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1 | |
2 | /* | |
3 | * server.c Set up and handle communications with a server process. | |
4 | * | |
5 | * Server Handling copyright 1992-1999 The Free Software Foundation | |
6 | * | |
7 | * Server Handling is free software. | |
8 | * You may redistribute it and/or modify it under the terms of the | |
9 | * GNU General Public License, as published by the Free Software | |
10 | * Foundation; either version 2, or (at your option) any later version. | |
11 | * | |
12 | * Server Handling is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with Server Handling. See the file "COPYING". If not, | |
19 | * write to: The Free Software Foundation, Inc., | |
20 | * 59 Temple Place - Suite 330, | |
21 | * Boston, MA 02111-1307, USA. | |
22 | * | |
23 | * As a special exception, The Free Software Foundation gives | |
24 | * permission for additional uses of the text contained in his release | |
25 | * of ServerHandler. | |
26 | * | |
27 | * The exception is that, if you link the ServerHandler library with other | |
28 | * files to produce an executable, this does not by itself cause the | |
29 | * resulting executable to be covered by the GNU General Public License. | |
30 | * Your use of that executable is in no way restricted on account of | |
31 | * linking the ServerHandler library code into it. | |
32 | * | |
33 | * This exception does not however invalidate any other reasons why | |
34 | * the executable file might be covered by the GNU General Public License. | |
35 | * | |
36 | * This exception applies only to the code released by The Free | |
37 | * Software Foundation under the name ServerHandler. If you copy code | |
38 | * from other sources under the General Public License into a copy of | |
39 | * ServerHandler, as the General Public License permits, the exception | |
40 | * does not apply to the code that you add in this way. To avoid | |
41 | * misleading anyone as to the status of such modified files, you must | |
42 | * delete this exception notice from them. | |
43 | * | |
44 | * If you write modifications of your own for ServerHandler, it is your | |
45 | * choice whether to permit this exception to apply to your modifications. | |
46 | * If you do not wish that, delete this exception notice. | |
47 | */ | |
7b33bb99 | 48 | #include "auto-host.h" |
2583397b RL |
49 | #include "gansidecl.h" |
50 | #include "system.h" | |
1f414ac4 BK |
51 | |
52 | #include "server.h" | |
53 | ||
54 | /* If this particular system's header files define the macro `MAXPATHLEN', | |
55 | we happily take advantage of it; otherwise we use a value which ought | |
56 | to be large enough. */ | |
57 | #ifndef MAXPATHLEN | |
58 | # define MAXPATHLEN 4096 | |
59 | #endif | |
60 | ||
61 | #ifndef STDIN_FILENO | |
62 | # define STDIN_FILENO 0 | |
63 | #endif | |
64 | #ifndef STDOUT_FILENO | |
65 | # define STDOUT_FILENO 1 | |
66 | #endif | |
67 | ||
68 | #ifdef DEBUG | |
69 | #define STATIC | |
70 | #else | |
71 | #define STATIC static | |
72 | #endif | |
73 | #ifndef tSCC | |
74 | #define tSCC static const char | |
75 | #endif | |
76 | #ifndef NUL | |
77 | #define NUL '\0' | |
78 | #endif | |
79 | ||
80 | STATIC t_pchar def_args[] = | |
81 | { (char *) NULL, (char *) NULL }; | |
82 | ||
83 | /* | |
84 | * chain_open | |
85 | * | |
86 | * Given an FD for an inferior process to use as stdin, | |
87 | * start that process and return a NEW FD that that process | |
88 | * will use for its stdout. Requires the argument vector | |
89 | * for the new process and, optionally, a pointer to a place | |
90 | * to store the child's process id. | |
91 | */ | |
92 | int | |
93 | chain_open (stdin_fd, pp_args, p_child) | |
94 | int stdin_fd; | |
95 | t_pchar *pp_args; | |
96 | pid_t *p_child; | |
97 | { | |
48ac9ce2 | 98 | t_fd_pair stdout_pair; |
1f414ac4 BK |
99 | pid_t ch_id; |
100 | char *pz_cmd; | |
101 | ||
48ac9ce2 AO |
102 | stdout_pair.read_fd = stdout_pair.write_fd = -1; |
103 | ||
1f414ac4 BK |
104 | /* |
105 | * Create a pipe it will be the child process' stdout, | |
106 | * and the parent will read from it. | |
107 | */ | |
108 | if (pipe ((int *) &stdout_pair) < 0) | |
109 | { | |
110 | if (p_child != (pid_t *) NULL) | |
111 | *p_child = NOPROCESS; | |
112 | return -1; | |
113 | } | |
114 | ||
115 | /* | |
116 | * If we did not get an arg list, use the default | |
117 | */ | |
118 | if (pp_args == (t_pchar *) NULL) | |
119 | pp_args = def_args; | |
120 | ||
121 | /* | |
122 | * If the arg list does not have a program, | |
123 | * assume the "SHELL" from the environment, or, failing | |
124 | * that, then sh. Set argv[0] to whatever we decided on. | |
125 | */ | |
126 | if (pz_cmd = *pp_args, | |
127 | (pz_cmd == (char *) NULL) || (*pz_cmd == '\0')) | |
128 | { | |
129 | ||
130 | pz_cmd = getenv ("SHELL"); | |
131 | if (pz_cmd == (char *) NULL) | |
132 | pz_cmd = "sh"; | |
133 | } | |
134 | ||
135 | #ifdef DEBUG_PRINT | |
136 | printf ("START: %s\n", pz_cmd); | |
137 | { | |
138 | int idx = 0; | |
139 | ||
140 | while (pp_args[++idx] != (char *) NULL) | |
141 | printf (" ARG %2d: %s\n", idx, pp_args[idx]); | |
142 | } | |
143 | #endif | |
144 | ||
145 | /* | |
146 | * Call fork() and see which process we become | |
147 | */ | |
148 | ch_id = fork (); | |
149 | switch (ch_id) | |
150 | { | |
151 | case NOPROCESS: /* parent - error in call */ | |
152 | close (stdout_pair.read_fd); | |
153 | close (stdout_pair.write_fd); | |
154 | if (p_child != (pid_t *) NULL) | |
155 | *p_child = NOPROCESS; | |
156 | return -1; | |
157 | ||
158 | default: /* parent - return opposite FD's */ | |
159 | if (p_child != (pid_t *) NULL) | |
160 | *p_child = ch_id; | |
161 | #ifdef DEBUG_PRINT | |
162 | printf ("for pid %d: stdin from %d, stdout to %d\n" | |
163 | "for parent: read from %d\n", | |
164 | ch_id, stdin_fd, stdout_pair.write_fd, stdout_pair.read_fd); | |
165 | #endif | |
166 | close (stdin_fd); | |
167 | close (stdout_pair.write_fd); | |
168 | return stdout_pair.read_fd; | |
169 | ||
170 | case NULLPROCESS: /* child - continue processing */ | |
171 | break; | |
172 | } | |
173 | ||
174 | /* | |
175 | * Close the pipe end handed back to the parent process | |
176 | */ | |
177 | close (stdout_pair.read_fd); | |
178 | ||
179 | /* | |
180 | * Close our current stdin and stdout | |
181 | */ | |
182 | close (STDIN_FILENO); | |
183 | close (STDOUT_FILENO); | |
184 | ||
185 | /* | |
186 | * Make the fd passed in the stdin, and the write end of | |
187 | * the new pipe become the stdout. | |
188 | */ | |
189 | fcntl (stdout_pair.write_fd, F_DUPFD, STDOUT_FILENO); | |
190 | fcntl (stdin_fd, F_DUPFD, STDIN_FILENO); | |
191 | ||
192 | if (*pp_args == (char *) NULL) | |
193 | *pp_args = pz_cmd; | |
194 | ||
195 | execvp (pz_cmd, pp_args); | |
196 | fprintf (stderr, "Error %d: Could not execvp( '%s', ... ): %s\n", | |
f95e46b9 | 197 | errno, pz_cmd, xstrerror (errno)); |
1f414ac4 BK |
198 | exit (EXIT_PANIC); |
199 | } | |
200 | ||
201 | ||
202 | /* | |
203 | * proc2_open | |
204 | * | |
205 | * Given a pointer to an argument vector, start a process and | |
206 | * place its stdin and stdout file descriptors into an fd pair | |
207 | * structure. The "write_fd" connects to the inferior process | |
208 | * stdin, and the "read_fd" connects to its stdout. The calling | |
209 | * process should write to "write_fd" and read from "read_fd". | |
210 | * The return value is the process id of the created process. | |
211 | */ | |
212 | pid_t | |
213 | proc2_open (p_pair, pp_args) | |
214 | t_fd_pair *p_pair; | |
215 | t_pchar *pp_args; | |
216 | { | |
217 | pid_t ch_id; | |
218 | ||
219 | /* Create a bi-directional pipe. Writes on 0 arrive on 1 and vice | |
220 | versa, so the parent and child processes will read and write to | |
221 | opposite FD's. */ | |
222 | if (pipe ((int *) p_pair) < 0) | |
223 | return NOPROCESS; | |
224 | ||
225 | p_pair->read_fd = chain_open (p_pair->read_fd, pp_args, &ch_id); | |
226 | if (ch_id == NOPROCESS) | |
227 | close (p_pair->write_fd); | |
228 | ||
229 | return ch_id; | |
230 | } | |
231 | ||
232 | ||
233 | /* | |
234 | * proc2_fopen | |
235 | * | |
236 | * Identical to "proc2_open()", except that the "fd"'s are | |
237 | * "fdopen(3)"-ed into file pointers instead. | |
238 | */ | |
239 | pid_t | |
240 | proc2_fopen (pf_pair, pp_args) | |
241 | t_pf_pair *pf_pair; | |
242 | t_pchar *pp_args; | |
243 | { | |
244 | t_fd_pair fd_pair; | |
245 | pid_t ch_id = proc2_open (&fd_pair, pp_args); | |
246 | ||
247 | if (ch_id == NOPROCESS) | |
248 | return ch_id; | |
249 | ||
250 | pf_pair->pf_read = fdopen (fd_pair.read_fd, "r"); | |
251 | pf_pair->pf_write = fdopen (fd_pair.write_fd, "w"); | |
252 | return ch_id; | |
253 | } |