1// SPDX-License-Identifier: GPL-2.0
2#include <string.h>
3#include <stdlib.h>
4#include "util/string2.h"
5
6#include "demangle-ocaml.h"
7
8#include <linux/ctype.h>
9
10static const char *caml_prefix = "caml";
11static const size_t caml_prefix_len = 4;
12
13/* mangled OCaml symbols start with "caml" followed by an upper-case letter */
14static bool
15ocaml_is_mangled(const char *sym)
16{
17	return 0 == strncmp(sym, caml_prefix, caml_prefix_len)
18		&& isupper(sym[caml_prefix_len]);
19}
20
21/*
22 * input:
23 *     sym: a symbol which may have been mangled by the OCaml compiler
24 * return:
25 *     if the input doesn't look like a mangled OCaml symbol, NULL is returned
26 *     otherwise, a newly allocated string containing the demangled symbol is returned
27 */
28char *
29ocaml_demangle_sym(const char *sym)
30{
31	char *result;
32	int j = 0;
33	int i;
34	int len;
35
36	if (!ocaml_is_mangled(sym)) {
37		return NULL;
38	}
39
40	len = strlen(sym);
41
42	/* the demangled symbol is always smaller than the mangled symbol */
43	result = malloc(len + 1);
44	if (!result)
45		return NULL;
46
47	/* skip "caml" prefix */
48	i = caml_prefix_len;
49
50	while (i < len) {
51		if (sym[i] == '_' && sym[i + 1] == '_') {
52			/* "__" -> "." */
53			result[j++] = '.';
54			i += 2;
55		}
56		else if (sym[i] == '$' && isxdigit(sym[i + 1]) && isxdigit(sym[i + 2])) {
57			/* "$xx" is a hex-encoded character */
58			result[j++] = (hex(sym[i + 1]) << 4) | hex(sym[i + 2]);
59			i += 3;
60		}
61		else {
62			result[j++] = sym[i++];
63		}
64	}
65	result[j] = '\0';
66
67	return result;
68}
69