Revert "Make grep more memory-efficient"

This reverts commit d9a098ae6bc07188cbaefcd188e5911dec41815d.

Conflicts:
	grep.c

Hiltjo Posthuma <hiltjo@codemadness.org> said:

(Re)compiling the regex for each line doesn't make sense (imho) and
slows it down a lot.

A simple test:

time seq 1 100000000 | grep 'a'

sbase grep (before patch):
    0m22.21s real     0m0.00s user     0m0.00s system

sbase grep (after patch):
    2m16.28s real     0m0.00s user     0m0.00s system

coreutils grep:
    0m1.15s real     0m0.00s user     0m0.00s system

So the patch should be reverted I think.

grep.c

@@ -11,7 +11,7 @@
 enum { Match = 0, NoMatch = 1, Error = 2 };
 
 static void addpattern(const char *);
-static bool grep(FILE *, const char *, int);
+static bool grep(FILE *, const char *);
 
 static bool eflag = false;
 static bool vflag = false;
@@ -20,6 +20,7 @@ static char mode = 0;
 
 static struct plist {
 	char *pattern;
+	regex_t preg;
 	struct plist *next;
 } *phead;
 
@@ -34,7 +35,7 @@ main(int argc, char *argv[])
 {
 	bool match = false;
 	struct plist *pnode, *tmp;
-	int i, flags = REG_NOSUB;
+	int i, n, flags = REG_NOSUB;
 	FILE *fp;
 
 	ARGBEGIN {
@@ -61,9 +62,8 @@ main(int argc, char *argv[])
 		usage();
 	} ARGEND;
 
-	/* no pattern */
 	if(argc == 0 && !eflag)
-		usage();
+		usage(); /* no pattern */
 
 	/* If -e is not specified treat it as if it were */
 	if(!eflag) {
@@ -72,14 +72,23 @@ main(int argc, char *argv[])
 		argv++;
 	}
 
+	/* Compile regex for all search patterns */
+	for(pnode = phead; pnode; pnode = pnode->next) {
+		if((n = regcomp(&pnode->preg, pnode->pattern, flags)) != 0) {
+			char buf[BUFSIZ];
+
+			regerror(n, &pnode->preg, buf, sizeof buf);
+			enprintf(Error, "invalid pattern: %s\n", buf);
+		}
+	}
 	many = (argc > 1);
 	if(argc == 0) {
-		match = grep(stdin, "<stdin>", flags);
+		match = grep(stdin, "<stdin>");
 	} else {
 		for(i = 0; i < argc; i++) {
 			if(!(fp = fopen(argv[i], "r")))
 				enprintf(Error, "fopen %s:", argv[i]);
-			if(grep(fp, argv[i], flags))
+			if(grep(fp, argv[i]))
 				match = true;
 			fclose(fp);
 		}
@@ -87,6 +96,7 @@ main(int argc, char *argv[])
 	pnode = phead;
 	while(pnode) {
 		tmp = pnode->next;
+		regfree(&pnode->preg);
 		free(pnode->pattern);
 		free(pnode);
 		pnode = tmp;
@@ -110,29 +120,20 @@ addpattern(const char *pattern)
 }
 
 bool
-grep(FILE *fp, const char *str, int flags)
+grep(FILE *fp, const char *str)
 {
-	char err[BUFSIZ];
 	char *buf = NULL;
 	long n, c = 0;
-	int r;
-	static regex_t preg;
 	size_t size = 0, len;
 	struct plist *pnode;
 	bool match = false;
 
 	for(n = 1; afgets(&buf, &size, fp); n++) {
 		for(pnode = phead; pnode; pnode = pnode->next) {
-			if((r = regcomp(&preg, pnode->pattern, flags)) != 0) {
-				regerror(r, &preg, err, sizeof err);
-				enprintf(Error, "invalid pattern: %s\n", err);
-			}
 			if(buf[(len = strlen(buf))-1] == '\n')
 				buf[--len] = '\0';
-			if(regexec(&preg, buf, 0, NULL, 0) ^ vflag){
+			if(regexec(&pnode->preg, buf, 0, NULL, 0) ^ vflag)
-				regfree(&preg);
 				continue;
-			}
 			switch(mode) {
 			case 'c':
 				c++;
@@ -158,7 +159,6 @@ grep(FILE *fp, const char *str, int flags)
 end:
 	if(ferror(fp))
 		enprintf(Error, "%s: read error:", str);
-	regfree(&preg);
 	free(buf);
 	return match;
 }