- Added support for backreferences in substitution expressions up to nine
(\1, \2...\9). This touched a lot of places in this file and I added a new function 'print_subst_w_backrefs' in order to keep 'do_subst_command' a little more tidy. * I tested this good 'n hard, but will always appreciate more testing from other, willing folks. - Noticed that the index_of_next_unescaped_slash was subtly wrong so I changed both the functionality and behavior (it used to skip over the first char in the string you passed it, assuming it was a leading '/'--this assumption is no longer made) this necessitated changing the lines that call this function just slightly.
This commit is contained in:
Mark Whitley
parent
21ddb38fcf
commit
97562bd9d7
@ -27,6 +27,7 @@
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- address matching: num|/matchstr/[,num|/matchstr/|$]command
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- commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
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- edit commands: (a)ppend, (i)nsert, (c)hange
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- backreferences in substitution expressions (\1, \2...\9)
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(Note: Specifying an address (range) to match is *optional*; commands
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default to the whole pattern space if no specific address match was
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@ -73,6 +74,9 @@ struct sed_cmd {
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/* substitution command specific fields */
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regex_t *sub_match; /* sed -e 's/sub_match/replace/' */
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char *replace; /* sed -e 's/sub_match/replace/' XXX: who will hold the \1 \2 \3s? */
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unsigned int num_backrefs:4; /* how many back references (\1..\9) */
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/* Note: GNU/POSIX sed does not save more than nine backrefs, so
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* we only use 4 bits to hold the number */
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unsigned int sub_g:1; /* sed -e 's/foo/bar/g' (global) */
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/* edit command (a,i,c) speicific field */
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@ -166,19 +170,19 @@ static size_t strrspn(const char *s, const char *accept)
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#endif
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/*
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* index_of_unescaped_slash - walks left to right through a string beginning
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* at a specified index and returns the index of the next unescaped slash.
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* index_of_next_unescaped_slash - walks left to right through a string
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* beginning at a specified index and returns the index of the next forward
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* slash ('/') not preceeded by a backslash ('\').
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*/
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static int index_of_next_unescaped_slash(const char *str, int idx)
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{
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do {
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idx++;
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/* test if we've hit the end */
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if (str[idx] == 0)
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return -1;
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} while (str[idx] != '/' && str[idx - 1] != '\\');
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for ( ; str[idx]; idx++) {
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if (str[idx] == '/' && str[idx-1] != '\\')
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return idx;
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}
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return idx;
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/* if we make it to here, we've hit the end of the string */
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return -1;
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}
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/*
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@ -201,7 +205,7 @@ static int get_address(const char *str, int *line, regex_t **regex)
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idx++;
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}
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else if (my_str[idx] == '/') {
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idx = index_of_next_unescaped_slash(my_str, idx);
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idx = index_of_next_unescaped_slash(my_str, ++idx);
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if (idx == -1)
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fatalError("unterminated match expression\n");
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my_str[idx] = '\0';
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@ -233,6 +237,7 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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int oldidx, cflags = REG_NEWLINE;
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char *match;
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int idx = 0;
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int j;
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/*
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* the string that gets passed to this function should look like this:
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@ -249,14 +254,26 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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/* save the match string */
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oldidx = idx+1;
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idx = index_of_next_unescaped_slash(substr, idx);
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idx = index_of_next_unescaped_slash(substr, ++idx);
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if (idx == -1)
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fatalError("bad format in substitution expression\n");
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match = strdup_substr(substr, oldidx, idx);
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/* determine the number of back references in the match string */
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/* Note: we compute this here rather than in the do_subst_command()
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* function to save processor time, at the expense of a little more memory
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* (4 bits) per sed_cmd */
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/* sed_cmd->num_backrefs = 0; */ /* XXX: not needed? --apparently not */
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for (j = 0; match[j]; j++) {
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/* GNU/POSIX sed does not save more than nine backrefs */
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if (match[j] == '\\' && match[j+1] == '(' && sed_cmd->num_backrefs < 9)
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sed_cmd->num_backrefs++;
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}
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/* save the replacement string */
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oldidx = idx+1;
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idx = index_of_next_unescaped_slash(substr, idx);
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idx = index_of_next_unescaped_slash(substr, ++idx);
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if (idx == -1)
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fatalError("bad format in substitution expression\n");
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sed_cmd->replace = strdup_substr(substr, oldidx, idx);
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@ -280,7 +297,7 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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}
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out:
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/* compile the regex */
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/* compile the match string into a regex */
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sed_cmd->sub_match = (regex_t *)xmalloc(sizeof(regex_t));
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xregcomp(sed_cmd->sub_match, match, cflags);
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free(match);
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@ -460,26 +477,64 @@ static void load_cmd_file(char *filename)
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}
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}
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static void print_subst_w_backrefs(const char *line, const char *replace, regmatch_t *regmatch)
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{
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int i;
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/* go through the replacement string */
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for (i = 0; replace[i]; i++) {
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/* if we find a backreference (\1, \2, etc.) print the backref'ed * text */
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if (replace[i] == '\\' && isdigit(replace[i+1])) {
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int j;
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char tmpstr[2];
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int backref;
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++i; /* i now indexes the backref number, instead of the leading slash */
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tmpstr[0] = replace[i];
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tmpstr[1] = 0;
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backref = atoi(tmpstr);
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/* print out the text held in regmatch[backref] */
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for (j = regmatch[backref].rm_so; j < regmatch[backref].rm_eo; j++)
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fputc(line[j], stdout);
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}
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/* if we find an unescaped '&' print out the whole matched text.
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* fortunately, regmatch[0] contains the indicies to the whole matched
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* expression (kinda seems like it was designed for just such a
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* purpose...) */
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else if (replace[i] == '&' && replace[i-1] != '\\') {
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int j;
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for (j = regmatch[0].rm_so; j < regmatch[0].rm_eo; j++)
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fputc(line[j], stdout);
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}
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/* nothing special, just print this char of the replacement string to stdout */
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else
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fputc(replace[i], stdout);
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}
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}
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static int do_subst_command(const struct sed_cmd *sed_cmd, const char *line)
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{
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int altered = 0;
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/* we only substitute if the substitution 'search' expression matches */
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if (regexec(sed_cmd->sub_match, line, 0, NULL, 0) == 0) {
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regmatch_t regmatch;
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regmatch_t *regmatch = xmalloc(sizeof(regmatch_t) * (sed_cmd->num_backrefs+1));
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int i;
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char *ptr = (char *)line;
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while (*ptr) {
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/* if we can match the search string... */
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if (regexec(sed_cmd->sub_match, ptr, 1, ®match, 0) == 0) {
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if (regexec(sed_cmd->sub_match, ptr, sed_cmd->num_backrefs+1, regmatch, 0) == 0) {
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/* print everything before the match, */
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for (i = 0; i < regmatch.rm_so; i++)
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for (i = 0; i < regmatch[0].rm_so; i++)
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fputc(ptr[i], stdout);
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/* then print the substitution in its place */
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fputs(sed_cmd->replace, stdout);
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print_subst_w_backrefs(ptr, sed_cmd->replace, regmatch);
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/* then advance past the match */
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ptr += regmatch.rm_eo;
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ptr += regmatch[0].rm_eo;
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/* and flag that something has changed */
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altered++;
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@ -496,6 +551,9 @@ static int do_subst_command(const struct sed_cmd *sed_cmd, const char *line)
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/* is there anything left to print? */
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if (*ptr)
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fputs(ptr, stdout);
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/* cleanup */
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free(regmatch);
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}
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return altered;
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94
sed.c
94
sed.c
@ -27,6 +27,7 @@
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- address matching: num|/matchstr/[,num|/matchstr/|$]command
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- commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
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- edit commands: (a)ppend, (i)nsert, (c)hange
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- backreferences in substitution expressions (\1, \2...\9)
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(Note: Specifying an address (range) to match is *optional*; commands
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default to the whole pattern space if no specific address match was
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@ -73,6 +74,9 @@ struct sed_cmd {
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/* substitution command specific fields */
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regex_t *sub_match; /* sed -e 's/sub_match/replace/' */
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char *replace; /* sed -e 's/sub_match/replace/' XXX: who will hold the \1 \2 \3s? */
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unsigned int num_backrefs:4; /* how many back references (\1..\9) */
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/* Note: GNU/POSIX sed does not save more than nine backrefs, so
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* we only use 4 bits to hold the number */
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unsigned int sub_g:1; /* sed -e 's/foo/bar/g' (global) */
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/* edit command (a,i,c) speicific field */
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@ -166,19 +170,19 @@ static size_t strrspn(const char *s, const char *accept)
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#endif
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/*
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* index_of_unescaped_slash - walks left to right through a string beginning
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* at a specified index and returns the index of the next unescaped slash.
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* index_of_next_unescaped_slash - walks left to right through a string
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* beginning at a specified index and returns the index of the next forward
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* slash ('/') not preceeded by a backslash ('\').
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*/
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static int index_of_next_unescaped_slash(const char *str, int idx)
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{
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do {
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idx++;
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/* test if we've hit the end */
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if (str[idx] == 0)
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return -1;
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} while (str[idx] != '/' && str[idx - 1] != '\\');
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for ( ; str[idx]; idx++) {
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if (str[idx] == '/' && str[idx-1] != '\\')
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return idx;
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}
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return idx;
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/* if we make it to here, we've hit the end of the string */
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return -1;
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}
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/*
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@ -201,7 +205,7 @@ static int get_address(const char *str, int *line, regex_t **regex)
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idx++;
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}
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else if (my_str[idx] == '/') {
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idx = index_of_next_unescaped_slash(my_str, idx);
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idx = index_of_next_unescaped_slash(my_str, ++idx);
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if (idx == -1)
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fatalError("unterminated match expression\n");
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my_str[idx] = '\0';
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@ -233,6 +237,7 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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int oldidx, cflags = REG_NEWLINE;
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char *match;
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int idx = 0;
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int j;
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/*
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* the string that gets passed to this function should look like this:
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@ -249,14 +254,26 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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/* save the match string */
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oldidx = idx+1;
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idx = index_of_next_unescaped_slash(substr, idx);
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idx = index_of_next_unescaped_slash(substr, ++idx);
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if (idx == -1)
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fatalError("bad format in substitution expression\n");
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match = strdup_substr(substr, oldidx, idx);
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/* determine the number of back references in the match string */
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/* Note: we compute this here rather than in the do_subst_command()
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* function to save processor time, at the expense of a little more memory
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* (4 bits) per sed_cmd */
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/* sed_cmd->num_backrefs = 0; */ /* XXX: not needed? --apparently not */
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for (j = 0; match[j]; j++) {
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/* GNU/POSIX sed does not save more than nine backrefs */
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if (match[j] == '\\' && match[j+1] == '(' && sed_cmd->num_backrefs < 9)
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sed_cmd->num_backrefs++;
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}
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/* save the replacement string */
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oldidx = idx+1;
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idx = index_of_next_unescaped_slash(substr, idx);
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idx = index_of_next_unescaped_slash(substr, ++idx);
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if (idx == -1)
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fatalError("bad format in substitution expression\n");
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sed_cmd->replace = strdup_substr(substr, oldidx, idx);
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@ -280,7 +297,7 @@ static int parse_subst_cmd(struct sed_cmd *sed_cmd, const char *substr)
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}
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out:
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/* compile the regex */
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/* compile the match string into a regex */
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sed_cmd->sub_match = (regex_t *)xmalloc(sizeof(regex_t));
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xregcomp(sed_cmd->sub_match, match, cflags);
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free(match);
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@ -460,26 +477,64 @@ static void load_cmd_file(char *filename)
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}
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}
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static void print_subst_w_backrefs(const char *line, const char *replace, regmatch_t *regmatch)
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{
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int i;
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/* go through the replacement string */
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for (i = 0; replace[i]; i++) {
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/* if we find a backreference (\1, \2, etc.) print the backref'ed * text */
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if (replace[i] == '\\' && isdigit(replace[i+1])) {
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int j;
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char tmpstr[2];
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int backref;
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++i; /* i now indexes the backref number, instead of the leading slash */
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tmpstr[0] = replace[i];
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tmpstr[1] = 0;
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backref = atoi(tmpstr);
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/* print out the text held in regmatch[backref] */
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for (j = regmatch[backref].rm_so; j < regmatch[backref].rm_eo; j++)
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fputc(line[j], stdout);
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}
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/* if we find an unescaped '&' print out the whole matched text.
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* fortunately, regmatch[0] contains the indicies to the whole matched
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* expression (kinda seems like it was designed for just such a
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* purpose...) */
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else if (replace[i] == '&' && replace[i-1] != '\\') {
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int j;
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for (j = regmatch[0].rm_so; j < regmatch[0].rm_eo; j++)
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fputc(line[j], stdout);
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}
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/* nothing special, just print this char of the replacement string to stdout */
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else
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fputc(replace[i], stdout);
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}
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}
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static int do_subst_command(const struct sed_cmd *sed_cmd, const char *line)
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{
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int altered = 0;
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/* we only substitute if the substitution 'search' expression matches */
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if (regexec(sed_cmd->sub_match, line, 0, NULL, 0) == 0) {
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regmatch_t regmatch;
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regmatch_t *regmatch = xmalloc(sizeof(regmatch_t) * (sed_cmd->num_backrefs+1));
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int i;
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char *ptr = (char *)line;
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while (*ptr) {
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/* if we can match the search string... */
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if (regexec(sed_cmd->sub_match, ptr, 1, ®match, 0) == 0) {
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if (regexec(sed_cmd->sub_match, ptr, sed_cmd->num_backrefs+1, regmatch, 0) == 0) {
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/* print everything before the match, */
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for (i = 0; i < regmatch.rm_so; i++)
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for (i = 0; i < regmatch[0].rm_so; i++)
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fputc(ptr[i], stdout);
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/* then print the substitution in its place */
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fputs(sed_cmd->replace, stdout);
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print_subst_w_backrefs(ptr, sed_cmd->replace, regmatch);
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/* then advance past the match */
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ptr += regmatch.rm_eo;
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ptr += regmatch[0].rm_eo;
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/* and flag that something has changed */
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altered++;
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@ -496,6 +551,9 @@ static int do_subst_command(const struct sed_cmd *sed_cmd, const char *line)
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/* is there anything left to print? */
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if (*ptr)
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fputs(ptr, stdout);
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/* cleanup */
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free(regmatch);
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}
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return altered;
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