diff options
| -rw-r--r-- | shell/bbsh.c | 193 |
1 files changed, 172 insertions, 21 deletions
diff --git a/shell/bbsh.c b/shell/bbsh.c index f2d76cc01..57a103bf8 100644 --- a/shell/bbsh.c +++ b/shell/bbsh.c @@ -7,49 +7,197 @@ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ -// Handle embedded NUL bytes in the command line. +// 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> -static int handle(char *command) +// 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 *pipe) { - int argc=0; - char *argv[10], *start = command; + struct command **cmd = &(pipe->cmd); + char *start = pipe->cmdline = cmdline; + + if (!cmdline) return 0; + + if (ENABLE_BBSH_JOBCTL) pipe->cmdline = cmdline; // Parse command into argv[] for (;;) { char *end; - // Skip leading whitespace and detect EOL. - while(isspace(*start)) start++; - if(!*start || *start=='#') break; + // Skip leading whitespace and detect end of line. + while (isspace(*start)) start++; + if (!*start || *start=='#') { + if (ENABLE_BBSH_JOBCTL) pipe->cmdlinelen = start-cmdline; + return 0; + } - // Grab next word. (Add dequote and envvar logic here) - end=start; - while(*end && !isspace(*end)) end++; - argv[argc++]=xstrndup(start,end-start); - start=end; + // 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; } - argv[argc]=0; - if (!argc) return 0; - if (argc==2 && !strcmp(argv[0],"cd")) chdir(argv[1]); - else if(!strcmp(argv[0],"exit")) exit(argc>1 ? atoi(argv[1]) : 0); + if (ENABLE_BBSH_JOBCTL) pipe->cmdlinelen = start-cmdline; + + return start; +} + +// Execute the commands in a pipeline +static int run_pipeline(struct pipeline *pipe) +{ + struct command *cmd = pipe->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(argv[0],argc,argv); - execvp(argv[0],argv); - printf("No %s",argv[0]); + 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); } - while(argc) free(argv[--argc]); 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 pipe; + char *start = command; + + for (;;) { + memset(&pipe,0,sizeof(struct pipeline)); + start = parse_pipeline(start, &pipe); + if (!pipe.cmd) break; + + run_pipeline(&pipe); + free_list(pipe.cmd, free_cmd); + } +} + int bbsh_main(int argc, char *argv[]) { char *command=NULL; @@ -62,8 +210,11 @@ int bbsh_main(int argc, char *argv[]) else { unsigned cmdlen=0; for (;;) { + struct pipeline pipe; + if(!f) putchar('$'); - if(1 > getline(&command,&cmdlen,f ? : stdin)) break; + if(1 > getline(&command, &cmdlen,f ? : stdin)) break; + handle(command); } if (ENABLE_FEATURE_CLEAN_UP) free(command); |