[20/25] Add function sys_get_page_size to replace platform dependent sysconf (_SC_PAGESIZE)

diff --git a/lib/crc32_file.c b/lib/crc32_file.c
index 66833702..45e1cc52 100644
--- a/lib/crc32_file.c
+++ b/lib/crc32_file.c
@@ -52,7 +52,7 @@  crc32_file (int fd, uint32_t *resp)
       void *mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE, fd, 0);
       if (mapped == MAP_FAILED && errno == ENOMEM)
 	{
-	  const size_t pagesize = sysconf (_SC_PAGESIZE);
+	  const size_t pagesize = sys_get_page_size();
 	  mapsize = ((mapsize / 2) + pagesize - 1) & -pagesize;
 	  while (mapsize >= pagesize
 		 && (mapped = mmap (NULL, mapsize, PROT_READ, MAP_PRIVATE,
diff --git a/lib/system.c b/lib/system.c
index 0fd28968..9ce1b62e 100644
--- a/lib/system.c
+++ b/lib/system.c
@@ -28,7 +28,12 @@ 
    the GNU Lesser General Public License along with this program.  If
    not, see <http://www.gnu.org/licenses/>.  */
 
+#include <errno.h>
+
 #include "system.h"
+#if defined(_WIN32)
+#include <windows.h>
+#endif
 
 ssize_t
 pwrite_retry(int fd, const void *buf, size_t len, off_t off)
@@ -85,3 +90,15 @@  pread_retry(int fd, void *buf, size_t len, off_t off)
 
   return recvd;
 }
+
+size_t
+sys_get_page_size(void)
+{
+#ifdef _WIN32
+  SYSTEM_INFO info;
+  GetSystemInfo(&info);
+  return info.dwPageSize;
+#else
+  return sysconf (_SC_PAGESIZE);
+#endif
+}
diff --git a/lib/system.h b/lib/system.h
index 05b2d8f9..675ed221 100644
--- a/lib/system.h
+++ b/lib/system.h
@@ -154,6 +154,9 @@  write_retry (int fd, const void *buf, size_t len);
 ssize_t
 pread_retry (int fd, void *buf, size_t len, off_t off);
 
+size_t
+sys_get_page_size(void);
+
 /* The demangler from libstdc++.  */
 extern char *__cxa_demangle (const char *mangled_name, char *output_buffer,
 			     size_t *length, int *status);
diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index 8fcef335..0f13e2f5 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -502,7 +502,7 @@  dwarf_begin_elf (Elf *elf, Dwarf_Cmd cmd, Elf_Scn *scngrp)
 
 
   /* Default memory allocation size.  */
-  size_t mem_default_size = sysconf (_SC_PAGESIZE) - 4 * sizeof (void *);
+  size_t mem_default_size = sys_get_page_size() - 4 * sizeof (void *);
   assert (sizeof (struct Dwarf) < mem_default_size);
 
   /* Allocate the data structure.  */
diff --git a/libdwelf/dwelf_strtab.c b/libdwelf/dwelf_strtab.c
index c95f9467..293b2d93 100644
--- a/libdwelf/dwelf_strtab.c
+++ b/libdwelf/dwelf_strtab.c
@@ -86,7 +86,7 @@  dwelf_strtab_init (bool nullstr)
 {
   if (ps == 0)
     {
-      ps = sysconf (_SC_PAGESIZE);
+      ps = sys_get_page_size();
       assert (sizeof (struct memoryblock) < ps - MALLOC_OVERHEAD);
     }
 
diff --git a/libdwfl/linux-kernel-modules.c b/libdwfl/linux-kernel-modules.c
index 58c0c417..65a58616 100644
--- a/libdwfl/linux-kernel-modules.c
+++ b/libdwfl/linux-kernel-modules.c
@@ -550,7 +550,7 @@  intuit_kernel_bounds (Dwarf_Addr *start, Dwarf_Addr *end, Dwarf_Addr *notes)
 	    *notes = *end;
 	}
 
-      Dwarf_Addr round_kernel = sysconf (_SC_PAGESIZE);
+      Dwarf_Addr round_kernel = sys_get_page_size();
       *start &= -(Dwarf_Addr) round_kernel;
       *end += round_kernel - 1;
       *end &= -(Dwarf_Addr) round_kernel;
diff --git a/libdwfl/linux-proc-maps.c b/libdwfl/linux-proc-maps.c
index 719cba68..40b8050b 100644
--- a/libdwfl/linux-proc-maps.c
+++ b/libdwfl/linux-proc-maps.c
@@ -422,7 +422,7 @@  dwfl_linux_proc_find_elf (Dwfl_Module *mod __attribute__ ((unused)),
       if (fd < 0)
 	goto detach;
 
-      *elfp = elf_from_remote_memory (base, sysconf (_SC_PAGESIZE), NULL,
+      *elfp = elf_from_remote_memory (base, sys_get_page_size(), NULL,
 				      &read_proc_memory, &fd);
 
       close (fd);
diff --git a/libelf/elf32_updatefile.c b/libelf/elf32_updatefile.c
index 8229fd26..af4518b8 100644
--- a/libelf/elf32_updatefile.c
+++ b/libelf/elf32_updatefile.c
@@ -474,7 +474,7 @@  __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
 
   /* Make sure the content hits the disk.  */
   char *msync_start = ((char *) elf->map_address
-		       + (elf->start_offset & ~(sysconf (_SC_PAGESIZE) - 1)));
+		       + (elf->start_offset & ~(sys_get_page_size() - 1)));
   char *msync_end = ((char *) elf->map_address
 		     + elf->start_offset + ehdr->e_shoff
 		     + ehdr->e_shentsize * shnum);
diff --git a/src/ar.c b/src/ar.c
index 3bcb18fe..d01f8482 100644
--- a/src/ar.c
+++ b/src/ar.c
@@ -428,7 +428,7 @@  copy_content (Elf *elf, int newfd, off_t off, size_t n)
   assert (off + n <= len);
 
   /* Tell the kernel we will read all the pages sequentially.  */
-  size_t ps = sysconf (_SC_PAGESIZE);
+  size_t ps = sys_get_page_size();
   if (n > 2 * ps)
     posix_madvise (rawfile + (off & ~(ps - 1)), n, POSIX_MADV_SEQUENTIAL);
 
diff --git a/src/ranlib.c b/src/ranlib.c
index 7838d69e..645b40ae 100644
--- a/src/ranlib.c
+++ b/src/ranlib.c
@@ -122,7 +122,7 @@  copy_content (Elf *elf, int newfd, off_t off, size_t n)
   assert (off + n <= len);
 
   /* Tell the kernel we will read all the pages sequentially.  */
-  size_t ps = sysconf (_SC_PAGESIZE);
+  size_t ps = sys_get_page_size();
   if (n > 2 * ps)
     posix_madvise (rawfile + (off & ~(ps - 1)), n, POSIX_MADV_SEQUENTIAL);
 
diff --git a/src/strings.c b/src/strings.c
index 55b047be..3341760d 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -163,7 +163,7 @@  main (int argc, char *argv[])
   elf_version (EV_CURRENT);
 
   /* Determine the page size.  We will likely need it a couple of times.  */
-  ps = sysconf (_SC_PAGESIZE);
+  ps = sys_get_page_size();
 
   struct stat st;
   int result = 0;