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