[project @ 1999-09-19 19:25:24 by sof]

Allow seeking on devices and beyond EOF

diff --git a/ghc/lib/std/cbits/seekFile.c b/ghc/lib/std/cbits/seekFile.c
index d4183ba..1a9ec62 100644 (file)
--- a/ghc/lib/std/cbits/seekFile.c
+++ b/ghc/lib/std/cbits/seekFile.c
@@ -1,7 +1,7 @@
 /* 
  * (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
  *
- * $Id: seekFile.c,v 1.3 1998/12/02 13:27:53 simonm Exp $
+ * $Id: seekFile.c,v 1.4 1999/09/19 19:25:24 sof Exp $
  *
  * hSeek and hIsSeekable Runtime Support
  */
@@ -32,10 +32,10 @@ StgByteArray d;
     int rc = 0;
 
     switch (whence) {
-     case 0: whence=SEEK_SET; break;
-     case 1: whence=SEEK_CUR; break;
-     case 2: whence=SEEK_END; break;
-     default: whence=SEEK_SET; break; /* Should never happen, really */
+     case 0:  whence=SEEK_SET; break;
+     case 1:  whence=SEEK_CUR; break;
+     case 2:  whence=SEEK_END; break;
+     default: whence=SEEK_SET; /* Should never happen, really */
     }
 
     /*
@@ -87,7 +87,7 @@ StgByteArray d;
     rc = flushBuffer(ptr);
     if (rc < 0) return rc;
 
-    /* Try to find out the file type & size for a physical file */
+    /* Try to find out the file type */
     while (fstat(fo->fd, &sb) < 0) {
        /* highly unlikely */
        if (errno != EINTR) {
@@ -96,44 +96,10 @@ StgByteArray d;
            return -1;
        }
     }
-    if (S_ISREG(sb.st_mode)) {
-       /* Verify that we are not seeking beyond end-of-file */
-       off_t posn;
-
-       switch (whence) {
-       case SEEK_SET:
-           posn = offset;
-           break;
-       case SEEK_CUR:
-           while ((posn = lseek(fo->fd, 0, SEEK_CUR)) == -1) {
-               /* the possibility seems awfully remote */
-               if (errno != EINTR) {
-                   cvtErrno();
-                   stdErrno();
-                   return -1;
-               }
-           }
-           posn -= posn_delta;
-           posn += offset;
-           offset -= posn_delta; /* adjust the offset to include the buffer delta */
-           break;
-       case SEEK_END:
-           posn = (off_t)sb.st_size + offset;
-           break;
-       }
-       if (posn > sb.st_size) {
-           ghc_errtype = ERR_INVALIDARGUMENT;
-           ghc_errstr = "seek position beyond end of file";
-           return -1;
-       }
-    } else if (S_ISFIFO(sb.st_mode)) {
+    if (S_ISFIFO(sb.st_mode)) {
        ghc_errtype = ERR_UNSUPPORTEDOPERATION;
        ghc_errstr = "can't seek on a pipe";
        return -1;
-    } else {
-        ghc_errtype = ERR_UNSUPPORTEDOPERATION;
-        ghc_errstr = "can't seek on a device";
-        return -1;
     }
     while ( lseek(fo->fd, offset, whence) == -1) {
        if (errno != EINTR) {
@@ -203,44 +169,10 @@ StgInt64 d;
            return -1;
        }
     }
-    if (S_ISREG(sb.st_mode)) {
-       /* Verify that we are not seeking beyond end-of-file */
-       off_t posn;
-
-       switch (whence) {
-       case SEEK_SET:
-           posn = offset;
-           break;
-       case SEEK_CUR:
-           while ((posn = lseek(fo->fd, 0, SEEK_CUR)) == -1) {
-               /* the possibility seems awfully remote */
-               if (errno != EINTR) {
-                   cvtErrno();
-                   stdErrno();
-                   return -1;
-               }
-           }
-           posn -= posn_delta;
-           posn += offset;
-           offset -= posn_delta; /* adjust the offset to include the buffer delta */
-           break;
-       case SEEK_END:
-           posn = (off_t)sb.st_size + offset;
-           break;
-       }
-       if (posn > sb.st_size) {
-           ghc_errtype = ERR_INVALIDARGUMENT;
-           ghc_errstr = "seek position beyond end of file";
-           return -1;
-       }
-    } else if (S_ISFIFO(sb.st_mode)) {
+    if (S_ISFIFO(sb.st_mode)) {
        ghc_errtype = ERR_UNSUPPORTEDOPERATION;
        ghc_errstr = "can't seek on a pipe";
        return -1;
-    } else {
-        ghc_errtype = ERR_UNSUPPORTEDOPERATION;
-        ghc_errstr = "can't seek on a device";
-        return -1;
     }
     while ( lseek(fo->fd, offset, whence) == -1) {
        if (errno != EINTR) {
@@ -270,12 +202,12 @@ StgForeignPtr ptr;
            return -1;
        }
     }
-    /* Regular files are okay */
-    if (S_ISREG(sb.st_mode)) {
-       return 1;
+    /* Pipes are not okay.. */
+    if (S_ISFIFO(sb.st_mode)) {
+       return 0;
     } 
-    /* For now, everything else is not */
+    /* ..for now, everything else is */
     else {
-       return 0;
+       return 1;
     }
 }