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/* vi: set sw=4 ts=4:
*
* toysh - toybox shell
*
* Copyright 2006 Rob Landley <rob@landley.net>
*
* The spec for this is at:
* http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html
* and
* http://www.opengroup.org/onlinepubs/007904975/utilities/sh.html
*
* Although things like the bash man page are good to read too.
*/
// Handle embedded NUL bytes in the command line.
#include "toys.h"
#define TT toy.toysh
// A single executable, its arguments, and other information we know about it.
#define TOYSH_FLAG_EXIT 1
#define TOYSH_FLAG_SUSPEND 2
#define TOYSH_FLAG_PIPE 4
#define TOYSH_FLAG_AND 8
#define TOYSH_FLAG_OR 16
#define TOYSH_FLAG_AMP 32
#define TOYSH_FLAG_SEMI 64
#define TOYSH_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; // Unparsed line for display purposes
int cmdlinelen; // How long is cmdline?
};
// 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 (CFG_TOYSH_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 (CFG_TOYSH_JOBCTL) line->cmdline = cmdline;
// Parse command into argv[]
for (;;) {
char *end;
// Skip leading whitespace and detect end of line.
while (isspace(*start)) start++;
if (!*start || *start=='#') {
if (CFG_TOYSH_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 (CFG_TOYSH_PIPES && *start) {
if (*start==';') {
start++;
break;
}
// handle | & < > >> << || &&
}
break;
}
start = end;
}
if (CFG_TOYSH_JOBCTL) line->cmdlinelen = start-cmdline;
return start;
}
// Execute the commands in a pipeline
static void run_pipeline(struct pipeline *line)
{
struct toy_list *tl;
struct command *cmd = line->cmd;
if (!cmd || !cmd->argc) return;
tl = toy_find(cmd->argv[0]);
// Is this command a builtin that should run in this process?
if (tl && (tl->flags & TOYFLAG_NOFORK)) {
struct toy_context temp;
// This fakes lots of what toybox_main() does.
memcpy(&temp, &toys, sizeof(struct toy_context));
bzero(&toys, sizeof(struct toy_context));
toy_init(tl, cmd->argv);
tl->toy_main();
cmd->pid = toys.exitval;
free(toys.optargs);
memcpy(&toys, &temp, sizeof(struct toy_context));
} else {
int status;
cmd->pid = vfork();
if (!cmd->pid) xexec(cmd->argv);
else waitpid(cmd->pid, &status, 0);
if (CFG_TOYSH_FLOWCTL || CFG_TOYSH_PIPES) {
if (WIFEXITED(status)) cmd->pid = WEXITSTATUS(status);
if (WIFSIGNALED(status)) cmd->pid = WTERMSIG(status);
}
}
return;
}
// Free the contents of a command structure
static void free_cmd(void *data)
{
struct command *cmd=(struct command *)data;
while(cmd->argc) free(cmd->argv[--cmd->argc]);
}
// Parse a command line and do what it says to do.
static void handle(char *command)
{
struct pipeline line;
char *start = command;
// Loop through commands in this line
for (;;) {
// Parse a group of connected commands
memset(&line,0,sizeof(struct pipeline));
start = parse_pipeline(start, &line);
if (!line.cmd) break;
// Run those commands
run_pipeline(&line);
llist_free(line.cmd, free_cmd);
}
}
void cd_main(void)
{
char *dest = *toys.optargs ? *toys.optargs : getenv("HOME");
if (chdir(dest)) error_exit("chdir %s",dest);
}
void exit_main(void)
{
exit(*toys.optargs ? atoi(*toys.optargs) : 0);
}
void toysh_main(void)
{
FILE *f;
// Set up signal handlers and grab control of this tty.
if (CFG_TOYSH_TTY) {
if (isatty(0)) toys.optflags |= 1;
}
f = *toys.optargs ? xfopen(*toys.optargs, "r") : NULL;
if (TT.command) handle(TT.command);
else {
size_t cmdlen = 0;
for (;;) {
char *command = 0;
if (!f) xputc('$');
if (1 > getline(&command, &cmdlen, f ? : stdin)) break;
handle(command);
free(command);
}
}
toys.exitval = 1;
}
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