hush/sed.c

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1999-10-28 16:06:25 +00:00
/*
* sed.c - very minimalist version of sed
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*
* Copyright (C) 1999,2000,2001 by Lineo, inc.
* Written by Mark Whitley <markw@lineo.com>, <markw@codepoet.org>
*
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* 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
*
*/
/*
Supported features and commands in this version of sed:
- comments ('#')
- address matching: num|/matchstr/[,num|/matchstr/|$]command
- commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
- edit commands: (a)ppend, (i)nsert, (c)hange
- backreferences in substitution expressions (\1, \2...\9)
(Note: Specifying an address (range) to match is *optional*; commands
default to the whole pattern space if no specific address match was
requested.)
Unsupported features:
- transliteration (y/source-chars/dest-chars/) (use 'tr')
- no pattern space hold space storing / swapping (x, etc.)
- no labels / branching (: label, b, t, and friends)
- and lots, lots more.
*/
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#include <stdio.h>
#include <unistd.h> /* for getopt() */
#include <regex.h>
#include <string.h> /* for strdup() */
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#include <errno.h>
#include <ctype.h> /* for isspace() */
#include <stdlib.h>
#include "busybox.h"
/* externs */
extern void xregcomp(regex_t *preg, const char *regex, int cflags);
extern int optind; /* in unistd.h */
extern char *optarg; /* ditto */
/* options */
static int be_quiet = 0;
struct sed_cmd {
/* GENERAL FIELDS */
char delimiter; /* The delimiter used to separate regexps */
/* address storage */
int beg_line; /* 'sed 1p' 0 == no begining line, apply commands to all lines */
int end_line; /* 'sed 1,3p' 0 == no end line, use only beginning. -1 == $ */
regex_t *beg_match; /* sed -e '/match/cmd' */
regex_t *end_match; /* sed -e '/match/,/end_match/cmd' */
/* the command */
char cmd; /* p,d,s (add more at your leisure :-) */
/* SUBSTITUTION COMMAND SPECIFIC FIELDS */
/* sed -e 's/sub_match/replace/' */
regex_t *sub_match;
char *replace;
unsigned int num_backrefs:4; /* how many back references (\1..\9) */
/* Note: GNU/POSIX sed does not save more than nine backrefs, so
* we only use 4 bits to hold the number */
unsigned int sub_g:1; /* sed -e 's/foo/bar/g' (global) */
unsigned int sub_p:2; /* sed -e 's/foo/bar/p' (print substitution) */
/* EDIT COMMAND (a,i,c) SPEICIFIC FIELDS */
char *editline;
};
/* globals */
static struct sed_cmd *sed_cmds = NULL; /* growable arrary holding a sequence of sed cmds */
static int ncmds = 0; /* number of sed commands */
/*static char *cur_file = NULL;*/ /* file currently being processed XXX: do I need this? */
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#ifdef BB_FEATURE_CLEAN_UP
static void destroy_cmd_strs()
{
if (sed_cmds == NULL)
return;
/* destroy all the elements in the array */
while (--ncmds >= 0) {
if (sed_cmds[ncmds].beg_match) {
regfree(sed_cmds[ncmds].beg_match);
free(sed_cmds[ncmds].beg_match);
}
if (sed_cmds[ncmds].end_match) {
regfree(sed_cmds[ncmds].end_match);
free(sed_cmds[ncmds].end_match);
}
if (sed_cmds[ncmds].sub_match) {
regfree(sed_cmds[ncmds].sub_match);
free(sed_cmds[ncmds].sub_match);
}
if (sed_cmds[ncmds].replace)
free(sed_cmds[ncmds].replace);
}
/* destroy the array */
free(sed_cmds);
sed_cmds = NULL;
}
#endif
/*
* index_of_next_unescaped_regexp_delim - walks left to right through a string
* beginning at a specified index and returns the index of the next regular
* expression delimiter (typically a forward * slash ('/')) not preceeded by
* a backslash ('\').
*/
static int index_of_next_unescaped_regexp_delim(struct sed_cmd *sed_cmd, const char *str, int idx)
{
for ( ; str[idx]; idx++) {
if (str[idx] == sed_cmd->delimiter && str[idx-1] != '\\')
return idx;
}
/* if we make it to here, we've hit the end of the string */
return -1;
}
/*
* returns the index in the string just past where the address ends.
*/
static int get_address(struct sed_cmd *sed_cmd, const char *str, int *line, regex_t **regex)
{
char *my_str = strdup(str);
int idx = 0;
char olddelimiter;
olddelimiter = sed_cmd->delimiter;
sed_cmd->delimiter = '/';
if (isdigit(my_str[idx])) {
do {
idx++;
} while (isdigit(my_str[idx]));
my_str[idx] = 0;
*line = atoi(my_str);
}
else if (my_str[idx] == '$') {
*line = -1;
idx++;
}
else if (my_str[idx] == '/') {
idx = index_of_next_unescaped_regexp_delim(sed_cmd, my_str, ++idx);
if (idx == -1)
error_msg_and_die("unterminated match expression");
my_str[idx] = '\0';
*regex = (regex_t *)xmalloc(sizeof(regex_t));
xregcomp(*regex, my_str+1, 0);
idx++; /* so it points to the next character after the last '/' */
}
else {
error_msg("get_address: no address found in string\n"
"\t(you probably didn't check the string you passed me)");
idx = -1;
}
free(my_str);
sed_cmd->delimiter = olddelimiter;
return idx;
}
static char *strdup_substr(const char *str, int start, int end)
{
int size = end - start + 1;
char *newstr = xmalloc(size);
memcpy(newstr, str+start, size-1);
newstr[size-1] = '\0';
return newstr;
}
static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
{
int oldidx, cflags = REG_NEWLINE;
char *match;
int idx = 0;
int j;
/*
* the string that gets passed to this function should look like this:
* s/match/replace/gIp
* || | |||
* mandatory optional
*
* (all three of the '/' slashes are mandatory)
*/
/* verify that the 's' is followed by something. That something
* (typically a 'slash') is now our regexp delimiter... */
if (!substr[++idx])
error_msg_and_die("bad format in substitution expression");
else
sed_cmd->delimiter=substr[idx];
/* save the match string */
oldidx = idx+1;
idx = index_of_next_unescaped_regexp_delim(sed_cmd, substr, ++idx);
if (idx == -1)
error_msg_and_die("bad format in substitution expression");
match = strdup_substr(substr, oldidx, idx);
/* determine the number of back references in the match string */
/* Note: we compute this here rather than in the do_subst_command()
* function to save processor time, at the expense of a little more memory
* (4 bits) per sed_cmd */
/* sed_cmd->num_backrefs = 0; */ /* XXX: not needed? --apparently not */
for (j = 0; match[j]; j++) {
/* GNU/POSIX sed does not save more than nine backrefs */
if (match[j] == '\\' && match[j+1] == '(' && sed_cmd->num_backrefs <= 9)
sed_cmd->num_backrefs++;
}
/* save the replacement string */
oldidx = idx+1;
idx = index_of_next_unescaped_regexp_delim(sed_cmd, substr, ++idx);
if (idx == -1)
error_msg_and_die("bad format in substitution expression");
sed_cmd->replace = strdup_substr(substr, oldidx, idx);
/* process the flags */
while (substr[++idx]) {
switch (substr[idx]) {
case 'g':
sed_cmd->sub_g = 1;
break;
case 'I':
cflags |= REG_ICASE;
break;
case 'p':
sed_cmd->sub_p = 1;
break;
default:
/* any whitespace or semicolon trailing after a s/// is ok */
if (strchr("; \t\v\n\r", substr[idx]))
goto out;
/* else */
error_msg_and_die("bad option in substitution expression");
}
}
out:
/* compile the match string into a regex */
sed_cmd->sub_match = (regex_t *)xmalloc(sizeof(regex_t));
xregcomp(sed_cmd->sub_match, match, cflags);
free(match);
return idx;
}
static int parse_edit_cmd(struct sed_cmd *sed_cmd, const char *editstr)
{
int idx = 0;
int slashes_eaten = 0;
char *ptr; /* shorthand */
/*
* the string that gets passed to this function should look like this:
*
* need one of these
* |
* | this backslash (immediately following the edit command) is mandatory
* | |
* [aic]\
* TEXT1\
* TEXT2\
* TEXTN
*
* as soon as we hit a TEXT line that has no trailing '\', we're done.
* this means a command like:
*
* i\
* INSERTME
*
* is a-ok.
*
*/
if (editstr[1] != '\\' && (editstr[2] != '\n' || editstr[2] != '\r'))
error_msg_and_die("bad format in edit expression");
/* store the edit line text */
/* make editline big enough to accomodate the extra '\n' we will tack on
* to the end */
sed_cmd->editline = xmalloc(strlen(&editstr[3]) + 2);
strcpy(sed_cmd->editline, &editstr[3]);
ptr = sed_cmd->editline;
/* now we need to go through * and: s/\\[\r\n]$/\n/g on the edit line */
while (ptr[idx]) {
while (ptr[idx] != '\\' && (ptr[idx+1] != '\n' || ptr[idx+1] != '\r')) {
idx++;
if (!ptr[idx]) {
goto out;
}
}
/* move the newline over the '\' before it (effectively eats the '\') */
memmove(&ptr[idx], &ptr[idx+1], strlen(&ptr[idx+1]));
ptr[strlen(ptr)-1] = 0;
slashes_eaten++;
/* substitue \r for \n if needed */
if (ptr[idx] == '\r')
ptr[idx] = '\n';
}
out:
ptr[idx] = '\n';
ptr[idx+1] = 0;
/* this accounts for discrepancies between the modified string and the
* original string passed in to this function */
idx += slashes_eaten;
/* this accounts for the fact that A) we started at index 3, not at index
* 0 and B) that we added an extra '\n' at the end (if you think the next
* line should read 'idx += 4' remember, arrays are zero-based) */
idx += 3;
return idx;
}
static char *parse_cmd_str(struct sed_cmd *sed_cmd, const char *cmdstr)
{
int idx = 0;
/* parse the command
* format is: [addr][,addr]cmd
* |----||-----||-|
* part1 part2 part3
*/
/* first part (if present) is an address: either a number or a /regex/ */
if (isdigit(cmdstr[idx]) || cmdstr[idx] == '/')
idx = get_address(sed_cmd, cmdstr, &sed_cmd->beg_line, &sed_cmd->beg_match);
/* second part (if present) will begin with a comma */
if (cmdstr[idx] == ',')
idx += get_address(sed_cmd, &cmdstr[++idx], &sed_cmd->end_line, &sed_cmd->end_match);
/* last part (mandatory) will be a command */
if (cmdstr[idx] == '\0')
error_msg_and_die("missing command");
if (!strchr("pdsaic", cmdstr[idx])) /* <-- XXX add new commands here */
error_msg_and_die("invalid command");
sed_cmd->cmd = cmdstr[idx];
/* special-case handling for (s)ubstitution */
if (sed_cmd->cmd == 's') {
idx += parse_subst_cmd(sed_cmd, &cmdstr[idx]);
}
/* special-case handling for (a)ppend, (i)nsert, and (c)hange */
else if (strchr("aic", cmdstr[idx])) {
if (sed_cmd->end_line || sed_cmd->end_match)
error_msg_and_die("only a beginning address can be specified for edit commands");
idx += parse_edit_cmd(sed_cmd, &cmdstr[idx]);
}
/* if it was a single-letter command (such as 'p' or 'd') we need to
* increment the index past that command */
else
idx++;
/* 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));
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}
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static void load_cmd_file(char *filename)
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{
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);
}
}
static void print_subst_w_backrefs(const char *line, const char *replace, regmatch_t *regmatch)
{
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] */
for (j = regmatch[backref].rm_so; j < regmatch[backref].rm_eo; j++)
fputc(line[j], stdout);
}
/* if we find a backslash escaped character, print the character */
else if (replace[i] == '\\') {
++i;
fputc(replace[i], stdout);
}
/* 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++)
fputc(line[j], stdout);
}
/* nothing special, just print this char of the replacement string to stdout */
else
fputc(replace[i], stdout);
}
}
static int do_subst_command(const struct sed_cmd *sed_cmd, const char *line)
{
char *hackline = (char *)line;
int altered = 0;
regmatch_t *regmatch = NULL;
/* we only proceed if the substitution 'search' expression matches */
if (regexec(sed_cmd->sub_match, line, 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));
/* 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 && (regexec(sed_cmd->sub_match, hackline,
sed_cmd->num_backrefs+1, regmatch, 0) == 0) ) {
int i;
/* print everything before the match */
for (i = 0; i < regmatch[0].rm_so; i++)
fputc(hackline[i], stdout);
/* then print the substitution string */
print_subst_w_backrefs(hackline, sed_cmd->replace, regmatch);
/* 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;
}
/* if there's anything left of the line, print it */
if (*hackline)
fputs(hackline, stdout);
/* cleanup */
free(regmatch);
return altered;
}
static int do_sed_command(const struct sed_cmd *sed_cmd, const char *line)
{
int altered = 0;
switch (sed_cmd->cmd) {
case 'p':
fputs(line, stdout);
break;
case 'd':
altered++;
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_cmd->sub_p)
break;
/* we print the line once, unless we were told to be quiet */
if (!be_quiet)
altered = do_subst_command(sed_cmd, line);
/* we also print the line if we were given the 'p' flag
* (this is quite possibly the second printing) */
if (sed_cmd->sub_p)
altered = do_subst_command(sed_cmd, line);
break;
case 'a':
fputs(line, stdout);
fputs(sed_cmd->editline, stdout);
altered++;
break;
case 'i':
fputs(sed_cmd->editline, stdout);
break;
case 'c':
fputs(sed_cmd->editline, stdout);
altered++;
break;
}
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 line_altered;
int i;
/* go through every line in the file */
while ((line = get_line_from_file(file)) != NULL) {
linenum++;
line_altered = 0;
/* for every line, go through all the commands */
for (i = 0; i < ncmds; i++) {
/* are we acting on a range of matched lines? */
if (sed_cmds[i].beg_match && sed_cmds[i].end_match) {
if (still_in_range || regexec(sed_cmds[i].beg_match, line, 0, NULL, 0) == 0) {
line_altered += do_sed_command(&sed_cmds[i], line);
if (still_in_range && regexec(sed_cmds[i].end_match, line, 0, NULL, 0) == 0)
still_in_range = 0;
else
still_in_range = 1;
}
}
/* are we trying to match a single line? */
else if (sed_cmds[i].beg_match) {
if (regexec(sed_cmds[i].beg_match, line, 0, NULL, 0) == 0)
line_altered += do_sed_command(&sed_cmds[i], line);
}
/* are we acting on a range of line numbers? */
else if (sed_cmds[i].beg_line > 0 && sed_cmds[i].end_line != 0) {
if (linenum >= sed_cmds[i].beg_line &&
(sed_cmds[i].end_line == -1 || linenum <= sed_cmds[i].end_line))
line_altered += do_sed_command(&sed_cmds[i], line);
}
/* are we acting on a specified line number */
else if (sed_cmds[i].beg_line > 0) {
if (linenum == sed_cmds[i].beg_line)
line_altered += do_sed_command(&sed_cmds[i], line);
}
/* not acting on matches or line numbers. act on every line */
else
line_altered += do_sed_command(&sed_cmds[i], line);
}
/* 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 && !line_altered)
fputs(line, stdout);
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);
}
}
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}
return 0;
}