1 /* Initial program startup for running under the GNU Hurd.
2 Copyright (C) 1991-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <stdlib.h>
21 #include <stdio.h>
22 #include <string.h>
23 #include <hurd.h>
24 #include <hurd/exec_startup.h>
25 #include <sysdep.h>
26 #include <unistd.h>
27 #include <elf.h>
28 #include <set-hooks.h>
29 #include "hurdstartup.h"
30 #include <argz.h>
31
32 mach_port_t *_hurd_init_dtable;
33 mach_msg_type_number_t _hurd_init_dtablesize;
34
35 extern void __mach_init (void);
36
37 /* Entry point. This is the first thing in the text segment.
38
39 The exec server started the initial thread in our task with this spot the
40 PC, and a stack that is presumably big enough. We do basic Mach
41 initialization so mig-generated stubs work, and then do an exec_startup
42 RPC on our bootstrap port, to which the exec server responds with the
43 information passed in the exec call, as well as our original bootstrap
44 port, and the base address and size of the preallocated stack. */
45
46
47 void
48 _hurd_startup (void **argptr, void (*main) (intptr_t *data))
49 {
50 error_t err;
51 mach_port_t in_bootstrap;
52 char *args, *env;
53 mach_msg_type_number_t argslen, envlen;
54 struct hurd_startup_data data;
55 char **argv, **envp;
56 int argc, envc;
57 intptr_t *argcptr;
58 vm_address_t addr;
59
60 /* Attempt to map page zero redzoned before we receive any RPC
61 data that might get allocated there. We can ignore errors. */
62 addr = 0;
63 __vm_map (__mach_task_self (),
64 &addr, __vm_page_size, 0, 0, MACH_PORT_NULL, 0, 1,
65 VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);
66
67 if (err = __task_get_special_port (__mach_task_self (), TASK_BOOTSTRAP_PORT,
68 &in_bootstrap))
69 LOSE;
70
71 if (in_bootstrap != MACH_PORT_NULL)
72 {
73 /* Call the exec server on our bootstrap port and
74 get all our standard information from it. */
75
76 argslen = envlen = 0;
77 data.dtablesize = data.portarraysize = data.intarraysize = 0;
78
79 err = __exec_startup_get_info (in_bootstrap,
80 &data.user_entry,
81 &data.phdr, &data.phdrsz,
82 &data.stack_base, &data.stack_size,
83 &data.flags,
84 &args, &argslen,
85 &env, &envlen,
86 &data.dtable, &data.dtablesize,
87 &data.portarray, &data.portarraysize,
88 &data.intarray, &data.intarraysize);
89 __mach_port_deallocate (__mach_task_self (), in_bootstrap);
90 }
91
92 if (err || in_bootstrap == MACH_PORT_NULL || (data.flags & EXEC_STACK_ARGS))
93 {
94 /* Either we have no bootstrap port, or the RPC to the exec server
95 failed, or whoever started us up passed the flag saying args are
96 on the stack. Try to snarf the args in the canonical Mach way.
97 Hopefully either they will be on the stack as expected, or the
98 stack will be zeros so we don't crash. */
99
100 argcptr = (intptr_t *) argptr;
101 argc = argcptr[0];
102 argv = (char **) &argcptr[1];
103 envp = &argv[argc + 1];
104 envc = 0;
105 while (envp[envc])
106 ++envc;
107 }
108 else
109 {
110 /* Turn the block of null-separated strings we were passed for the
111 arguments and environment into vectors of pointers to strings. */
112
113 /* Count up the arguments so we can allocate ARGV. */
114 argc = __argz_count (args, argslen);
115 /* Count up the environment variables so we can allocate ENVP. */
116 envc = __argz_count (env, envlen);
117
118 /* There were some arguments. Allocate space for the vectors of
119 pointers and fill them in. We allocate the space for the
120 environment pointers immediately after the argv pointers because
121 the ELF ABI will expect it. */
122 argcptr = __alloca (sizeof (intptr_t)
123 + (argc + 1 + envc + 1) * sizeof (char *)
124 + sizeof (struct hurd_startup_data));
125 *argcptr = argc;
126 argv = (void *) (argcptr + 1);
127 __argz_extract (args, argslen, argv);
128
129 /* There was some environment. */
130 envp = &argv[argc + 1];
131 __argz_extract (env, envlen, envp);
132 }
133
134 if (err || in_bootstrap == MACH_PORT_NULL)
135 {
136 /* Either we have no bootstrap port, or the RPC to the exec server
137 failed. Set all our other variables to have empty information. */
138
139 data.flags = 0;
140 args = env = NULL;
141 argslen = envlen = 0;
142 data.dtable = NULL;
143 data.dtablesize = 0;
144 data.portarray = NULL;
145 data.portarraysize = 0;
146 data.intarray = NULL;
147 data.intarraysize = 0;
148 data.stack_base = 0;
149 data.stack_size = 0;
150 data.phdr = 0;
151 data.phdrsz = 0;
152 data.user_entry = 0;
153 }
154 else if ((void *) &envp[envc + 1] == argv[0])
155 {
156 /* The arguments arrived on the stack from the kernel, but our
157 protocol requires some space after them for a `struct
158 hurd_startup_data'. Move them. */
159 struct
160 {
161 intptr_t count;
162 char *argv[argc + 1];
163 char *envp[envc + 1];
164 struct hurd_startup_data data;
165 } *args = alloca (sizeof *args);
166 if ((void *) &args[1] == (void *) argcptr)
167 args = alloca (-((char *) &args->data - (char *) args));
168 memmove (args, argcptr, (char *) &args->data - (char *) args);
169 argcptr = (void *) args;
170 argv = args->argv;
171 envp = args->envp;
172 }
173
174 {
175 struct hurd_startup_data *d = (void *) &envp[envc + 1];
176
177 if ((void *) d != argv[0])
178 {
179 *d = data;
180 _hurd_init_dtable = d->dtable;
181 _hurd_init_dtablesize = d->dtablesize;
182 }
183
184 (*main) (argcptr);
185 }
186
187 /* Should never get here. */
188 LOSE;
189 abort ();
190 }