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 
10 static const char *caml_prefix = "caml";
11 static const size_t caml_prefix_len = 4;
12 
13 /* mangled OCaml symbols start with "caml" followed by an upper-case letter */
14 static bool
ocaml_is_mangled(const char * sym)15 ocaml_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  */
28 char *
ocaml_demangle_sym(const char * sym)29 ocaml_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