76 lines
1.5 KiB
C
76 lines
1.5 KiB
C
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/* chstack - set stack size */
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#include <stdio.h>
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#define OFF 48L /* offset of stacksize in file */
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#define MAX 32768L /* maximum accepted stacksize */
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main(argc, argv)
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int argc;
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char *argv[];
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{
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char *p;
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long n;
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int fd;
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long current;
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long old;
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long atol(), lseek();
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p = argv[1];
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if (argc != 3 || (*p != '=' && *p != '+' && *p != '-')) {
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fprintf(stderr, "Usage: %s {=+-}amount file\n", argv[0]);
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exit(1);
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}
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n = atol(p+1);
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fd = open(argv[2], 2);
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if (fd < 0) {
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fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[2]);
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exit(1);
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}
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if (lseek(fd, OFF, 0) < 0 || getlong(fd, ¤t) < 0) {
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fprintf(stderr, "%s: cannot read %s\n", argv[0], argv[2]);
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exit(1);
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}
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old = current;
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if (*p == '=') current = n;
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else if (*p == '-') current -= n;
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else current += n;
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if (current > MAX || current <= 0) {
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fprintf(stderr, "%s: resulting stack size %ld too large or too small\n", argv[0], current);
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exit(1);
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}
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if (lseek(fd, OFF, 0) < 0 || putlong(fd, ¤t) < 0) {
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fprintf(stderr, "%s: can't modify %s\n", argv[0], argv[2]);
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exit(1);
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}
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printf("%s: Stack area changed from %ld to %ld bytes.\n",
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argv[2], old, current);
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exit(0);
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}
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getlong(fd, l)
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long *l;
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{
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char buf[4];
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if (read(fd, buf, 4) < 4) return -1;
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*l = ((((long)(buf[3]&0377)<<8)|(long)(buf[2]&0377)<<8)|(long)(buf[1]&0377)<<8)|(long)(buf[0]&0377);
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return 0;
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}
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putlong(fd, l)
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long *l;
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{
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char buf[4];
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buf[3] = *l >> 24;
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buf[2] = *l >> 16;
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buf[1] = *l >> 8;
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buf[0] = *l;
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if (write(fd, buf, 4) < 4) return -1;
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return 0;
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}
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