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1 | |
2 | /* | |
3 | * server.c Set up and handle communications with a server process. | |
4 | * | |
f4a8f279 | 5 | * Server Handling copyright 1992-1999, 2004 The Free Software Foundation |
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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., | |
df065c82 KC |
20 | * 51 Franklin Street, Fifth Floor, |
21 | * Boston, MA 02110-1301, USA. | |
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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 | */ | |
1f414ac4 | 48 | |
2629a114 | 49 | #include "fixlib.h" |
4977bab6 | 50 | #include "server.h" |
1f414ac4 | 51 | |
2629a114 | 52 | STATIC const char* def_args[] = |
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53 | { (char *) NULL, (char *) NULL }; |
54 | ||
55 | /* | |
56 | * chain_open | |
57 | * | |
58 | * Given an FD for an inferior process to use as stdin, | |
59 | * start that process and return a NEW FD that that process | |
60 | * will use for its stdout. Requires the argument vector | |
61 | * for the new process and, optionally, a pointer to a place | |
62 | * to store the child's process id. | |
63 | */ | |
64 | int | |
f4dbf936 | 65 | chain_open (int stdin_fd, tCC** pp_args, pid_t* p_child) |
1f414ac4 | 66 | { |
48ac9ce2 | 67 | t_fd_pair stdout_pair; |
1f414ac4 | 68 | pid_t ch_id; |
2629a114 | 69 | tCC *pz_cmd; |
1f414ac4 | 70 | |
48ac9ce2 AO |
71 | stdout_pair.read_fd = stdout_pair.write_fd = -1; |
72 | ||
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73 | /* |
74 | * Create a pipe it will be the child process' stdout, | |
75 | * and the parent will read from it. | |
76 | */ | |
77 | if (pipe ((int *) &stdout_pair) < 0) | |
78 | { | |
79 | if (p_child != (pid_t *) NULL) | |
80 | *p_child = NOPROCESS; | |
81 | return -1; | |
82 | } | |
83 | ||
84 | /* | |
85 | * If we did not get an arg list, use the default | |
86 | */ | |
2629a114 | 87 | if (pp_args == (tCC **) NULL) |
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88 | pp_args = def_args; |
89 | ||
90 | /* | |
91 | * If the arg list does not have a program, | |
92 | * assume the "SHELL" from the environment, or, failing | |
93 | * that, then sh. Set argv[0] to whatever we decided on. | |
94 | */ | |
95 | if (pz_cmd = *pp_args, | |
96 | (pz_cmd == (char *) NULL) || (*pz_cmd == '\0')) | |
97 | { | |
98 | ||
99 | pz_cmd = getenv ("SHELL"); | |
100 | if (pz_cmd == (char *) NULL) | |
101 | pz_cmd = "sh"; | |
102 | } | |
103 | ||
104 | #ifdef DEBUG_PRINT | |
105 | printf ("START: %s\n", pz_cmd); | |
106 | { | |
107 | int idx = 0; | |
108 | ||
109 | while (pp_args[++idx] != (char *) NULL) | |
110 | printf (" ARG %2d: %s\n", idx, pp_args[idx]); | |
111 | } | |
112 | #endif | |
113 | ||
114 | /* | |
115 | * Call fork() and see which process we become | |
116 | */ | |
117 | ch_id = fork (); | |
118 | switch (ch_id) | |
119 | { | |
120 | case NOPROCESS: /* parent - error in call */ | |
121 | close (stdout_pair.read_fd); | |
122 | close (stdout_pair.write_fd); | |
123 | if (p_child != (pid_t *) NULL) | |
124 | *p_child = NOPROCESS; | |
125 | return -1; | |
126 | ||
127 | default: /* parent - return opposite FD's */ | |
128 | if (p_child != (pid_t *) NULL) | |
129 | *p_child = ch_id; | |
130 | #ifdef DEBUG_PRINT | |
131 | printf ("for pid %d: stdin from %d, stdout to %d\n" | |
132 | "for parent: read from %d\n", | |
133 | ch_id, stdin_fd, stdout_pair.write_fd, stdout_pair.read_fd); | |
134 | #endif | |
135 | close (stdin_fd); | |
136 | close (stdout_pair.write_fd); | |
137 | return stdout_pair.read_fd; | |
138 | ||
139 | case NULLPROCESS: /* child - continue processing */ | |
140 | break; | |
141 | } | |
142 | ||
143 | /* | |
144 | * Close the pipe end handed back to the parent process | |
145 | */ | |
146 | close (stdout_pair.read_fd); | |
147 | ||
148 | /* | |
149 | * Close our current stdin and stdout | |
150 | */ | |
151 | close (STDIN_FILENO); | |
152 | close (STDOUT_FILENO); | |
153 | ||
154 | /* | |
155 | * Make the fd passed in the stdin, and the write end of | |
156 | * the new pipe become the stdout. | |
157 | */ | |
f4a8f279 AL |
158 | dup2 (stdout_pair.write_fd, STDOUT_FILENO); |
159 | dup2 (stdin_fd, STDIN_FILENO); | |
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160 | |
161 | if (*pp_args == (char *) NULL) | |
162 | *pp_args = pz_cmd; | |
163 | ||
2629a114 | 164 | execvp (pz_cmd, (char**)pp_args); |
1f414ac4 | 165 | fprintf (stderr, "Error %d: Could not execvp( '%s', ... ): %s\n", |
f95e46b9 | 166 | errno, pz_cmd, xstrerror (errno)); |
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167 | exit (EXIT_PANIC); |
168 | } | |
169 | ||
170 | ||
171 | /* | |
172 | * proc2_open | |
173 | * | |
174 | * Given a pointer to an argument vector, start a process and | |
175 | * place its stdin and stdout file descriptors into an fd pair | |
176 | * structure. The "write_fd" connects to the inferior process | |
177 | * stdin, and the "read_fd" connects to its stdout. The calling | |
178 | * process should write to "write_fd" and read from "read_fd". | |
179 | * The return value is the process id of the created process. | |
180 | */ | |
181 | pid_t | |
f4dbf936 | 182 | proc2_open (t_fd_pair* p_pair, tCC** pp_args) |
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183 | { |
184 | pid_t ch_id; | |
185 | ||
186 | /* Create a bi-directional pipe. Writes on 0 arrive on 1 and vice | |
187 | versa, so the parent and child processes will read and write to | |
188 | opposite FD's. */ | |
189 | if (pipe ((int *) p_pair) < 0) | |
190 | return NOPROCESS; | |
191 | ||
192 | p_pair->read_fd = chain_open (p_pair->read_fd, pp_args, &ch_id); | |
193 | if (ch_id == NOPROCESS) | |
194 | close (p_pair->write_fd); | |
195 | ||
196 | return ch_id; | |
197 | } | |
198 | ||
199 | ||
200 | /* | |
201 | * proc2_fopen | |
202 | * | |
203 | * Identical to "proc2_open()", except that the "fd"'s are | |
204 | * "fdopen(3)"-ed into file pointers instead. | |
205 | */ | |
206 | pid_t | |
f4dbf936 | 207 | proc2_fopen (t_pf_pair* pf_pair, tCC** pp_args) |
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208 | { |
209 | t_fd_pair fd_pair; | |
210 | pid_t ch_id = proc2_open (&fd_pair, pp_args); | |
211 | ||
212 | if (ch_id == NOPROCESS) | |
213 | return ch_id; | |
214 | ||
215 | pf_pair->pf_read = fdopen (fd_pair.read_fd, "r"); | |
216 | pf_pair->pf_write = fdopen (fd_pair.write_fd, "w"); | |
217 | return ch_id; | |
218 | } |