Add util.ringbuffer, a ringbuffer with a file handle like interface

diff --git a/util-src/Makefile b/util-src/Makefile
index 5f35b81b72f139da6d5d2d985f22e782bdb0a6d0..85b190b9ae4dd9f7a719143a55e99d314391b549 100644 (file)
--- a/util-src/Makefile
+++ b/util-src/Makefile
@@ -1,12 +1,12 @@
 
 include ../config.unix
 
-CFLAGS+=-ggdb -I$(LUA_INCDIR)
+CFLAGS+=-ggdb -Wall -pedantic -I$(LUA_INCDIR)
 
 INSTALL_DATA=install -m644
 TARGET?=../util/
 
-ALL=encodings.so hashes.so net.so pposix.so signal.so table.so
+ALL=encodings.so hashes.so net.so pposix.so signal.so table.so ringbuffer.so
 
 .PHONY: all install clean
 .SUFFIXES: .c .o .so

diff --git a/util-src/ringbuffer.c b/util-src/ringbuffer.c
new file mode 100644 (file)
index 0000000..f5fa136
--- /dev/null
+++ b/util-src/ringbuffer.c
@@ -0,0 +1,232 @@
+
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <lua.h>
+#include <lauxlib.h>
+
+#define MIN(a, b) ((a)>(b)?(b):(a))
+#define MAX(a, b) ((a)>(b)?(a):(b))
+
+typedef struct {
+       size_t rpos; /* read position */
+       size_t wpos; /* write position */
+       size_t alen; /* allocated size */
+       size_t blen; /* current content size */
+       char* buffer;
+} ringbuffer;
+
+char readchar(ringbuffer* b) {
+       b->blen--;
+       return b->buffer[(b->rpos++) % b->alen];
+}
+
+void writechar(ringbuffer* b, char c) {
+       b->blen++;
+       b->buffer[(b->wpos++) % b->alen] = c;
+}
+
+/* make sure position counters stay within the allocation */
+void modpos(ringbuffer* b) {
+       b->rpos = b->rpos % b->alen;
+       b->wpos = b->wpos % b->alen;
+}
+
+int find(ringbuffer* b, const char* s, int l) {
+       size_t i, j;
+       int m;
+
+       if(b->rpos == b->wpos) { /* empty */
+               return 0;
+       }
+
+       for(i = 0; i <= b->blen - l; i++) {
+               if(b->buffer[(b->rpos + i) % b->alen] == *s) {
+                       m = 1;
+
+                       for(j = 1; j < l; j++)
+                               if(b->buffer[(b->rpos + i + j) % b->alen] != s[j]) {
+                                       m = 0;
+                                       break;
+                               }
+
+                       if(m) {
+                               return i + l;
+                       }
+               }
+       }
+
+       return 0;
+}
+
+int rb_find(lua_State* L) {
+       size_t l, m;
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       const char* s = luaL_checklstring(L, 2, &l);
+       m = find(b, s, l);
+
+       if(m > 0) {
+               lua_pushinteger(L, m);
+               return 1;
+       }
+
+       return 0;
+}
+
+
+int rb_read(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       int r = luaL_checkinteger(L, 2);
+       int peek = lua_toboolean(L, 3);
+
+       if(r > b->blen) {
+               lua_pushnil(L);
+               return 1;
+       }
+
+       if((b->rpos + r) > b->alen) {
+               lua_pushlstring(L, &b->buffer[b->rpos], b->alen - b->rpos);
+               lua_pushlstring(L, b->buffer, r - (b->alen - b->rpos));
+               lua_concat(L, 2);
+       } else {
+               lua_pushlstring(L, &b->buffer[b->rpos], r);
+       }
+
+       if(!peek) {
+               b->blen -= r;
+               b->rpos += r;
+               modpos(b);
+       }
+
+       return 1;
+}
+
+
+int rb_readuntil(lua_State* L) {
+       size_t l, m;
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       const char* s = luaL_checklstring(L, 2, &l);
+       m = find(b, s, l);
+
+       if(m > 0) {
+               lua_settop(L, 1);
+               lua_pushinteger(L, m);
+               return rb_read(L);
+       }
+
+       return 0;
+}
+
+int rb_write(lua_State* L) {
+       size_t l, w = 0;
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       const char* s = luaL_checklstring(L, 2, &l);
+
+       /* Does `l` bytes fit? */
+       if((l + b->blen) > b->alen) {
+               lua_pushnil(L);
+               return 1;
+       }
+
+       while(l-- > 0) {
+               writechar(b, *s++);
+               w++;
+       }
+
+       modpos(b);
+
+       lua_pushinteger(L, w);
+
+       return 1;
+}
+
+int rb_tostring(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       lua_pushfstring(L, "ringbuffer: %p->%p %d/%d", b, b->buffer, b->blen, b->alen);
+       return 1;
+}
+
+int rb_length(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       lua_pushinteger(L, b->blen);
+       return 1;
+}
+
+int rb_size(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       lua_pushinteger(L, b->alen);
+       return 1;
+}
+
+int rb_free(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+       lua_pushinteger(L, b->alen - b->blen);
+       return 1;
+}
+
+int rb_new(lua_State* L) {
+       size_t size = luaL_optinteger(L, 1, sysconf(_SC_PAGESIZE));
+       ringbuffer* b = lua_newuserdata(L, sizeof(ringbuffer));
+       b->rpos = 0;
+       b->wpos = 0;
+       b->alen = size;
+       b->blen = 0;
+       b->buffer = malloc(size);
+
+       if(b->buffer == NULL) {
+               return 0;
+       }
+
+       luaL_getmetatable(L, "ringbuffer_mt");
+       lua_setmetatable(L, -2);
+
+       return 1;
+}
+
+int rb_gc(lua_State* L) {
+       ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
+
+       if(b->buffer != NULL) {
+               free(b->buffer);
+       }
+
+       return 0;
+}
+
+int luaopen_util_ringbuffer(lua_State* L) {
+       if(luaL_newmetatable(L, "ringbuffer_mt")) {
+               lua_pushcfunction(L, rb_tostring);
+               lua_setfield(L, -2, "__tostring");
+               lua_pushcfunction(L, rb_length);
+               lua_setfield(L, -2, "__len");
+               lua_pushcfunction(L, rb_gc);
+               lua_setfield(L, -2, "__gc");
+
+               lua_newtable(L); /* __index */
+               {
+                       lua_pushcfunction(L, rb_find);
+                       lua_setfield(L, -2, "find");
+                       lua_pushcfunction(L, rb_read);
+                       lua_setfield(L, -2, "read");
+                       lua_pushcfunction(L, rb_readuntil);
+                       lua_setfield(L, -2, "readuntil");
+                       lua_pushcfunction(L, rb_write);
+                       lua_setfield(L, -2, "write");
+                       lua_pushcfunction(L, rb_size);
+                       lua_setfield(L, -2, "size");
+                       lua_pushcfunction(L, rb_length);
+                       lua_setfield(L, -2, "length");
+                       lua_pushcfunction(L, rb_free);
+                       lua_setfield(L, -2, "free");
+               }
+               lua_setfield(L, -2, "__index");
+       }
+
+       lua_newtable(L);
+       lua_pushcfunction(L, rb_new);
+       lua_setfield(L, -2, "new");
+       return 1;
+}