busybox/shell/bbsh.c

/* vi: set ts=4 :
 *
 * bbsh - busybox shell
 *
 * Copyright 2006 Rob Landley <rob@landley.net>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

// A section of code that gets repeatedly or conditionally executed is stored
// as a string and parsed each time it's run.


// Wheee, debugging.

// Terminal control
#define ENABLE_BBSH_TTY        0

// &, fg, bg, jobs.  (ctrl-z with tty.)
#define ENABLE_BBSH_JOBCTL     0

// Flow control (if, while, for, functions { })
#define ENABLE_BBSH_FLOWCTL    0

#define ENABLE_BBSH_ENVVARS    0  // Environment variable support

// Local and synthetic variables, fancy prompts, set, $?, etc.
#define ENABLE_BBSH_LOCALVARS  0

// Pipes and redirects: | > < >> << && || & () ;
#define ENABLE_BBSH_PIPES      0

/* Fun:

  echo `echo hello#comment " woot` and more
*/

#include "busybox.h"

// A single executable, its arguments, and other information we know about it.
#define BBSH_FLAG_EXIT    1
#define BBSH_FLAG_SUSPEND 2
#define BBSH_FLAG_PIPE    4
#define BBSH_FLAG_AND     8
#define BBSH_FLAG_OR      16
#define BBSH_FLAG_AMP     32
#define BBSH_FLAG_SEMI    64
#define BBSH_FLAG_PAREN   128

// What we know about a single process.
struct command {
	struct command *next;
	int flags;		// exit, suspend, && ||
	int pid;		// pid (or exit code)
	int argc;
	char *argv[0];
};

// A collection of processes piped into/waiting on each other.
struct pipeline {
	struct pipeline *next;
	int job_id;
	struct command *cmd;
	char *cmdline;
	int cmdlinelen;
};

static void free_list(void *list, void (*freeit)(void *data))
{
	while(list) {
		void **next = (void **)list;
		void *list_next = *next;
		freeit(list);
		free(list);
		list = list_next;
	}
}

// Parse one word from the command line, appending one or more argv[] entries
// to struct command.  Handles environment variable substitution and
// substrings.  Returns pointer to next used byte, or NULL if it
// hit an ending token.
static char *parse_word(char *start, struct command **cmd)
{
	char *end;

	// Detect end of line (and truncate line at comment)
	if (ENABLE_BBSH_PIPES && strchr("><&|(;", *start)) return 0;

	// Grab next word.  (Add dequote and envvar logic here)
	end = start;
	while (*end && !isspace(*end)) end++;
	(*cmd)->argv[(*cmd)->argc++] = xstrndup(start, end-start);

	// Allocate more space if there's no room for NULL terminator.

	if (!((*cmd)->argc & 7))
			*cmd = xrealloc(*cmd,
					sizeof(struct command) + ((*cmd)->argc+8)*sizeof(char *));
	(*cmd)->argv[(*cmd)->argc] = 0;
	return end;
}

// Parse a line of text into a pipeline.
// Returns a pointer to the next line.

static char *parse_pipeline(char *cmdline, struct pipeline *line)
{
	struct command **cmd = &(line->cmd);
	char *start = line->cmdline = cmdline;

	if (!cmdline) return 0;

	if (ENABLE_BBSH_JOBCTL) line->cmdline = cmdline;

	// Parse command into argv[]
	for (;;) {
		char *end;

		// Skip leading whitespace and detect end of line.
		start = skip_whitespace(start);
		if (!*start || *start=='#') {
			if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;
			return 0;
		}

		// Allocate next command structure if necessary
		if (!*cmd) *cmd = xzalloc(sizeof(struct command)+8*sizeof(char *));

		// Parse next argument and add the results to argv[]
		end = parse_word(start, cmd);

		// If we hit the end of this command, how did it end?
		if (!end) {
			if (ENABLE_BBSH_PIPES && *start) {
				if (*start==';') {
					start++;
					break;
				}
				// handle | & < > >> << || &&
			}
			break;
		}
		start = end;
	}

	if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;

	return start;
}

// Execute the commands in a pipeline
static int run_pipeline(struct pipeline *line)
{
	struct command *cmd = line->cmd;
	if (!cmd || !cmd->argc) return 0;

	// Handle local commands.  This is totally fake and plastic.
	if (cmd->argc==2 && !strcmp(cmd->argv[0],"cd"))
		chdir(cmd->argv[1]);
	else if(!strcmp(cmd->argv[0],"exit"))
		exit(cmd->argc>1 ? atoi(cmd->argv[1]) : 0);
	else {
		int status;
		pid_t pid=fork();
		if(!pid) {
			run_applet_by_name(cmd->argv[0],cmd->argc,cmd->argv);
			execvp(cmd->argv[0],cmd->argv);
			printf("No %s",cmd->argv[0]);
			exit(1);
		} else waitpid(pid, &status, 0);
	}

	return 0;
}

static void free_cmd(void *data)
{
	struct command *cmd=(struct command *)data;

	while(cmd->argc) free(cmd->argv[--cmd->argc]);
}


static void handle(char *command)
{
	struct pipeline line;
	char *start = command;

	for (;;) {
		memset(&line,0,sizeof(struct pipeline));
		start = parse_pipeline(start, &line);
		if (!line.cmd) break;

		run_pipeline(&line);
		free_list(line.cmd, free_cmd);
	}
}

int bbsh_main(int argc, char *argv[])
{
	char *command=NULL;
	FILE *f;

	getopt32(argc, argv, "c:", &command);

	f = argv[optind] ? xfopen(argv[optind],"r") : NULL;
	if (command) handle(command);
	else {
		unsigned cmdlen=0;
		for (;;) {
			if(!f) putchar('$');
			if(1 > getline(&command, &cmdlen,f ? : stdin)) break;

			handle(command);
		}
		if (ENABLE_FEATURE_CLEAN_UP) free(command);
	}

	return 1;
}
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 "busybox.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.
52	struct 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.
61	struct pipeline {
62	struct pipeline *next;
63	int job_id;
64	struct command *cmd;
65	char *cmdline;
66	int cmdlinelen;
67	};
68
69	static 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.
84	static 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	while (end && !isspace(end)) 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
108	static 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)+8sizeof(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
154	static 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_by_name(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
178	static 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
186	static 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
201	int bbsh_main(int argc, char *argv[])
202	{
203	char *command=NULL;
204	FILE *f;
205
206	getopt32(argc, argv, "c:", &command);
207
208	f = argv[optind] ? xfopen(argv[optind],"r") : NULL;
209	if (command) handle(command);
210	else {
211	unsigned cmdlen=0;
212	for (;;) {
213	if(!f) putchar('$');
214	if(1 > getline(&command, &cmdlen,f ? : stdin)) break;
215
216	handle(command);
217	}
218	if (ENABLE_FEATURE_CLEAN_UP) free(command);
219	}
220
221	return 1;
222	}