sed.c

手机嵌入式Linux下可用的busybox源码

	/* if it was a single-letter command that takes no arguments (such as 'p'
	 * or 'd') all we need to do is increment the index past that command */
	if (strchr("pd", cmdstr[idx])) {
		idx++;
	}
	/* handle (s)ubstitution command */
	else if (sed_cmd->cmd == 's') {
		idx += parse_subst_cmd(sed_cmd, &cmdstr[idx]);
	}
	/* handle edit cmds: (a)ppend, (i)nsert, and (c)hange */
	else if (strchr("aic", sed_cmd->cmd)) {
		if ((sed_cmd->end_line || sed_cmd->end_match) && sed_cmd->cmd != 'c')
			error_msg_and_die("only a beginning address can be specified for edit commands");
		idx += parse_edit_cmd(sed_cmd, &cmdstr[idx]);
	}
	/* handle file cmds: (r)ead */
	else if (sed_cmd->cmd == 'r') {
		if (sed_cmd->end_line || sed_cmd->end_match)
			error_msg_and_die("Command only uses one address");
		idx += parse_file_cmd(sed_cmd, &cmdstr[idx]);
	}
	else {
		error_msg_and_die("invalid command");
	}

	/* give back whatever's left over */
	return (char *)&cmdstr[idx];
}

static void add_cmd_str(const char *cmdstr)
{
	char *mystr = (char *)cmdstr;

	do {

		/* trim leading whitespace and semicolons */
		memmove(mystr, &mystr[strspn(mystr, "; \n\r\t\v")], strlen(mystr));
		/* if we ate the whole thing, that means there was just trailing
		 * whitespace or a final / no-op semicolon. either way, get out */
		if (strlen(mystr) == 0)
			return;
		/* if this is a comment, jump past it and keep going */
		if (mystr[0] == '#') {
			mystr = strpbrk(mystr, ";\n\r");
			continue;
		}
		/* grow the array */
		sed_cmds = xrealloc(sed_cmds, sizeof(struct sed_cmd) * (++ncmds));
		/* zero new element */
		memset(&sed_cmds[ncmds-1], 0, sizeof(struct sed_cmd));
		/* load command string into new array element, get remainder */
		mystr = parse_cmd_str(&sed_cmds[ncmds-1], mystr);

	} while (mystr && strlen(mystr));
}


static void load_cmd_file(char *filename)
{
	FILE *cmdfile;
	char *line;
	char *nextline;

	cmdfile = xfopen(filename, "r");

	while ((line = get_line_from_file(cmdfile)) != NULL) {
		/* if a line ends with '\' it needs the next line appended to it */
		while (line[strlen(line)-2] == '\\' &&
				(nextline = get_line_from_file(cmdfile)) != NULL) {
			line = xrealloc(line, strlen(line) + strlen(nextline) + 1);
			strcat(line, nextline);
			free(nextline);
		}
		/* eat trailing newline (if any) --if I don't do this, edit commands
		 * (aic) will print an extra newline */
		chomp(line);
		add_cmd_str(line);
		free(line);
	}
}

#define PIPE_MAGIC 0x7f
#define PIPE_GROW 64  
#define pipeputc(c) \
{ if (pipeline[pipeline_idx] == PIPE_MAGIC) { \
	pipeline = xrealloc(pipeline, pipeline_len+PIPE_GROW); \
	memset(pipeline+pipeline_len, 0, PIPE_GROW); \
	pipeline_len += PIPE_GROW; \
	pipeline[pipeline_len-1] = PIPE_MAGIC; } \
	pipeline[pipeline_idx++] = (c); }

static void print_subst_w_backrefs(const char *line, const char *replace, 
	regmatch_t *regmatch, char **pipeline_p, int *pipeline_idx_p, 
	int *pipeline_len_p, int matches)
{
	char *pipeline = *pipeline_p;
	int pipeline_idx = *pipeline_idx_p;
	int pipeline_len = *pipeline_len_p;
	int i;

	/* go through the replacement string */
	for (i = 0; replace[i]; i++) {
		/* if we find a backreference (\1, \2, etc.) print the backref'ed * text */
		if (replace[i] == '\\' && isdigit(replace[i+1])) {
			int j;
			char tmpstr[2];
			int backref;
			++i; /* i now indexes the backref number, instead of the leading slash */
			tmpstr[0] = replace[i];
			tmpstr[1] = 0;
			backref = atoi(tmpstr);
			/* print out the text held in regmatch[backref] */
			if (backref <= matches && regmatch[backref].rm_so != -1)
				for (j = regmatch[backref].rm_so; j < regmatch[backref].rm_eo; j++)
					pipeputc(line[j]);
		}

		/* if we find a backslash escaped character, print the character */
		else if (replace[i] == '\\') {
			++i;
			pipeputc(replace[i]);
		}

		/* if we find an unescaped '&' print out the whole matched text.
		 * fortunately, regmatch[0] contains the indicies to the whole matched
		 * expression (kinda seems like it was designed for just such a
		 * purpose...) */
		else if (replace[i] == '&' && replace[i-1] != '\\') {
			int j;
			for (j = regmatch[0].rm_so; j < regmatch[0].rm_eo; j++)
				pipeputc(line[j]);
		}
		/* nothing special, just print this char of the replacement string to stdout */
		else
			pipeputc(replace[i]);
	}
	*pipeline_p = pipeline;
	*pipeline_idx_p = pipeline_idx;
	*pipeline_len_p = pipeline_len;
}

static int do_subst_command(const struct sed_cmd *sed_cmd, char **line)
{
	char *hackline = *line;
	char *pipeline = 0;
	int pipeline_idx = 0;
	int pipeline_len = 0;
	int altered = 0;
	regmatch_t *regmatch = NULL;

	/* we only proceed if the substitution 'search' expression matches */
	if (regexec(sed_cmd->sub_match, hackline, 0, NULL, 0) == REG_NOMATCH)
		return 0;

	/* whaddaya know, it matched. get the number of back references */
	regmatch = xmalloc(sizeof(regmatch_t) * (sed_cmd->num_backrefs+1));

	/* allocate more PIPE_GROW bytes
	   if replaced string is larger than original */
	pipeline_len = strlen(hackline)+PIPE_GROW;
	pipeline = xmalloc(pipeline_len);
	memset(pipeline, 0, pipeline_len);
	/* buffer magic */
	pipeline[pipeline_len-1] = PIPE_MAGIC;

	/* and now, as long as we've got a line to try matching and if we can match
	 * the search string, we make substitutions */
	while ((*hackline || !altered) && (regexec(sed_cmd->sub_match, hackline,
					sed_cmd->num_backrefs+1, regmatch, 0) != REG_NOMATCH) ) {
		int i;

		/* print everything before the match */
		for (i = 0; i < regmatch[0].rm_so; i++)
			pipeputc(hackline[i]);

		/* then print the substitution string */
		print_subst_w_backrefs(hackline, sed_cmd->replace, regmatch, 
				&pipeline, &pipeline_idx, &pipeline_len,
				sed_cmd->num_backrefs);

		/* advance past the match */
		hackline += regmatch[0].rm_eo;
		/* flag that something has changed */
		altered++;

		/* if we're not doing this globally, get out now */
		if (!sed_cmd->sub_g)
			break;
	}

	for (; *hackline; hackline++) pipeputc(*hackline);
	if (pipeline[pipeline_idx] == PIPE_MAGIC) pipeline[pipeline_idx] = 0;

	/* cleanup */
	free(regmatch);

	free(*line);
	*line = pipeline;
	return altered;
}


static void process_file(FILE *file)
{
	char *line = NULL;
	static int linenum = 0; /* GNU sed does not restart counting lines at EOF */
	unsigned int still_in_range = 0;
	int altered;
	int i;

	/* go through every line in the file */
	while ((line = get_line_from_file(file)) != NULL) {

		chomp(line);
		linenum++;
		altered = 0;

		/* for every line, go through all the commands */
		for (i = 0; i < ncmds; i++) {


			/*
			 * entry point into sedding...
			 */
			if (
					/* no range necessary */
					(sed_cmds[i].beg_line == 0 && sed_cmds[i].end_line == 0 &&
					 sed_cmds[i].beg_match == NULL &&
					 sed_cmds[i].end_match == NULL) ||
					/* this line number is the first address we're looking for */
					(sed_cmds[i].beg_line && (sed_cmds[i].beg_line == linenum)) ||
					/* this line matches our first address regex */
					(sed_cmds[i].beg_match && (regexec(sed_cmds[i].beg_match, line, 0, NULL, 0) == 0)) ||
					/* we are currently within the beginning & ending address range */
					still_in_range
			   ) {
				int deleted = 0;

				/*
				 * actual sedding
				 */
				switch (sed_cmds[i].cmd) {

					case 'p':
						puts(line);
						break;

					case 'd':
						altered++;
						deleted = 1;
						break;

					case 's':

						/*
						 * Some special cases for 's' printing to make it compliant with
						 * GNU sed printing behavior (aka "The -n | s///p Matrix"):
						 *
						 *    -n ONLY = never print anything regardless of any successful
						 *    substitution
						 *
						 *    s///p ONLY = always print successful substitutions, even if
						 *    the line is going to be printed anyway (line will be printed
						 *    twice).
						 *
						 *    -n AND s///p = print ONLY a successful substitution ONE TIME;
						 *    no other lines are printed - this is the reason why the 'p'
						 *    flag exists in the first place.
						 */

						/* if the user specified that they didn't want anything printed (i.e., a -n
						 * flag and no 'p' flag after the s///), then there's really no point doing
						 * anything here. */
						if (be_quiet && !sed_cmds[i].sub_p)
							break;

						/* we print the line once, unless we were told to be quiet */
						if (!be_quiet)
							altered |= do_subst_command(&sed_cmds[i], &line);

						/* we also print the line if we were given the 'p' flag
						 * (this is quite possibly the second printing) */
						if (sed_cmds[i].sub_p)
							altered |= do_subst_command(&sed_cmds[i], &line);
						if (altered && (i+1 >= ncmds || sed_cmds[i+1].cmd != 's'))
							puts(line);

						break;

					case 'a':
						puts(line);
						fputs(sed_cmds[i].editline, stdout);
						altered++;
						break;

					case 'i':
						fputs(sed_cmds[i].editline, stdout);
						break;

					case 'c':
						/* single-address case */
						if (sed_cmds[i].end_match == NULL && sed_cmds[i].end_line == 0) {
							fputs(sed_cmds[i].editline, stdout);
						}
						/* multi-address case */
						else {
							/* matching text */
							if (sed_cmds[i].end_match && (regexec(sed_cmds[i].end_match, line, 0, NULL, 0) == 0))
								fputs(sed_cmds[i].editline, stdout);
							/* matching line numbers */
							if (sed_cmds[i].end_line > 0 && sed_cmds[i].end_line == linenum)
								fputs(sed_cmds[i].editline, stdout);
						}
						altered++;

						break;

					case 'r': {
								  FILE *outfile;
								  puts(line);
								  outfile = fopen(sed_cmds[i].filename, "r");
								  if (outfile)
									  print_file(outfile);
								  /* else if we couldn't open the output file,
								   * no biggie, just don't print anything */
								  altered++;
							  }
							  break;
				}

				/*
				 * exit point from sedding...
				 */
				if (
					/* this is a single-address command or... */
					(sed_cmds[i].end_line == 0 && sed_cmds[i].end_match == NULL) || (
						/* we were in the middle of our address range (this
						 * isn't the first time through) and.. */
						(still_in_range == 1) && (
							/* this line number is the last address we're looking for or... */
							(sed_cmds[i].end_line && (sed_cmds[i].end_line == linenum)) ||
							/* this line matches our last address regex */
							(sed_cmds[i].end_match && (regexec(sed_cmds[i].end_match, line, 0, NULL, 0) == 0))
						)
					)
				) {
					/* we're out of our address range */
					still_in_range = 0;
				}

				/* didn't hit the exit? then we're still in the middle of an address range */
				else {
					still_in_range = 1;
				}
				if (deleted)
					break;

			}
		}

		/* we will print the line unless we were told to be quiet or if the
		 * line was altered (via a 'd'elete or 's'ubstitution), in which case
		 * the altered line was already printed */
		if (!be_quiet && !altered)
			puts(line);

		free(line);
	}
}

extern int sed_main(int argc, char **argv)
{
	int opt;

#ifdef BB_FEATURE_CLEAN_UP
	/* destroy command strings on exit */
	if (atexit(destroy_cmd_strs) == -1)
		perror_msg_and_die("atexit");
#endif

	/* do normal option parsing */
	while ((opt = getopt(argc, argv, "ne:f:")) > 0) {
		switch (opt) {
			case 'n':
				be_quiet++;
				break;
			case 'e':
				add_cmd_str(optarg);
				break;
			case 'f': 
				load_cmd_file(optarg);
				break;
			default:
				show_usage();
		}
	}

	/* if we didn't get a pattern from a -e and no command file was specified,
	 * argv[optind] should be the pattern. no pattern, no worky */
	if (ncmds == 0) {
		if (argv[optind] == NULL)
			show_usage();
		else {
			add_cmd_str(argv[optind]);
			optind++;
		}
	}


	/* argv[(optind)..(argc-1)] should be names of file to process. If no
	 * files were specified or '-' was specified, take input from stdin.
	 * Otherwise, we process all the files specified. */
	if (argv[optind] == NULL || (strcmp(argv[optind], "-") == 0)) {
		process_file(stdin);
	}
	else {
		int i;
		FILE *file;
		for (i = optind; i < argc; i++) {
			file = fopen(argv[i], "r");
			if (file == NULL) {
				perror_msg("%s", argv[i]);
			} else {
				process_file(file);
				fclose(file);
			}
		}
	}
	
	return 0;
}