/* 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; }