Werner's Miscellanea
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Source at commit 2db4c1a3a80a5d22de58ed81b9932afe7ea15626 created 12 years 8 months ago. By Werner Almesberger, cad/test1/: experiment with Free scripted CAD systems (OpenSCAD and Cadmium) | |
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1 | /* |
2 | * libbb/libbbd.c - Bitbang library daemon |
3 | * |
4 | * Written 2010-2011 by Werner Almesberger |
5 | * Copyright 2010-2011 Werner Almesberger |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation; either version 2 of the License, or |
10 | * (at your option) any later version. |
11 | */ |
12 | |
13 | |
14 | #include <stdlib.h> |
15 | #include <stdio.h> |
16 | #include <unistd.h> |
17 | #include <string.h> |
18 | #include <fcntl.h> |
19 | #include <dirent.h> |
20 | #include <poll.h> |
21 | #include <errno.h> |
22 | #include <syslog.h> |
23 | #include <sys/types.h> |
24 | #include <sys/socket.h> |
25 | |
26 | #include "libbb.h" |
27 | |
28 | |
29 | #define FD_DIR "/proc/self/fd" |
30 | |
31 | #define DRIVER_NAME "jz4740-mmc.0" |
32 | #define UNBIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/unbind" |
33 | #define BIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/bind" |
34 | |
35 | |
36 | static void closefds(void) |
37 | { |
38 | DIR *dir; |
39 | const struct dirent *de; |
40 | int fd; |
41 | |
42 | dir = opendir(FD_DIR); |
43 | if (!dir) { |
44 | perror(FD_DIR); |
45 | exit(1); |
46 | } |
47 | while ((de = readdir(dir))) { |
48 | if (*de->d_name == '.') |
49 | continue; |
50 | fd = atoi(de->d_name); |
51 | if (fd == 1 || fd == 2) |
52 | continue; |
53 | if (fd == dirfd(dir)) |
54 | continue; |
55 | (void) close(fd); |
56 | } |
57 | closedir(dir); |
58 | } |
59 | |
60 | |
61 | static int echo(const char *msg, const char *path) |
62 | { |
63 | int fd; |
64 | ssize_t wrote; |
65 | int len = strlen(msg); |
66 | |
67 | fd = open(path, O_WRONLY); |
68 | if (fd < 0) { |
69 | perror(path); |
70 | return -errno; |
71 | } |
72 | wrote = write(fd, msg, len); |
73 | if (wrote < 0) { |
74 | perror(path); |
75 | return -errno; |
76 | } |
77 | if (wrote != len) { |
78 | fprintf(stderr, "short write: %d < %d\n", (int) wrote, len); |
79 | return -ENOSPC; |
80 | } |
81 | if (close(fd) < 0) { |
82 | perror(path); |
83 | return -errno; |
84 | } |
85 | return 0; |
86 | } |
87 | |
88 | |
89 | static void lock_area(int fd, off_t from, off_t len) |
90 | { |
91 | if (lseek(fd, from, SEEK_SET) == (off_t) -1) { |
92 | perror("lseek"); |
93 | exit(1); |
94 | } |
95 | if (lockf(fd, F_LOCK, len) < 0) { |
96 | perror("lockf"); |
97 | exit(1); |
98 | } |
99 | } |
100 | |
101 | |
102 | static int send_fd(int s, int fd) |
103 | { |
104 | struct msghdr msg; |
105 | struct cmsg { |
106 | struct cmsghdr hdr; |
107 | int fd; |
108 | } cmsg; |
109 | |
110 | memset(&msg, 0, sizeof(msg)); |
111 | msg.msg_control = &cmsg; |
112 | msg.msg_controllen = sizeof(cmsg); |
113 | cmsg.hdr.cmsg_level = SOL_SOCKET; |
114 | cmsg.hdr.cmsg_type = SCM_RIGHTS; |
115 | cmsg.hdr.cmsg_len = sizeof(cmsg); |
116 | cmsg.fd = fd; |
117 | if (sendmsg(s, &msg, 0) >= 0) |
118 | return 0; |
119 | perror("sendmsg"); |
120 | return -1; |
121 | } |
122 | |
123 | |
124 | static int wait_for_close(int s) |
125 | { |
126 | struct pollfd fds[1]; |
127 | int res; |
128 | |
129 | fds->fd = s; |
130 | fds->events = 0; |
131 | fds->revents = POLLHUP; |
132 | res = poll(fds, 1, -1); |
133 | if (res < 0) { |
134 | perror("poll"); |
135 | return -1; |
136 | } |
137 | if (!res) { |
138 | fprintf(stderr, "poll inexplicably returned 0\n"); |
139 | return -1; |
140 | } |
141 | return 0; |
142 | } |
143 | |
144 | |
145 | int main(int argc, char **argv) |
146 | { |
147 | int fd, res; |
148 | int exit_code = 1; |
149 | |
150 | fprintf(stderr, "setsid\n"); |
151 | if (setsid() == (pid_t) -1) { |
152 | perror("setsid"); |
153 | exit(1); |
154 | } |
155 | fprintf(stderr, "closefds\n"); |
156 | closefds(); |
157 | |
158 | fprintf(stderr, "open devmem\n"); |
159 | fd = open("/dev/mem", O_RDWR | O_SYNC); |
160 | if (fd < 0) { |
161 | perror("/dev/mem"); |
162 | exit(1); |
163 | } |
164 | fprintf(stderr, "lock_area\n"); |
165 | lock_area(fd, LIBBB_GPIO_BASE+LIBBB_PORT_D_OFFSET, |
166 | LIBBB_PORT_D_WINDOW); |
167 | |
168 | fprintf(stderr, "echo (unbind)\n"); |
169 | if (echo(DRIVER_NAME "\n", UNBIND_PATH) < 0) |
170 | exit(1); |
171 | |
172 | fprintf(stderr, "send_fd\n"); |
173 | if (send_fd(1, fd) < 0) |
174 | goto cleanup; |
175 | |
176 | fprintf(stderr, "wait_for_close\n"); |
177 | if (wait_for_close(1) < 0) |
178 | goto cleanup; |
179 | |
180 | exit_code = 0; |
181 | |
182 | cleanup: |
183 | fprintf(stderr, "echo (bind)n"); |
184 | res = echo(DRIVER_NAME "\n", BIND_PATH); |
185 | if (res < 0) { |
186 | /* stderr may no longer exist. report to syslog. */ |
187 | openlog("libbbd", LOG_CONS, LOG_USER); |
188 | syslog(LOG_CRIT, "libbd failed to re-bind driver (%d)", res); |
189 | } |
190 | |
191 | fprintf(stderr, "exit\n"); |
192 | return exit_code; |
193 | } |
194 |
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