1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * alias.c is a C version of the alias.sh wrapper (which links ksh
29 * builtins to commands in /usr/bin/, e.g. calling this wrapper as
30 * /usr/bin/alias will call the ksh "alias" builtin, running it as
31 * /usr/bin/cut will call the ksh "cut" builtin etc.
32 */
33
34 #include <shell.h>
35 #include <nval.h>
36 #include <cmdext.h>
37 #include <stdio.h>
38
39 typedef struct {
40 const char *name;
41 int (* func)(int, char **, void *);
42 } bfastpathrec;
43
44 /*
45 * We've disabled the "fastpath" codepath for some commands below
46 * because it causes a paradoxon for large input files (as used by
47 * ON PerfPIT for testing). For /usr/bin/rev (where the issue was
48 * first discovered) it looks like this:
49 * - for small files like /etc/profile the fastpath is faster in a loop
50 * with 1000 iterations (8 seconds with fastpath, 14 seconds without
51 * fastpath)
52 * - for large files (/usr/pub/UTF-8 replicated until the test file
53 * reaches 24884706 bytes) the benchmark reverses: The fastpath now
54 * needs 40 seconds and without fastpath it needs 30 seconds (for 100
55 * iterations).
56 */
57 #if 0
58 #define ENABLE_PERFORMANCE_PARADOXON 1
59 #endif
60
61 /*
62 * List of libcmd builtins which do not require a |Shell_t| context.
63 * This list was automatically generated from <ast/cmdext.h>
64 */
65 static const
66 bfastpathrec fastpath_builtins[] =
67 {
68 /* This list must be alphabetically sorted for |strcmp()| usage */
69 { "basename", b_basename },
70 { "cat", b_cat },
71 { "chgrp", b_chgrp },
72 { "chmod", b_chmod },
73 { "chown", b_chown },
74 #ifdef ENABLE_PERFORMANCE_PARADOXON
75 { "cksum", b_cksum },
76 #endif /* ENABLE_PERFORMANCE_PARADOXON */
77 { "cmp", b_cmp },
78 { "comm", b_comm },
79 { "cp", b_cp },
80 { "cut", b_cut },
81 { "date", b_date },
82 { "dirname", b_dirname },
83 { "egrep", b_egrep },
84 { "expr", b_expr },
85 { "fds", b_fds },
86 { "fgrep", b_fgrep },
87 { "fmt", b_fmt },
88 { "fold", b_fold },
89 { "getconf", b_getconf },
90 { "grep", b_grep },
91 { "head", b_head },
92 { "id", b_id },
93 { "join", b_join },
94 { "ln", b_ln },
95 { "logname", b_logname },
96 { "md5sum", b_md5sum },
97 { "mkdir", b_mkdir },
98 { "mkfifo", b_mkfifo },
99 { "mktemp", b_mktemp },
100 { "mv", b_mv },
101 { "paste", b_paste },
102 { "pathchk", b_pathchk },
103 { "pids", b_pids },
104 { "readlink", b_readlink },
105 #ifdef ENABLE_PERFORMANCE_PARADOXON
106 { "rev", b_rev },
107 #endif /* ENABLE_PERFORMANCE_PARADOXON */
108 { "rm", b_rm },
109 { "rmdir", b_rmdir },
110 { "stty", b_stty },
111 #ifdef ENABLE_PERFORMANCE_PARADOXON
112 { "sum", b_sum },
113 #endif /* ENABLE_PERFORMANCE_PARADOXON */
114 { "sync", b_sync },
115 { "tail", b_tail },
116 { "tee", b_tee },
117 { "tty", b_tty },
118 { "uname", b_uname },
119 { "uniq", b_uniq },
120 { "wc", b_wc },
121 { "xgrep", b_xgrep },
122 { NULL, (int (*)(int, char **, void *))NULL }
123 };
124
125 static inline
126 const bfastpathrec *
find_bfastpathrec(const char * name)127 find_bfastpathrec(const char *name)
128 {
129 unsigned int i;
130 signed int cmpres;
131 for (i = 0; fastpath_builtins[i].name != NULL; i++) {
132 cmpres = strcmp(fastpath_builtins[i].name, name);
133 if (cmpres == 0)
134 return (&fastpath_builtins[i]);
135 else if (cmpres > 0)
136 return (NULL);
137
138 }
139 return (NULL);
140 }
141
142 static inline
143 int
fastpath_builtin_main(const bfastpathrec * brec,int argc,char * argv[])144 fastpath_builtin_main(const bfastpathrec *brec, int argc, char *argv[])
145 {
146 setlocale(LC_ALL, ""); /* calls |_ast_setlocale()| */
147
148 return ((*brec->func)(argc, argv, NULL));
149 }
150
151
152 /* Builtin script, original derived from alias.sh */
153 static const char *script = "\n"
154 /* Get name of builtin */
155 "typeset cmd=\"${0##*/}\"\n"
156 /*
157 * If the requested command is not an alias load it explicitly
158 * to make sure it is not bound to a path (those built-ins which
159 * are mapped via shell aliases point to commands which are
160 * "special shell built-ins" which cannot be bound to a specific
161 * PATH element) - otherwise we may execute the wrong command
162 * if an executable with the same name sits in a PATH element
163 * before /usr/bin (e.g. /usr/xpg4/bin/ls would be executed
164 * before /usr/bin/ls if the path was something like
165 * PATH=/usr/xpg4/bin:/usr/bin).
166 */
167 "if [[ \"${cmd}\" != ~(Elr)(alias|unalias|command) ]] && "
168 "! alias \"${cmd}\" >/dev/null 2>&1 ; then\n"
169 "PATH='' builtin \"${cmd}\"\n"
170 "fi\n"
171 /* command is a keyword and needs to be handled separately */
172 "if [[ \"${cmd}\" == \"command\" ]] ; then\n"
173 "command \"$@\"\n"
174 "else\n"
175 #ifdef WORKAROUND_FOR_ALIAS_CRASH
176 /*
177 * Work around a crash in /usr/bin/alias when invalid options are
178 * passed (e.g. $ /usr/bin/alias -c #). The shell code will call
179 * an error handler which does a |longjmp()| but somehow the code
180 * failed to do the |setjmp()| before this point.
181 * Putting the "alias" command in a subshell avoids the crash.
182 * Real cause of the issue is under investigation and a fix be
183 * delivered with the next ast-ksh update.
184 */
185 "( \"${cmd}\" \"$@\" )\n"
186 #else
187 "\"${cmd}\" \"$@\"\n"
188 #endif /* WORKAROUND_FOR_ALIAS_CRASH */
189 "fi\n"
190 "exitval=$?";
191
192
193 static inline
194 int
script_builtin_main(int argc,char * argv[])195 script_builtin_main(int argc, char *argv[])
196 {
197 int i;
198 Shell_t *shp;
199 Namval_t *np;
200 int exitval;
201
202 /*
203 * Create copy of |argv| array shifted by one position to
204 * emulate $ /usr/bin/sh <scriptname> <args1> <arg2> ... #.
205 * First position is set to "/usr/bin/sh" since other
206 * values may trigger special shell modes (e.g. *rsh* will
207 * trigger "restricted" shell mode etc.).
208 */
209 char *xargv[argc+2];
210 xargv[0] = "/usr/bin/sh";
211 xargv[1] = "scriptname";
212 for (i = 0; i < argc; i++) {
213 xargv[i+1] = argv[i];
214 }
215 xargv[i+1] = NULL;
216
217 shp = sh_init(argc+1, xargv, 0);
218 if (!shp)
219 error(ERROR_exit(1), "shell initialisation failed.");
220 (void) sh_trap(script, 0);
221
222 np = nv_open("exitval", shp->var_tree, 0);
223 if (!np)
224 error(ERROR_exit(1), "variable %s not found.", "exitval");
225 exitval = (int)nv_getnum(np);
226 nv_close(np);
227
228 return (exitval);
229 }
230
231 int
main(int argc,char * argv[])232 main(int argc, char *argv[])
233 {
234 const char *progname;
235 const bfastpathrec *brec;
236 char execnamebuff[PATH_MAX+1];
237
238 /* Get program name */
239 if (pathprog(argv[0], execnamebuff, sizeof (execnamebuff)) <= 0)
240 error(ERROR_exit(1), "could not determinate exec name.");
241
242 progname = (const char *)strrchr(execnamebuff, '/');
243 if (progname != NULL) {
244 progname++;
245 }
246 else
247 {
248 progname = execnamebuff;
249 }
250
251 /* Execute command... */
252 if (brec = find_bfastpathrec(progname)) {
253 /* ... either via a fast path (calling the code directly) ... */
254 return (fastpath_builtin_main(brec, argc, argv));
255 }
256 else
257 {
258 /* ... or from within a full shell. */
259 return (script_builtin_main(argc, argv));
260 }
261 }
262