Class LinuxLibcFunctions

java.lang.Object
oshi.ffm.ForeignFunctions
oshi.ffm.linux.LinuxLibcFunctions
public final class LinuxLibcFunctions extends ForeignFunctions
FFM bindings for Linux libc functions used by OSHI.

Covers: getpid, gettid, syscall, getloadavg, sysinfo, statvfs, gethostname, getaddrinfo/freeaddrinfo/gai_strerror, and getrlimit.

  • Field Details

    • RLIMIT_NOFILE

      public static final int RLIMIT_NOFILE
      See Also:

    • AI_CANONNAME

      public static final int AI_CANONNAME
      See Also:

    • SYSINFO_LAYOUT

      public static final StructLayout SYSINFO_LAYOUT
      struct sysinfo layout (64-bit Linux). 
        long    uptime       (8)
  long[3] loads        (24)
  long    totalram     (8)
  long    freeram      (8)
  long    sharedram    (8)
  long    bufferram    (8)
  long    totalswap    (8)
  long    freeswap     (8)
  short   procs        (2)
  ... padding/high memory fields follow

    • STATVFS_LAYOUT

      public static final StructLayout STATVFS_LAYOUT
      struct statvfs layout (64-bit Linux, no _f_unused padding field).

    • RLIMIT_LAYOUT

      public static final StructLayout RLIMIT_LAYOUT
      struct rlimit layout: two unsigned long fields.

    • ADDRINFO_LAYOUT

      public static final StructLayout ADDRINFO_LAYOUT
      struct addrinfo layout (64-bit Linux). 
        int     ai_flags     (4)
  int     ai_family    (4)
  int     ai_socktype  (4)
  int     ai_protocol  (4)
  long    ai_addrlen   (8)   -- socklen_t padded to 8
  ptr     ai_addr      (8)
  ptr     ai_canonname (8)   -- offset 32
  ptr     ai_next      (8)

  • Method Details

    • hasGettid

      public static boolean hasGettid()
      Returns whether gettid() is directly available in libc.
      Returns:
      true if gettid is available

    • getpid

      public static int getpid() throws Throwable
      Calls getpid().
      Returns:
      the process ID of the calling process
      Throws:
      Throwable - if the native call fails

    • gettid

      public static int gettid() throws Throwable
      Calls gettid() directly. Only valid if hasGettid() is true.
      Returns:
      the thread ID of the calling thread
      Throws:
      Throwable - if the native call fails

    • syscallGettid

      public static long syscallGettid() throws Throwable
      Calls syscall(SYS_GETTID).
      Returns:
      the thread ID of the calling thread
      Throws:
      Throwable - if the native call fails

    • getloadavg

      public static int getloadavg(MemorySegment loadavg, int nelem) throws Throwable
      Calls getloadavg(double[] loadavg, int nelem).
      Parameters:
      loadavg - pre-allocated segment of nelem doubles
      nelem - number of load average values to retrieve (1–3)
      Returns:
      number of samples set, or -1 on error
      Throws:
      Throwable

    • sysinfo

      public static int sysinfo(MemorySegment info) throws Throwable
      Calls sysinfo(struct sysinfo *info).
      Parameters:
      info - segment allocated with SYSINFO_LAYOUT
      Returns:
      0 on success, -1 on error
      Throws:
      Throwable

    • sysinfoProcs

      public static int sysinfoProcs(MemorySegment info)
      Reads the procs field from a sysinfo segment.
      Parameters:
      info - segment populated by sysinfo(MemorySegment)
      Returns:
      number of current processes

    • statvfs

      public static int statvfs(MemorySegment path, MemorySegment buf) throws Throwable
      Calls statvfs(const char *path, struct statvfs *buf).
      Parameters:
      path - path segment (null-terminated UTF-8)
      buf - segment allocated with STATVFS_LAYOUT
      Returns:
      0 on success, -1 on error
      Throws:
      Throwable

    • statvfsFrsize

      public static long statvfsFrsize(MemorySegment buf)
      Reads f_frsize from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      fragment size in bytes

    • statvfsBlocks

      public static long statvfsBlocks(MemorySegment buf)
      Reads f_blocks from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      total data blocks in filesystem

    • statvfsBfree

      public static long statvfsBfree(MemorySegment buf)
      Reads f_bfree from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      free blocks in filesystem

    • statvfsBavail

      public static long statvfsBavail(MemorySegment buf)
      Reads f_bavail from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      free blocks available to unprivileged users

    • statvfsFiles

      public static long statvfsFiles(MemorySegment buf)
      Reads f_files from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      total file nodes in filesystem

    • statvfsFfree

      public static long statvfsFfree(MemorySegment buf)
      Reads f_ffree from a statvfs segment.
      Parameters:
      buf - segment populated by statvfs(MemorySegment, MemorySegment)
      Returns:
      free file nodes in filesystem

    • gethostname

      public static int gethostname(MemorySegment buf, long len) throws Throwable
      Calls gethostname(char *name, size_t len).
      Parameters:
      buf - segment of at least len bytes
      len - buffer length
      Returns:
      0 on success, -1 on error
      Throws:
      Throwable

    • getaddrinfo

      public static int getaddrinfo(MemorySegment node, MemorySegment service, MemorySegment hints, MemorySegment res) throws Throwable
      Calls getaddrinfo(node, service, hints, res).
      Parameters:
      node - hostname segment (null-terminated UTF-8)
      service - NULL segment or service name
      hints - segment allocated with ADDRINFO_LAYOUT, or NULL
      res - pointer-to-pointer output segment (ADDRESS-sized)
      Returns:
      0 on success, non-zero error code on failure
      Throws:
      Throwable

    • freeaddrinfo

      public static void freeaddrinfo(MemorySegment res) throws Throwable
      Calls freeaddrinfo(struct addrinfo *res).
      Parameters:
      res - the addrinfo pointer returned by getaddrinfo
      Throws:
      Throwable

    • gaiStrerror

      public static String gaiStrerror(int errcode, Arena arena) throws Throwable
      Calls gai_strerror(int errcode) and returns the error string.
      Parameters:
      errcode - error code from getaddrinfo
      arena - arena to scope the string reinterpret
      Returns:
      human-readable error string
      Throws:
      Throwable

    • addrinfoCanoname

      public static String addrinfoCanoname(MemorySegment resPtr, Arena arena)
      Reads ai_canonname from the first addrinfo result pointer.
      Parameters:
      resPtr - the raw pointer value stored in the output segment after getaddrinfo
      arena - arena to scope the reinterpret
      Returns:
      the canonical name string, or null if the pointer is NULL

    • getrlimit

      public static int getrlimit(int resource, MemorySegment rlim) throws Throwable
      Calls getrlimit(int resource, struct rlimit *rlim).
      Parameters:
      resource - resource constant (e.g. RLIMIT_NOFILE)
      rlim - segment allocated with RLIMIT_LAYOUT
      Returns:
      0 on success, -1 on error
      Throws:
      Throwable

    • rlimitCur

      public static long rlimitCur(MemorySegment rlim)
      Reads rlim_cur from a rlimit segment.
      Parameters:
      rlim - segment populated by getrlimit(int, MemorySegment)
      Returns:
      the soft resource limit

    • rlimitMax

      public static long rlimitMax(MemorySegment rlim)
      Reads rlim_max from a rlimit segment.
      Parameters:
      rlim - segment populated by getrlimit(int, MemorySegment)
      Returns:
      the hard resource limit