1 /*
2 * 8obj.c - identify and parse a 386 object file
3 */
4 #include <u.h>
5 #include <libc.h>
6 #include <bio.h>
7 #include <mach.h>
8 #include "8c/8.out.h"
9 #include "obj.h"
10
11 typedef struct Addr Addr;
12 struct Addr
13 {
14 char sym;
15 char flags;
16 };
17 static Addr addr(Biobuf*);
18 static char type2char(int);
19 static void skip(Biobuf*, int);
20
21 int
_is8(char * t)22 _is8(char *t)
23 {
24 uchar *s = (uchar*)t;
25
26 return s[0] == (ANAME&0xff) /* aslo = ANAME */
27 && s[1] == ((ANAME>>8)&0xff)
28 && s[2] == D_FILE /* type */
29 && s[3] == 1 /* sym */
30 && s[4] == '<'; /* name of file */
31 }
32
33 int
_read8(Biobuf * bp,Prog * p)34 _read8(Biobuf *bp, Prog* p)
35 {
36 int as, n, c;
37 Addr a;
38
39 as = Bgetc(bp); /* as(low) */
40 if(as < 0)
41 return 0;
42 c = Bgetc(bp); /* as(high) */
43 if(c < 0)
44 return 0;
45 as |= ((c & 0xff) << 8);
46 p->kind = aNone;
47 p->sig = 0;
48 if(as == ANAME || as == ASIGNAME){
49 if(as == ASIGNAME){
50 Bread(bp, &p->sig, 4);
51 p->sig = leswal(p->sig);
52 }
53 p->kind = aName;
54 p->type = type2char(Bgetc(bp)); /* type */
55 p->sym = Bgetc(bp); /* sym */
56 n = 0;
57 for(;;) {
58 as = Bgetc(bp);
59 if(as < 0)
60 return 0;
61 n++;
62 if(as == 0)
63 break;
64 }
65 p->id = malloc(n);
66 if(p->id == 0)
67 return 0;
68 Bseek(bp, -n, 1);
69 if(Bread(bp, p->id, n) != n)
70 return 0;
71 return 1;
72 }
73 if(as == ATEXT)
74 p->kind = aText;
75 if(as == AGLOBL)
76 p->kind = aData;
77 skip(bp, 4); /* lineno(4) */
78 a = addr(bp);
79 addr(bp);
80 if(!(a.flags & T_SYM))
81 p->kind = aNone;
82 p->sym = a.sym;
83 return 1;
84 }
85
86 static Addr
addr(Biobuf * bp)87 addr(Biobuf *bp)
88 {
89 Addr a;
90 int t;
91 long off;
92
93 off = 0;
94 a.sym = -1;
95 a.flags = Bgetc(bp); /* flags */
96 if(a.flags & T_INDEX)
97 skip(bp, 2);
98 if(a.flags & T_OFFSET){
99 off = Bgetc(bp);
100 off |= Bgetc(bp) << 8;
101 off |= Bgetc(bp) << 16;
102 off |= Bgetc(bp) << 24;
103 if(off < 0)
104 off = -off;
105 }
106 if(a.flags & T_SYM)
107 a.sym = Bgetc(bp);
108 if(a.flags & T_FCONST)
109 skip(bp, 8);
110 else
111 if(a.flags & T_SCONST)
112 skip(bp, NSNAME);
113 if(a.flags & T_TYPE) {
114 t = Bgetc(bp);
115 if(a.sym > 0 && (t==D_PARAM || t==D_AUTO))
116 _offset(a.sym, off);
117 }
118 return a;
119 }
120
121 static char
type2char(int t)122 type2char(int t)
123 {
124 switch(t){
125 case D_EXTERN: return 'U';
126 case D_STATIC: return 'b';
127 case D_AUTO: return 'a';
128 case D_PARAM: return 'p';
129 default: return UNKNOWN;
130 }
131 }
132
133 static void
skip(Biobuf * bp,int n)134 skip(Biobuf *bp, int n)
135 {
136 while (n-- > 0)
137 Bgetc(bp);
138 }
139