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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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v_02_01
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2n01060a
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1990-09-16
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#include <io.h>
#include <errno.h>
#include <dos.h>
#include "redirector.h"
/*******************************************************************
* lock_read() - read shared data from a network file
*
* Parameters:
* handle (in) - file handle to read from
* buffer (in) - buffer to place data in
* length (in) - number of bytes to read
*
* Returns:
* Return code is identical to read()
*
* Notes:
* 1. If the desired record is locked, this routine will
* retry at 1 second intervals for RETRY attempts.
*
* History:
* Original code by William H. Roetzheim, 1989
**********************************************************************/
#define RETRY 5
int lock_read(int fh, char *buffer, unsigned int length)
{
int timeout = RETRY;
unsigned int count = EACCES; /* DOS error code */
while ((lock(fh, lseek(fh, 0, SEEK_CUR), length) != 0) && (timeout > 0))
{
timeout--;
sleep(1); /* wait one second */
}
if (timeout > 0)/* record is successfully locked */
{
count = read(fh, buffer, length);
}
return count;
}