source: MondoRescue/branches/stable/mindi-busybox/editors/sed.c

/* vi: set sw=4 ts=4: */
/*
 * sed.c - very minimalist version of sed
 *
 * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
 * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
 * Copyright (C) 2002  Matt Kraai
 * Copyright (C) 2003 by Glenn McGrath <bug1@iinet.net.au>
 * Copyright (C) 2003,2004 by Rob Landley <rob@landley.net>
 *
 * MAINTAINER: Rob Landley <rob@landley.net>
 *
 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
 */

/* Code overview.

  Files are laid out to avoid unnecessary function declarations.  So for
  example, every function add_cmd calls occurs before add_cmd in this file.

  add_cmd() is called on each line of sed command text (from a file or from
  the command line).  It calls get_address() and parse_cmd_args().  The
  resulting sed_cmd_t structures are appended to a linked list
  (G.sed_cmd_head/G.sed_cmd_tail).

  add_input_file() adds a FILE * to the list of input files.  We need to
  know all input sources ahead of time to find the last line for the $ match.

  process_files() does actual sedding, reading data lines from each input FILE *
  (which could be stdin) and applying the sed command list (sed_cmd_head) to
  each of the resulting lines.

  sed_main() is where external code calls into this, with a command line.
*/


/*
    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
     - file commands: (r)ead
     - backreferences in substitution expressions (\0, \1, \2...\9)
     - grouped commands: {cmd1;cmd2}
     - transliteration (y/source-chars/dest-chars/)
     - pattern space hold space storing / swapping (g, h, x)
     - labels / branching (: label, b, t, T)

     (Note: Specifying an address (range) to match is *optional*; commands
     default to the whole pattern space if no specific address match was
     requested.)

    Todo:
     - Create a wrapper around regex to make libc's regex conform with sed

    Reference http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
*/

#include "libbb.h"
#include "xregex.h"

/* Each sed command turns into one of these structures. */
typedef struct sed_cmd_s {
    /* Ordered by alignment requirements: currently 36 bytes on x86 */
    struct sed_cmd_s *next; /* Next command (linked list, NULL terminated) */

    /* address storage */
    regex_t *beg_match;     /* sed -e '/match/cmd' */
    regex_t *end_match;     /* sed -e '/match/,/end_match/cmd' */
    regex_t *sub_match;     /* For 's/sub_match/string/' */
    int beg_line;           /* 'sed 1p'   0 == apply commands to all lines */
    int end_line;           /* 'sed 1,3p' 0 == one line only. -1 = last line ($) */

    FILE *sw_file;          /* File (sw) command writes to, -1 for none. */
    char *string;           /* Data string for (saicytb) commands. */

    unsigned short which_match; /* (s) Which match to replace (0 for all) */

    /* Bitfields (gcc won't group them if we don't) */
    unsigned invert:1;      /* the '!' after the address */
    unsigned in_match:1;    /* Next line also included in match? */
    unsigned sub_p:1;       /* (s) print option */

    char sw_last_char;      /* Last line written by (sw) had no '\n' */

    /* GENERAL FIELDS */
    char cmd;               /* The command char: abcdDgGhHilnNpPqrstwxy:={} */
} sed_cmd_t;

static const char semicolon_whitespace[] ALIGN1 = "; \n\r\t\v";

struct globals {
    /* options */
    int be_quiet, regex_type;
    FILE *nonstdout;
    char *outname, *hold_space;

    /* List of input files */
    int input_file_count, current_input_file;
    FILE **input_file_list;

    regmatch_t regmatch[10];
    regex_t *previous_regex_ptr;

    /* linked list of sed commands */
    sed_cmd_t sed_cmd_head, *sed_cmd_tail;

    /* Linked list of append lines */
    llist_t *append_head;

    char *add_cmd_line;

    struct pipeline {
        char *buf;  /* Space to hold string */
        int idx;    /* Space used */
        int len;    /* Space allocated */
    } pipeline;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
void BUG_sed_globals_too_big(void);
#define INIT_G() do { \
    if (sizeof(struct globals) > COMMON_BUFSIZE) \
        BUG_sed_globals_too_big(); \
    G.sed_cmd_tail = &G.sed_cmd_head; \
} while (0)


#if ENABLE_FEATURE_CLEAN_UP
static void sed_free_and_close_stuff(void)
{
    sed_cmd_t *sed_cmd = G.sed_cmd_head.next;

    llist_free(G.append_head, free);

    while (sed_cmd) {
        sed_cmd_t *sed_cmd_next = sed_cmd->next;

        if (sed_cmd->sw_file)
            xprint_and_close_file(sed_cmd->sw_file);

        if (sed_cmd->beg_match) {
            regfree(sed_cmd->beg_match);
            free(sed_cmd->beg_match);
        }
        if (sed_cmd->end_match) {
            regfree(sed_cmd->end_match);
            free(sed_cmd->end_match);
        }
        if (sed_cmd->sub_match) {
            regfree(sed_cmd->sub_match);
            free(sed_cmd->sub_match);
        }
        free(sed_cmd->string);
        free(sed_cmd);
        sed_cmd = sed_cmd_next;
    }

    if (G.hold_space) free(G.hold_space);

    while (G.current_input_file < G.input_file_count)
        fclose(G.input_file_list[G.current_input_file++]);
}
#else
void sed_free_and_close_stuff(void);
#endif

/* If something bad happens during -i operation, delete temp file */

static void cleanup_outname(void)
{
    if (G.outname) unlink(G.outname);
}

/* strdup, replacing "\n" with '\n', and "\delimiter" with 'delimiter' */

static void parse_escapes(char *dest, const char *string, int len, char from, char to)
{
    int i = 0;

    while (i < len) {
        if (string[i] == '\\') {
            if (!to || string[i+1] == from) {
                *dest++ = to ? to : string[i+1];
                i += 2;
                continue;
            }
            *dest++ = string[i++];
        }
        *dest++ = string[i++];
    }
    *dest = 0;
}

static char *copy_parsing_escapes(const char *string, int len)
{
    char *dest = xmalloc(len + 1);

    parse_escapes(dest, string, len, 'n', '\n');
    return dest;
}


/*
 * 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 preceded by
 * a backslash ('\').  A negative delimiter disables square bracket checking.
 */
static int index_of_next_unescaped_regexp_delim(int delimiter, const char *str)
{
    int bracket = -1;
    int escaped = 0;
    int idx = 0;
    char ch;

    if (delimiter < 0) {
        bracket--;
        delimiter = -delimiter;
    }

    for (; (ch = str[idx]); idx++) {
        if (bracket >= 0) {
            if (ch == ']' && !(bracket == idx - 1 || (bracket == idx - 2
                    && str[idx - 1] == '^')))
                bracket = -1;
        } else if (escaped)
            escaped = 0;
        else if (ch == '\\')
            escaped = 1;
        else if (bracket == -1 && ch == '[')
            bracket = idx;
        else if (ch == delimiter)
            return idx;
    }

    /* if we make it to here, we've hit the end of the string */
    bb_error_msg_and_die("unmatched '%c'", delimiter);
}

/*
 *  Returns the index of the third delimiter
 */
static int parse_regex_delim(const char *cmdstr, char **match, char **replace)
{
    const char *cmdstr_ptr = cmdstr;
    char delimiter;
    int idx = 0;

    /* verify that the 's' or 'y' is followed by something.  That something
     * (typically a 'slash') is now our regexp delimiter... */
    if (*cmdstr == '\0')
        bb_error_msg_and_die("bad format in substitution expression");
    delimiter = *cmdstr_ptr++;

    /* save the match string */
    idx = index_of_next_unescaped_regexp_delim(delimiter, cmdstr_ptr);
    *match = copy_parsing_escapes(cmdstr_ptr, idx);

    /* save the replacement string */
    cmdstr_ptr += idx + 1;
    idx = index_of_next_unescaped_regexp_delim(-delimiter, cmdstr_ptr);
    *replace = copy_parsing_escapes(cmdstr_ptr, idx);

    return ((cmdstr_ptr - cmdstr) + idx);
}

/*
 * returns the index in the string just past where the address ends.
 */
static int get_address(const char *my_str, int *linenum, regex_t ** regex)
{
    const char *pos = my_str;

    if (isdigit(*my_str)) {
        *linenum = strtol(my_str, (char**)&pos, 10);
        /* endstr shouldnt ever equal NULL */
    } else if (*my_str == '$') {
        *linenum = -1;
        pos++;
    } else if (*my_str == '/' || *my_str == '\\') {
        int next;
        char delimiter;
        char *temp;

        delimiter = '/';
        if (*my_str == '\\') delimiter = *++pos;
        next = index_of_next_unescaped_regexp_delim(delimiter, ++pos);
        temp = copy_parsing_escapes(pos, next);
        *regex = xmalloc(sizeof(regex_t));
        xregcomp(*regex, temp, G.regex_type|REG_NEWLINE);
        free(temp);
        /* Move position to next character after last delimiter */
        pos += (next+1);
    }
    return pos - my_str;
}

/* Grab a filename.  Whitespace at start is skipped, then goes to EOL. */
static int parse_file_cmd(sed_cmd_t *sed_cmd, const char *filecmdstr, char **retval)
{
    int start = 0, idx, hack = 0;

    /* Skip whitespace, then grab filename to end of line */
    while (isspace(filecmdstr[start]))
        start++;
    idx = start;
    while (filecmdstr[idx] && filecmdstr[idx] != '\n')
        idx++;

    /* If lines glued together, put backslash back. */
    if (filecmdstr[idx] == '\n')
        hack = 1;
    if (idx == start)
        bb_error_msg_and_die("empty filename");
    *retval = xstrndup(filecmdstr+start, idx-start+hack+1);
    if (hack)
        (*retval)[idx] = '\\';

    return idx;
}

static int parse_subst_cmd(sed_cmd_t *sed_cmd, const char *substr)
{
    int cflags = G.regex_type;
    char *match;
    int idx;

    /*
     * A substitution command should look something like this:
     *    s/match/replace/ #gIpw
     *    ||     |        |||
     *    mandatory       optional
     */
    idx = parse_regex_delim(substr, &match, &sed_cmd->string);

    /* 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 */

    /* process the flags */

    sed_cmd->which_match = 1;
    while (substr[++idx]) {
        /* Parse match number */
        if (isdigit(substr[idx])) {
            if (match[0] != '^') {
                /* Match 0 treated as all, multiple matches we take the last one. */
                const char *pos = substr + idx;
/* FIXME: error check? */
                sed_cmd->which_match = (unsigned short)strtol(substr+idx, (char**) &pos, 10);
                idx = pos - substr;
            }
            continue;
        }
        /* Skip spaces */
        if (isspace(substr[idx])) continue;

        switch (substr[idx]) {
        /* Replace all occurrences */
        case 'g':
            if (match[0] != '^') sed_cmd->which_match = 0;
            break;
        /* Print pattern space */
        case 'p':
            sed_cmd->sub_p = 1;
            break;
        /* Write to file */
        case 'w':
        {
            char *temp;
            idx += parse_file_cmd(sed_cmd, substr+idx, &temp);
            break;
        }
        /* Ignore case (gnu exension) */
        case 'I':
            cflags |= REG_ICASE;
            break;
        /* Comment */
        case '#':
            while (substr[++idx]) /*skip all*/;
            /* Fall through */
        /* End of command */
        case ';':
        case '}':
            goto out;
        default:
            bb_error_msg_and_die("bad option in substitution expression");
        }
    }
out:
    /* compile the match string into a regex */
    if (*match != '\0') {
        /* If match is empty, we use last regex used at runtime */
        sed_cmd->sub_match = xmalloc(sizeof(regex_t));
        xregcomp(sed_cmd->sub_match, match, cflags);
    }
    free(match);

    return idx;
}

/*
 *  Process the commands arguments
 */
static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
{
    /* handle (s)ubstitution command */
    if (sed_cmd->cmd == 's')
        cmdstr += parse_subst_cmd(sed_cmd, cmdstr);
    /* 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')
            bb_error_msg_and_die
                ("only a beginning address can be specified for edit commands");
        for (;;) {
            if (*cmdstr == '\n' || *cmdstr == '\\') {
                cmdstr++;
                break;
            } else if (isspace(*cmdstr))
                cmdstr++;
            else
                break;
        }
        sed_cmd->string = xstrdup(cmdstr);
        parse_escapes(sed_cmd->string, sed_cmd->string, strlen(cmdstr), 0, 0);
        cmdstr += strlen(cmdstr);
    /* handle file cmds: (r)ead */
    } else if (strchr("rw", sed_cmd->cmd)) {
        if (sed_cmd->end_line || sed_cmd->end_match)
            bb_error_msg_and_die("command only uses one address");
        cmdstr += parse_file_cmd(sed_cmd, cmdstr, &sed_cmd->string);
        if (sed_cmd->cmd == 'w') {
            sed_cmd->sw_file = xfopen(sed_cmd->string, "w");
            sed_cmd->sw_last_char = '\n';
        }
    /* handle branch commands */
    } else if (strchr(":btT", sed_cmd->cmd)) {
        int length;

        cmdstr = skip_whitespace(cmdstr);
        length = strcspn(cmdstr, semicolon_whitespace);
        if (length) {
            sed_cmd->string = xstrndup(cmdstr, length);
            cmdstr += length;
        }
    }
    /* translation command */
    else if (sed_cmd->cmd == 'y') {
        char *match, *replace;
        int i = cmdstr[0];

        cmdstr += parse_regex_delim(cmdstr, &match, &replace)+1;
        /* \n already parsed, but \delimiter needs unescaping. */
        parse_escapes(match, match, strlen(match), i, i);
        parse_escapes(replace, replace, strlen(replace), i, i);

        sed_cmd->string = xzalloc((strlen(match) + 1) * 2);
        for (i = 0; match[i] && replace[i]; i++) {
            sed_cmd->string[i*2] = match[i];
            sed_cmd->string[i*2+1] = replace[i];
        }
        free(match);
        free(replace);
    }
    /* if it wasnt a single-letter command that takes no arguments
     * then it must be an invalid command.
     */
    else if (strchr("dDgGhHlnNpPqx={}", sed_cmd->cmd) == 0) {
        bb_error_msg_and_die("unsupported command %c", sed_cmd->cmd);
    }

    /* give back whatever's left over */
    return cmdstr;
}


/* Parse address+command sets, skipping comment lines. */

static void add_cmd(const char *cmdstr)
{
    sed_cmd_t *sed_cmd;
    int temp;

    /* Append this line to any unfinished line from last time. */
    if (G.add_cmd_line) {
        char *tp = xasprintf("%s\n%s", G.add_cmd_line, cmdstr);
        free(G.add_cmd_line);
        cmdstr = G.add_cmd_line = tp;
    }

    /* If this line ends with backslash, request next line. */
    temp = strlen(cmdstr);
    if (temp && cmdstr[--temp] == '\\') {
        if (!G.add_cmd_line)
            G.add_cmd_line = xstrdup(cmdstr);
        G.add_cmd_line[temp] = '\0';
        return;
    }

    /* Loop parsing all commands in this line. */
    while (*cmdstr) {
        /* Skip leading whitespace and semicolons */
        cmdstr += strspn(cmdstr, semicolon_whitespace);

        /* If no more commands, exit. */
        if (!*cmdstr) break;

        /* if this is a comment, jump past it and keep going */
        if (*cmdstr == '#') {
            /* "#n" is the same as using -n on the command line */
            if (cmdstr[1] == 'n')
                G.be_quiet++;
            cmdstr = strpbrk(cmdstr, "\n\r");
            if (!cmdstr) break;
            continue;
        }

        /* parse the command
         * format is: [addr][,addr][!]cmd
         *            |----||-----||-|
         *            part1 part2  part3
         */

        sed_cmd = xzalloc(sizeof(sed_cmd_t));

        /* first part (if present) is an address: either a '$', a number or a /regex/ */
        cmdstr += get_address(cmdstr, &sed_cmd->beg_line, &sed_cmd->beg_match);

        /* second part (if present) will begin with a comma */
        if (*cmdstr == ',') {
            int idx;

            cmdstr++;
            idx = get_address(cmdstr, &sed_cmd->end_line, &sed_cmd->end_match);
            if (!idx)
                bb_error_msg_and_die("no address after comma");
            cmdstr += idx;
        }

        /* skip whitespace before the command */
        cmdstr = skip_whitespace(cmdstr);

        /* Check for inversion flag */
        if (*cmdstr == '!') {
            sed_cmd->invert = 1;
            cmdstr++;

            /* skip whitespace before the command */
            cmdstr = skip_whitespace(cmdstr);
        }

        /* last part (mandatory) will be a command */
        if (!*cmdstr)
            bb_error_msg_and_die("missing command");
        sed_cmd->cmd = *(cmdstr++);
        cmdstr = parse_cmd_args(sed_cmd, cmdstr);

        /* Add the command to the command array */
        G.sed_cmd_tail->next = sed_cmd;
        G.sed_cmd_tail = G.sed_cmd_tail->next;
    }

    /* If we glued multiple lines together, free the memory. */
    free(G.add_cmd_line);
    G.add_cmd_line = NULL;
}

/* Append to a string, reallocating memory as necessary. */

#define PIPE_GROW 64

static void pipe_putc(char c)
{
    if (G.pipeline.idx == G.pipeline.len) {
        G.pipeline.buf = xrealloc(G.pipeline.buf,
                G.pipeline.len + PIPE_GROW);
        G.pipeline.len += PIPE_GROW;
    }
    G.pipeline.buf[G.pipeline.idx++] = c;
}

static void do_subst_w_backrefs(char *line, char *replace)
{
    int i,j;

    /* 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] == '\\') {
            unsigned backref = replace[++i] - '0';
            if (backref <= 9) {
                /* print out the text held in G.regmatch[backref] */
                if (G.regmatch[backref].rm_so != -1) {
                    j = G.regmatch[backref].rm_so;
                    while (j < G.regmatch[backref].rm_eo)
                        pipe_putc(line[j++]);
                }
                continue;
            }
            /* I _think_ it is impossible to get '\' to be
             * the last char in replace string. Thus we dont check
             * for replace[i] == NUL. (counterexample anyone?) */
            /* if we find a backslash escaped character, print the character */
            pipe_putc(replace[i]);
            continue;
        }
        /* if we find an unescaped '&' print out the whole matched text. */
        if (replace[i] == '&') {
            j = G.regmatch[0].rm_so;
            while (j < G.regmatch[0].rm_eo)
                pipe_putc(line[j++]);
            continue;
        }
        /* Otherwise just output the character. */
        pipe_putc(replace[i]);
    }
}

static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
{
    char *oldline = *line;
    int altered = 0;
    int match_count = 0;
    regex_t *current_regex;

    /* Handle empty regex. */
    if (sed_cmd->sub_match == NULL) {
        current_regex = G.previous_regex_ptr;
        if (!current_regex)
            bb_error_msg_and_die("no previous regexp");
    } else
        G.previous_regex_ptr = current_regex = sed_cmd->sub_match;

    /* Find the first match */
    if (REG_NOMATCH == regexec(current_regex, oldline, 10, G.regmatch, 0))
        return 0;

    /* Initialize temporary output buffer. */
    G.pipeline.buf = xmalloc(PIPE_GROW);
    G.pipeline.len = PIPE_GROW;
    G.pipeline.idx = 0;

    /* Now loop through, substituting for matches */
    do {
        int i;

        /* Work around bug in glibc regexec, demonstrated by:
           echo " a.b" | busybox sed 's [^ .]* x g'
           The match_count check is so not to break
           echo "hi" | busybox sed 's/^/!/g' */
        if (!G.regmatch[0].rm_so && !G.regmatch[0].rm_eo && match_count) {
            pipe_putc(*oldline++);
            continue;
        }

        match_count++;

        /* If we aren't interested in this match, output old line to
           end of match and continue */
        if (sed_cmd->which_match && sed_cmd->which_match != match_count) {
            for (i = 0; i < G.regmatch[0].rm_eo; i++)
                pipe_putc(*oldline++);
            continue;
        }

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

        /* then print the substitution string */
        do_subst_w_backrefs(oldline, sed_cmd->string);

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

        /* if we're not doing this globally, get out now */
        if (sed_cmd->which_match) break;
    } while (*oldline && (regexec(current_regex, oldline, 10, G.regmatch, 0) != REG_NOMATCH));

    /* Copy rest of string into output pipeline */

    while (*oldline)
        pipe_putc(*oldline++);
    pipe_putc(0);

    free(*line);
    *line = G.pipeline.buf;
    return altered;
}

/* Set command pointer to point to this label.  (Does not handle null label.) */
static sed_cmd_t *branch_to(char *label)
{
    sed_cmd_t *sed_cmd;

    for (sed_cmd = G.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next) {
        if (sed_cmd->cmd == ':' && sed_cmd->string && !strcmp(sed_cmd->string, label)) {
            return sed_cmd;
        }
    }
    bb_error_msg_and_die("can't find label for jump to '%s'", label);
}

static void append(char *s)
{
    llist_add_to_end(&G.append_head, xstrdup(s));
}

static void flush_append(void)
{
    char *data;

    /* Output appended lines. */
    while ((data = (char *)llist_pop(&G.append_head))) {
        fprintf(G.nonstdout, "%s\n", data);
        free(data);
    }
}

static void add_input_file(FILE *file)
{
    G.input_file_list = xrealloc(G.input_file_list,
            (G.input_file_count + 1) * sizeof(FILE *));
    G.input_file_list[G.input_file_count++] = file;
}

/* Get next line of input from G.input_file_list, flushing append buffer and
 * noting if we ran out of files without a newline on the last line we read.
 */
enum {
    NO_EOL_CHAR = 1,
    LAST_IS_NUL = 2,
};
static char *get_next_line(char *gets_char)
{
    char *temp = NULL;
    int len;
    char gc;

    flush_append();

    /* will be returned if last line in the file
     * doesn't end with either '\n' or '\0' */
    gc = NO_EOL_CHAR;
    while (G.current_input_file < G.input_file_count) {
        FILE *fp = G.input_file_list[G.current_input_file];
        /* Read line up to a newline or NUL byte, inclusive,
         * return malloc'ed char[]. length of the chunk read
         * is stored in len. NULL if EOF/error */
        temp = bb_get_chunk_from_file(fp, &len);
        if (temp) {
            /* len > 0 here, it's ok to do temp[len-1] */
            char c = temp[len-1];
            if (c == '\n' || c == '\0') {
                temp[len-1] = '\0';
                gc = c;
                if (c == '\0') {
                    int ch = fgetc(fp);
                    if (ch != EOF)
                        ungetc(ch, fp);
                    else
                        gc = LAST_IS_NUL;
                }
            }
            /* else we put NO_EOL_CHAR into *gets_char */
            break;

        /* NB: I had the idea of peeking next file(s) and returning
         * NO_EOL_CHAR only if it is the *last* non-empty
         * input file. But there is a case where this won't work:
         * file1: "a woo\nb woo"
         * file2: "c no\nd no"
         * sed -ne 's/woo/bang/p' input1 input2 => "a bang\nb bang"
         * (note: *no* newline after "b bang"!) */
        }
        /* Close this file and advance to next one */
        fclose(fp);
        G.current_input_file++;
    }
    *gets_char = gc;
    return temp;
}

/* Output line of text. */
/* Note:
 * The tricks with NO_EOL_CHAR and last_puts_char are there to emulate gnu sed.
 * Without them, we had this:
 * echo -n thingy >z1
 * echo -n again >z2
 * >znull
 * sed "s/i/z/" z1 z2 znull | hexdump -vC
 * output:
 * gnu sed 4.1.5:
 * 00000000  74 68 7a 6e 67 79 0a 61  67 61 7a 6e              |thzngy.agazn|
 * bbox:
 * 00000000  74 68 7a 6e 67 79 61 67  61 7a 6e                 |thzngyagazn|
 */
static void puts_maybe_newline(char *s, FILE *file, char *last_puts_char, char last_gets_char)
{
    char lpc = *last_puts_char;

    /* Need to insert a '\n' between two files because first file's
     * last line wasn't terminated? */
    if (lpc != '\n' && lpc != '\0') {
        fputc('\n', file);
        lpc = '\n';
    }
    fputs(s, file);

    /* 'x' - just something which is not '\n', '\0' or NO_EOL_CHAR */
    if (s[0])
        lpc = 'x';

    /* had trailing '\0' and it was last char of file? */
    if (last_gets_char == LAST_IS_NUL) {
        fputc('\0', file);
        lpc = 'x'; /* */
    } else
    /* had trailing '\n' or '\0'? */
    if (last_gets_char != NO_EOL_CHAR) {
        fputc(last_gets_char, file);
        lpc = last_gets_char;
    }

    if (ferror(file)) {
        xfunc_error_retval = 4;  /* It's what gnu sed exits with... */
        bb_error_msg_and_die(bb_msg_write_error);
    }
    *last_puts_char = lpc;
}

#define sed_puts(s, n) (puts_maybe_newline(s, G.nonstdout, &last_puts_char, n))

static int beg_match(sed_cmd_t *sed_cmd, const char *pattern_space)
{
    int retval = sed_cmd->beg_match && !regexec(sed_cmd->beg_match, pattern_space, 0, NULL, 0);
    if (retval)
        G.previous_regex_ptr = sed_cmd->beg_match;
    return retval;
}

/* Process all the lines in all the files */

static void process_files(void)
{
    char *pattern_space, *next_line;
    int linenum = 0;
    char last_puts_char = '\n';
    char last_gets_char, next_gets_char;
    sed_cmd_t *sed_cmd;
    int substituted;

    /* Prime the pump */
    next_line = get_next_line(&next_gets_char);

    /* go through every line in each file */
again:
    substituted = 0;

    /* Advance to next line.  Stop if out of lines. */
    pattern_space = next_line;
    if (!pattern_space) return;
    last_gets_char = next_gets_char;

    /* Read one line in advance so we can act on the last line,
     * the '$' address */
    next_line = get_next_line(&next_gets_char);
    linenum++;
restart:
    /* for every line, go through all the commands */
    for (sed_cmd = G.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next) {
        int old_matched, matched;

        old_matched = sed_cmd->in_match;

        /* Determine if this command matches this line: */

        /* Are we continuing a previous multi-line match? */
        sed_cmd->in_match = sed_cmd->in_match
            /* Or is no range necessary? */
            || (!sed_cmd->beg_line && !sed_cmd->end_line
                && !sed_cmd->beg_match && !sed_cmd->end_match)
            /* Or did we match the start of a numerical range? */
            || (sed_cmd->beg_line > 0 && (sed_cmd->beg_line == linenum))
            /* Or does this line match our begin address regex? */
            || (beg_match(sed_cmd, pattern_space))
            /* Or did we match last line of input? */
            || (sed_cmd->beg_line == -1 && next_line == NULL);

        /* Snapshot the value */

        matched = sed_cmd->in_match;

        /* Is this line the end of the current match? */

        if (matched) {
            sed_cmd->in_match = !(
                /* has the ending line come, or is this a single address command? */
                (sed_cmd->end_line ?
                    sed_cmd->end_line == -1 ?
                        !next_line
                        : (sed_cmd->end_line <= linenum)
                    : !sed_cmd->end_match
                )
                /* or does this line matches our last address regex */
                || (sed_cmd->end_match && old_matched
                     && (regexec(sed_cmd->end_match,
                                 pattern_space, 0, NULL, 0) == 0))
            );
        }

        /* Skip blocks of commands we didn't match. */
        if (sed_cmd->cmd == '{') {
            if (sed_cmd->invert ? matched : !matched) {
                while (sed_cmd->cmd != '}') {
                    sed_cmd = sed_cmd->next;
                    if (!sed_cmd)
                        bb_error_msg_and_die("unterminated {");
                }
            }
            continue;
        }

        /* Okay, so did this line match? */
        if (sed_cmd->invert ? !matched : matched) {
            /* Update last used regex in case a blank substitute BRE is found */
            if (sed_cmd->beg_match) {
                G.previous_regex_ptr = sed_cmd->beg_match;
            }

            /* actual sedding */
            switch (sed_cmd->cmd) {

            /* Print line number */
            case '=':
                fprintf(G.nonstdout, "%d\n", linenum);
                break;

            /* Write the current pattern space up to the first newline */
            case 'P':
            {
                char *tmp = strchr(pattern_space, '\n');

                if (tmp) {
                    *tmp = '\0';
                    /* TODO: explain why '\n' below */
                    sed_puts(pattern_space, '\n');
                    *tmp = '\n';
                    break;
                }
                /* Fall Through */
            }

            /* Write the current pattern space to output */
            case 'p':
                /* NB: we print this _before_ the last line
                 * (of current file) is printed. Even if
                 * that line is nonterminated, we print
                 * '\n' here (gnu sed does the same) */
                sed_puts(pattern_space, '\n');
                break;
            /* Delete up through first newline */
            case 'D':
            {
                char *tmp = strchr(pattern_space, '\n');

                if (tmp) {
                    tmp = xstrdup(tmp+1);
                    free(pattern_space);
                    pattern_space = tmp;
                    goto restart;
                }
            }
            /* discard this line. */
            case 'd':
                goto discard_line;

            /* Substitute with regex */
            case 's':
                if (!do_subst_command(sed_cmd, &pattern_space))
                    break;
                substituted |= 1;

                /* handle p option */
                if (sed_cmd->sub_p)
                    sed_puts(pattern_space, last_gets_char);
                /* handle w option */
                if (sed_cmd->sw_file)
                    puts_maybe_newline(
                        pattern_space, sed_cmd->sw_file,
                        &sed_cmd->sw_last_char, last_gets_char);
                break;

            /* Append line to linked list to be printed later */
            case 'a':
                append(sed_cmd->string);
                break;

            /* Insert text before this line */
            case 'i':
                sed_puts(sed_cmd->string, '\n');
                break;

            /* Cut and paste text (replace) */
            case 'c':
                /* Only triggers on last line of a matching range. */
                if (!sed_cmd->in_match)
                    sed_puts(sed_cmd->string, NO_EOL_CHAR);
                goto discard_line;

            /* Read file, append contents to output */
            case 'r':
            {
                FILE *rfile;

                rfile = fopen(sed_cmd->string, "r");
                if (rfile) {
                    char *line;

                    while ((line = xmalloc_getline(rfile))
                            != NULL)
                        append(line);
                    xprint_and_close_file(rfile);
                }

                break;
            }

            /* Write pattern space to file. */
            case 'w':
                puts_maybe_newline(
                    pattern_space, sed_cmd->sw_file,
                    &sed_cmd->sw_last_char, last_gets_char);
                break;

            /* Read next line from input */
            case 'n':
                if (!G.be_quiet)
                    sed_puts(pattern_space, last_gets_char);
                if (next_line) {
                    free(pattern_space);
                    pattern_space = next_line;
                    last_gets_char = next_gets_char;
                    next_line = get_next_line(&next_gets_char);
                    linenum++;
                    break;
                }
                /* fall through */

            /* Quit.  End of script, end of input. */
            case 'q':
                /* Exit the outer while loop */
                free(next_line);
                next_line = NULL;
                goto discard_commands;

            /* Append the next line to the current line */
            case 'N':
            {
                int len;
                /* If no next line, jump to end of script and exit. */
                if (next_line == NULL) {
                    /* Jump to end of script and exit */
                    free(next_line);
                    next_line = NULL;
                    goto discard_line;
                /* append next_line, read new next_line. */
                }
                len = strlen(pattern_space);
                pattern_space = realloc(pattern_space, len + strlen(next_line) + 2);
                pattern_space[len] = '\n';
                strcpy(pattern_space + len+1, next_line);
                last_gets_char = next_gets_char;
                next_line = get_next_line(&next_gets_char);
                linenum++;
                break;
            }

            /* Test/branch if substitution occurred */
            case 't':
                if (!substituted) break;
                substituted = 0;
                /* Fall through */
            /* Test/branch if substitution didn't occur */
            case 'T':
                if (substituted) break;
                /* Fall through */
            /* Branch to label */
            case 'b':
                if (!sed_cmd->string) goto discard_commands;
                else sed_cmd = branch_to(sed_cmd->string);
                break;
            /* Transliterate characters */
            case 'y':
            {
                int i, j;

                for (i = 0; pattern_space[i]; i++) {
                    for (j = 0; sed_cmd->string[j]; j += 2) {
                        if (pattern_space[i] == sed_cmd->string[j]) {
                            pattern_space[i] = sed_cmd->string[j + 1];
                            break;
                        }
                    }
                }

                break;
            }
            case 'g':   /* Replace pattern space with hold space */
                free(pattern_space);
                pattern_space = xstrdup(G.hold_space ? G.hold_space : "");
                break;
            case 'G':   /* Append newline and hold space to pattern space */
            {
                int pattern_space_size = 2;
                int hold_space_size = 0;

                if (pattern_space)
                    pattern_space_size += strlen(pattern_space);
                if (G.hold_space)
                    hold_space_size = strlen(G.hold_space);
                pattern_space = xrealloc(pattern_space,
                        pattern_space_size + hold_space_size);
                if (pattern_space_size == 2)
                    pattern_space[0] = 0;
                strcat(pattern_space, "\n");
                if (G.hold_space)
                    strcat(pattern_space, G.hold_space);
                last_gets_char = '\n';

                break;
            }
            case 'h':   /* Replace hold space with pattern space */
                free(G.hold_space);
                G.hold_space = xstrdup(pattern_space);
                break;
            case 'H':   /* Append newline and pattern space to hold space */
            {
                int hold_space_size = 2;
                int pattern_space_size = 0;

                if (G.hold_space)
                    hold_space_size += strlen(G.hold_space);
                if (pattern_space)
                    pattern_space_size = strlen(pattern_space);
                G.hold_space = xrealloc(G.hold_space,
                        hold_space_size + pattern_space_size);

                if (hold_space_size == 2)
                    *G.hold_space = 0;
                strcat(G.hold_space, "\n");
                if (pattern_space)
                    strcat(G.hold_space, pattern_space);

                break;
            }
            case 'x': /* Exchange hold and pattern space */
            {
                char *tmp = pattern_space;
                pattern_space = G.hold_space ? : xzalloc(1);
                last_gets_char = '\n';
                G.hold_space = tmp;
                break;
            }
            }
        }
    }

    /*
     * exit point from sedding...
     */
 discard_commands:
    /* we will print the line unless we were told to be quiet ('-n')
       or if the line was suppressed (ala 'd'elete) */
    if (!G.be_quiet)
        sed_puts(pattern_space, last_gets_char);

    /* Delete and such jump here. */
 discard_line:
    flush_append();
    free(pattern_space);

    goto again;
}

/* It is possible to have a command line argument with embedded
 * newlines.  This counts as multiple command lines.
 * However, newline can be escaped: 's/e/z\<newline>z/'
 * We check for this.
 */

static void add_cmd_block(char *cmdstr)
{
    char *sv, *eol;

    cmdstr = sv = xstrdup(cmdstr);
    do {
        eol = strchr(cmdstr, '\n');
 next:
        if (eol) {
            /* Count preceding slashes */
            int slashes = 0;
            char *sl = eol;

            while (sl != cmdstr && *--sl == '\\')
                slashes++;
            /* Odd number of preceding slashes - newline is escaped */
            if (slashes & 1) {
                strcpy(eol-1, eol);
                eol = strchr(eol, '\n');
                goto next;
            }
            *eol = '\0';
        }
        add_cmd(cmdstr);
        cmdstr = eol + 1;
    } while (eol);
    free(sv);
}

int sed_main(int argc, char **argv);
int sed_main(int argc, char **argv)
{
    enum {
        OPT_in_place = 1 << 0,
    };
    unsigned opt;
    llist_t *opt_e, *opt_f;
    int status = EXIT_SUCCESS;

    INIT_G();

    /* destroy command strings on exit */
    if (ENABLE_FEATURE_CLEAN_UP) atexit(sed_free_and_close_stuff);

    /* Lie to autoconf when it starts asking stupid questions. */
    if (argc == 2 && !strcmp(argv[1], "--version")) {
        puts("This is not GNU sed version 4.0");
        return 0;
    }

    /* do normal option parsing */
    opt_e = opt_f = NULL;
    opt_complementary = "e::f::" /* can occur multiple times */
                        "nn"; /* count -n */
    opt = getopt32(argv, "irne:f:", &opt_e, &opt_f,
                &G.be_quiet); /* counter for -n */
    argc -= optind;
    argv += optind;
    if (opt & OPT_in_place) { // -i
        atexit(cleanup_outname);
    }
    if (opt & 0x2) G.regex_type |= REG_EXTENDED; // -r
    //if (opt & 0x4) G.be_quiet++; // -n
    while (opt_e) { // -e
        add_cmd_block(opt_e->data);
        opt_e = opt_e->link;
        /* we leak opt_e here... */
    }
    while (opt_f) { // -f
        char *line;
        FILE *cmdfile;
        cmdfile = xfopen(opt_f->data, "r");
        while ((line = xmalloc_getline(cmdfile)) != NULL) {
            add_cmd(line);
            free(line);
        }
        fclose(cmdfile);
        opt_f = opt_f->link;
        /* we leak opt_f here... */
    }
    /* if we didn't get a pattern from -e or -f, use argv[0] */
    if (!(opt & 0x18)) {
        if (!argc)
            bb_show_usage();
        add_cmd_block(*argv++);
        argc--;
    }
    /* Flush any unfinished commands. */
    add_cmd("");

    /* By default, we write to stdout */
    G.nonstdout = stdout;

    /* argv[0..(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[0] == NULL) {
        if (opt & OPT_in_place)
            bb_error_msg_and_die(bb_msg_requires_arg, "-i");
        add_input_file(stdin);
        process_files();
    } else {
        int i;
        FILE *file;

        for (i = 0; i < argc; i++) {
            struct stat statbuf;
            int nonstdoutfd;

            if (LONE_DASH(argv[i]) && !(opt & OPT_in_place)) {
                add_input_file(stdin);
                process_files();
                continue;
            }
            file = fopen_or_warn(argv[i], "r");
            if (!file) {
                status = EXIT_FAILURE;
                continue;
            }
            if (!(opt & OPT_in_place)) {
                add_input_file(file);
                continue;
            }

            G.outname = xasprintf("%sXXXXXX", argv[i]);
            nonstdoutfd = mkstemp(G.outname);
            if (-1 == nonstdoutfd)
                bb_perror_msg_and_die("cannot create temp file %s", G.outname);
            G.nonstdout = fdopen(nonstdoutfd, "w");

            /* Set permissions of output file */

            fstat(fileno(file), &statbuf);
            fchmod(nonstdoutfd, statbuf.st_mode);
            add_input_file(file);
            process_files();
            fclose(G.nonstdout);

            G.nonstdout = stdout;
            /* unlink(argv[i]); */
            // FIXME: error check / message?
            rename(G.outname, argv[i]);
            free(G.outname);
            G.outname = 0;
        }
        if (G.input_file_count > G.current_input_file)
            process_files();
    }

    return status;
}