universal7885: interfaces: Do not use hardcoded cmd

Use standard C/C++ functions

universal7885-common/interfaces/hardware/parts/1.0/default/Android.bp

@@ -8,6 +8,7 @@ cc_binary {
         "FlashLight.cpp",
         "Display.cpp",
         "Swap.cpp",
+        "SwapHelpers.cpp",
         "service.cpp",
     ],
     shared_libs: [

universal7885-common/interfaces/hardware/parts/1.0/default/Swap.cpp

@@ -15,11 +15,15 @@
 #include "Swap.h"
 #include <fstream>
 #include <iostream>
+#include <sys/swap.h>
+#include <stdio.h>
 
 static int mSwapSize = 100;
+extern int mkswap (const std::string filename);
+extern void mkfile(const int filesize, const std::string name);
 
 #define SWAP_PATH "/data/swap/swapfile"
-using namespace std;
+
 namespace vendor::eureka::hardware::parts::V1_0 {
 
 Return<void> SwapOnData::setSwapSize(int32_t size) {
@@ -28,21 +32,15 @@ Return<void> SwapOnData::setSwapSize(int32_t size) {
 }
 
 Return<void> SwapOnData::setSwapOn() {
-  string cmd = string("dd if=/dev/zero of=") + string(SWAP_PATH) +
-               string(" bs=") + std::to_string(mSwapSize) + "M count=10";
-  system(cmd.c_str());
-  cmd = string("mkswap ") + string(SWAP_PATH);
-  system(cmd.c_str());
-  cmd = string("swapon -p 99 ") + string(SWAP_PATH);
-  system(cmd.c_str());
+  mkfile(mSwapSize * 1024 * 1024 * 10, SWAP_PATH);
+  mkswap(SWAP_PATH);
+  swapon(SWAP_PATH, (10 << SWAP_FLAG_PRIO_SHIFT) & SWAP_FLAG_PRIO_MASK);
   return Void();
 }
 
 Return<void> SwapOnData::setSwapOff() {
-  std::string cmd = string("swapoff ") + string(SWAP_PATH);
-  system(cmd.c_str());
-  cmd = string("rm ") + string(SWAP_PATH);
-  system(cmd.c_str());
+  swapoff(SWAP_PATH);
+  remove(SWAP_PATH);
   return Void();
 }
 

universal7885-common/interfaces/hardware/parts/1.0/default/SwapHelpers.cpp

@@ -0,0 +1,78 @@
+#include <cstring>
+#include <errno.h>
+#include <fcntl.h>
+#include <iostream>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/swap.h>
+#include <sys/types.h>
+#include <unistd.h>
+/* XXX This needs to be obtained from kernel headers. See b/9336527 */
+struct linux_swap_header {
+  char bootbits[1024]; /* Space for disklabel etc. */
+  u_int32_t version;
+  u_int32_t last_page;
+  u_int32_t nr_badpages;
+  unsigned char sws_uuid[16];
+  unsigned char sws_volume[16];
+  u_int32_t padding[117];
+  u_int32_t badpages[1];
+};
+void mkfile(const int filesize, const std::string& name){
+        FILE *fp = fopen(name.c_str(), "we");
+        fseek(fp, filesize , SEEK_SET);
+        fputc('\0', fp);
+        fclose(fp);
+}
+#define MAGIC_SWAP_HEADER "SWAPSPACE2"
+#define MAGIC_SWAP_HEADER_LEN 10
+#define MIN_PAGES 10
+int mkswap(const std::string& filename) {
+  int err = 0;
+  int fd;
+  ssize_t len;
+  off_t swap_size;
+  int pagesize;
+  struct linux_swap_header sw_hdr;
+  fd = open(filename.c_str(), O_WRONLY | O_CLOEXEC);
+  if (fd < 0) {
+    err = errno;
+    return err;
+  }
+  pagesize = getpagesize();
+  /* Determine the length of the swap file */
+  swap_size = lseek(fd, 0, SEEK_END);
+  if (swap_size < MIN_PAGES * pagesize) {
+    err = -ENOSPC;
+    goto err;
+  }
+  if (lseek(fd, 0, SEEK_SET)) {
+    err = errno;
+    goto err;
+  }
+  memset(&sw_hdr, 0, sizeof(sw_hdr));
+  sw_hdr.version = 1;
+  sw_hdr.last_page = (swap_size / pagesize) - 1;
+  len = write(fd, &sw_hdr, sizeof(sw_hdr));
+  if (len != sizeof(sw_hdr)) {
+    err = errno;
+    goto err;
+  }
+  /* Write the magic header */
+  if (lseek(fd, pagesize - MAGIC_SWAP_HEADER_LEN, SEEK_SET) < 0) {
+    err = errno;
+    goto err;
+  }
+  len = write(fd, MAGIC_SWAP_HEADER, MAGIC_SWAP_HEADER_LEN);
+  if (len != MAGIC_SWAP_HEADER_LEN) {
+    err = errno;
+    goto err;
+  }
+  if (fsync(fd) < 0) {
+    err = errno;
+    goto err;
+  }
+err:
+  close(fd);
+  return err;
+}