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
33 #if defined(__APPLE__)
getdelim(char ** linep,size_t * np,int delim,FILE * stream)34 ssize_t getdelim(char **linep, size_t *np, int delim, FILE *stream)
35 {
36 int ch;
37 size_t new_len;
38 ssize_t i = 0;
39 char *line, *new_line;
40
41 // Invalid input
42 if (!linep || !np) {
43 errno = EINVAL;
44 return -1;
45 }
46
47 if (*linep == NULL || *np == 0) {
48 *np = 1024;
49 *linep = calloc(1, *np);
50 if (*linep == NULL) return -1;
51 }
52 line = *linep;
53
54 while ((ch = getc(stream)) != EOF) {
55 if (i > *np) {
56 // Need more space
57 new_len = *np + 1024;
58 new_line = realloc(*linep, new_len);
59 if (!new_line) return -1;
60 *np = new_len;
61 line = *linep = new_line;
62 }
63
64 line[i] = ch;
65 if (ch == delim) break;
66 i += 1;
67 }
68
69 if (i > *np) {
70 // Need more space
71 new_len = i + 2;
72 new_line = realloc(*linep, new_len);
73 if (!new_line) return -1;
74 *np = new_len;
75 line = *linep = new_line;
76 }
77 line[i + 1] = '\0';
78
79 return i > 0 ? i : -1;
80 }
81
getline(char ** linep,size_t * np,FILE * stream)82 ssize_t getline(char **linep, size_t *np, FILE *stream)
83 {
84 return getdelim(linep, np, '\n', stream);
85 }
86
87 extern char **environ;
88
clearenv(void)89 int clearenv(void)
90 {
91 *environ = NULL;
92 return 0;
93 }
94 #endif
95