remove cgo (#5)

* remove cgo

Go can call POSIX API without using cgo.

* update glide.yaml and glide.lock

* miss

* review changes

* match the original C code.

cachectl/activepages.go

@@ -1,74 +1,55 @@
 package cachectl
 
-/*
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
-
-int activePages(const char *path)
-{
-    int i, j, fd, pages, pagesize;
-    struct stat st;
-    void *m;
-    char *pageinfo;
-
-    fd = open(path, O_RDONLY);
-    if(fd == -1) {
-        return -1;
-    }
-
-    if(fstat(fd, &st) == -1) {
-        goto error;
-    }
-
-    pagesize = getpagesize();
-    pages = (st.st_size + pagesize - 1) / pagesize;
-    pageinfo = calloc(sizeof(*pageinfo), pages);
-    if(!pageinfo) {
-        goto error;
-    }
-
-    m = mmap(NULL, st.st_size, PROT_NONE, MAP_SHARED, fd, 0);
-    if(m == MAP_FAILED) {
-        free(pageinfo);
-        goto error;
-    }
-
-    if(mincore(m, st.st_size, pageinfo) == -1) {
-        free(pageinfo);
-        munmap(m, st.st_size);
-        goto error;
-    }
-
-    i = 0;
-    j = 0;
-    for (i = 0; i < pages; i++) {
-        if(pageinfo[i] & 1) {
-            j++;
-        }
-    }
-
-    free(pageinfo);
-    munmap(m, st.st_size);
-
-    return j;
-error:
-    close(fd);
-    return -1;
-}
-*/
-import "C"
 import (
+	"os"
 	"unsafe"
+
+	"golang.org/x/sys/unix"
 )
 
-func activePages(path string) int {
-	cs := C.CString(path)
-	result := C.activePages(cs)
-	C.free(unsafe.Pointer(cs))
-	return int(result)
+func activePages(path string) (int, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		return 0, err
+	}
+	fsize := fi.Size()
+
+	if fsize == 0 {
+		return 0, nil
+	}
+
+	mmap, err := unix.Mmap(int(f.Fd()), 0, int(fsize), unix.PROT_NONE, unix.MAP_SHARED)
+	if err != nil {
+		return 0, err
+	}
+	defer unix.Munmap(mmap)
+
+	pagesize := int64(os.Getpagesize())
+	pages := (fsize + pagesize - 1) / pagesize
+	pageinfo := make([]byte, pages)
+
+	mmapPtr := uintptr(unsafe.Pointer(&mmap[0]))
+	sizePtr := uintptr(fsize)
+	pageinfoPtr := uintptr(unsafe.Pointer(&pageinfo[0]))
+
+	ret, _, err := unix.Syscall(unix.SYS_MINCORE, mmapPtr, sizePtr, pageinfoPtr)
+	if ret != 0 {
+		return 0, err
+	}
+
+	result := 0
+
+	for _, p := range pageinfo {
+		if p&1 == 1 {
+			result++
+		}
+	}
+
+	return result, nil
 }

cachectl/purge.go

@@ -1,56 +1,32 @@
 package cachectl
 
-/*
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-
-int fadvise(const char *path, float r)
-{
-    int fd;
-    struct stat st;
-    off_t l;
-    fd = open(path, O_RDONLY);
-    if(fd == -1) {
-        return -1;
-    }
-
-    if(fstat(fd, &st) == -1) {
-        goto error;
-    }
-
-    l = (off_t)(st.st_size * r);
-
-    if(posix_fadvise(fd, 0, l, POSIX_FADV_DONTNEED) != 0) {
-        goto error;
-    }
-
-    close(fd);
-    return 1;
-error:
-    close(fd);
-    return -1;
-}
-
-*/
-import "C"
 import (
 	"fmt"
 	"log"
-	"unsafe"
+	"os"
+
+	"golang.org/x/sys/unix"
 )
 
 func purgePages(fpath string, fsize int64, rate float64) error {
 	if rate < 0.0 || rate > 1.0 {
 		return fmt.Errorf("%.1f: rate should be over 0.0 and less than 1.0\n", rate)
 	}
 
-	cs := C.CString(fpath)
-	defer C.free(unsafe.Pointer(cs))
-	result := C.fadvise(cs, C.float(rate))
-	if result == -1 {
+	f, err := os.Open(fpath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		return err
+	}
+	size := fi.Size()
+
+	err = unix.Fadvise(int(f.Fd()), 0, int64(float64(size)*rate), unix.FADV_DONTNEED)
+	if err != nil {
 		return fmt.Errorf("failed to purge page cache for %s", fpath)
 	}
 

cachectl/stat.go

@@ -16,7 +16,12 @@ func PrintPagesStat(fpath string, fsize int64) {
 
 	pages := (fsize + int64(pagesize) - 1) / int64(pagesize)
 
-	pagesActive := activePages(fpath)
+	pagesActive, err := activePages(fpath)
+	if err != nil {
+		log.Printf("%v\n", err)
+		return
+	}
+
 	activeRate := float64(0)
 	if pagesActive == -1 {
 		pagesActive = 0

glide.yaml

@@ -2,3 +2,6 @@ package: github.com/cubicdaiya/cachectl
 import:
 - package: github.com/BurntSushi/toml
   version: v0.2.0
+- package: golang.org/x/sys
+  subpackages:
+  - unix