From ef44d9d9f2aa5d0333d5a7a2749e32c6be94365d Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Wed, 17 Jan 2007 23:16:16 +0000 Subject: sed,get_line_from_file: improve comments --- editors/sed.c | 44 +++++++++++++++++++++++++++----------------- 1 file changed, 27 insertions(+), 17 deletions(-) (limited to 'editors') diff --git a/editors/sed.c b/editors/sed.c index 23d73faa9..674381b56 100644 --- a/editors/sed.c +++ b/editors/sed.c @@ -576,28 +576,33 @@ static void do_subst_w_backrefs(char *line, char *replace) /* 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] == '\\' && replace[i+1] >= '0' && replace[i+1] <= '9') { - int backref = replace[++i]-'0'; - - /* print out the text held in bbg.regmatch[backref] */ - if (bbg.regmatch[backref].rm_so != -1) { - j = bbg.regmatch[backref].rm_so; - while (j < bbg.regmatch[backref].rm_eo) - pipe_putc(line[j++]); + if (replace[i] == '\\') { + unsigned backref = replace[++i] - '0'; + if (backref <= 9) { + /* print out the text held in bbg.regmatch[backref] */ + if (bbg.regmatch[backref].rm_so != -1) { + j = bbg.regmatch[backref].rm_so; + while (j < bbg.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 a backslash escaped character, print the character */ - else if (replace[i] == '\\') pipe_putc(replace[++i]); - /* if we find an unescaped '&' print out the whole matched text. */ - else if (replace[i] == '&') { + if (replace[i] == '&') { j = bbg.regmatch[0].rm_so; while (j < bbg.regmatch[0].rm_eo) pipe_putc(line[j++]); + continue; } /* Otherwise just output the character. */ - else pipe_putc(replace[i]); + pipe_putc(replace[i]); } } @@ -722,6 +727,9 @@ static char *get_next_line(int *last_char) lc = 0; flush_append(); while (bbg.current_input_file < bbg.input_file_count) { + /* 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( bbg.input_file_list[bbg.current_input_file], &len); if (temp) { @@ -753,7 +761,8 @@ static char *get_next_line(int *last_char) * echo -n thingy >z1 * echo -n again >z2 * >znull - * sed "s/i/z/" z1 z2 znull | hexdump -vC output: + * 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: @@ -771,8 +780,9 @@ static int puts_maybe_newline(char *s, FILE *file, int prev_last_char, int last_ last_puts_char = '\n'; } fputs(s, file); - /* 'x': we don't care what is it, but we know it isn't '\n' */ - if (s[0]) last_puts_char = 'x'; + /* why 'x'? - just something which is not '\n' */ + if (s[0]) + last_puts_char = 'x'; if (!(last_char & 0x100)) { /* had trailing '\n' or '\0'? */ last_char &= 0xff; fputc(last_char, file); -- cgit v1.2.3