[PATCH v3] man/man2/getdents.2: Document system call interface of getdents64

[vursc <vursc@vursc.org>]

The count argument of the getdents64 system call is assumed to not exceed
INT_MAX. The glibc function accepts a size_t and passes INT_MAX to the kernel
if count exceeds INT_MAX.

Also document the dirent64 structure in glibc.

Signed-off-by: vursc <vursc@vursc.org>
---
 man/man2/getdents.2 | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/man/man2/getdents.2 b/man/man2/getdents.2
index 8c5bbebbc..de91f3800 100644
--- a/man/man2/getdents.2
+++ b/man/man2/getdents.2
@@ -42,7 +42,6 @@ These are not the interfaces you are interested in.
 Look at
 .BR readdir (3)
 for the POSIX-conforming C library interface.
-This page documents the bare kernel system call interfaces.
 .SS getdents()
 The system call
 .BR getdents ()
@@ -216,10 +215,31 @@ using
 .BR syscall (2).
 In that case you will need to define the
 .I linux_dirent
-or
-.I linux_dirent64
 structure yourself.
 .P
+The
+.B getdents64
+system call accepts an
+.B unsigned int
+argument
+.I count
+and assumes that
+.I count
+does not exceed
+.BR INT_MAX .
+The glibc wrapper function sets
+.I count
+to
+.B INT_MAX
+if it exceeds
+.BR INT_MAX .
+glibc defines a
+.I dirent64 
+structure, which is similar to
+.I linux_dirent64
+but with a 256-byte
+.IR d_name .
+.P
 Probably, you want to use
 .BR readdir (3)
 instead of these system calls.
-- 
2.53.0