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 "libbb.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[];
};

// 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;
	end = skip_non_whitespace(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_and_exit(cmd->argv[0],cmd->argc,cmd->argv);
			execvp(cmd->argv[0],cmd->argv);
			printf("No %s", cmd->argv[0]);
			exit(EXIT_FAILURE);
		} 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) MAIN_EXTERNALLY_VISIBLE;
int bbsh_main(int argc UNUSED_PARAM, char **argv)
{
	char *command=NULL;
	FILE *f;

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

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

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

	return 1;
}
1	niro	532	/* 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	niro	816	#include "libbb.h"
40	niro	532
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	niro	984	char *argv[];
58	niro	532	};
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	niro	816	while (list) {
72	niro	532	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	niro	816	end = skip_non_whitespace(end);
94	niro	532	(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	niro	816	else if (!strcmp(cmd->argv[0],"exit"))
163	niro	532	exit(cmd->argc>1 ? atoi(cmd->argv[1]) : 0);
164			else {
165			int status;
166			pid_t pid=fork();
167	niro	816	if (!pid) {
168			run_applet_and_exit(cmd->argv[0],cmd->argc,cmd->argv);
169	niro	532	execvp(cmd->argv[0],cmd->argv);
170	niro	816	printf("No %s", cmd->argv[0]);
171			exit(EXIT_FAILURE);
172	niro	532	} 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	niro	816	while (cmd->argc) free(cmd->argv[--cmd->argc]);
183	niro	532	}
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	niro	816	int bbsh_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
202	niro	984	int bbsh_main(int argc UNUSED_PARAM, char **argv)
203	niro	532	{
204			char *command=NULL;
205			FILE *f;
206
207	niro	816	getopt32(argv, "c:", &command);
208	niro	532
209	niro	816	f = argv[optind] ? xfopen_for_read(argv[optind]) : NULL;
210	niro	532	if (command) handle(command);
211			else {
212			unsigned cmdlen=0;
213			for (;;) {
214	niro	816	if (!f) putchar('$');
215	niro	984	if (1 > getline(&command, &cmdlen, f ? f : stdin)) break;
216	niro	532
217			handle(command);
218			}
219			if (ENABLE_FEATURE_CLEAN_UP) free(command);
220			}
221
222			return 1;
223			}