hush.c

为samsung2410 ARM移植的busybox工具包

			}
		}
	}

	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 !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
		if (!(child->pid = fork()))
#else
		if (!(child->pid = vfork())) 
#endif
		{
			/* Set the handling for job control signals back to the default.  */
			signal(SIGINT, SIG_DFL);
			signal(SIGQUIT, SIG_DFL);
			signal(SIGTERM, SIG_DFL);
			signal(SIGTSTP, SIG_DFL);
			signal(SIGTTIN, SIG_DFL);
			signal(SIGTTOU, SIG_DFL);
			signal(SIGCHLD, 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 (interactive && pi->followup!=PIPE_BG) {
				/* If we (the child) win the race, put ourselves in the process
				 * group whose leader is the first process in this pipe. */
				if (pi->pgrp < 0) {
					pi->pgrp = getpid();
				}
				if (setpgid(0, pi->pgrp) == 0) {
					tcsetpgrp(2, pi->pgrp);
				}
			}

			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);
		debug_printf("run_pipe_real returned %d\n",rcode);
		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 */
				if (tcsetpgrp(shell_terminal, pi->pgrp) && errno != ENOTTY)
					perror_msg("tcsetpgrp-3");
				rcode = checkjobs(pi);
				/* move the shell to the foreground */
				if (tcsetpgrp(shell_terminal, getpgid(0)) && errno != ENOTTY)
					perror_msg("tcsetpgrp-4");
			} else {
				rcode = checkjobs(pi);
			}
			debug_printf("checkjobs returned %d\n",rcode);
		}
		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;
		checkjobs(NULL);
	}
	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 free_pipe(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);

	if (pi->stopped_progs > 0)
		return ret_code;
	final_printf("%s run pipe: (pid %d)\n",ind,getpid());
	for (i=0; i<pi->num_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 = free_pipe_list(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) {
				/* guard against the case >$FOO, where foo is unset or blank */
				if (r->word.gl_pathv) {
					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 free_pipe_list(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) {
		final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode);
		rcode = free_pipe(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);
	} 
	/* free_pipe_list 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. */
	free_pipe_list(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=0, pathc;
	const char *s;
	char *dest;
	for (cnt=1, s=src; s && *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; 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; i<pglob->gl_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)
		error_msg_and_die("out of memory during glob");
	if (gr != 0) { /* GLOB_ABORTED ? */
		error_msg("glob(3) error %d",gr);
	}
	/* globprint(glob_target); */
	return gr;
}

/* This is used to get/check local shell variables */
static char *get_local_var(const char *s)
{
	struct variables *cur;

	if (!s)
		return NULL;
	for (cur = top_vars; cur; cur=cur->next)
		if(strcmp(cur->name, s)==0)
			return cur->value;
	return NULL;
}

/* This is used to set local shell variables
   flg_export==0 if only local (not exporting) variable
   flg_export==1 if "new" exporting environ
   flg_export>1  if current startup environ (not call putenv()) */
static int set_local_var(const char *s, int flg_export)
{
	char *name, *value;
	int result=0;
	struct variables *cur;

	name=strdup(s);

	/* Assume when we enter this function that we are already in
	 * NAME=VALUE format.  So the first order of business is to
	 * split 's' on the '=' into 'name' and 'value' */ 
	value = strchr(name, '=');
	if (value==0 && ++value==0) {
		free(name);
		return -1;
	}
	*value++ = 0;

	for(cur = top_vars; cur; cur = cur->next) {
		if(strcmp(cur->name, name)==0)
			break;
	}

	if(cur) {
		if(strcmp(cur->value, value)==0) {
			if(flg_export>0 && cur->flg_export==0)
				cur->flg_export=flg_export;
			else
				result++;
		} else {
			if(cur->flg_read_only) {
				error_msg("%s: readonly variable", name);
				result = -1;
			} else {
				if(flg_export>0 || cur->flg_export>1)
					cur->flg_export=1;
				free(cur->value);

				cur->value = strdup(value);
			}
		}
	} else {
		cur = malloc(sizeof(struct variables));
		if(!cur) {
			result = -1;
		} else {
			cur->name = strdup(name);
			if(cur->name == 0) {
				free(cur);
				result = -1;
			} else {
				struct variables *bottom = top_vars;
				cur->value = strdup(value);
				cur->next = 0;
				cur->flg_export = flg_export;
				cur->flg_read_only = 0;
				while(bottom->next) bottom=bottom->next;
				bottom->next = cur;
			}
		}
	}

	if(result==0 && cur->flg_export==1) {
		*(value-1) = '=';
		result = putenv(name);
	} else {
		free(name);
		if(result>0)            /* equivalent to previous set */
			result = 0;
	}
	return result;
}

static void unset_local_var(const char *name)
{
	struct variables *cur;

	if (name) {
		for (cur = top_vars; cur; cur=cur->next) {
			if(strcmp(cur->name, name)==0)
				break;
		}
		if(cur!=0) {
			struct variables *next = top_vars;
			if(cur->flg_read_only) {
				error_msg("%s: readonly variable", name);
				return;
			} else {
				if(cur->flg_export)
					unsetenv(cur->name);
				free(cur->name);
				free(cur->value);
				while (next->next != cur)
					next = next->next;
				next->next = cur->next;
			}
			free(cur);
		}
	}
}

static int is_assignment(const char *s)
{
	if (s==NULL || !isalpha(*s)) return 0;
	++s;
	while(isalnum(*s) || *s=='_') ++s;
	return *s=='=';
}

/* 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;
	redir->word.gl_pathv=NULL;