50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
/* read for MMIXware.
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Copyright (C) 2001 Hans-Peter Nilsson.
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Permission to use, copy, modify, and distribute this software is freely
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granted, provided that this notice is preserved with no changes.
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THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE. */
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#include <_ansi.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include "sys/syscall.h"
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#include <errno.h>
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int
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_read (int file,
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char *ptr,
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size_t len)
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{
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long ret;
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if ((unsigned int) file >= 32 || _MMIX_allocated_filehandle[file] == 0)
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{
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errno = EBADF;
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return -1;
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}
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ret = TRAP3f (SYS_Fread, file, ptr, len);
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/* Map the return codes:
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-1-len: an error. We return -1.
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0: success. We return len.
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n-len: end-of-file after n chars read. We return n. */
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if (ret == 0)
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return len;
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if (ret == -1 - (long) len)
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{
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/* We don't know the nature of the failure, so this is an
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approximation. */
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errno = EIO;
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return -1;
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}
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return ret + len;
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}
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