1 #include <sys/types.h>
2 #include <signal.h>
3 #include <pwd.h>
4 #include <sys/resource.h>
5 #include <sys/wait.h>
6 #include <fcntl.h>
7
8 #include "dat.h"
9 #include "fns.h"
10 #include "error.h"
11
12 enum
13 {
14 Debug = 0
15 };
16
17 /*
18 * os-specific devcmd support.
19 * this version should be reasonably portable across Unix systems.
20 */
21 typedef struct Targ Targ;
22 struct Targ
23 {
24 int fd[3]; /* fd[0] is standard input, fd[1] is standard output, fd[2] is standard error */
25 char** args;
26 char* dir;
27 int pid;
28 int wfd; /* child writes errors that occur after the fork or on exec */
29 int uid;
30 int gid;
31 };
32
33 extern int gidnobody;
34 extern int uidnobody;
35
36 static int
childproc(Targ * t)37 childproc(Targ *t)
38 {
39 int i, nfd;
40
41 if(Debug)
42 print("devcmd: '%s'", t->args[0]);
43
44 nfd = getdtablesize();
45 for(i = 0; i < nfd; i++)
46 if(i != t->fd[0] && i != t->fd[1] && i != t->fd[2] && i != t->wfd)
47 close(i);
48
49 dup2(t->fd[0], 0);
50 dup2(t->fd[1], 1);
51 dup2(t->fd[2], 2);
52 close(t->fd[0]);
53 close(t->fd[1]);
54 close(t->fd[2]);
55
56 /* should have an auth file to do host-specific authorisation? */
57 if(t->gid != -1){
58 if(setgid(t->gid) < 0 && getegid() == 0){
59 fprint(t->wfd, "can't set gid %d: %s", t->gid, strerror(errno));
60 _exit(1);
61 }
62 }
63
64 if(t->uid != -1){
65 if(setuid(t->uid) < 0 && geteuid() == 0){
66 fprint(t->wfd, "can't set uid %d: %s", t->uid, strerror(errno));
67 _exit(1);
68 }
69 }
70
71 if(t->dir != nil && chdir(t->dir) < 0){
72 fprint(t->wfd, "can't chdir to %s: %s", t->dir, strerror(errno));
73 _exit(1);
74 }
75
76 signal(SIGPIPE, SIG_DFL);
77
78 execvp(t->args[0], t->args);
79 if(Debug)
80 print("execvp: %s\n",strerror(errno));
81 fprint(t->wfd, "exec failed: %s", strerror(errno));
82
83 _exit(1);
84 }
85
86 void*
oscmd(char ** args,int nice,char * dir,int * fd)87 oscmd(char **args, int nice, char *dir, int *fd)
88 {
89 Targ *t;
90 int r, fd0[2], fd1[2], fd2[2], wfd[2], n, pid;
91
92 t = mallocz(sizeof(*t), 1);
93 if(t == nil)
94 return nil;
95
96 fd0[0] = fd0[1] = -1;
97 fd1[0] = fd1[1] = -1;
98 fd2[0] = fd2[1] = -1;
99 wfd[0] = wfd[1] = -1;
100 if(pipe(fd0) < 0 || pipe(fd1) < 0 || pipe(fd2) < 0 || pipe(wfd) < 0)
101 goto Error;
102 if(fcntl(wfd[1], F_SETFD, FD_CLOEXEC) < 0) /* close on exec to give end of file on success */
103 goto Error;
104
105 t->fd[0] = fd0[0];
106 t->fd[1] = fd1[1];
107 t->fd[2] = fd2[1];
108 t->wfd = wfd[1];
109 t->args = args;
110 t->dir = dir;
111 t->gid = up->env->gid;
112 if(t->gid == -1)
113 t->gid = gidnobody;
114 t->uid = up->env->uid;
115 if(t->uid == -1)
116 t->uid = uidnobody;
117
118 signal(SIGCHLD, SIG_DFL);
119 switch(pid = fork()) {
120 case -1:
121 goto Error;
122 case 0:
123 setpgid(0, getpid());
124 if(nice)
125 oslopri();
126 childproc(t);
127 _exit(1);
128 default:
129 t->pid = pid;
130 if(Debug)
131 print("cmd pid %d\n", t->pid);
132 break;
133 }
134
135 close(fd0[0]);
136 close(fd1[1]);
137 close(fd2[1]);
138 close(wfd[1]);
139
140 n = read(wfd[0], up->genbuf, sizeof(up->genbuf)-1);
141 close(wfd[0]);
142 if(n > 0){
143 close(fd0[1]);
144 close(fd1[0]);
145 close(fd2[0]);
146 free(t);
147 up->genbuf[n] = 0;
148 if(Debug)
149 print("oscmd: bad exec: %q\n", up->genbuf);
150 error(up->genbuf);
151 return nil;
152 }
153
154 fd[0] = fd0[1];
155 fd[1] = fd1[0];
156 fd[2] = fd2[0];
157 return t;
158
159 Error:
160 r = errno;
161 if(Debug)
162 print("oscmd: %q\n",strerror(r));
163 close(fd0[0]);
164 close(fd0[1]);
165 close(fd1[0]);
166 close(fd1[1]);
167 close(fd2[0]);
168 close(fd2[1]);
169 close(wfd[0]);
170 close(wfd[1]);
171 error(strerror(r));
172 return nil;
173 }
174
175 int
oscmdkill(void * a)176 oscmdkill(void *a)
177 {
178 Targ *t = a;
179
180 if(Debug)
181 print("kill: %d\n", t->pid);
182 return kill(-t->pid, SIGTERM);
183 }
184
185 int
oscmdwait(void * a,char * buf,int n)186 oscmdwait(void *a, char *buf, int n)
187 {
188 Targ *t = a;
189 int s;
190
191 if(waitpid(t->pid, &s, 0) == -1){
192 if(Debug)
193 print("wait error: %d [in %d] %q\n", t->pid, getpid(), strerror(errno));
194 return -1;
195 }
196 if(WIFEXITED(s)){
197 if(WEXITSTATUS(s) == 0)
198 return snprint(buf, n, "%d 0 0 0 ''", t->pid);
199 return snprint(buf, n, "%d 0 0 0 'exit: %d'", t->pid, WEXITSTATUS(s));
200 }
201 if(WIFSIGNALED(s)){
202 if(WTERMSIG(s) == SIGTERM || WTERMSIG(s) == SIGKILL)
203 return snprint(buf, n, "%d 0 0 0 killed", t->pid);
204 return snprint(buf, n, "%d 0 0 0 'signal: %d'", t->pid, WTERMSIG(s));
205 }
206 return snprint(buf, n, "%d 0 0 0 'odd status: 0x%x'", t->pid, s);
207 }
208
209 void
oscmdfree(void * a)210 oscmdfree(void *a)
211 {
212 free(a);
213 }
214