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seqno.c
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C/C++ Source or Header
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1989-12-17
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546b
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31 lines
/*
* Get the sequence number to use, and update it.
*/
#include "defs.h"
int
get_seqno()
{
int seqno;
FILE *fp;
if ( (fp = fopen(SEQNO_FILE, "r+")) == NULL)
err_sys("can't open %s", SEQNO_FILE);
my_lock(fileno(fp)); /* exclusive lock on file */
if (fscanf(fp, "%d", &seqno) != 1)
err_quit("fscanf error for sequence number");
rewind(fp);
fprintf(fp, "%03d\n", (seqno+1) % 1000 ); /* next seq# to use */
fflush(fp);
my_unlock(fileno(fp)); /* unlock file */
fclose(fp); /* and close it, we're done */
return(seqno);
}