a portable way to tell malloc() to start a new heap without freeing the old
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// one, you pretty much need the exec().)
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// So we exec ourselves (via /proc/self/exe, if anybody knows a way to
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// re-exec self without depending on the filesystem, I'm all ears),
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// and use the arguments to signal reentry.
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#if CFG_TOYBOX_FORK
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pid_t xfork(void)
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{
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pid_t pid = fork();
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if (pid < 0) perror_exit("fork");
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return pid;
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}
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#endif
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int xgetrandom(void *buf, unsigned buflen, unsigned flags)
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{
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int fd;
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#if CFG_TOYBOX_GETRANDOM
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if (buflen == getrandom(buf, buflen, flags&~WARN_ONLY)) return 1;
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if (errno!=ENOSYS && !(flags&WARN_ONLY)) perror_exit("getrandom");
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#endif
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fd = xopen(flags ? "/dev/random" : "/dev/urandom",O_RDONLY|(flags&WARN_ONLY));
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if (fd == -1) return 0;
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xreadall(fd, buf, buflen);
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close(fd);
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return 1;
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}
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#if defined(__APPLE__)
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extern char **environ;
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int clearenv(void)
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{
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*environ = NULL;
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return 0;
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}
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#endif
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// Get a linked list of mount points, with stat information.
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#if defined(__APPLE__) || defined(__FreeBSD__)
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// Not implemented for macOS.
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// See <sys/mount.h>'s getmntinfo(3) for the BSD API.
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#else
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#include <mntent.h>
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static void octal_deslash(char *s)
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{
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char *o = s;
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while (*s) {
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if (*s == '\\') {
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int i, oct = 0;
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for (i = 1; i < 4; i++) {
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if (!isdigit(s[i])) break;
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oct = (oct<<3)+s[i]-'0';
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}
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if (i == 4) {
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*o++ = oct;
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s += i;
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continue;
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}
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}
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*o++ = *s++;
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}
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*o = 0;
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}
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// Check if this type matches list.
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// Odd syntax: typelist all yes = if any, typelist all no = if none.
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int mountlist_istype(struct mtab_list *ml, char *typelist)
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{
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int len, skip;
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char *t;
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if (!typelist) return 1;
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skip = strncmp(typelist, "no", 2);
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for (;;) {
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if (!(t = comma_iterate(&typelist, &len))) break;
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if (!skip) {
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// If one -t starts with "no", the rest must too
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if (strncmp(t, "no", 2)) error_exit("bad typelist");
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if (!strncmp(t+2, ml->type, len-2)) {
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skip = 1;
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break;
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}
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} else if (!strncmp(t, ml->type, len) && !ml->type[len]) {
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skip = 0;
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break;
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}
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}
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return !skip;
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}
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// Get list of mounted filesystems, including stat and statvfs info.
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// Returns a reversed list, which is good for finding overmounts and such.
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struct mtab_list *xgetmountlist(char *path)
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{
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struct mtab_list *mtlist = 0, *mt;
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struct mntent *me;
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FILE *fp;
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char *p = path ? path : "/proc/mounts";
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if (!(fp = setmntent(p, "r"))) perror_exit("bad %s", p);
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// The "test" part of the loop is done before the first time through and
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// again after each "increment", so putting the actual load there avoids
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// duplicating it. If the load was NULL, the loop stops.
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while ((me = getmntent(fp))) {
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mt = xzalloc(sizeof(struct mtab_list) + strlen(me->mnt_fsname) +
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strlen(me->mnt_dir) + strlen(me->mnt_type) + strlen(me->mnt_opts) + 4);
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dlist_add_nomalloc((void *)&mtlist, (void *)mt);
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// Collect details about mounted filesystem
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// Don't report errors, just leave data zeroed
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if (!path) {
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stat(me->mnt_dir, &(mt->stat));
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statvfs(me->mnt_dir, &(mt->statvfs));
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}
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// Remember information from /proc/mounts
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mt->dir = stpcpy(mt->type, me->mnt_type)+1;
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mt->device = stpcpy(mt->dir, me->mnt_dir)+1;
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mt->opts = stpcpy(mt->device, me->mnt_fsname)+1;
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strcpy(mt->opts, me->mnt_opts);
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octal_deslash(mt->dir);
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octal_deslash(mt->device);
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}
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endmntent(fp);
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return mtlist;
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}
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#endif
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