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/* 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;
}
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