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authorRob Landley <rob@landley.net>2019-05-04 18:22:51 -0500
committerRob Landley <rob@landley.net>2019-05-04 18:22:51 -0500
commit9f781cd5c3f7b071a3d9a62bf0a4aeb8c3cda8ec (patch)
tree2961c963afd068ec959ae60c449a1cce5808aead /toys/posix
parent121322285aa143a748fb7c725a5e2559a038eefd (diff)
downloadtoybox-9f781cd5c3f7b071a3d9a62bf0a4aeb8c3cda8ec.tar.gz
Optimize s//g to avoid fresh strdup/free of entire line for each match.
Instead have one target string and fill it out from start to finish writing to each location once.
Diffstat (limited to 'toys/posix')
-rw-r--r--toys/posix/sed.c61
1 files changed, 36 insertions, 25 deletions
diff --git a/toys/posix/sed.c b/toys/posix/sed.c
index 0c31d2af..d9bb5c94 100644
--- a/toys/posix/sed.c
+++ b/toys/posix/sed.c
@@ -466,20 +466,21 @@ static void sed_line(char **pline, long plen)
break;
} else if (c=='s') {
- char *rline = line, *new = command->arg2 + (char *)command, *swap, *rswap;
+ char *rline = line, *new = command->arg2 + (char *)command, *l2 = 0;
regmatch_t *match = (void *)toybuf;
regex_t *reg = get_regex(command, command->arg1);
- int mflags = 0, count = 0, zmatch = 1, rlen = len, mlen, off, newlen;
+ int mflags = 0, count = 0, l2used = 0, zmatch = 1, l2l = len,
+ mlen, off, newlen;
- // Find match in remaining line (up to remaining len)
- while (!regexec0(reg, rline, rlen, 10, match, mflags)) {
+ // Loop finding match in remaining line (up to remaining len)
+ while (!regexec0(reg, rline, len-(rline-line), 10, match, mflags)) {
mflags = REG_NOTBOL;
// Zero length matches don't count immediately after a previous match
mlen = match[0].rm_eo-match[0].rm_so;
if (!mlen && !zmatch) {
- if (!rlen--) break;
- rline++;
+ if (rline-line == len) break;
+ l2[l2used++] = *rline++;
zmatch++;
continue;
} else zmatch = 0;
@@ -487,8 +488,9 @@ static void sed_line(char **pline, long plen)
// If we're replacing only a specific match, skip if this isn't it
off = command->sflags>>3;
if (off && off != ++count) {
+ memcpy(l2+l2used, rline, match[0].rm_eo);
+ l2used += match[0].rm_eo;
rline += match[0].rm_eo;
- rlen -= match[0].rm_eo;
continue;
}
@@ -509,13 +511,15 @@ static void sed_line(char **pline, long plen)
newlen += match[cc].rm_eo-match[cc].rm_so;
}
- // Allocate new size, copy start/end around match. (Can't extend in
- // place because backrefs may refer to text after it's overwritten.)
- len += newlen-mlen;
- swap = xmalloc(len+1);
- rswap = swap+(rline-line)+match[0].rm_so;
- memcpy(swap, line, (rline-line)+match[0].rm_so);
- memcpy(rswap+newlen, rline+match[0].rm_eo, (rlen -= match[0].rm_eo)+1);
+ // Copy changed data to new string
+
+ // Adjust allocation size of new string, copy data we know we'll keep
+ l2l += newlen-mlen;
+ if (newlen>mlen || !l2) l2 = xrealloc(l2, l2l+1);
+ if (match[0].rm_so) {
+ memcpy(l2+l2used, rline, match[0].rm_so);
+ l2used += match[0].rm_so;
+ }
// copy in new replacement text
for (off = mlen = 0; new[off]; off++) {
@@ -524,33 +528,40 @@ static void sed_line(char **pline, long plen)
if (new[off] == '\\') {
cc = new[++off] - '0';
if (cc<0 || cc>9) {
- if (!(rswap[mlen++] = unescape(new[off])))
- rswap[mlen-1] = new[off];
+ if (!(l2[l2used+mlen++] = unescape(new[off])))
+ l2[l2used+mlen-1] = new[off];
continue;
} else if (cc > reg->re_nsub) error_exit("no s//\\%d/", cc);
} else if (new[off] != '&') {
- rswap[mlen++] = new[off];
+ l2[l2used+mlen++] = new[off];
continue;
}
- if (match[cc].rm_so == -1) ll = 0; // Empty match.
- else {
+ if (match[cc].rm_so != -1) {
ll = match[cc].rm_eo-match[cc].rm_so;
- memcpy(rswap+mlen, rline+match[cc].rm_so, ll);
+ memcpy(l2+l2used+mlen, rline+match[cc].rm_so, ll);
+ mlen += ll;
}
- mlen += ll;
}
-
- rline = rswap+newlen;
- free(line);
- line = swap;
+ l2used += newlen;
+ rline += match[0].rm_eo;
// Stop after first substitution unless we have flag g
if (!(command->sflags & 2)) break;
}
+ // If we made any changes, finish off l2 and swap it for line
+ if (l2) {
+ // grab trailing unmatched data and null terminator, swap with original
+ mlen = len-(rline-line);
+ memcpy(l2+l2used, rline, mlen+1);
+ len = l2used + mlen;
+ free(line);
+ line = l2;
+ }
+
if (mflags) {
// flag p
if (command->sflags & 4) emit(line, len, eol);