mirror of
https://github.com/autc04/Retro68.git
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238 lines
6.1 KiB
C
238 lines
6.1 KiB
C
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/* open for MMIXware.
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Copyright (C) 2001, 2002 Hans-Peter Nilsson
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Permission to use, copy, modify, and distribute this software is
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freely granted, provided that the above copyright notice, this notice
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and the following disclaimer are 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 <stdlib.h>
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#include <fcntl.h>
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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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/* Let's keep the filehandle array here, since this is a primary
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initializer of it. */
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unsigned char _MMIX_allocated_filehandle[32] =
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{
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1,
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1,
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1,
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0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0
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};
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int
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_open (const char *path,
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int flags, ...)
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{
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long fileno;
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unsigned char mode;
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long append_contents = 0;
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unsigned long prev_contents_size = 0;
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char *prev_contents = NULL;
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long ret;
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for (fileno = 0;
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fileno < (sizeof (_MMIX_allocated_filehandle) /
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sizeof (_MMIX_allocated_filehandle[0]));
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fileno++)
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if (_MMIX_allocated_filehandle[fileno] == 0)
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break;
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if (fileno == (sizeof (_MMIX_allocated_filehandle) /
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sizeof (_MMIX_allocated_filehandle[0])))
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{
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errno = EMFILE;
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return -1;
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}
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/* We map this to a fopen call. The flags parameter is stymied because
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we don't support other than these flags. */
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if (flags & ~(O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_APPEND | O_TRUNC))
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{
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UNIMPLEMENTED (("path: %s, flags: %d", path, flags));
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errno = ENOSYS;
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return -1;
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}
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if ((flags & O_ACCMODE) == O_RDONLY)
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mode = BinaryRead;
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else if ((flags & (O_WRONLY | O_APPEND)) == (O_WRONLY | O_APPEND))
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{
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mode = BinaryReadWrite;
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append_contents = 1;
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}
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else if ((flags & (O_RDWR | O_APPEND)) == (O_RDWR | O_APPEND))
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{
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mode = BinaryReadWrite;
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append_contents = 1;
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}
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else if ((flags & (O_WRONLY | O_CREAT)) == (O_WRONLY | O_CREAT)
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|| (flags & (O_WRONLY | O_TRUNC)) == (O_WRONLY | O_TRUNC))
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mode = BinaryWrite;
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else if ((flags & (O_RDWR | O_CREAT)) == (O_RDWR | O_CREAT))
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mode = BinaryReadWrite;
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else if (flags & O_RDWR)
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mode = BinaryReadWrite;
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else
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{
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errno = EINVAL;
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return -1;
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}
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if (append_contents)
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{
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/* BinaryReadWrite is equal to "w+", so it truncates the file rather
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than keeping the contents, as can be imagined if you're looking
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for append functionality. The only way we can keep the contents
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so we can append to it, is by first reading in and saving the
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contents, then re-opening the file as BinaryReadWrite and write
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the previous contents. This seems to work for the needs of
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simple test-programs. */
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long openexist = TRAP3f (SYS_Fopen, fileno, path, BinaryRead);
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if (openexist == 0)
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{
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/* Yes, this file exists, now opened, so let's read it and keep
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the contents. Better have the memory around for this to
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work. */
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long seekval = TRAP2f (SYS_Fseek, fileno, -1);
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if (seekval == 0)
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{
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prev_contents_size = TRAP1f (SYS_Ftell, fileno);
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/* If the file has non-zero size, we have something to
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append to. */
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if (prev_contents_size != 0)
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{
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/* Start reading from the beginning. Ignore the return
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value from this call: we'll notice if we can't read
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as much as we want. */
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TRAP2f (SYS_Fseek, fileno, 0);
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prev_contents = malloc (prev_contents_size);
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if (prev_contents != 0)
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{
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/* I don't like the thought of trying to read the
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whole file all at once, disregarding the size,
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because the host system might not support that
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and we'd get funky errors. Read in 32k at a
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time. */
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char *ptr = prev_contents;
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unsigned long read_more = prev_contents_size;
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unsigned long chunk_size = 1 << 15;
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while (read_more >= chunk_size)
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{
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long readval
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= TRAP3f (SYS_Fread, fileno, ptr, chunk_size);
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if (readval != 0)
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{
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free (prev_contents);
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TRAP1f (SYS_Fclose, fileno);
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errno = EIO;
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return -1;
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}
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read_more -= chunk_size;
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ptr += chunk_size;
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}
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if (read_more != 0)
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{
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long readval
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= TRAP3f (SYS_Fread, fileno, ptr, read_more);
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if (readval != 0)
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{
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free (prev_contents);
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TRAP1f (SYS_Fclose, fileno);
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errno = EIO;
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return -1;
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}
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}
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}
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else
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{
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/* Malloc of area to copy to failed. The glibc
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manpage says its open can return ENOMEM due to
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kernel memory failures, so let's do that too
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here. */
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errno = ENOMEM;
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return -1;
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}
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}
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}
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else
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{
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/* Seek failed. Gotta be some I/O error. */
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errno = EIO;
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return -1;
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}
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TRAP1f (SYS_Fclose, fileno);
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}
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}
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ret = TRAP3f (SYS_Fopen, fileno, path, mode);
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if (ret < 0)
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{
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/* It's totally unknown what the error was. We'll just take our
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chances and assume ENOENT. */
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errno = ENOENT;
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return -1;
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}
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if (prev_contents_size != 0)
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{
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/* Write out the previous contents, a chunk at a time. Leave the
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file pointer at the end of the file. */
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unsigned long write_more = prev_contents_size;
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unsigned long chunk_size = 1 << 15;
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char *ptr = prev_contents;
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while (write_more >= chunk_size)
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{
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long writeval
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= TRAP3f (SYS_Fwrite, fileno, ptr, chunk_size);
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if (writeval != 0)
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{
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free (prev_contents);
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TRAP1f (SYS_Fclose, fileno);
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errno = EIO;
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return -1;
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}
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write_more -= chunk_size;
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ptr += chunk_size;
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}
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if (write_more != 0)
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{
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long writeval
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= TRAP3f (SYS_Fwrite, fileno, ptr, write_more);
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if (writeval != 0)
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{
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free (prev_contents);
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TRAP1f (SYS_Fclose, fileno);
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errno = EIO;
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return -1;
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}
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}
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free (prev_contents);
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}
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_MMIX_allocated_filehandle[fileno] = 1;
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return fileno;
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}
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