hush.c

uboot详细解读可用启动引导LINUX2.6内核

		if (rmode == RES_UNTIL)
			flag_rep = last_return_code;
		if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
		     (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
			skip_more_in_this_rmode=rmode;
#ifndef __U_BOOT__
		checkjobs(NULL);
#endif
	}
	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;
#ifndef __U_BOOT__
	struct redir_struct *r, *rnext;
#endif
	int a, i, ret_code=0;
	char *ind = indenter(indent);

#ifndef __U_BOOT__
	if (pi->stopped_progs > 0)
		return ret_code;
	final_printf("%s run pipe: (pid %d)\n",ind,getpid());
#endif
	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);
			}
#ifndef __U_BOOT__
			globfree(&child->glob_result);
#else
			for (a = child->argc;a >= 0;a--) {
				free(child->argv[a]);
			}
					free(child->argv);
			child->argc = 0;
#endif
			child->argv=NULL;
		} else if (child->group) {
#ifndef __U_BOOT__
			final_printf("%s   begin group (subshell:%d)\n",ind, child->subshell);
#endif
			ret_code = free_pipe_list(child->group,indent+3);
			final_printf("%s   end group\n",ind);
		} else {
			final_printf("%s   (nil)\n",ind);
		}
#ifndef __U_BOOT__
		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;
#endif
	}
	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;
#ifndef __U_BOOT__
	if (fake_mode==0) {
#endif
		rcode = run_list_real(pi);
#ifndef __U_BOOT__
	}
#endif
	/* 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.
 */
#ifndef __U_BOOT__
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;
}
#endif

#ifdef __U_BOOT__
static char *get_dollar_var(char ch);
#endif

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

	if (!s)
		return NULL;

#ifdef __U_BOOT__
	if (*s == '$')
		return get_dollar_var(s[1]);
#endif

	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;

#ifdef __U_BOOT__
	/* might be possible! */
	if (!isalpha(*s))
		return -1;
#endif

	name=strdup(s);

#ifdef __U_BOOT__
	if (getenv(name) != NULL) {
		printf ("ERROR: "
				"There is a global environment variable with the same name.\n");
		free(name);
		return -1;
	}
#endif
	/* 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;
			}
		}
	}

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

#ifndef __U_BOOT__
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);
		}
	}
}
#endif

static int is_assignment(const char *s)
{
	if (s == NULL)
		return 0;

	if (!isalpha(*s)) return 0;
	++s;
	while(isalnum(*s) || *s=='_') ++s;
	return *s=='=';
}

#ifndef __U_BOOT__
/* 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;
	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;
}
#endif

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 */
	pi->r_mode = RES_NONE;
	return pi;
}

static void initialize_context(struct p_context *ctx)
{
	ctx->pipe=NULL;
#ifndef __U_BOOT__
	ctx->pending_redirect=NULL;
#endif
	ctx->child=NULL;
	ctx->list_head=new_pipe();
	ctx->pipe=ctx->list_head;
	ctx->w=RES_NONE;
	ctx->stack=NULL;
#ifdef __U_BOOT__
	ctx->old_flag=0;
#endif
	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.
 */
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_IN   | FLAG_START },
	{ "while", RES_WHILE, FLAG_DO   | FLAG_START },
	{ "until", RES_UNTIL, FLAG_DO   | FLAG_START },
	{ "in",    RES_IN,    FLAG_DO   },
	{ "do",    RES_DO,    FLAG_DONE },
	{ "done",  RES_DONE,  FLAG_END  }
};
#define NRES (sizeof(reserved_list)/sizeof(struct reserved_combo))

int reserved_word(o_string *dest, struct p_context *ctx)
{
	struc