Change `sendfile' to loop until everything has been sent.

[bpt/guile.git] / libguile / filesys.c

diff --git a/libguile/filesys.c b/libguile/filesys.c
index d318ae7..d2e565b 100644 (file)
--- a/libguile/filesys.c
+++ b/libguile/filesys.c
@@ -1111,9 +1111,10 @@ SCM_DEFINE (scm_copy_file, "copy-file", 2, 0, 0,
 SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
            (SCM out, SCM in, SCM count, SCM offset),
            "Send @var{count} bytes from @var{in} to @var{out}, both of which "
-           "are either open file ports or file descriptors.  When "
+           "must be either open file ports or file descriptors.  When "
            "@var{offset} is omitted, start reading from @var{in}'s current "
-           "position; otherwise, start reading at @var{offset}.")
+           "position; otherwise, start reading at @var{offset}.  Return "
+           "the number of bytes actually sent.")
 #define FUNC_NAME s_scm_sendfile
 {
 #define VALIDATE_FD_OR_PORT(cvar, svar, pos)   \
@@ -1126,9 +1127,9 @@ SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
       cvar = SCM_FPORT_FDES (svar);            \
     }
 
-  size_t c_count;
+  ssize_t result SCM_UNUSED;
+  size_t c_count, total = 0;
   scm_t_off c_offset;
-  ssize_t result;
   int in_fd, out_fd;
 
   VALIDATE_FD_OR_PORT (out_fd, out, 1);
@@ -1139,9 +1140,30 @@ SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
 #if defined HAVE_SYS_SENDFILE_H && defined HAVE_SENDFILE
   /* The Linux-style sendfile(2), which is different from the BSD-style.  */
 
-  result = sendfile_or_sendfile64 (out_fd, in_fd,
-                                  SCM_UNBNDP (offset) ? NULL : &c_offset,
-                                  c_count);
+  {
+    off_t *offset_ptr;
+
+    offset_ptr = SCM_UNBNDP (offset) ? NULL : &c_offset;
+
+    /* On Linux, when OUT_FD is a file, everything is transferred at once and
+       RESULT == C_COUNT.  However, when OUT_FD is a pipe or other "slow"
+       device, fewer bytes may be transferred, hence the loop.  RESULT == 0
+       means EOF on IN_FD, so leave the loop in that case.  */
+    do
+      {
+       result = sendfile_or_sendfile64 (out_fd, in_fd, offset_ptr,
+                                        c_count - total);
+       if (result > 0)
+         /* At this point, either OFFSET_PTR is non-NULL and it has been
+            updated to the current offset in IN_FD, or it is NULL and IN_FD's
+            offset has been updated.  */
+         total += result;
+       else if (result < 0 && (errno == EINTR || errno == EAGAIN))
+         /* Keep going.  */
+         result = 0;
+      }
+    while (total < c_count && result > 0);
+  }
 
   /* Quoting the Linux man page: "In Linux kernels before 2.6.33, out_fd
      must refer to a socket.  Since Linux 2.6.33 it can be any file."
@@ -1152,12 +1174,12 @@ SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
 #endif
   {
     char buf[8192];
-    size_t result, left;
+    size_t left;
 
     if (!SCM_UNBNDP (offset))
       {
        if (SCM_PORTP (in))
-         scm_seek (in, offset, scm_from_int (SEEK_SET));
+         scm_seek (in, scm_from_off_t (c_offset), scm_from_int (SEEK_SET));
        else
          {
            if (lseek_or_lseek64 (in_fd, c_offset, SEEK_SET) < 0)
@@ -1165,7 +1187,7 @@ SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
          }
       }
 
-    for (result = 0, left = c_count; result < c_count; )
+    for (total = 0, left = c_count; total < c_count; )
       {
        size_t asked, obtained;
 
@@ -1180,13 +1202,12 @@ SCM_DEFINE (scm_sendfile, "sendfile", 3, 1, 0,
        if (obtained < asked)
          SCM_SYSERROR;
 
-       result += obtained;
+       total += obtained;
       }
 
-    return scm_from_size_t (result);
   }
 
-  return scm_from_ssize_t (result);
+  return scm_from_size_t (total);
 
 #undef VALIDATE_FD_OR_PORT
 }