xref: /freebsd/lib/libutil/kinfo_getfile.c (revision f4b37ed0f8b307b1f3f0f630ca725d68f1dff30d)
1 #include <sys/cdefs.h>
2 __FBSDID("$FreeBSD$");
3 
4 #include <sys/param.h>
5 #include <sys/user.h>
6 #include <sys/sysctl.h>
7 #include <stdlib.h>
8 #include <string.h>
9 
10 #include "libutil.h"
11 
12 struct kinfo_file *
13 kinfo_getfile(pid_t pid, int *cntp)
14 {
15 	int mib[4];
16 	int error;
17 	int cnt;
18 	size_t len;
19 	char *buf, *bp, *eb;
20 	struct kinfo_file *kif, *kp, *kf;
21 
22 	*cntp = 0;
23 	len = 0;
24 	mib[0] = CTL_KERN;
25 	mib[1] = KERN_PROC;
26 	mib[2] = KERN_PROC_FILEDESC;
27 	mib[3] = pid;
28 
29 	error = sysctl(mib, 4, NULL, &len, NULL, 0);
30 	if (error)
31 		return (NULL);
32 	len = len * 4 / 3;
33 	buf = malloc(len);
34 	if (buf == NULL)
35 		return (NULL);
36 	error = sysctl(mib, 4, buf, &len, NULL, 0);
37 	if (error) {
38 		free(buf);
39 		return (NULL);
40 	}
41 	/* Pass 1: count items */
42 	cnt = 0;
43 	bp = buf;
44 	eb = buf + len;
45 	while (bp < eb) {
46 		kf = (struct kinfo_file *)(uintptr_t)bp;
47 		bp += kf->kf_structsize;
48 		cnt++;
49 	}
50 
51 	kif = calloc(cnt, sizeof(*kif));
52 	if (kif == NULL) {
53 		free(buf);
54 		return (NULL);
55 	}
56 	bp = buf;
57 	eb = buf + len;
58 	kp = kif;
59 	/* Pass 2: unpack */
60 	while (bp < eb) {
61 		kf = (struct kinfo_file *)(uintptr_t)bp;
62 		/* Copy/expand into pre-zeroed buffer */
63 		memcpy(kp, kf, kf->kf_structsize);
64 		/* Advance to next packed record */
65 		bp += kf->kf_structsize;
66 		/* Set field size to fixed length, advance */
67 		kp->kf_structsize = sizeof(*kp);
68 		kp++;
69 	}
70 	free(buf);
71 	*cntp = cnt;
72 	return (kif);	/* Caller must free() return value */
73 }
74