1/* vi: set ts=4 :
2 *
3 * bbsh - busybox shell
4 *
5 * Copyright 2006 Rob Landley <rob@landley.net>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10// A section of code that gets repeatedly or conditionally executed is stored
11// as a string and parsed each time it's run.
12
13
14
15// Wheee, debugging.
16
17// Terminal control
18#define ENABLE_BBSH_TTY        0
19
20// &, fg, bg, jobs.  (ctrl-z with tty.)
21#define ENABLE_BBSH_JOBCTL     0
22
23// Flow control (if, while, for, functions { })
24#define ENABLE_BBSH_FLOWCTL    0
25
26#define ENABLE_BBSH_ENVVARS    0  // Environment variable support
27
28// Local and synthetic variables, fancy prompts, set, $?, etc.
29#define ENABLE_BBSH_LOCALVARS  0
30
31// Pipes and redirects: | > < >> << && || & () ;
32#define ENABLE_BBSH_PIPES      0
33
34/* Fun:
35
36  echo `echo hello#comment " woot` and more
37*/
38
39#include "libbb.h"
40
41// A single executable, its arguments, and other information we know about it.
42#define BBSH_FLAG_EXIT    1
43#define BBSH_FLAG_SUSPEND 2
44#define BBSH_FLAG_PIPE    4
45#define BBSH_FLAG_AND     8
46#define BBSH_FLAG_OR      16
47#define BBSH_FLAG_AMP     32
48#define BBSH_FLAG_SEMI    64
49#define BBSH_FLAG_PAREN   128
50
51// What we know about a single process.
52struct command {
53	struct command *next;
54	int flags;		// exit, suspend, && ||
55	int pid;		// pid (or exit code)
56	int argc;
57	char *argv[0];
58};
59
60// A collection of processes piped into/waiting on each other.
61struct pipeline {
62	struct pipeline *next;
63	int job_id;
64	struct command *cmd;
65	char *cmdline;
66	int cmdlinelen;
67};
68
69static void free_list(void *list, void (*freeit)(void *data))
70{
71	while (list) {
72		void **next = (void **)list;
73		void *list_next = *next;
74		freeit(list);
75		free(list);
76		list = list_next;
77	}
78}
79
80// Parse one word from the command line, appending one or more argv[] entries
81// to struct command.  Handles environment variable substitution and
82// substrings.  Returns pointer to next used byte, or NULL if it
83// hit an ending token.
84static char *parse_word(char *start, struct command **cmd)
85{
86	char *end;
87
88	// Detect end of line (and truncate line at comment)
89	if (ENABLE_BBSH_PIPES && strchr("><&|(;", *start)) return 0;
90
91	// Grab next word.  (Add dequote and envvar logic here)
92	end = start;
93	end = skip_non_whitespace(end);
94	(*cmd)->argv[(*cmd)->argc++] = xstrndup(start, end-start);
95
96	// Allocate more space if there's no room for NULL terminator.
97
98	if (!((*cmd)->argc & 7))
99			*cmd = xrealloc(*cmd,
100					sizeof(struct command) + ((*cmd)->argc+8)*sizeof(char *));
101	(*cmd)->argv[(*cmd)->argc] = 0;
102	return end;
103}
104
105// Parse a line of text into a pipeline.
106// Returns a pointer to the next line.
107
108static char *parse_pipeline(char *cmdline, struct pipeline *line)
109{
110	struct command **cmd = &(line->cmd);
111	char *start = line->cmdline = cmdline;
112
113	if (!cmdline) return 0;
114
115	if (ENABLE_BBSH_JOBCTL) line->cmdline = cmdline;
116
117	// Parse command into argv[]
118	for (;;) {
119		char *end;
120
121		// Skip leading whitespace and detect end of line.
122		start = skip_whitespace(start);
123		if (!*start || *start=='#') {
124			if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;
125			return 0;
126		}
127
128		// Allocate next command structure if necessary
129		if (!*cmd) *cmd = xzalloc(sizeof(struct command)+8*sizeof(char *));
130
131		// Parse next argument and add the results to argv[]
132		end = parse_word(start, cmd);
133
134		// If we hit the end of this command, how did it end?
135		if (!end) {
136			if (ENABLE_BBSH_PIPES && *start) {
137				if (*start==';') {
138					start++;
139					break;
140				}
141				// handle | & < > >> << || &&
142			}
143			break;
144		}
145		start = end;
146	}
147
148	if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;
149
150	return start;
151}
152
153// Execute the commands in a pipeline
154static int run_pipeline(struct pipeline *line)
155{
156	struct command *cmd = line->cmd;
157	if (!cmd || !cmd->argc) return 0;
158
159	// Handle local commands.  This is totally fake and plastic.
160	if (cmd->argc==2 && !strcmp(cmd->argv[0],"cd"))
161		chdir(cmd->argv[1]);
162	else if (!strcmp(cmd->argv[0],"exit"))
163		exit(cmd->argc>1 ? atoi(cmd->argv[1]) : 0);
164	else {
165		int status;
166		pid_t pid=fork();
167		if (!pid) {
168			run_applet_and_exit(cmd->argv[0],cmd->argc,cmd->argv);
169			execvp(cmd->argv[0],cmd->argv);
170			printf("No %s",cmd->argv[0]);
171			exit(1);
172		} else waitpid(pid, &status, 0);
173	}
174
175	return 0;
176}
177
178static void free_cmd(void *data)
179{
180	struct command *cmd=(struct command *)data;
181
182	while (cmd->argc) free(cmd->argv[--cmd->argc]);
183}
184
185
186static void handle(char *command)
187{
188	struct pipeline line;
189	char *start = command;
190
191	for (;;) {
192		memset(&line,0,sizeof(struct pipeline));
193		start = parse_pipeline(start, &line);
194		if (!line.cmd) break;
195
196		run_pipeline(&line);
197		free_list(line.cmd, free_cmd);
198	}
199}
200
201int bbsh_main(int argc, char **argv);
202int bbsh_main(int argc, char **argv)
203{
204	char *command=NULL;
205	FILE *f;
206
207	getopt32(argv, "c:", &command);
208
209	f = argv[optind] ? xfopen(argv[optind],"r") : NULL;
210	if (command) handle(command);
211	else {
212		unsigned cmdlen=0;
213		for (;;) {
214			if (!f) putchar('$');
215			if (1 > getline(&command, &cmdlen,f ? : stdin)) break;
216
217			handle(command);
218		}
219		if (ENABLE_FEATURE_CLEAN_UP) free(command);
220	}
221
222	return 1;
223}
224