Large file support.

* stream.h (struct strm_ops): seek operation's second argument
is now just a val.

* stream.c (unimpl_seek, null_seek): Second argument is a val,
not cnum, to conform with function pointer in stream
structure.
(stdio_seek): Accept offset as val, which could be a fixnum
or bignum. Use new stdio_ftell and stdio_fseek functions
so large values work.
(seek_stream): No need to convert offset argument to cnum;
pass the val directly to seek virtual function.

* sysif.c (off_t_num, num_off_t, stdio_ftell,
stdio_fseek): New functions.

* sysif.h (OFF_T_MAX, OFF_T_MIN): New preprocessor symbols.
(off_t_num, num_off_t, stdio_ftell, stdio_fseek): Declared.

4 files changed, 116 insertions, 11 deletions

diff --git a/stream.c b/stream.c
index 54f7533d..fd170bc0 100644
--- a/stream.c
+++ b/stream.c
@@ -55,6 +55,7 @@
 #include "signal.h"
 #include "unwind.h"
 #include "args.h"
+#include "sysif.h"
 #include "stream.h"
 #include "utf8.h"
 #include "eval.h"
@@ -152,7 +153,7 @@ static noreturn val unimpl_unget_byte(val stream, int byte)
   unimpl(stream, lit("unget-byte"));
 }
 
-static noreturn val unimpl_seek(val stream, cnum off, enum strm_whence whence)
+static noreturn val unimpl_seek(val stream, val off, enum strm_whence whence)
 {
   unimpl(stream, lit("seek-stream"));
 }
@@ -202,7 +203,7 @@ static val null_flush(val stream)
   return nil;
 }
 
-static val null_seek(val stream, cnum off, enum strm_whence whence)
+static val null_seek(val stream, val off, enum strm_whence whence)
 {
   return nil;
 }
@@ -466,19 +467,17 @@ static val stdio_flush(val stream)
          ? t : stdio_maybe_error(stream, lit("flushing"));
 }
 
-static val stdio_seek(val stream, cnum offset, enum strm_whence whence)
+static val stdio_seek(val stream, val offset, enum strm_whence whence)
 {
   struct stdio_handle *h = coerce(struct stdio_handle *, stream->co.handle);
 
   errno = 0;
 
   if (h->f != 0) {
-    if (offset == 0 && whence == strm_cur) {
-      long where = ftell(h->f);
-      if (where >= 0)
-        return num(where);
+    if (offset == zero && whence == strm_cur) {
+      return stdio_ftell(h->f);
     } else {
-      if (fseek(h->f, offset, whence) == 0) {
+      if (stdio_fseek(h->f, offset, whence) != negone) {
         utf8_decoder_init(&h->ud);
         h->unget_c = nil;
         return t;
@@ -2754,7 +2753,6 @@ val seek_stream(val stream, val offset, val whence)
 {
   struct strm_ops *ops = coerce(struct strm_ops *, cobj_ops(stream, stream_s));
   enum strm_whence w;
-  cnum off = c_num(offset);
 
   if (whence == from_start_k)
     w = strm_start;
@@ -2766,7 +2764,7 @@ val seek_stream(val stream, val offset, val whence)
     uw_throwf(file_error_s, lit("seek: ~a is not a valid whence argument"),
               whence, nao);
 
-  return ops->seek(stream, off, w);
+  return ops->seek(stream, offset, w);
 }
 
 val truncate_stream(val stream, val len)
diff --git a/stream.h b/stream.h
index d3ec649a..bfaf76c9 100644
--- a/stream.h
+++ b/stream.h
@@ -57,7 +57,7 @@ struct strm_ops {
   val (*unget_byte)(val, int);
   val (*close)(val, val);
   val (*flush)(val);
-  val (*seek)(val, cnum, enum strm_whence);
+  val (*seek)(val, val, enum strm_whence);
   val (*truncate)(val, val);
   val (*get_prop)(val, val ind);
   val (*set_prop)(val, val ind, val);
diff --git a/sysif.c b/sysif.c
index 7c6f697d..95a65c5d 100644
--- a/sysif.c
+++ b/sysif.c
@@ -72,6 +72,7 @@
 #include "eval.h"
 #include "args.h"
 #include "struct.h"
+#include "arith.h"
 #include "txr.h"
 #include "sysif.h"
 
@@ -1036,6 +1037,98 @@ static val getgrnam_wrap(val wname)
 
 #endif
 
+off_t off_t_num(val num)
+{
+  switch (type(num)) {
+  case NUM:
+    if (sizeof (cnum) <= sizeof (off_t)) {
+      return c_num(num);
+    } else {
+      cnum n = c_num(num);
+      if (n > OFF_T_MAX || n < OFF_T_MIN)
+        goto toobig;
+      return n;
+    }
+  case BGNUM:
+    {
+      const int odig = (sizeof (off_t) / sizeof (mp_digit));
+      int i;
+      off_t out;
+      mp_int *mpn = mp(num);
+
+      if (odig > 1) {
+        if (USED(mpn) > odig)
+          goto toobig;
+
+        if (USED(mpn) == odig &&
+            (DIGITS(mpn)[USED(mpn) - 1] >> (MP_DIGIT_BIT - 1)) != 0)
+          goto toobig;
+
+        for (out = 0, i = USED(mpn) - 1; i >= 0; i--) {
+          out <<= MP_DIGIT_BIT * (odig > 1);
+          out |= DIGITS(mpn)[i];
+        }
+
+        return (ISNEG(mpn)) ? -out : out;
+      } else {
+        mp_digit d = DIGITS(mpn)[0];
+
+        if (USED(mpn) > 1)
+          goto toobig;
+
+        if (d > OFF_T_MAX)
+          goto toobig;
+
+        return (ISNEG(mpn)) ? d : -d;
+      }
+    }
+  default:
+    uw_throwf(error_s, lit("~s isn't a file offset"), num, nao);
+  toobig:
+    uw_throwf(error_s, lit("~s cannot fit into a file offset"), num, nao);
+  }
+}
+
+val num_off_t(off_t off)
+{
+  if (sizeof (off_t) <= sizeof (cnum)) {
+    return num(off);
+  } else if (NUM_MIN <= off && off <= NUM_MAX) {
+      return num(off);
+  } else {
+#if HAVE_DOUBLE_INTPTR_T
+    if (sizeof (off_t) <= sizeof (double_intptr_t)) {
+      val n = make_bignum();
+      mp_set_double_intptr(mp(n), off);
+      return n;
+    } else {
+      abort();
+    }
+#else
+#error port me!
+#endif
+  }
+}
+
+val stdio_ftell(FILE *f)
+{
+#if HAVE_FSEEKO
+  return num_off_t(ftello(f));
+#else
+  return num_off_t(ftell(f));
+#endif
+}
+
+val stdio_fseek(FILE *f, val off, int whence)
+{
+#if HAVE_FSEEKO
+  return num_off_t(fseeko(f, off_t_num(off), whence));
+#else
+  int ret = fseek(f, off_t_num(off), whence);
+  return (ret == -1) ? num_fast(ret) : stdio_ftell(f);
+#endif
+}
+
 void sysif_init(void)
 {
   stat_s = intern(lit("stat"), user_package);
diff --git a/sysif.h b/sysif.h
index 22e87b89..ea4b69d7 100644
--- a/sysif.h
+++ b/sysif.h
@@ -32,7 +32,21 @@ extern val dev_s, ino_s, mode_s, nlink_s, uid_s;
 extern val gid_s, rdev_s, size_s, blksize_s, blocks_s;
 extern val atime_s, mtime_s, ctime_s;
 
+#if !HAVE_FTRUNCATE
+typedef long off_t;
+#define OFF_T_MAX LONG_MAX
+#define OFF_T_MIN LONG_MIN
+#else
+#define OFF_T_MAX ((((convert(off_t, 1) << \
+                      ((sizeof(off_t) * CHAR_BIT) - 2)) - 1) << 1) + 1)
+#define OFF_T_MIN (-OFF_T_MAX)
+#endif
+
 val getenv_wrap(val name);
 val statp(val path);
 val statf(val path);
+off_t off_t_num(val num);
+val num_off_t(off_t offnum);
+val stdio_ftell(FILE *);
+val stdio_fseek(FILE *, val, int whence);
 void sysif_init(void);