1 #include <u.h>
2 #include <libc.h>
3 #include <mach.h>
4 #include "macho.h"
5 
6 /*
7 http://www.channelu.com/NeXT/NeXTStep/3.3/nd/DevTools/14_MachO/MachO.htmld/ 
8 */
9 
10 Macho*
11 machoopen(char *name)
12 {
13 	int fd;
14 	Macho *m;
15 
16 	if((fd = open(name, OREAD)) < 0)
17 		return nil;
18 	m = machoinit(fd);
19 	if(m == nil)
20 		close(fd);
21 	return m;
22 }
23 
24 static int
25 unpackseg(uchar *p, Macho *m, MachoCmd *c, uint type, uint sz)
26 {
27 	u32int (*e4)(uchar*);
28 
29 	e4 = m->e4;
30 
31 	c->type = type;
32 	c->size = sz;
33 	switch(type){
34 	default:
35 		return -1;
36 	case MachoCmdSegment:
37 		if(sz < 56)
38 			return -1;
39 		strecpy(c->seg.name, c->seg.name+sizeof c->seg.name, (char*)p+8);
40 		c->seg.vmaddr = e4(p+24);
41 		c->seg.vmsize = e4(p+28);
42 		c->seg.fileoff = e4(p+32);
43 		c->seg.filesz = e4(p+36);
44 		c->seg.maxprot = e4(p+40);
45 		c->seg.initprot = e4(p+44);
46 		c->seg.nsect = e4(p+48);
47 		c->seg.flags = e4(p+52);
48 		break;
49 	case MachoCmdSymtab:
50 		if(sz < 24)
51 			return -1;
52 		c->sym.symoff = e4(p+8);
53 		c->sym.nsyms = e4(p+12);
54 		c->sym.stroff = e4(p+16);
55 		c->sym.strsize = e4(p+20);
56 		break;
57 	}
58 	return 0;
59 }
60 
61 
62 Macho*
63 machoinit(int fd)
64 {
65 	int i;
66 	uchar hdr[7*4], *cmdp;
67 	u32int (*e4)(uchar*);
68 	ulong ncmd, cmdsz, ty, sz, off;
69 	Macho *m;
70 
71 	if(seek(fd, 0, 0) < 0 || readn(fd, hdr, sizeof hdr) != sizeof hdr)
72 		return nil;
73 
74 	if(beload4(hdr) == 0xFEEDFACE)
75 		e4 = beload4;
76 	else if(leload4(hdr) == 0xFEEDFACE)
77 		e4 = leload4;
78 	else{
79 		werrstr("bad magic - not mach-o file");
80 		return nil;
81 	}
82 
83 	ncmd = e4(hdr+4*4);
84 	cmdsz = e4(hdr+5*4);
85 	if(ncmd > 0x10000 || cmdsz >= 0x01000000){
86 		werrstr("implausible mach-o header ncmd=%lud cmdsz=%lud", ncmd, cmdsz);
87 		return nil;
88 	}
89 
90 	m = mallocz(sizeof(*m)+ncmd*sizeof(MachoCmd)+cmdsz, 1);
91 	if(m == nil)
92 		return nil;
93 
94 	m->fd = fd;
95 	m->e4 = e4;
96 	m->cputype = e4(hdr+1*4);
97 	m->subcputype = e4(hdr+2*4);
98 	m->filetype = e4(hdr+3*4);
99 	m->ncmd = ncmd;
100 	m->flags = e4(hdr+6*4);
101 
102 	m->cmd = (MachoCmd*)(m+1);
103 	off = sizeof hdr;
104 	cmdp = (uchar*)(m->cmd+ncmd);
105 	if(readn(fd, cmdp, cmdsz) != cmdsz){
106 		werrstr("reading cmds: %r");
107 		free(m);
108 		return nil;
109 	}
110 
111 	for(i=0; i<ncmd; i++){
112 		ty = e4(cmdp);
113 		sz = e4(cmdp+4);
114 		m->cmd[i].off = off;
115 		unpackseg(cmdp, m, &m->cmd[i], ty, sz);
116 		cmdp += sz;
117 		off += sz;
118 	}
119 
120 	return m;
121 }
122 
123 void
124 machoclose(Macho *m)
125 {
126 	close(m->fd);
127 	free(m);
128 }