smugfs(4): new program

src/cmd/smugfs/icache.c

@@ -0,0 +1,171 @@
+#include "a.h"
+
+// This code is almost certainly wrong.
+
+typedef struct Icache Icache;
+struct Icache
+{
+	char *url;
+	HTTPHeader hdr;
+	char *tmpfile;
+	int fd;
+	Icache *next;
+	Icache *prev;
+	Icache *hash;
+};
+
+enum {
+	NHASH = 128,
+	MAXCACHE = 128,
+};
+static struct {
+	Icache *hash[NHASH];
+	Icache *head;
+	Icache *tail;
+	int n;
+} icache;
+
+static Icache*
+icachefind(char *url)
+{
+	int h;
+	Icache *ic;
+	
+	h = hash(url) % NHASH;
+	for(ic=icache.hash[h]; ic; ic=ic->hash){
+		if(strcmp(ic->url, url) == 0){
+			/* move to front */
+			if(ic->prev) {
+				ic->prev->next = ic->next;
+				if(ic->next)
+					ic->next->prev = ic->prev;
+				else
+					icache.tail = ic->prev;
+				ic->prev = nil;
+				ic->next = icache.head;
+				icache.head->prev = ic;
+				icache.head = ic;
+			}
+			return ic;
+		}
+	}
+	return nil;
+}
+
+static Icache*
+icacheinsert(char *url, HTTPHeader *hdr, char *file, int fd)
+{
+	int h;
+	Icache *ic, **l;
+
+	if(icache.n == MAXCACHE){
+		ic = icache.tail;
+		icache.tail = ic->prev;
+		if(ic->prev)
+			ic->prev->next = nil;
+		else
+			icache.head = ic->prev;
+		h = hash(ic->url) % NHASH;
+		for(l=&icache.hash[h]; *l; l=&(*l)->hash){
+			if(*l == ic){
+				*l = ic->hash;
+				goto removed;
+			}
+		}
+		sysfatal("cannot find ic in cache");
+	removed:
+		free(ic->url);
+		close(ic->fd);
+		remove(ic->file);
+		free(ic->file);
+	}else{
+		ic = emalloc(sizeof *ic);
+		icache.n++;
+	}
+	
+	ic->url = estrdup(url);
+	ic->fd = dup(fd, -1);
+	ic->file = estrdup(file);
+	ic->hdr = *hdr;
+	h = hash(url) % NHASH;
+	ic->hash = icache.hash[h];
+	icache.hash[h] = ic;
+	ic->prev = nil;
+	ic->next = icache.head;
+	if(ic->next)
+		ic->next->prev = ic;
+	else
+		icache.tail = ic;
+	return ic;
+}
+
+void
+icacheflush(char *substr)
+{
+	Icache **l, *ic;
+	
+	for(l=&icache.head; (ic=*l); ) {
+		if(substr == nil || strstr(ic->url, substr)) {
+			icache.n--;
+			*l = ic->next;
+			free(ic->url);
+			close(ic->fd);
+			remove(ic->file);
+			free(ic->file);
+			free(ic);
+		}else
+			l = &ic->next;
+	}
+	
+	if(icache.head) {
+		icache.head->prev = nil;
+		for(ic=icache.head; ic; ic=ic->next){
+			if(ic->next)
+				ic->next->prev = ic;
+			else
+				icache.tail = ic;
+		}
+	}else
+		icache.tail = nil;
+}
+
+int
+urlfetch(char *url, HTTPHeader hdr)
+{
+	Icache *ic;
+	char buf[50], *host, *path, *p;
+	int fd, len;
+
+	ic = icachefind(url);
+	if(ic != nil){
+		*hdr = ic->hdr;
+		return dup(ic->fd, -1);
+	}
+
+	if(memcmp(url, "http://", 7) != 0){
+		werrstr("non-http url");
+		return -1;
+	}
+	p = strchr(url+7, '/');
+	if(p == nil)
+		p = url+strlen(url);
+	len = p - (url+7);
+	host = emalloc(len+1);
+	memmove(host, url+7, len);
+	host[len] = 0;
+	if(*p == 0)
+		p = "/";
+
+	strcpy(buf, "/var/tmp/smugfs.XXXXXX");
+	fd = opentemp(buf, ORDWR|ORCLOSE);
+	if(fd < 0)
+		return -1;
+	if(httptofile(http, host, req, &hdr, fd) < 0){
+		free(host);
+		return -1;
+	}
+	free(host);
+	icacheinsert(url, &hdr, buf, fd);
+	return fd;
+}
+