[hackers] [sbase] Make grep more memory-efficient || FRIGN

[git]

commit fb1bfe24bb4ae08bdd56732244a74d89033dd130
Author: FRIGN <d...@frign.de>
Date:   Mon May 12 00:31:07 2014 +0200

    Make grep more memory-efficient

diff --git a/grep.c b/grep.c
index 269ec92..f6bbcc1 100644
--- a/grep.c
+++ b/grep.c
@@ -11,7 +11,7 @@
 enum { Match = 0, NoMatch = 1, Error = 2 };
 
 static void addpattern(const char *);
-static bool grep(FILE *, const char *);
+static bool grep(FILE *, const char *, int);
 
 static bool eflag = false;
 static bool vflag = false;
@@ -20,7 +20,6 @@ static char mode = 0;
 
 static struct plist {
        char *pattern;
-       regex_t preg;
        struct plist *next;
 } *phead;
 
@@ -35,7 +34,7 @@ main(int argc, char *argv[])
 {
        bool match = false;
        struct plist *pnode, *tmp;
-       int i, n, flags = REG_NOSUB;
+       int i, flags = REG_NOSUB;
        FILE *fp;
 
        ARGBEGIN {
@@ -62,8 +61,9 @@ main(int argc, char *argv[])
                usage();
        } ARGEND;
 
+       /* no pattern */
        if(argc == 0 && !eflag)
-               usage(); /* no pattern */
+               usage();
 
        /* If -e is not specified treat it as if it were */
        if(!eflag) {
@@ -72,23 +72,14 @@ 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
", buf);
-               }
-       }
        many = (argc > 1);
        if(argc == 0) {
-               match = grep(stdin, "<stdin>");
+               match = grep(stdin, "<stdin>", flags);
        } else {
                for(i = 0; i < argc; i++) {
                        if(!(fp = fopen(argv[i], "r")))
                                enprintf(Error, "fopen %s:", argv[i]);
-                       if(grep(fp, argv[i]))
+                       if(grep(fp, argv[i], flags))
                                match = true;
                        fclose(fp);
                }
@@ -96,7 +87,6 @@ main(int argc, char *argv[])
        pnode = phead;
        while(pnode) {
                tmp = pnode->next;
-               regfree(&pnode->preg);
                free(pnode->pattern);
                free(pnode);
                pnode = tmp;
@@ -120,20 +110,30 @@ addpattern(const char *pattern)
 }
 
 bool
-grep(FILE *fp, const char *str)
+grep(FILE *fp, const char *str, int flags)
 {
        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) {
+                               char err[BUFSIZ];
+
+                               regerror(r, &preg, err, sizeof err);
+                               enprintf(Error, "invalid pattern: %s
", err);
+                       }
                        if(buf[(len = strlen(buf))-1] == '
')
                                buf[--len] = '