diff -up texinfo-5.1/install-info/install-info.c.orig texinfo-5.1/install-info/install-info.c

--- texinfo-5.1/install-info/install-info.c.orig	2013-03-09 03:21:55.000000000 +0100

+++ texinfo-5.1/install-info/install-info.c	2013-03-18 12:47:02.721136885 +0100

@@ -22,6 +22,7 @@

 #include <getopt.h>

 #include <regex.h>

 #include <argz.h>

+#include <zlib.h>

 #define TAB_WIDTH 8

@@ -670,7 +671,7 @@ The first time you invoke Info you start

    MAGIC number, not the filename.  */

-FILE *

+void *

 open_possibly_compressed_file (char *filename,

     void (*create_callback) (char *),

     char **opened_filename, char **compression_program, int *is_pipe) 

@@ -678,7 +679,7 @@ open_possibly_compressed_file (char *fil

   char *local_opened_filename, *local_compression_program;

   int nread;

   char data[13];

-  FILE *f;

+  gzFile *f;

   /* We let them pass NULL if they don't want this info, but it's easier

      to always determine it.  */

@@ -686,48 +687,48 @@ open_possibly_compressed_file (char *fil

     opened_filename = &local_opened_filename;

   *opened_filename = filename;

-  f = fopen (*opened_filename, FOPEN_RBIN);

+  f = gzopen (*opened_filename, FOPEN_RBIN);

   if (!f)

     {

       *opened_filename = concat (filename, ".gz", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

   if (!f)

     {

       free (*opened_filename);

       *opened_filename = concat (filename, ".xz", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

   if (!f)

     {

       free (*opened_filename);

       *opened_filename = concat (filename, ".bz2", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

   if (!f)

     {

       free (*opened_filename);

       *opened_filename = concat (filename, ".lz", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

   if (!f)

     {

      free (*opened_filename);

      *opened_filename = concat (filename, ".lzma", "");

-     f = fopen (*opened_filename, FOPEN_RBIN);

+     f = gzopen (*opened_filename, FOPEN_RBIN);

     }

 #ifdef __MSDOS__

   if (!f)

     {

       free (*opened_filename);

       *opened_filename = concat (filename, ".igz", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

   if (!f)

     {

       free (*opened_filename);

       *opened_filename = concat (filename, ".inz", "");

-      f = fopen (*opened_filename, FOPEN_RBIN);

+      f = gzopen (*opened_filename, FOPEN_RBIN);

     }

 #endif /* __MSDOS__ */

    if (!f)

@@ -739,7 +740,7 @@ open_possibly_compressed_file (char *fil

            /* And try opening it again.  */

            free (*opened_filename);

            *opened_filename = filename;

-           f = fopen (*opened_filename, FOPEN_RBIN);

+           f = gzopen (*opened_filename, FOPEN_RBIN);

            if (!f)

              pfatal_with_name (filename);

          }

@@ -749,12 +750,12 @@ open_possibly_compressed_file (char *fil

   /* Read first few bytes of file rather than relying on the filename.

      If the file is shorter than this it can't be usable anyway.  */

-  nread = fread (data, sizeof (data), 1, f);

-  if (nread != 1)

+  nread = gzread (f, data, sizeof (data));

+  if (nread != sizeof (data))

     {

       /* Empty files don't set errno, so we get something like

          "install-info: No error for foo", which is confusing.  */

-      if (nread == 0)

+      if (nread >= 0)

         fatal (_("%s: empty file"), *opened_filename);

       pfatal_with_name (*opened_filename);

     }

@@ -821,20 +822,22 @@ open_possibly_compressed_file (char *fil

   if (*compression_program)

     { /* It's compressed, so fclose the file and then open a pipe.  */

+      FILE *p;

       char *command = concat (*compression_program," -cd <", *opened_filename);

-      if (fclose (f) < 0)

+      if (gzclose (f) < 0)

         pfatal_with_name (*opened_filename);

-      f = popen (command, "r");

-      if (f)

+      p = popen (command, "r");

+      if (p)

         *is_pipe = 1;

       else

         pfatal_with_name (command);

+      return p;

     }

   else

     { /* It's a plain file, seek back over the magic bytes.  */

-      if (fseek (f, 0, 0) < 0)

+      if (gzseek (f, 0, SEEK_SET) < 0)

         pfatal_with_name (*opened_filename);

-#if O_BINARY

+#if 0 && O_BINARY

       /* Since this is a text file, and we opened it in binary mode,

          switch back to text mode.  */

       f = freopen (*opened_filename, "r", f);

@@ -859,7 +862,7 @@ readfile (char *filename, int *sizep,

     char **compression_program)

 {

   char *real_name;

-  FILE *f;

+  void *f;

   int pipe_p;

   int filled = 0;

   int data_size = 8192;

@@ -873,7 +876,12 @@ readfile (char *filename, int *sizep,

   for (;;)

     {

-      int nread = fread (data + filled, 1, data_size - filled, f);

+      int nread;

+

+      if (pipe_p)

+        nread = fread (data + filled, 1, data_size - filled, f);

+      else

+        nread = gzread (f, data + filled, data_size - filled);

       if (nread < 0)

         pfatal_with_name (real_name);

       if (nread == 0)

@@ -895,7 +903,7 @@ readfile (char *filename, int *sizep,

   if (pipe_p)

     pclose (f);

   else

-    fclose (f);

+    gzclose (f);

   *sizep = filled;

   return data;

diff -up texinfo-5.1/install-info/Makefile.in.orig texinfo-5.1/install-info/Makefile.in

--- texinfo-5.1/install-info/Makefile.in.orig	2013-03-12 23:56:43.000000000 +0100

+++ texinfo-5.1/install-info/Makefile.in	2013-03-18 12:42:57.165767101 +0100

@@ -171,7 +171,7 @@ am__installdirs = "$(DESTDIR)$(bindir)"

 PROGRAMS = $(bin_PROGRAMS)

 am_ginstall_info_OBJECTS = install-info.$(OBJEXT)

 ginstall_info_OBJECTS = $(am_ginstall_info_OBJECTS)

-ginstall_info_LDADD = $(LDADD)

+ginstall_info_LDADD = $(LDADD) -lz

 am__DEPENDENCIES_1 =

 ginstall_info_DEPENDENCIES = $(top_builddir)/gnulib/lib/libgnu.a \

 	$(am__DEPENDENCIES_1)