linux: improve kernel feature detection

Do not check for minimum kernel and glibc versions, just check that the kernel headers export the syscall number and invoke the syscall directly. Effectively bypasses glibc.
joyent · Nov 17, 2011 · d5b2615 · d5b2615
1 parent 4ae40b6
commit d5b2615
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Showing 3 changed files with 59 additions and 20 deletions.
diff --git a/src/unix/core.c b/src/unix/core.c
@@ -727,8 +727,8 @@ int uv__accept(int sockfd, struct sockaddr* saddr, socklen_t slen) {
   assert(sockfd >= 0);
 
   while (1) {
-#if HAVE_ACCEPT4
-    peerfd = accept4(sockfd, saddr, &slen, SOCK_NONBLOCK | SOCK_CLOEXEC);
+#if HAVE_SYS_ACCEPT4
+    peerfd = sys_accept4(sockfd, saddr, &slen, SOCK_NONBLOCK | SOCK_CLOEXEC);
 
     if (peerfd != -1)
       break;

diff --git a/src/unix/internal.h b/src/unix/internal.h
@@ -28,30 +28,69 @@
 #include <stddef.h> /* offsetof */
 
 #undef HAVE_FUTIMES
-#undef HAVE_PIPE2
-#undef HAVE_ACCEPT4
 #undef HAVE_KQUEUE
 #undef HAVE_PORTS_FS
 
 #if defined(__linux__)
 
-#include <linux/version.h>
-#include <features.h>
+# undef HAVE_SYS_UTIMESAT
+# undef HAVE_SYS_PIPE2
+# undef HAVE_SYS_ACCEPT4
 
-/* futimes() requires linux >= 2.6.22 and glib >= 2.6 */
-#if LINUX_VERSION_CODE >= 0x20616 && __GLIBC_PREREQ(2, 6)
-#define HAVE_FUTIMES 1
-#endif
+# undef _GNU_SOURCE
+# define _GNU_SOURCE
 
-/* pipe2() requires linux >= 2.6.27 and glibc >= 2.9 */
-#if LINUX_VERSION_CODE >= 0x2061B && __GLIBC_PREREQ(2, 9)
-#define HAVE_PIPE2 1
-#endif
+# include <linux/version.h>
+# include <sys/syscall.h>
+# include <features.h>
+# include <unistd.h>
 
-/* accept4() requires linux >= 2.6.28 and glib >= 2.10 */
-#if LINUX_VERSION_CODE >= 0x2061C && __GLIBC_PREREQ(2, 10)
-#define HAVE_ACCEPT4 1
-#endif
+# if __NR_utimensat
+#  define HAVE_SYS_UTIMESAT 1
+# endif
+# if __NR_pipe2
+#  define HAVE_SYS_PIPE2 1
+# endif
+# if __NR_accept4
+#  define HAVE_SYS_ACCEPT4 1
+# endif
+
+# if HAVE_SYS_UTIMESAT
+inline static int sys_utimesat(int dirfd,
+                               const char* path,
+                               const struct timespec times[2],
+                               int flags)
+{
+  return syscall(__NR_utimensat, dirfd, path, times, flags);
+}
+inline static int sys_futimes(int fd, const struct timeval times[2])
+{
+  struct timespec ts[2];
+  ts[0].tv_sec = times[0].tv_sec, ts[0].tv_nsec = times[0].tv_usec * 1000;
+  ts[1].tv_sec = times[1].tv_sec, ts[1].tv_nsec = times[1].tv_usec * 1000;
+  return sys_utimesat(fd, NULL, ts, 0);
+}
+#  undef HAVE_FUTIMES
+#  define HAVE_FUTIMES 1
+#  define futimes(fd, times) sys_futimes(fd, times)
+# endif /* HAVE_SYS_FUTIMESAT */
+
+# if HAVE_SYS_PIPE2
+inline static int sys_pipe2(int pipefd[2], int flags)
+{
+  return syscall(__NR_pipe2, pipefd, flags);
+}
+# endif /* HAVE_SYS_PIPE2 */
+
+# if HAVE_SYS_ACCEPT4
+inline static int sys_accept4(int fd,
+                              struct sockaddr* addr,
+                              socklen_t* addrlen,
+                              int flags)
+{
+  return syscall(__NR_accept4, fd, addr, addrlen, flags);
+}
+# endif /* HAVE_SYS_ACCEPT4 */
 
 #endif /* __linux__ */
 

diff --git a/src/unix/process.c b/src/unix/process.c
@@ -104,15 +104,15 @@ static int uv__make_socketpair(int fds[2], int flags) {
 
 
 static int uv__make_pipe(int fds[2], int flags) {
-#if HAVE_PIPE2
+#if HAVE_SYS_PIPE2
   int fl;
 
   fl = O_CLOEXEC;
 
   if (flags & UV__F_NONBLOCK)
     fl |= O_NONBLOCK;
 
-  if (pipe2(fds, fl) == 0)
+  if (sys_pipe2(fds, fl) == 0)
     return 0;
 
   if (errno != ENOSYS)