/* vi: set sw=4 ts=4: */ /* * sh.c -- a prototype Bourne shell grammar parser * Intended to follow the original Thompson and Ritchie * "small and simple is beautiful" philosophy, which * incidentally is a good match to today's BusyBox. * * Copyright (C) 2000,2001 Larry Doolittle * * Credits: * The parser routines proper are all original material, first * written Dec 2000 and Jan 2001 by Larry Doolittle. * The execution engine, the builtins, and much of the underlying * support has been adapted from busybox-0.49pre's lash, * which is Copyright (C) 2000 by Lineo, Inc., and * written by Erik Andersen , . * That, in turn, is based in part on ladsh.c, by Michael K. Johnson and * Erik W. Troan, which they placed in the public domain. I don't know * how much of the Johnson/Troan code has survived the repeated rewrites. * Other credits: * simple_itoa() was lifted from boa-0.93.15 * b_addchr() derived from similar w_addchar function in glibc-2.2 * setup_redirect(), redirect_opt_num(), and big chunks of main() * and many builtins derived from contributions by Erik Andersen * miscellaneous bugfixes from Matt Kraai * * There are two big (and related) architecture differences between * this parser and the lash parser. One is that this version is * actually designed from the ground up to understand nearly all * of the Bourne grammar. The second, consequential change is that * the parser and input reader have been turned inside out. Now, * the parser is in control, and asks for input as needed. The old * way had the input reader in control, and it asked for parsing to * take place as needed. The new way makes it much easier to properly * handle the recursion implicit in the various substitutions, especially * across continuation lines. * * Bash grammar not implemented: (how many of these were in original sh?) * $@ (those sure look like weird quoting rules) * $_ * ! negation operator for pipes * &> and >& redirection of stdout+stderr * Brace Expansion * Tilde Expansion * fancy forms of Parameter Expansion * Arithmetic Expansion * <(list) and >(list) Process Substitution * reserved words: case, esac, select, function * Here Documents ( << word ) * Functions * Major bugs: * job handling woefully incomplete and buggy * reserved word execution woefully incomplete and buggy * to-do: * port selected bugfixes from post-0.49 busybox lash - done? * finish implementing reserved words: for, while, until, do, done * change { and } from special chars to reserved words * builtins: break, continue, eval, return, set, trap, ulimit * test magic exec * handle children going into background * clean up recognition of null pipes * have builtin_exec set flag to avoid restore_redirects * check setting of global_argc and global_argv * control-C handling, probably with longjmp * VAR=value prefix for simple commands * follow IFS rules more precisely, including update semantics * figure out what to do with backslash-newline * explain why we use signal instead of sigaction * propagate syntax errors, die on resource errors? * continuation lines, both explicit and implicit - done? * memory leak finding and plugging - done? * more testing, especially quoting rules and redirection * maybe change map[] to use 2-bit entries * (eventually) remove all the printf's * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include /* isalpha, isdigit */ #include /* getpid */ #include /* getenv, atoi */ #include /* strchr */ #include /* popen etc. */ #include /* glob, of course */ #include /* va_list */ #include #include #include /* should be pretty obvious */ #include /* ulimit */ #include #include #include /* #include */ /* #define DEBUG_SHELL */ #ifdef BB_VER #include "busybox.h" #include "cmdedit.h" #else #define applet_name "hush" #include "standalone.h" #define shell_main main #define BB_FEATURE_SH_SIMPLE_PROMPT #endif typedef enum { REDIRECT_INPUT = 1, REDIRECT_OVERWRITE = 2, REDIRECT_APPEND = 3, REDIRECT_HEREIS = 4, REDIRECT_IO = 5 } redir_type; /* The descrip member of this structure is only used to make debugging * output pretty */ struct {int mode; int default_fd; char *descrip;} redir_table[] = { { 0, 0, "()" }, { O_RDONLY, 0, "<" }, { O_CREAT|O_TRUNC|O_WRONLY, 1, ">" }, { O_CREAT|O_APPEND|O_WRONLY, 1, ">>" }, { O_RDONLY, -1, "<<" }, { O_RDWR, 1, "<>" } }; typedef enum { PIPE_SEQ = 1, PIPE_AND = 2, PIPE_OR = 3, PIPE_BG = 4, } pipe_style; /* might eventually control execution */ typedef enum { RES_NONE = 0, RES_IF = 1, RES_THEN = 2, RES_ELIF = 3, RES_ELSE = 4, RES_FI = 5, RES_FOR = 6, RES_WHILE = 7, RES_UNTIL = 8, RES_DO = 9, RES_DONE = 10, RES_XXXX = 11, RES_SNTX = 12 } reserved_style; #define FLAG_END (1<, but protected with __USE_GNU */ /* Variables we export */ unsigned int shell_context; /* Used in cmdedit.c to reset the * context when someone hits ^C */ /* "globals" within this file */ static char *ifs=NULL; static char map[256]; static int fake_mode=0; static int interactive=0; static struct close_me *close_me_head = NULL; static char *cwd; static struct jobset *job_list; static unsigned int last_bg_pid=0; static char *PS1; static char *PS2 = "> "; #define B_CHUNK (100) #define B_NOSPAC 1 #define MAX_LINE 256 /* for cwd */ #define MAX_READ 256 /* for builtin_read */ typedef struct { char *data; int length; int maxlen; int quote; int nonnull; } o_string; #define NULL_O_STRING {NULL,0,0,0,0} /* used for initialization: o_string foo = NULL_O_STRING; */ /* I can almost use ordinary FILE *. Is open_memstream() universally * available? Where is it documented? */ struct in_str { const char *p; int __promptme; int promptmode; FILE *file; int (*get) (struct in_str *); int (*peek) (struct in_str *); }; #define b_getch(input) ((input)->get(input)) #define b_peek(input) ((input)->peek(input)) #define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n" struct built_in_command { char *cmd; /* name */ char *descr; /* description */ int (*function) (struct child_prog *); /* function ptr */ }; /* belongs in busybox.h */ static inline int max(int a, int b) { return (a>b)?a:b; } /* This should be in utility.c */ #ifdef DEBUG_SHELL static void debug_printf(const char *format, ...) { va_list args; va_start(args, format); vfprintf(stderr, format, args); va_end(args); } #else static void debug_printf(const char *format, ...) { } #endif #define final_printf debug_printf void __syntax(char *file, int line) { fprintf(stderr,"syntax error %s:%d\n",file,line); } #define syntax() __syntax(__FILE__, __LINE__) /* Index of subroutines: */ /* function prototypes for builtins */ static int builtin_cd(struct child_prog *child); static int builtin_env(struct child_prog *child); static int builtin_exec(struct child_prog *child); static int builtin_exit(struct child_prog *child); static int builtin_export(struct child_prog *child); static int builtin_fg_bg(struct child_prog *child); static int builtin_help(struct child_prog *child); static int builtin_jobs(struct child_prog *child); static int builtin_pwd(struct child_prog *child); static int builtin_read(struct child_prog *child); static int builtin_shift(struct child_prog *child); static int builtin_source(struct child_prog *child); static int builtin_umask(struct child_prog *child); static int builtin_unset(struct child_prog *child); static int builtin_not_written(struct child_prog *child); /* o_string manipulation: */ static int b_check_space(o_string *o, int len); static int b_addchr(o_string *o, int ch); static void b_reset(o_string *o); static int b_addqchr(o_string *o, int ch, int quote); static int b_adduint(o_string *o, unsigned int i); /* in_str manipulations: */ static int static_get(struct in_str *i); static int static_peek(struct in_str *i); static int file_get(struct in_str *i); static int file_peek(struct in_str *i); static void setup_file_in_str(struct in_str *i, FILE *f); static void setup_string_in_str(struct in_str *i, const char *s); /* close_me manipulations: */ static void mark_open(int fd); static void mark_closed(int fd); static void close_all(); /* "run" the final data structures: */ static char *indenter(int i); static int run_list_test(struct pipe *head, int indent); static int run_pipe_test(struct pipe *pi, int indent); /* really run the final data structures: */ static int setup_redirects(struct child_prog *prog, int squirrel[]); static int pipe_wait(struct pipe *pi); static int run_list_real(struct pipe *pi); static void pseudo_exec(struct child_prog *child) __attribute__ ((noreturn)); static int run_pipe_real(struct pipe *pi); /* extended glob support: */ static int globhack(const char *src, int flags, glob_t *pglob); static int glob_needed(const char *s); static int xglob(o_string *dest, int flags, glob_t *pglob); /* data structure manipulation: */ static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input); static void initialize_context(struct p_context *ctx); static int done_word(o_string *dest, struct p_context *ctx); static int done_command(struct p_context *ctx); static int done_pipe(struct p_context *ctx, pipe_style type); /* primary string parsing: */ static int redirect_dup_num(struct in_str *input); static int redirect_opt_num(o_string *o); static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end); static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch); static void lookup_param(o_string *dest, struct p_context *ctx, o_string *src); static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input); static int parse_string(o_string *dest, struct p_context *ctx, const char *src); static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger); /* setup: */ static int parse_stream_outer(struct in_str *inp); static int parse_string_outer(const char *s); static int parse_file_outer(FILE *f); /* job management: */ static void checkjobs(); static void insert_bg_job(struct pipe *pi); static void remove_bg_job(struct pipe *pi); static void free_pipe(struct pipe *pi); /* Table of built-in functions. They can be forked or not, depending on * context: within pipes, they fork. As simple commands, they do not. * When used in non-forking context, they can change global variables * in the parent shell process. If forked, of course they can not. * For example, 'unset foo | whatever' will parse and run, but foo will * still be set at the end. */ static struct built_in_command bltins[] = { {"bg", "Resume a job in the background", builtin_fg_bg}, {"break", "Exit for, while or until loop", builtin_not_written}, {"cd", "Change working directory", builtin_cd}, {"continue", "Continue for, while or until loop", builtin_not_written}, {"env", "Print all environment variables", builtin_env}, {"eval", "Construct and run shell command", builtin_not_written}, {"exec", "Exec command, replacing this shell with the exec'd process", builtin_exec}, {"exit", "Exit from shell()", builtin_exit}, {"export", "Set environment variable", builtin_export}, {"fg", "Bring job into the foreground", builtin_fg_bg}, {"jobs", "Lists the active jobs", builtin_jobs}, {"pwd", "Print current directory", builtin_pwd}, {"read", "Input environment variable", builtin_read}, {"return", "Return from a function", builtin_not_written}, {"set", "Set/unset shell options", builtin_not_written}, {"shift", "Shift positional parameters", builtin_shift}, {"trap", "Trap signals", builtin_not_written}, {"ulimit","Controls resource limits", builtin_not_written}, {"umask","Sets file creation mask", builtin_umask}, {"unset", "Unset environment variable", builtin_unset}, {".", "Source-in and run commands in a file", builtin_source}, {"help", "List shell built-in commands", builtin_help}, {NULL, NULL, NULL} }; /* built-in 'cd ' handler */ static int builtin_cd(struct child_prog *child) { char *newdir; if (child->argv[1] == NULL) newdir = getenv("HOME"); else newdir = child->argv[1]; if (chdir(newdir)) { printf("cd: %s: %s\n", newdir, strerror(errno)); return EXIT_FAILURE; } getcwd(cwd, sizeof(char)*MAX_LINE); return EXIT_SUCCESS; } /* built-in 'env' handler */ static int builtin_env(struct child_prog *dummy) { char **e = environ; if (e == NULL) return EXIT_FAILURE; for (; *e; e++) { puts(*e); } return EXIT_SUCCESS; } /* built-in 'exec' handler */ static int builtin_exec(struct child_prog *child) { if (child->argv[1] == NULL) return EXIT_SUCCESS; /* Really? */ child->argv++; pseudo_exec(child); /* never returns */ } /* built-in 'exit' handler */ static int builtin_exit(struct child_prog *child) { if (child->argv[1] == NULL) exit(last_return_code); exit (atoi(child->argv[1])); } /* built-in 'export VAR=value' handler */ static int builtin_export(struct child_prog *child) { int res; if (child->argv[1] == NULL) { return (builtin_env(child)); } /* FIXME -- I leak memory. This will be * fixed up properly when we add local * variable support -- I hope */ res = putenv(strdup(child->argv[1])); if (res) fprintf(stderr, "export: %s\n", strerror(errno)); return (res); } /* built-in 'fg' and 'bg' handler */ static int builtin_fg_bg(struct child_prog *child) { int i, jobnum; struct pipe *pi=NULL; /* If they gave us no args, assume they want the last backgrounded task */ if (!child->argv[1]) { for (pi = job_list->head; pi; pi = pi->next) { if (pi->progs && pi->progs->pid == last_bg_pid) { break; } } if (!pi) { error_msg("%s: no current job", child->argv[0]); return EXIT_FAILURE; } } else { if (sscanf(child->argv[1], "%%%d", &jobnum) != 1) { error_msg("%s: bad argument '%s'", child->argv[0], child->argv[1]); return EXIT_FAILURE; } for (pi = job_list->head; pi; pi = pi->next) { if (pi->jobid == jobnum) { break; } } if (!pi) { error_msg("%s: %d: no such job", child->argv[0], jobnum); return EXIT_FAILURE; } } if (*child->argv[0] == 'f') { /* Make this job the foreground job */ signal(SIGTTOU, SIG_IGN); /* suppress messages when run from /linuxrc mag@sysgo.de */ if (tcsetpgrp(0, pi->pgrp) && errno != ENOTTY) perror_msg("tcsetpgrp"); signal(SIGTTOU, SIG_DFL); job_list->fg = pi; } /* Restart the processes in the job */ for (i = 0; i < pi->num_progs; i++) pi->progs[i].is_stopped = 0; kill(-pi->pgrp, SIGCONT); pi->stopped_progs = 0; return EXIT_SUCCESS; } /* built-in 'help' handler */ static int builtin_help(struct child_prog *dummy) { struct built_in_command *x; printf("\nBuilt-in commands:\n"); printf("-------------------\n"); for (x = bltins; x->cmd; x++) { if (x->descr==NULL) continue; printf("%s\t%s\n", x->cmd, x->descr); } printf("\n\n"); return EXIT_SUCCESS; } /* built-in 'jobs' handler */ static int builtin_jobs(struct child_prog *child) { struct pipe *job; char *status_string; for (job = job_list->head; job; job = job->next) { if (job->running_progs == job->stopped_progs) status_string = "Stopped"; else status_string = "Running"; printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text); } return EXIT_SUCCESS; } /* built-in 'pwd' handler */ static int builtin_pwd(struct child_prog *dummy) { getcwd(cwd, MAX_LINE); puts(cwd); return EXIT_SUCCESS; } /* built-in 'read VAR' handler */ static int builtin_read(struct child_prog *child) { int res = 0, len, newlen; char *s; char string[MAX_READ]; if (child->argv[1]) { /* argument (VAR) given: put "VAR=" into buffer */ strcpy(string, child->argv[1]); len = strlen(string); string[len++] = '='; string[len] = '\0'; /* XXX would it be better to go through in_str? */ fgets(&string[len], sizeof(string) - len, stdin); /* read string */ newlen = strlen(string); if(newlen > len) string[--newlen] = '\0'; /* chomp trailing newline */ /* ** string should now contain "VAR=" ** copy it (putenv() won't do that, so we must make sure ** the string resides in a static buffer!) */ res = -1; if((s = strdup(string))) res = putenv(s); if (res) fprintf(stderr, "read: %s\n", strerror(errno)); } else fgets(string, sizeof(string), stdin); return (res); } /* Built-in 'shift' handler */ static int builtin_shift(struct child_prog *child) { int n=1; if (child->argv[1]) { n=atoi(child->argv[1]); } if (n>=0 && nargv[1] == NULL) return EXIT_FAILURE; /* XXX search through $PATH is missing */ input = fopen(child->argv[1], "r"); if (!input) { fprintf(stderr, "Couldn't open file '%s'\n", child->argv[1]); return EXIT_FAILURE; } /* Now run the file */ /* XXX argv and argc are broken; need to save old global_argv * (pointer only is OK!) on this stack frame, * set global_argv=child->argv+1, recurse, and restore. */ mark_open(fileno(input)); status = parse_file_outer(input); mark_closed(fileno(input)); fclose(input); return (status); } static int builtin_umask(struct child_prog *child) { mode_t new_umask; const char *arg = child->argv[1]; char *end; if (arg) { new_umask=strtoul(arg, &end, 8); if (*end!='\0' || end == arg) { return EXIT_FAILURE; } } else { printf("%.3o\n", (unsigned int) (new_umask=umask(0))); } umask(new_umask); return EXIT_SUCCESS; } /* built-in 'unset VAR' handler */ static int builtin_unset(struct child_prog *child) { if (child->argv[1] == NULL) { fprintf(stderr, "unset: parameter required.\n"); return EXIT_FAILURE; } unsetenv(child->argv[1]); return EXIT_SUCCESS; } static int builtin_not_written(struct child_prog *child) { printf("builtin_%s not written\n",child->argv[0]); return EXIT_FAILURE; } static int b_check_space(o_string *o, int len) { /* It would be easy to drop a more restrictive policy * in here, such as setting a maximum string length */ if (o->length + len > o->maxlen) { char *old_data = o->data; /* assert (data == NULL || o->maxlen != 0); */ o->maxlen += max(2*len, B_CHUNK); o->data = realloc(o->data, 1 + o->maxlen); if (o->data == NULL) { free(old_data); } } return o->data == NULL; } static int b_addchr(o_string *o, int ch) { debug_printf("b_addchr: %c %d %p\n", ch, o->length, o); if (b_check_space(o, 1)) return B_NOSPAC; o->data[o->length] = ch; o->length++; o->data[o->length] = '\0'; return 0; } static void b_reset(o_string *o) { o->length = 0; o->nonnull = 0; if (o->data != NULL) *o->data = '\0'; } static void b_free(o_string *o) { b_reset(o); if (o->data != NULL) free(o->data); o->data = NULL; o->maxlen = 0; } /* My analysis of quoting semantics tells me that state information * is associated with a destination, not a source. */ static int b_addqchr(o_string *o, int ch, int quote) { if (quote && strchr("*?[\\",ch)) { int rc; rc = b_addchr(o, '\\'); if (rc) return rc; } return b_addchr(o, ch); } /* belongs in utility.c */ char *simple_itoa(unsigned int i) { /* 21 digits plus null terminator, good for 64-bit or smaller ints */ static char local[22]; char *p = &local[21]; *p-- = '\0'; do { *p-- = '0' + i % 10; i /= 10; } while (i > 0); return p + 1; } static int b_adduint(o_string *o, unsigned int i) { int r; char *p = simple_itoa(i); /* no escape checking necessary */ do r=b_addchr(o, *p++); while (r==0 && *p); return r; } static int static_get(struct in_str *i) { int ch=*i->p++; if (ch=='\0') return EOF; return ch; } static int static_peek(struct in_str *i) { return *i->p; } static inline void cmdedit_set_initial_prompt(void) { #ifdef BB_FEATURE_SH_SIMPLE_PROMPT PS1 = NULL; #else PS1 = getenv("PS1"); if(PS1==0) PS1 = "\\w \\$ "; #endif } static inline void setup_prompt_string(int promptmode, char **prompt_str) { debug_printf("setup_prompt_string %d ",promptmode); #ifdef BB_FEATURE_SH_SIMPLE_PROMPT /* Set up the prompt */ if (promptmode == 1) { if (PS1) free(PS1); PS1=xmalloc(strlen(cwd)+4); sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ? "$ ":"# "); *prompt_str = PS1; } else { *prompt_str = PS2; } #else *prompt_str = (promptmode==0)? PS1 : PS2; #endif debug_printf("result %s\n",*prompt_str); } static void get_user_input(struct in_str *i) { char *prompt_str; static char the_command[BUFSIZ]; setup_prompt_string(i->promptmode, &prompt_str); #ifdef BB_FEATURE_COMMAND_EDITING /* ** enable command line editing only while a command line ** is actually being read; otherwise, we'll end up bequeathing ** atexit() handlers and other unwanted stuff to our ** child processes (rob@sysgo.de) */ cmdedit_read_input(prompt_str, the_command); cmdedit_terminate(); #else fputs(prompt_str, stdout); fflush(stdout); the_command[0]=fgetc(i->file); the_command[1]='\0'; #endif i->p = the_command; } /* This is the magic location that prints prompts * and gets data back from the user */ static int file_get(struct in_str *i) { int ch; ch = 0; /* If there is data waiting, eat it up */ if (i->p && *i->p) { ch=*i->p++; } else { /* need to double check i->file because we might be doing something * more complicated by now, like sourcing or substituting. */ if (i->__promptme && interactive && i->file == stdin) { get_user_input(i); i->promptmode=2; i->__promptme = 0; if (i->p && *i->p) { ch=*i->p++; } } else { ch = fgetc(i->file); } debug_printf("b_getch: got a %d\n", ch); } if (ch == '\n') i->__promptme=1; return ch; } /* All the callers guarantee this routine will never be * used right after a newline, so prompting is not needed. */ static int file_peek(struct in_str *i) { if (i->p && *i->p) { return *i->p; } else { static char buffer[2]; buffer[0] = fgetc(i->file); buffer[1] = '\0'; i->p = buffer; debug_printf("b_peek: got a %d\n", *i->p); return *i->p; } } static void setup_file_in_str(struct in_str *i, FILE *f) { i->peek = file_peek; i->get = file_get; i->__promptme=1; i->promptmode=1; i->file = f; i->p = NULL; } static void setup_string_in_str(struct in_str *i, const char *s) { i->peek = static_peek; i->get = static_get; i->__promptme=1; i->promptmode=1; i->p = s; } static void mark_open(int fd) { struct close_me *new = xmalloc(sizeof(struct close_me)); new->fd = fd; new->next = close_me_head; close_me_head = new; } static void mark_closed(int fd) { struct close_me *tmp; if (close_me_head == NULL || close_me_head->fd != fd) error_msg_and_die("corrupt close_me"); tmp = close_me_head; close_me_head = close_me_head->next; free(tmp); } static void close_all() { struct close_me *c; for (c=close_me_head; c; c=c->next) { close(c->fd); } close_me_head = NULL; } /* squirrel != NULL means we squirrel away copies of stdin, stdout, * and stderr if they are redirected. */ static int setup_redirects(struct child_prog *prog, int squirrel[]) { int openfd, mode; struct redir_struct *redir; for (redir=prog->redirects; redir; redir=redir->next) { if (redir->dup == -1) { mode=redir_table[redir->type].mode; openfd = open(redir->word.gl_pathv[0], mode, 0666); if (openfd < 0) { /* this could get lost if stderr has been redirected, but bash and ash both lose it as well (though zsh doesn't!) */ fprintf(stderr,"error opening %s: %s\n", redir->word.gl_pathv[0], strerror(errno)); return 1; } } else { openfd = redir->dup; } if (openfd != redir->fd) { if (squirrel && redir->fd < 3) { squirrel[redir->fd] = dup(redir->fd); } if (openfd == -3) { close(openfd); } else { dup2(openfd, redir->fd); close(openfd); } } } return 0; } static void restore_redirects(int squirrel[]) { int i, fd; for (i=0; i<3; i++) { fd = squirrel[i]; if (fd != -1) { /* No error checking. I sure wouldn't know what * to do with an error if I found one! */ dup2(fd, i); close(fd); } } } /* XXX this definitely needs some more thought, work, and * cribbing from other shells */ static int pipe_wait(struct pipe *pi) { int rcode=0, i, pid, running, status; running = pi->num_progs; while (running) { pid=waitpid(-1, &status, 0); if (pid < 0) perror_msg_and_die("waitpid"); for (i=0; i < pi->num_progs; i++) { if (pi->progs[i].pid == pid) { if (i==pi->num_progs-1) rcode=WEXITSTATUS(status); pi->progs[i].pid = 0; running--; break; } } } return rcode; } /* very simple version for testing */ static void pseudo_exec(struct child_prog *child) { int rcode; struct built_in_command *x; if (child->argv) { /* * Check if the command matches any of the builtins. * Depending on context, this might be redundant. But it's * easier to waste a few CPU cycles than it is to figure out * if this is one of those cases. */ for (x = bltins; x->cmd; x++) { if (strcmp(child->argv[0], x->cmd) == 0 ) { debug_printf("builtin exec %s\n", child->argv[0]); exit(x->function(child)); } } /* Check if the command matches any busybox internal commands * ("applets") here. * FIXME: This feature is not 100% safe, since * BusyBox is not fully reentrant, so we have no guarantee the things * from the .bss are still zeroed, or that things from .data are still * at their defaults. We could exec ourself from /proc/self/exe, but I * really dislike relying on /proc for things. We could exec ourself * from global_argv[0], but if we are in a chroot, we may not be able * to find ourself... */ #ifdef BB_FEATURE_SH_STANDALONE_SHELL { int argc_l; char** argv_l=child->argv; char *name = child->argv[0]; #ifdef BB_FEATURE_SH_APPLETS_ALWAYS_WIN /* Following discussions from November 2000 on the busybox mailing * list, the default configuration, (without * get_last_path_component()) lets the user force use of an * external command by specifying the full (with slashes) filename. * If you enable BB_FEATURE_SH_APPLETS_ALWAYS_WIN, then applets * _aways_ override external commands, so if you want to run * /bin/cat, it will use BusyBox cat even if /bin/cat exists on the * filesystem and is _not_ busybox. Some systems may want this, * most do not. */ name = get_last_path_component(name); #endif /* Count argc for use in a second... */ for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++); optind = 1; debug_printf("running applet %s\n", name); run_applet_by_name(name, argc_l, child->argv); } #endif debug_printf("exec of %s\n",child->argv[0]); execvp(child->argv[0],child->argv); perror("execvp"); exit(1); } else if (child->group) { debug_printf("runtime nesting to group\n"); interactive=0; /* crucial!!!! */ rcode = run_list_real(child->group); /* OK to leak memory by not calling run_list_test, * since this process is about to exit */ exit(rcode); } else { /* Can happen. See what bash does with ">foo" by itself. */ debug_printf("trying to pseudo_exec null command\n"); exit(EXIT_SUCCESS); } } static void insert_bg_job(struct pipe *pi) { struct pipe *thejob; /* Linear search for the ID of the job to use */ pi->jobid = 1; for (thejob = job_list->head; thejob; thejob = thejob->next) if (thejob->jobid >= pi->jobid) pi->jobid = thejob->jobid + 1; /* add thejob to the list of running jobs */ if (!job_list->head) { thejob = job_list->head = xmalloc(sizeof(*thejob)); } else { for (thejob = job_list->head; thejob->next; thejob = thejob->next) /* nothing */; thejob->next = xmalloc(sizeof(*thejob)); thejob = thejob->next; } /* physically copy the struct job */ memcpy(thejob, pi, sizeof(struct pipe)); thejob->next = NULL; thejob->running_progs = thejob->num_progs; thejob->stopped_progs = 0; thejob->text = xmalloc(MAX_LINE); //if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0]) { char *bar=thejob->text; char **foo=pi->progs[0].argv; while(foo && *foo) { bar += sprintf(bar, "%s ", *foo++); } } /* we don't wait for background thejobs to return -- append it to the list of backgrounded thejobs and leave it alone */ printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid); last_bg_pid = thejob->progs[0].pid; } /* remove a backgrounded job from a jobset */ static void remove_bg_job(struct pipe *pi) { struct pipe *prev_pipe; free_pipe(pi); if (pi == job_list->head) { job_list->head = pi->next; } else { prev_pipe = job_list->head; while (prev_pipe->next != pi) prev_pipe = prev_pipe->next; prev_pipe->next = pi->next; } free(pi); } /* free up all memory from a pipe */ static void free_pipe(struct pipe *pi) { int i; for (i = 0; i < pi->num_progs; i++) { free(pi->progs[i].argv); if (pi->progs[i].redirects) free(pi->progs[i].redirects); } if (pi->progs) free(pi->progs); if (pi->text) free(pi->text); if (pi->cmdbuf) free(pi->cmdbuf); memset(pi, 0, sizeof(struct pipe)); } /* Checks to see if any background processes have exited -- if they have, figure out why and see if a job has completed */ static void checkjobs() { int status; int prognum = 0; struct pipe *pi; pid_t childpid; while ((childpid = waitpid(-1, &status, WNOHANG | WUNTRACED)) > 0) { for (pi = job_list->head; pi; pi = pi->next) { prognum = 0; while (prognum < pi->num_progs && pi->progs[prognum].pid != childpid) prognum++; if (prognum < pi->num_progs) break; } if (WIFEXITED(status) || WIFSIGNALED(status)) { /* child exited */ pi->running_progs--; pi->progs[prognum].pid = 0; if (!pi->running_progs) { printf(JOB_STATUS_FORMAT, pi->jobid, "Done", pi->text); remove_bg_job(pi); } } else { if(pi==NULL) break; /* child stopped */ pi->stopped_progs++; pi->progs[prognum].is_stopped = 1; if (pi->stopped_progs == pi->num_progs) { printf(JOB_STATUS_FORMAT, pi->jobid, "Stopped", pi->text); } } } if (childpid == -1 && errno != ECHILD) perror_msg("waitpid"); /* move the shell to the foreground */ if (tcsetpgrp(0, getpgrp()) && errno != ENOTTY) perror_msg("tcsetpgrp"); } /* run_pipe_real() starts all the jobs, but doesn't wait for anything * to finish. See pipe_wait(). * * return code is normally -1, when the caller has to wait for children * to finish to determine the exit status of the pipe. If the pipe * is a simple builtin command, however, the action is done by the * time run_pipe_real returns, and the exit code is provided as the * return value. * * The input of the pipe is always stdin, the output is always * stdout. The outpipe[] mechanism in BusyBox-0.48 lash is bogus, * because it tries to avoid running the command substitution in * subshell, when that is in fact necessary. The subshell process * now has its stdout directed to the input of the appropriate pipe, * so this routine is noticeably simpler. */ static int run_pipe_real(struct pipe *pi) { int i; int ctty; int nextin, nextout; int pipefds[2]; /* pipefds[0] is for reading */ struct child_prog *child; struct built_in_command *x; ctty = -1; nextin = 0; pi->pgrp = 0; /* Check if we are supposed to run in the foreground */ if (interactive && pi->followup!=PIPE_BG) { if ((pi->pgrp = tcgetpgrp(ctty = 2)) < 0 && (pi->pgrp = tcgetpgrp(ctty = 0)) < 0 && (pi->pgrp = tcgetpgrp(ctty = 1)) < 0) return errno = ENOTTY, -1; if (pi->pgrp < 0 && pi->pgrp != getpgrp()) return errno = EPERM, -1; } /* Check if this is a simple builtin (not part of a pipe). * Builtins within pipes have to fork anyway, and are handled in * pseudo_exec. "echo foo | read bar" doesn't work on bash, either. */ if (pi->num_progs == 1 && pi->progs[0].argv != NULL) { child = & (pi->progs[0]); if (child->group && ! child->subshell) { int squirrel[] = {-1, -1, -1}; int rcode; debug_printf("non-subshell grouping\n"); setup_redirects(child, squirrel); /* XXX could we merge code with following builtin case, * by creating a pseudo builtin that calls run_list_real? */ rcode = run_list_real(child->group); restore_redirects(squirrel); return rcode; } for (x = bltins; x->cmd; x++) { if (strcmp(child->argv[0], x->cmd) == 0 ) { int squirrel[] = {-1, -1, -1}; int rcode; if (x->function == builtin_exec && child->argv[1]==NULL) { debug_printf("magic exec\n"); setup_redirects(child,NULL); return EXIT_SUCCESS; } debug_printf("builtin inline %s\n", child->argv[0]); /* XXX setup_redirects acts on file descriptors, not FILEs. * This is perfect for work that comes after exec(). * Is it really safe for inline use? Experimentally, * things seem to work with glibc. */ setup_redirects(child, squirrel); rcode = x->function(child); restore_redirects(squirrel); return rcode; } } } for (i = 0; i < pi->num_progs; i++) { child = & (pi->progs[i]); /* pipes are inserted between pairs of commands */ if ((i + 1) < pi->num_progs) { if (pipe(pipefds)<0) perror_msg_and_die("pipe"); nextout = pipefds[1]; } else { nextout=1; pipefds[0] = -1; } /* XXX test for failed fork()? */ if (!(child->pid = fork())) { signal(SIGTTOU, SIG_DFL); close_all(); if (nextin != 0) { dup2(nextin, 0); close(nextin); } if (nextout != 1) { dup2(nextout, 1); close(nextout); } if (pipefds[0]!=-1) { close(pipefds[0]); /* opposite end of our output pipe */ } /* Like bash, explicit redirects override pipes, * and the pipe fd is available for dup'ing. */ setup_redirects(child,NULL); if (pi->followup!=PIPE_BG) { /* Put our child in the process group whose leader is the * first process in this pipe. */ if (pi->pgrp < 0) { pi->pgrp = child->pid; } /* Don't check for errors. The child may be dead already, * in which case setpgid returns error code EACCES. */ if (setpgid(0, pi->pgrp) == 0) { signal(SIGTTOU, SIG_IGN); tcsetpgrp(ctty, pi->pgrp); signal(SIGTTOU, SIG_DFL); } } pseudo_exec(child); } /* Put our child in the process group whose leader is the * first process in this pipe. */ if (pi->pgrp < 0) { pi->pgrp = child->pid; } /* Don't check for errors. The child may be dead already, * in which case setpgid returns error code EACCES. */ setpgid(child->pid, pi->pgrp); if (nextin != 0) close(nextin); if (nextout != 1) close(nextout); /* If there isn't another process, nextin is garbage but it doesn't matter */ nextin = pipefds[0]; } return -1; } static int run_list_real(struct pipe *pi) { int rcode=0; int if_code=0, next_if_code=0; /* need double-buffer to handle elif */ reserved_style rmode, skip_more_in_this_rmode=RES_XXXX; for (;pi;pi=pi->next) { rmode = pi->r_mode; debug_printf("rmode=%d if_code=%d next_if_code=%d skip_more=%d\n", rmode, if_code, next_if_code, skip_more_in_this_rmode); if (rmode == skip_more_in_this_rmode) continue; skip_more_in_this_rmode = RES_XXXX; if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code; if (rmode == RES_THEN && if_code) continue; if (rmode == RES_ELSE && !if_code) continue; if (rmode == RES_ELIF && !if_code) continue; if (pi->num_progs == 0) continue; rcode = run_pipe_real(pi); if (rcode!=-1) { /* We only ran a builtin: rcode was set by the return value * of run_pipe_real(), and we don't need to wait for anything. */ } else if (pi->followup==PIPE_BG) { /* XXX check bash's behavior with nontrivial pipes */ /* XXX compute jobid */ /* XXX what does bash do with attempts to background builtins? */ insert_bg_job(pi); rcode = EXIT_SUCCESS; } else { if (interactive) { /* move the new process group into the foreground */ /* suppress messages when run from /linuxrc mag@sysgo.de */ //signal(SIGTTIN, SIG_IGN); //signal(SIGTTOU, SIG_IGN); if (tcsetpgrp(0, pi->pgrp) && errno != ENOTTY) perror_msg("tcsetpgrp"); rcode = pipe_wait(pi); if (tcsetpgrp(0, getpgrp()) && errno != ENOTTY) perror_msg("tcsetpgrp"); //signal(SIGTTIN, SIG_DFL); //signal(SIGTTOU, SIG_DFL); } else { rcode = pipe_wait(pi); } } last_return_code=rcode; if ( rmode == RES_IF || rmode == RES_ELIF ) next_if_code=rcode; /* can be overwritten a number of times */ if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) || (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) ) skip_more_in_this_rmode=rmode; /* return rcode; */ /* XXX broken if list is part of if/then/else */ } checkjobs(); return rcode; } /* broken, of course, but OK for testing */ static char *indenter(int i) { static char blanks[]=" "; return &blanks[sizeof(blanks)-i-1]; } /* return code is the exit status of the pipe */ static int run_pipe_test(struct pipe *pi, int indent) { char **p; struct child_prog *child; struct redir_struct *r, *rnext; int a, i, ret_code=0; char *ind = indenter(indent); final_printf("%s run pipe: (pid %d)\n",ind,getpid()); for (i=0; inum_progs; i++) { child = &pi->progs[i]; final_printf("%s command %d:\n",ind,i); if (child->argv) { for (a=0,p=child->argv; *p; a++,p++) { final_printf("%s argv[%d] = %s\n",ind,a,*p); } globfree(&child->glob_result); child->argv=NULL; } else if (child->group) { final_printf("%s begin group (subshell:%d)\n",ind, child->subshell); ret_code = run_list_test(child->group,indent+3); final_printf("%s end group\n",ind); } else { final_printf("%s (nil)\n",ind); } for (r=child->redirects; r; r=rnext) { final_printf("%s redirect %d%s", ind, r->fd, redir_table[r->type].descrip); if (r->dup == -1) { final_printf(" %s\n", *r->word.gl_pathv); globfree(&r->word); } else { final_printf("&%d\n", r->dup); } rnext=r->next; free(r); } child->redirects=NULL; } free(pi->progs); /* children are an array, they get freed all at once */ pi->progs=NULL; return ret_code; } static int run_list_test(struct pipe *head, int indent) { int rcode=0; /* if list has no members */ struct pipe *pi, *next; char *ind = indenter(indent); for (pi=head; pi; pi=next) { if (pi->num_progs == 0) break; final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode); rcode = run_pipe_test(pi, indent); final_printf("%s pipe followup code %d\n", ind, pi->followup); next=pi->next; pi->next=NULL; free(pi); } return rcode; } /* Select which version we will use */ static int run_list(struct pipe *pi) { int rcode=0; if (fake_mode==0) { rcode = run_list_real(pi); } /* run_list_test has the side effect of clearing memory * In the long run that function can be merged with run_list_real, * but doing that now would hobble the debugging effort. */ run_list_test(pi,0); return rcode; } /* The API for glob is arguably broken. This routine pushes a non-matching * string into the output structure, removing non-backslashed backslashes. * If someone can prove me wrong, by performing this function within the * original glob(3) api, feel free to rewrite this routine into oblivion. * Return code (0 vs. GLOB_NOSPACE) matches glob(3). * XXX broken if the last character is '\\', check that before calling. */ static int globhack(const char *src, int flags, glob_t *pglob) { int cnt, pathc; const char *s; char *dest; for (cnt=1, s=src; *s; s++) { if (*s == '\\') s++; cnt++; } dest = malloc(cnt); if (!dest) return GLOB_NOSPACE; if (!(flags & GLOB_APPEND)) { pglob->gl_pathv=NULL; pglob->gl_pathc=0; pglob->gl_offs=0; pglob->gl_offs=0; } pathc = ++pglob->gl_pathc; pglob->gl_pathv = realloc(pglob->gl_pathv, (pathc+1)*sizeof(*pglob->gl_pathv)); if (pglob->gl_pathv == NULL) return GLOB_NOSPACE; pglob->gl_pathv[pathc-1]=dest; pglob->gl_pathv[pathc]=NULL; for (s=src; *s; s++, dest++) { if (*s == '\\') s++; *dest = *s; } *dest='\0'; return 0; } /* XXX broken if the last character is '\\', check that before calling */ static int glob_needed(const char *s) { for (; *s; s++) { if (*s == '\\') s++; if (strchr("*[?",*s)) return 1; } return 0; } #if 0 static void globprint(glob_t *pglob) { int i; debug_printf("glob_t at %p:\n", pglob); debug_printf(" gl_pathc=%d gl_pathv=%p gl_offs=%d gl_flags=%d\n", pglob->gl_pathc, pglob->gl_pathv, pglob->gl_offs, pglob->gl_flags); for (i=0; igl_pathc; i++) debug_printf("pglob->gl_pathv[%d] = %p = %s\n", i, pglob->gl_pathv[i], pglob->gl_pathv[i]); } #endif static int xglob(o_string *dest, int flags, glob_t *pglob) { int gr; /* short-circuit for null word */ /* we can code this better when the debug_printf's are gone */ if (dest->length == 0) { if (dest->nonnull) { /* bash man page calls this an "explicit" null */ gr = globhack(dest->data, flags, pglob); debug_printf("globhack returned %d\n",gr); } else { return 0; } } else if (glob_needed(dest->data)) { gr = glob(dest->data, flags, NULL, pglob); debug_printf("glob returned %d\n",gr); if (gr == GLOB_NOMATCH) { /* quote removal, or more accurately, backslash removal */ gr = globhack(dest->data, flags, pglob); debug_printf("globhack returned %d\n",gr); } } else { gr = globhack(dest->data, flags, pglob); debug_printf("globhack returned %d\n",gr); } if (gr == GLOB_NOSPACE) { fprintf(stderr,"out of memory during glob\n"); exit(1); } if (gr != 0) { /* GLOB_ABORTED ? */ fprintf(stderr,"glob(3) error %d\n",gr); } /* globprint(glob_target); */ return gr; } /* the src parameter allows us to peek forward to a possible &n syntax * for file descriptor duplication, e.g., "2>&1". * Return code is 0 normally, 1 if a syntax error is detected in src. * Resource errors (in xmalloc) cause the process to exit */ static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input) { struct child_prog *child=ctx->child; struct redir_struct *redir = child->redirects; struct redir_struct *last_redir=NULL; /* Create a new redir_struct and drop it onto the end of the linked list */ while(redir) { last_redir=redir; redir=redir->next; } redir = xmalloc(sizeof(struct redir_struct)); redir->next=NULL; if (last_redir) { last_redir->next=redir; } else { child->redirects=redir; } redir->type=style; redir->fd= (fd==-1) ? redir_table[style].default_fd : fd ; debug_printf("Redirect type %d%s\n", redir->fd, redir_table[style].descrip); /* Check for a '2>&1' type redirect */ redir->dup = redirect_dup_num(input); if (redir->dup == -2) return 1; /* syntax error */ if (redir->dup != -1) { /* Erik had a check here that the file descriptor in question * is legit; I postpone that to "run time" * A "-" representation of "close me" shows up as a -3 here */ debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup); } else { /* We do _not_ try to open the file that src points to, * since we need to return and let src be expanded first. * Set ctx->pending_redirect, so we know what to do at the * end of the next parsed word. */ ctx->pending_redirect = redir; } return 0; } struct pipe *new_pipe(void) { struct pipe *pi; pi = xmalloc(sizeof(struct pipe)); pi->num_progs = 0; pi->progs = NULL; pi->next = NULL; pi->followup = 0; /* invalid */ return pi; } static void initialize_context(struct p_context *ctx) { ctx->pipe=NULL; ctx->pending_redirect=NULL; ctx->child=NULL; ctx->list_head=new_pipe(); ctx->pipe=ctx->list_head; ctx->w=RES_NONE; ctx->stack=NULL; done_command(ctx); /* creates the memory for working child */ } /* normal return is 0 * if a reserved word is found, and processed, return 1 * should handle if, then, elif, else, fi, for, while, until, do, done. * case, function, and select are obnoxious, save those for later. */ int reserved_word(o_string *dest, struct p_context *ctx) { struct reserved_combo { char *literal; int code; long flag; }; /* Mostly a list of accepted follow-up reserved words. * FLAG_END means we are done with the sequence, and are ready * to turn the compound list into a command. * FLAG_START means the word must start a new compound list. */ static struct reserved_combo reserved_list[] = { { "if", RES_IF, FLAG_THEN | FLAG_START }, { "then", RES_THEN, FLAG_ELIF | FLAG_ELSE | FLAG_FI }, { "elif", RES_ELIF, FLAG_THEN }, { "else", RES_ELSE, FLAG_FI }, { "fi", RES_FI, FLAG_END }, { "for", RES_FOR, FLAG_DO | FLAG_START }, { "while", RES_WHILE, FLAG_DO | FLAG_START }, { "until", RES_UNTIL, FLAG_DO | FLAG_START }, { "do", RES_DO, FLAG_DONE }, { "done", RES_DONE, FLAG_END } }; struct reserved_combo *r; for (r=reserved_list; #define NRES sizeof(reserved_list)/sizeof(struct reserved_combo) rdata, r->literal) == 0) { debug_printf("found reserved word %s, code %d\n",r->literal,r->code); if (r->flag & FLAG_START) { struct p_context *new = xmalloc(sizeof(struct p_context)); debug_printf("push stack\n"); *new = *ctx; /* physical copy */ initialize_context(ctx); ctx->stack=new; } else if ( ctx->w == RES_NONE || ! (ctx->old_flag & (1<code))) { syntax(); ctx->w = RES_SNTX; b_reset (dest); return 1; } ctx->w=r->code; ctx->old_flag = r->flag; if (ctx->old_flag & FLAG_END) { struct p_context *old; debug_printf("pop stack\n"); old = ctx->stack; old->child->group = ctx->list_head; *ctx = *old; /* physical copy */ free(old); } b_reset (dest); return 1; } } return 0; } /* normal return is 0. * Syntax or xglob errors return 1. */ static int done_word(o_string *dest, struct p_context *ctx) { struct child_prog *child=ctx->child; glob_t *glob_target; int gr, flags = 0; debug_printf("done_word: %s %p\n", dest->data, child); if (dest->length == 0 && !dest->nonnull) { debug_printf(" true null, ignored\n"); return 0; } if (ctx->pending_redirect) { glob_target = &ctx->pending_redirect->word; } else { if (child->group) { syntax(); return 1; /* syntax error, groups and arglists don't mix */ } if (!child->argv) { debug_printf("checking %s for reserved-ness\n",dest->data); if (reserved_word(dest,ctx)) return ctx->w==RES_SNTX; } glob_target = &child->glob_result; if (child->argv) flags |= GLOB_APPEND; } gr = xglob(dest, flags, glob_target); if (gr != 0) return 1; b_reset(dest); if (ctx->pending_redirect) { ctx->pending_redirect=NULL; if (glob_target->gl_pathc != 1) { fprintf(stderr, "ambiguous redirect\n"); return 1; } } else { child->argv = glob_target->gl_pathv; } return 0; } /* The only possible error here is out of memory, in which case * xmalloc exits. */ static int done_command(struct p_context *ctx) { /* The child is really already in the pipe structure, so * advance the pipe counter and make a new, null child. * Only real trickiness here is that the uncommitted * child structure, to which ctx->child points, is not * counted in pi->num_progs. */ struct pipe *pi=ctx->pipe; struct child_prog *prog=ctx->child; if (prog && prog->group == NULL && prog->argv == NULL && prog->redirects == NULL) { debug_printf("done_command: skipping null command\n"); return 0; } else if (prog) { pi->num_progs++; debug_printf("done_command: num_progs incremented to %d\n",pi->num_progs); } else { debug_printf("done_command: initializing\n"); } pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1)); prog = pi->progs + pi->num_progs; prog->redirects = NULL; prog->argv = NULL; prog->is_stopped = 0; prog->group = NULL; prog->glob_result.gl_pathv = NULL; prog->family = pi; ctx->child=prog; /* but ctx->pipe and ctx->list_head remain unchanged */ return 0; } static int done_pipe(struct p_context *ctx, pipe_style type) { struct pipe *new_p; done_command(ctx); /* implicit closure of previous command */ debug_printf("done_pipe, type %d\n", type); ctx->pipe->followup = type; ctx->pipe->r_mode = ctx->w; new_p=new_pipe(); ctx->pipe->next = new_p; ctx->pipe = new_p; ctx->child = NULL; done_command(ctx); /* set up new pipe to accept commands */ return 0; } /* peek ahead in the in_str to find out if we have a "&n" construct, * as in "2>&1", that represents duplicating a file descriptor. * returns either -2 (syntax error), -1 (no &), or the number found. */ static int redirect_dup_num(struct in_str *input) { int ch, d=0, ok=0; ch = b_peek(input); if (ch != '&') return -1; b_getch(input); /* get the & */ ch=b_peek(input); if (ch == '-') { b_getch(input); return -3; /* "-" represents "close me" */ } while (isdigit(ch)) { d = d*10+(ch-'0'); ok=1; b_getch(input); ch = b_peek(input); } if (ok) return d; fprintf(stderr, "ambiguous redirect\n"); return -2; } /* If a redirect is immediately preceded by a number, that number is * supposed to tell which file descriptor to redirect. This routine * looks for such preceding numbers. In an ideal world this routine * needs to handle all the following classes of redirects... * echo 2>foo # redirects fd 2 to file "foo", nothing passed to echo * echo 49>foo # redirects fd 49 to file "foo", nothing passed to echo * echo -2>foo # redirects fd 1 to file "foo", "-2" passed to echo * echo 49x>foo # redirects fd 1 to file "foo", "49x" passed to echo * A -1 output from this program means no valid number was found, so the * caller should use the appropriate default for this redirection. */ static int redirect_opt_num(o_string *o) { int num; if (o->length==0) return -1; for(num=0; numlength; num++) { if (!isdigit(*(o->data+num))) { return -1; } } /* reuse num (and save an int) */ num=atoi(o->data); b_reset(o); return num; } FILE *generate_stream_from_list(struct pipe *head) { FILE *pf; #if 1 int pid, channel[2]; if (pipe(channel)<0) perror_msg_and_die("pipe"); pid=fork(); if (pid<0) { perror_msg_and_die("fork"); } else if (pid==0) { close(channel[0]); if (channel[1] != 1) { dup2(channel[1],1); close(channel[1]); } #if 0 #define SURROGATE "surrogate response" write(1,SURROGATE,sizeof(SURROGATE)); exit(run_list(head)); #else exit(run_list_real(head)); /* leaks memory */ #endif } debug_printf("forked child %d\n",pid); close(channel[1]); pf = fdopen(channel[0],"r"); debug_printf("pipe on FILE *%p\n",pf); #else run_list_test(head,0); pf=popen("echo surrogate response","r"); debug_printf("started fake pipe on FILE *%p\n",pf); #endif return pf; } /* this version hacked for testing purposes */ /* return code is exit status of the process that is run. */ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end) { int retcode; o_string result=NULL_O_STRING; struct p_context inner; FILE *p; struct in_str pipe_str; initialize_context(&inner); /* recursion to generate command */ retcode = parse_stream(&result, &inner, input, subst_end); if (retcode != 0) return retcode; /* syntax error or EOF */ done_word(&result, &inner); done_pipe(&inner, PIPE_SEQ); b_free(&result); p=generate_stream_from_list(inner.list_head); if (p==NULL) return 1; mark_open(fileno(p)); setup_file_in_str(&pipe_str, p); /* now send results of command back into original context */ retcode = parse_stream(dest, ctx, &pipe_str, '\0'); /* XXX In case of a syntax error, should we try to kill the child? * That would be tough to do right, so just read until EOF. */ if (retcode == 1) { while (b_getch(&pipe_str)!=EOF) { /* discard */ }; } debug_printf("done reading from pipe, pclose()ing\n"); /* This is the step that wait()s for the child. Should be pretty * safe, since we just read an EOF from its stdout. We could try * to better, by using wait(), and keeping track of background jobs * at the same time. That would be a lot of work, and contrary * to the KISS philosophy of this program. */ mark_closed(fileno(p)); retcode=pclose(p); debug_printf("pclosed, retcode=%d\n",retcode); /* XXX this process fails to trim a single trailing newline */ return retcode; } static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch) { int rcode, endch=0; struct p_context sub; struct child_prog *child = ctx->child; if (child->argv) { syntax(); return 1; /* syntax error, groups and arglists don't mix */ } initialize_context(&sub); switch(ch) { case '(': endch=')'; child->subshell=1; break; case '{': endch='}'; break; default: syntax(); /* really logic error */ } rcode=parse_stream(dest,&sub,input,endch); done_word(dest,&sub); /* finish off the final word in the subcontext */ done_pipe(&sub, PIPE_SEQ); /* and the final command there, too */ child->group = sub.list_head; return rcode; /* child remains "open", available for possible redirects */ } /* basically useful version until someone wants to get fancier, * see the bash man page under "Parameter Expansion" */ static void lookup_param(o_string *dest, struct p_context *ctx, o_string *src) { const char *p=NULL; if (src->data) p = getenv(src->data); if (p) parse_string(dest, ctx, p); /* recursion */ b_free(src); } /* return code: 0 for OK, 1 for syntax error */ static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input) { int i, advance=0; o_string alt=NULL_O_STRING; char sep[]=" "; int ch = input->peek(input); /* first character after the $ */ debug_printf("handle_dollar: ch=%c\n",ch); if (isalpha(ch)) { while(ch=b_peek(input),isalnum(ch) || ch=='_') { b_getch(input); b_addchr(&alt,ch); } lookup_param(dest, ctx, &alt); } else if (isdigit(ch)) { i = ch-'0'; /* XXX is $0 special? */ if (i 0) b_adduint(dest, last_bg_pid); advance = 1; break; case '?': b_adduint(dest,last_return_code); advance = 1; break; case '#': b_adduint(dest,global_argc ? global_argc-1 : 0); advance = 1; break; case '{': b_getch(input); /* XXX maybe someone will try to escape the '}' */ while(ch=b_getch(input),ch!=EOF && ch!='}') { b_addchr(&alt,ch); } if (ch != '}') { syntax(); return 1; } lookup_param(dest, ctx, &alt); break; case '(': b_getch(input); process_command_subs(dest, ctx, input, ')'); break; case '*': sep[0]=ifs[0]; for (i=1; iquote); } /* Eat the character if the flag was set. If the compiler * is smart enough, we could substitute "b_getch(input);" * for all the "advance = 1;" above, and also end up with * a nice size-optimized program. Hah! That'll be the day. */ if (advance) b_getch(input); return 0; } int parse_string(o_string *dest, struct p_context *ctx, const char *src) { struct in_str foo; setup_string_in_str(&foo, src); return parse_stream(dest, ctx, &foo, '\0'); } /* return code is 0 for normal exit, 1 for syntax error */ int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input, int end_trigger) { unsigned int ch, m; int redir_fd; redir_type redir_style; int next; /* Only double-quote state is handled in the state variable dest->quote. * A single-quote triggers a bypass of the main loop until its mate is * found. When recursing, quote state is passed in via dest->quote. */ debug_printf("parse_stream, end_trigger=%d\n",end_trigger); while ((ch=b_getch(input))!=EOF) { m = map[ch]; next = (ch == '\n') ? 0 : b_peek(input); debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n", ch,ch,m,dest->quote); if (m==0 || ((m==1 || m==2) && dest->quote)) { b_addqchr(dest, ch, dest->quote); } else { if (m==2) { /* unquoted IFS */ done_word(dest, ctx); /* If we aren't performing a substitution, treat a newline as a * command separator. */ if (end_trigger != '\0' && ch=='\n') done_pipe(ctx,PIPE_SEQ); } if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) { debug_printf("leaving parse_stream\n"); return 0; } #if 0 if (ch=='\n') { /* Yahoo! Time to run with it! */ done_pipe(ctx,PIPE_SEQ); run_list(ctx->list_head); initialize_context(ctx); } #endif if (m!=2) switch (ch) { case '#': if (dest->length == 0 && !dest->quote) { while(ch=b_peek(input),ch!=EOF && ch!='\n') { b_getch(input); } } else { b_addqchr(dest, ch, dest->quote); } break; case '\\': if (next == EOF) { syntax(); return 1; } b_addqchr(dest, '\\', dest->quote); b_addqchr(dest, b_getch(input), dest->quote); break; case '$': if (handle_dollar(dest, ctx, input)!=0) return 1; break; case '\'': dest->nonnull = 1; while(ch=b_getch(input),ch!=EOF && ch!='\'') { b_addchr(dest,ch); } if (ch==EOF) { syntax(); return 1; } break; case '"': dest->nonnull = 1; dest->quote = !dest->quote; break; case '`': process_command_subs(dest, ctx, input, '`'); break; case '>': redir_fd = redirect_opt_num(dest); done_word(dest, ctx); redir_style=REDIRECT_OVERWRITE; if (next == '>') { redir_style=REDIRECT_APPEND; b_getch(input); } else if (next == '(') { syntax(); /* until we support >(list) Process Substitution */ return 1; } setup_redirect(ctx, redir_fd, redir_style, input); break; case '<': redir_fd = redirect_opt_num(dest); done_word(dest, ctx); redir_style=REDIRECT_INPUT; if (next == '<') { redir_style=REDIRECT_HEREIS; b_getch(input); } else if (next == '>') { redir_style=REDIRECT_IO; b_getch(input); } else if (next == '(') { syntax(); /* until we support <(list) Process Substitution */ return 1; } setup_redirect(ctx, redir_fd, redir_style, input); break; case ';': done_word(dest, ctx); done_pipe(ctx,PIPE_SEQ); break; case '&': done_word(dest, ctx); if (next=='&') { b_getch(input); done_pipe(ctx,PIPE_AND); } else { done_pipe(ctx,PIPE_BG); } break; case '|': done_word(dest, ctx); if (next=='|') { b_getch(input); done_pipe(ctx,PIPE_OR); } else { /* we could pick up a file descriptor choice here * with redirect_opt_num(), but bash doesn't do it. * "echo foo 2| cat" yields "foo 2". */ done_command(ctx); } break; case '(': case '{': if (parse_group(dest, ctx, input, ch)!=0) return 1; break; case ')': case '}': syntax(); /* Proper use of this character caught by end_trigger */ return 1; break; default: syntax(); /* this is really an internal logic error */ return 1; } } } /* complain if quote? No, maybe we just finished a command substitution * that was quoted. Example: * $ echo "`cat foo` plus more" * and we just got the EOF generated by the subshell that ran "cat foo" * The only real complaint is if we got an EOF when end_trigger != '\0', * that is, we were really supposed to get end_trigger, and never got * one before the EOF. Can't use the standard "syntax error" return code, * so that parse_stream_outer can distinguish the EOF and exit smoothly. */ if (end_trigger != '\0') return -1; return 0; } void mapset(const unsigned char *set, int code) { const unsigned char *s; for (s=set; *s; s++) map[*s] = code; } void update_ifs_map(void) { /* char *ifs and char map[256] are both globals. */ ifs = getenv("IFS"); if (ifs == NULL) ifs=" \t\n"; /* Precompute a list of 'flow through' behavior so it can be treated * quickly up front. Computation is necessary because of IFS. * Special case handling of IFS == " \t\n" is not implemented. * The map[] array only really needs two bits each, and on most machines * that would be faster because of the reduced L1 cache footprint. */ memset(map,0,256); /* most characters flow through always */ mapset("\\$'\"`", 3); /* never flow through */ mapset("<>;&|(){}#", 1); /* flow through if quoted */ mapset(ifs, 2); /* also flow through if quoted */ } /* most recursion does not come through here, the exeception is * from builtin_source() */ int parse_stream_outer(struct in_str *inp) { struct p_context ctx; o_string temp=NULL_O_STRING; int rcode; do { initialize_context(&ctx); update_ifs_map(); inp->promptmode=1; rcode = parse_stream(&temp, &ctx, inp, '\n'); done_word(&temp, &ctx); done_pipe(&ctx,PIPE_SEQ); run_list(ctx.list_head); } while (rcode != -1); /* loop on syntax errors, return on EOF */ return 0; } static int parse_string_outer(const char *s) { struct in_str input; setup_string_in_str(&input, s); return parse_stream_outer(&input); } static int parse_file_outer(FILE *f) { int rcode; struct in_str input; setup_file_in_str(&input, f); rcode = parse_stream_outer(&input); return rcode; } int shell_main(int argc, char **argv) { int opt; FILE *input; struct jobset joblist_end = { NULL, NULL }; job_list = &joblist_end; last_return_code=EXIT_SUCCESS; /* XXX what should these be while sourcing /etc/profile? */ global_argc = argc; global_argv = argv; /* don't pay any attention to this signal; it just confuses things and isn't really meant for shells anyway */ signal(SIGTTOU, SIG_IGN); if (argv[0] && argv[0][0] == '-') { debug_printf("\nsourcing /etc/profile\n"); input = xfopen("/etc/profile", "r"); mark_open(fileno(input)); parse_file_outer(input); mark_closed(fileno(input)); fclose(input); } input=stdin; /* initialize the cwd -- this is never freed...*/ cwd = xgetcwd(0); #ifdef BB_FEATURE_COMMAND_EDITING cmdedit_set_initial_prompt(); #else PS1 = NULL; #endif while ((opt = getopt(argc, argv, "c:xif")) > 0) { switch (opt) { case 'c': { global_argv = argv+optind; global_argc = argc-optind; opt = parse_string_outer(optarg); goto final_return; } break; case 'i': interactive++; break; case 'f': fake_mode++; break; default: fprintf(stderr, "Usage: sh [FILE]...\n" " or: sh -c command [args]...\n\n"); exit(EXIT_FAILURE); } } /* A shell is interactive if the `-i' flag was given, or if all of * the following conditions are met: * no -c command * no arguments remaining or the -s flag given * standard input is a terminal * standard output is a terminal * Refer to Posix.2, the description of the `sh' utility. */ if (argv[optind]==NULL && input==stdin && isatty(fileno(stdin)) && isatty(fileno(stdout))) { interactive++; } debug_printf("\ninteractive=%d\n", interactive); if (interactive) { /* Looks like they want an interactive shell */ fprintf(stdout, "\nhush -- the humble shell v0.01 (testing)\n\n"); opt=parse_file_outer(stdin); goto final_return; } debug_printf("\nrunning script '%s'\n", argv[optind]); global_argv = argv+optind; global_argc = argc-optind; input = xfopen(argv[optind], "r"); opt = parse_file_outer(input); #ifdef BB_FEATURE_CLEAN_UP fclose(input.file); #endif final_return: return(opt?opt:last_return_code); }