sysdeps/nacl/open.c

   1
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #include <stdarg.h>
   5 #include <sysdep.h>
   6 #include <unistd.h>
   7
   8 #include <nacl_syscalls.h>
   9
  10
  11 #define COMMS_FD 3
  12
  13 static int is_initialised = 0;
  14 static int use_rpc = 0;
  15
  16 static int should_use_rpc(void)
  17 {
  18   if(!is_initialised) {
  19     use_rpc = getenv("NACL_FD") != NULL;
  20     is_initialised = 1;
  21   }
  22   return use_rpc;
  23 }
  24
  25 static int nacl_open_rpc(const char *filename)
  26 {
  27   int (*imc_sendmsg)(int fd, const struct NaClImcMsgHdr *msg, int flags) =
  28     NACL_SYSCALL_ADDR(NACL_sys_imc_sendmsg);
  29   int (*imc_recvmsg)(int fd, struct NaClImcMsgHdr *msg, int flags) =
  30     NACL_SYSCALL_ADDR(NACL_sys_imc_recvmsg);
  31
  32   struct NaClImcMsgIoVec iov;
  33   struct NaClImcMsgHdr msg;
  34   int filename_len = strlen(filename);
  35   char *msg_data = alloca(4 + filename_len);
  36   memcpy(msg_data, "Open", 4);
  37   memcpy(msg_data + 4, filename, filename_len);
  38   iov.base = msg_data;
  39   iov.length = 4 + filename_len;
  40   msg.iov = &iov;
  41   msg.iov_length = 1;
  42   msg.descv = NULL;
  43   msg.desc_length = 0;
  44   if(imc_sendmsg(COMMS_FD, &msg, 0) < 0)
  45     return -1;
  46
  47   char buf[4];
  48   int fd;
  49   iov.base = buf;
  50   iov.length = sizeof(buf);
  51   msg.descv = &fd;
  52   msg.desc_length = 1;
  53   int got = imc_recvmsg(COMMS_FD, &msg, 0);
  54   if(got >= 0 && msg.desc_length == 1)
  55     return fd;
  56   else {
  57     errno = ENOENT;
  58     return -1;
  59   }
  60 }
  61
  62 int __open(const char *filename, int flags, ...)
  63 {
  64   int (*nacl_open)(char const *pathname, int flags, int mode) =
  65     NACL_SYSCALL_ADDR(NACL_sys_open);
  66   int mode = 0;
  67   if(flags & O_CREAT) {
  68     va_list arg;
  69     va_start(arg, flags);
  70     mode = va_arg(arg, int);
  71     va_end(arg);
  72   }
  73
  74   if(should_use_rpc())
  75     return nacl_open_rpc(filename);
  76
  77   int result = nacl_open(filename, flags, mode);
  78   if (result < 0) {
  79     errno = -result;
  80     return -1;
  81   }
  82   return result;
  83 }
  84 libc_hidden_def (__open)
  85 weak_alias (__open, open)
  86 strong_alias (__open, __libc_open)
  87 strong_alias (__open, __open_nocancel)