1 /* C declarator syntax glue.
2 Copyright (C) 2019-2023 Free Software Foundation, Inc.
3
4 This file is part of libctf.
5
6 libctf is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 This program is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
14 See the GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; see the file COPYING. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 /* CTF Declaration Stack
21
22 In order to implement ctf_type_name(), we must convert a type graph back
23 into a C type declaration. Unfortunately, a type graph represents a storage
24 class ordering of the type whereas a type declaration must obey the C rules
25 for operator precedence, and the two orderings are frequently in conflict.
26 For example, consider these CTF type graphs and their C declarations:
27
28 CTF_K_POINTER -> CTF_K_FUNCTION -> CTF_K_INTEGER : int (*)()
29 CTF_K_POINTER -> CTF_K_ARRAY -> CTF_K_INTEGER : int (*)[]
30
31 In each case, parentheses are used to raise operator * to higher lexical
32 precedence, so the string form of the C declaration cannot be constructed by
33 walking the type graph links and forming the string from left to right.
34
35 The functions in this file build a set of stacks from the type graph nodes
36 corresponding to the C operator precedence levels in the appropriate order.
37 The code in ctf_type_name() can then iterate over the levels and nodes in
38 lexical precedence order and construct the final C declaration string. */
39
40 #include <ctf-impl.h>
41 #include <string.h>
42
43 void
44 ctf_decl_init (ctf_decl_t *cd)
45 {
46 int i;
47
48 memset (cd, 0, sizeof (ctf_decl_t));
49
50 for (i = CTF_PREC_BASE; i < CTF_PREC_MAX; i++)
51 cd->cd_order[i] = CTF_PREC_BASE - 1;
52
53 cd->cd_qualp = CTF_PREC_BASE;
54 cd->cd_ordp = CTF_PREC_BASE;
55 }
56
57 void
58 ctf_decl_fini (ctf_decl_t *cd)
59 {
60 ctf_decl_node_t *cdp, *ndp;
61 int i;
62
63 for (i = CTF_PREC_BASE; i < CTF_PREC_MAX; i++)
64 {
65 for (cdp = ctf_list_next (&cd->cd_nodes[i]); cdp != NULL; cdp = ndp)
66 {
67 ndp = ctf_list_next (cdp);
68 free (cdp);
69 }
70 }
71 free (cd->cd_buf);
72 }
73
74 void
75 ctf_decl_push (ctf_decl_t *cd, ctf_dict_t *fp, ctf_id_t type)
76 {
77 ctf_decl_node_t *cdp;
78 ctf_decl_prec_t prec;
79 uint32_t kind, n = 1;
80 int is_qual = 0;
81
82 const ctf_type_t *tp;
83 ctf_arinfo_t ar;
84
85 if ((tp = ctf_lookup_by_id (&fp, type)) == NULL)
86 {
87 cd->cd_err = fp->ctf_errno;
88 return;
89 }
90
91 switch (kind = LCTF_INFO_KIND (fp, tp->ctt_info))
92 {
93 case CTF_K_ARRAY:
94 (void) ctf_array_info (fp, type, &ar);
95 ctf_decl_push (cd, fp, ar.ctr_contents);
96 n = ar.ctr_nelems;
97 prec = CTF_PREC_ARRAY;
98 break;
99
100 case CTF_K_TYPEDEF:
101 if (ctf_strptr (fp, tp->ctt_name)[0] == '\0')
102 {
103 ctf_decl_push (cd, fp, tp->ctt_type);
104 return;
105 }
106 prec = CTF_PREC_BASE;
107 break;
108
109 case CTF_K_FUNCTION:
110 ctf_decl_push (cd, fp, tp->ctt_type);
111 prec = CTF_PREC_FUNCTION;
112 break;
113
114 case CTF_K_POINTER:
115 ctf_decl_push (cd, fp, tp->ctt_type);
116 prec = CTF_PREC_POINTER;
117 break;
118
119 case CTF_K_SLICE:
120 /* Slices themselves have no print representation and should not appear in
121 the decl stack. */
122 ctf_decl_push (cd, fp, ctf_type_reference (fp, type));
123 return;
124
125 case CTF_K_VOLATILE:
126 case CTF_K_CONST:
127 case CTF_K_RESTRICT:
128 ctf_decl_push (cd, fp, tp->ctt_type);
129 prec = cd->cd_qualp;
130 is_qual++;
131 break;
132
133 default:
134 prec = CTF_PREC_BASE;
135 }
136
137 if ((cdp = malloc (sizeof (ctf_decl_node_t))) == NULL)
138 {
139 cd->cd_err = EAGAIN;
140 return;
141 }
142
143 cdp->cd_type = type;
144 cdp->cd_kind = kind;
145 cdp->cd_n = n;
146
147 if (ctf_list_next (&cd->cd_nodes[prec]) == NULL)
148 cd->cd_order[prec] = cd->cd_ordp++;
149
150 /* Reset cd_qualp to the highest precedence level that we've seen so
151 far that can be qualified (CTF_PREC_BASE or CTF_PREC_POINTER). */
152
153 if (prec > cd->cd_qualp && prec < CTF_PREC_ARRAY)
154 cd->cd_qualp = prec;
155
156 /* By convention qualifiers of base types precede the type specifier (e.g.
157 const int vs. int const) even though the two forms are equivalent. */
158
159 if (is_qual && prec == CTF_PREC_BASE)
160 ctf_list_prepend (&cd->cd_nodes[prec], cdp);
161 else
162 ctf_list_append (&cd->cd_nodes[prec], cdp);
163 }
164
165 _libctf_printflike_ (2, 3)
166 void ctf_decl_sprintf (ctf_decl_t *cd, const char *format, ...)
167 {
168 va_list ap;
169 char *str;
170 int n;
171
172 if (cd->cd_enomem)
173 return;
174
175 va_start (ap, format);
176 n = vasprintf (&str, format, ap);
177 va_end (ap);
178
179 if (n > 0)
180 {
181 char *newbuf;
182 if ((newbuf = ctf_str_append (cd->cd_buf, str)) != NULL)
183 cd->cd_buf = newbuf;
184 }
185
186 /* Sticky error condition. */
187 if (n < 0 || cd->cd_buf == NULL)
188 {
189 free (cd->cd_buf);
190 cd->cd_buf = NULL;
191 cd->cd_enomem = 1;
192 }
193
194 free (str);
195 }
196
197 char *ctf_decl_buf (ctf_decl_t *cd)
198 {
199 char *buf = cd->cd_buf;
200 cd->cd_buf = NULL;
201 return buf;
202 }