1 /* portability.c - code to workaround the deficiencies of various platforms.
2 *
3 * Copyright 2012 Rob Landley <rob@landley.net>
4 * Copyright 2012 Georgi Chorbadzhiyski <gf@unixsol.org>
5 */
6
7 #include "toys.h"
8
9 // We can't fork() on nommu systems, and vfork() requires an exec() or exit()
10 // before resuming the parent (because they share a heap until then). And no,
11 // we can't implement our own clone() call that does the equivalent of fork()
12 // because nommu heaps use physical addresses so if we copy the heap all our
13 // pointers are wrong. (You need an mmu in order to map two heaps to the same
14 // address range without interfering with each other.) In the absence of
15 // a portable way to tell malloc() to start a new heap without freeing the old
16 // one, you pretty much need the exec().)
17
18 // So we exec ourselves (via /proc/self/exe, if anybody knows a way to
19 // re-exec self without depending on the filesystem, I'm all ears),
20 // and use the arguments to signal reentry.
21
22 #if CFG_TOYBOX_FORK
xfork(void)23 pid_t xfork(void)
24 {
25 pid_t pid = fork();
26
27 if (pid < 0) perror_exit("fork");
28
29 return pid;
30 }
31 #endif
32
xgetrandom(void * buf,unsigned buflen,unsigned flags)33 int xgetrandom(void *buf, unsigned buflen, unsigned flags)
34 {
35 int fd;
36
37 #if CFG_TOYBOX_GETRANDOM
38 if (buflen == getrandom(buf, buflen, flags&~WARN_ONLY)) return 1;
39 if (errno!=ENOSYS && !(flags&WARN_ONLY)) perror_exit("getrandom");
40 #endif
41 fd = xopen(flags ? "/dev/random" : "/dev/urandom",O_RDONLY|(flags&WARN_ONLY));
42 if (fd == -1) return 0;
43 xreadall(fd, buf, buflen);
44 close(fd);
45
46 return 1;
47 }
48
49 #if defined(__APPLE__)
50 extern char **environ;
51
clearenv(void)52 int clearenv(void)
53 {
54 *environ = NULL;
55 return 0;
56 }
57 #endif
58
59 // Get a linked list of mount points, with stat information.
60 #if defined(__APPLE__) || defined(__FreeBSD__)
61
62 // Not implemented for macOS.
63 // See <sys/mount.h>'s getmntinfo(3) for the BSD API.
64
65 #else
66
67 #include <mntent.h>
68
octal_deslash(char * s)69 static void octal_deslash(char *s)
70 {
71 char *o = s;
72
73 while (*s) {
74 if (*s == '\\') {
75 int i, oct = 0;
76
77 for (i = 1; i < 4; i++) {
78 if (!isdigit(s[i])) break;
79 oct = (oct<<3)+s[i]-'0';
80 }
81 if (i == 4) {
82 *o++ = oct;
83 s += i;
84 continue;
85 }
86 }
87 *o++ = *s++;
88 }
89
90 *o = 0;
91 }
92
93 // Check if this type matches list.
94 // Odd syntax: typelist all yes = if any, typelist all no = if none.
95
mountlist_istype(struct mtab_list * ml,char * typelist)96 int mountlist_istype(struct mtab_list *ml, char *typelist)
97 {
98 int len, skip;
99 char *t;
100
101 if (!typelist) return 1;
102
103 skip = strncmp(typelist, "no", 2);
104
105 for (;;) {
106 if (!(t = comma_iterate(&typelist, &len))) break;
107 if (!skip) {
108 // If one -t starts with "no", the rest must too
109 if (strncmp(t, "no", 2)) error_exit("bad typelist");
110 if (!strncmp(t+2, ml->type, len-2)) {
111 skip = 1;
112 break;
113 }
114 } else if (!strncmp(t, ml->type, len) && !ml->type[len]) {
115 skip = 0;
116 break;
117 }
118 }
119
120 return !skip;
121 }
122
123 // Get list of mounted filesystems, including stat and statvfs info.
124 // Returns a reversed list, which is good for finding overmounts and such.
125
xgetmountlist(char * path)126 struct mtab_list *xgetmountlist(char *path)
127 {
128 struct mtab_list *mtlist = 0, *mt;
129 struct mntent *me;
130 FILE *fp;
131 char *p = path ? path : "/proc/mounts";
132
133 if (!(fp = setmntent(p, "r"))) perror_exit("bad %s", p);
134
135 // The "test" part of the loop is done before the first time through and
136 // again after each "increment", so putting the actual load there avoids
137 // duplicating it. If the load was NULL, the loop stops.
138
139 while ((me = getmntent(fp))) {
140 mt = xzalloc(sizeof(struct mtab_list) + strlen(me->mnt_fsname) +
141 strlen(me->mnt_dir) + strlen(me->mnt_type) + strlen(me->mnt_opts) + 4);
142 dlist_add_nomalloc((void *)&mtlist, (void *)mt);
143
144 // Collect details about mounted filesystem
145 // Don't report errors, just leave data zeroed
146 if (!path) {
147 stat(me->mnt_dir, &(mt->stat));
148 statvfs(me->mnt_dir, &(mt->statvfs));
149 }
150
151 // Remember information from /proc/mounts
152 mt->dir = stpcpy(mt->type, me->mnt_type)+1;
153 mt->device = stpcpy(mt->dir, me->mnt_dir)+1;
154 mt->opts = stpcpy(mt->device, me->mnt_fsname)+1;
155 strcpy(mt->opts, me->mnt_opts);
156
157 octal_deslash(mt->dir);
158 octal_deslash(mt->device);
159 }
160 endmntent(fp);
161
162 return mtlist;
163 }
164
165 #endif
166