LibC+Kernel: Start implementing sysconf

For now, only the non-standard _SC_NPROCESSORS_CONF and
_SC_NPROCESSORS_ONLN are implemented.

Use them to make ninja pick a better default -j value.
While here, make the ninja package script not fail if
no other port has been built yet.

Kernel/API/Syscall.h

@@ -191,7 +191,8 @@ namespace Kernel {
  __ENUMERATE_SYSCALL(ptrace) \
  __ENUMERATE_SYSCALL(minherit) \
  __ENUMERATE_SYSCALL(sendfd) \
- __ENUMERATE_SYSCALL(recvfd)
+ __ENUMERATE_SYSCALL(recvfd) \
+ __ENUMERATE_SYSCALL(sysconf)
 
 namespace Syscall {
 

Kernel/Arch/i386/CPU.h

@@ -744,6 +744,8 @@ class Processor {
 
  static Processor& by_id(u32 cpu);
 
+ static size_t processor_count() { return processors().size(); }
+
  template<typename Callback>
  static inline IterationDecision for_each(Callback callback)
  {

Kernel/Process.cpp

@@ -5308,4 +5308,15 @@ int Process::sys$recvfd(int sockfd)
  m_fds[new_fd].set(*received_descriptor_or_error.value(), 0);
  return new_fd;
 }
+
+long Process::sys$sysconf(int name)
+{
+ switch (name) {
+ case _SC_NPROCESSORS_CONF:
+ case _SC_NPROCESSORS_ONLN:
+ return Processor::processor_count();
+ default:
+ return -EINVAL;
+ }
+}
 }

Kernel/Process.h

@@ -327,6 +327,7 @@ class Process : public InlineLinkedListNode<Process> {
  int sys$ptrace(const Syscall::SC_ptrace_params*);
  int sys$sendfd(int sockfd, int fd);
  int sys$recvfd(int sockfd);
+ long sys$sysconf(int name);
 
  template<bool sockname, typename Params>
  int get_sock_or_peer_name(const Params&);

Kernel/UnixTypes.h

@@ -55,6 +55,11 @@
 #define MS_RDONLY (1 << 4)
 #define MS_REMOUNT (1 << 5)
 
+enum {
+ _SC_NPROCESSORS_CONF,
+ _SC_NPROCESSORS_ONLN,
+};
+
 #define PERF_EVENT_MALLOC 1
 #define PERF_EVENT_FREE 2
 

Libraries/LibC/unistd.cpp

@@ -722,4 +722,10 @@ char* getpass(const char* prompt)
  dbg() << "FIXME: getpass(\"" << prompt << "\")";
  ASSERT_NOT_REACHED();
 }
+
+long sysconf(int name)
+{
+ int rc = syscall(SC_sysconf, name);
+ __RETURN_WITH_ERRNO(rc, rc, -1);
+}
 }

Libraries/LibC/unistd.h

@@ -172,4 +172,10 @@ enum {
 #define _POSIX_PRIORITY_SCHEDULING
 #define _POSIX_VDISABLE '\0'
 
+enum {
+ _SC_NPROCESSORS_CONF,
+ _SC_NPROCESSORS_ONLN,
+};
+long sysconf(int name);
+
 __END_DECLS

Ports/ninja/package.sh

@@ -13,5 +13,6 @@ build() {
 }
 
 install() {
+ mkdir -p "${SERENITY_ROOT}/Build/Root/usr/local/bin"
  cp "${workdir}/ninja" "${SERENITY_ROOT}/Build/Root/usr/local/bin/ninja"
 }