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Bug 50724 - scanf does not recognize signed infinities
scanf does not recognize signed infinities
Product: Red Hat Linux
Classification: Retired
Component: glibc (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Jakub Jelinek
Aaron Brown
Depends On:
  Show dependency treegraph
Reported: 2001-08-02 12:29 EDT by Trevin Beattie
Modified: 2016-11-24 10:12 EST (History)
1 user (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2006-08-04 16:27:43 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)

External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2001:121 normal SHIPPED_LIVE GNU C Library bugfix update 2001-10-04 00:00:00 EDT

  None (edit)
Description Trevin Beattie 2001-08-02 12:29:05 EDT
From Bugzilla Helper:
User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.2-2 i586)

Description of problem:
While all floating-point conversions work for scanning "inf" and "infinity"
(regardless of case), they all fail for "+inf" and "-inf" (and "+infinity"
and "-infinity", regardless of case).

The C standard requires that %a, %e, %f, and %g match an optionally signed
floating-point number, infinity, or NaN, in the same format expected for
the strtod() function.

How reproducible:

Steps to Reproduce:
Compile and run the following program:

#include <stdio.h>
#define __USE_ISOC99 1
#include <math.h>
#include <stdlib.h>

const char *test_strings[] = {
  "inf", "INF", "infinity", "INFINITY", "Inf", "iNfInItY",
  "+inf", "+INF", "+infinity", "+INFINITY", "+Inf", "+InFiNiTy",
  "-inf", "-INF", "-infinity", "-INFINITY", "-Inf", "-INFinitY",

const char *test_formats[] = { "%a%n", "%e%n", "%f%n", "%g%n",
			       "%A%n", "%E%n", "%F%n", "%G%n" };

main ()
  int i, j, l, n;
  float f;
  char *endp;

  for (i = 0; i < sizeof (test_strings) / sizeof (test_strings[0]); i++) {
    f = strtof (test_strings[i], &endp);
    if (*endp)
      fprintf (stderr, "Error: strtof(\"%s\") scanned %d characters\n",
	       test_strings[i], endp - &test_strings[i][0]);
    else if (!isinf(f))
      fprintf (stderr, "Error: strtof(\"%s\") returned %g\n",
	       test_strings[i], f);
      fprintf (stderr, "strtof(\"%s\") passed\n", test_strings[i]);

    for (j = 0; j < sizeof (test_formats) / sizeof (test_formats[0]); j++)
      f = 0.0F;
      l = -1;
      n = sscanf (test_strings[i], test_formats[j], &f, &l);
      if (n < 1)
	fprintf (stderr, "Error: sscanf(\"%s\",\"%s\",&f) returned %d\n",
		 test_strings[i], test_formats[j], n);
      if ((l >= 0) && test_strings[i][l])
	fprintf (stderr,
		 "Error: sscanf(\"%s\",\"%s\",&f) scanned %d characters\n",
		 test_strings[i], test_formats[j], l);
      if (!isinf (f) && ((n >= 1) || (f != 0.0F)))
	fprintf (stderr, "Error: sscanf(\"%s\",\"%s\",&f) stored %g\n",
		 test_strings[i], test_formats[j], f);
      if ((n >= 1) && isinf (f))
	fprintf (stderr, "sscanf(\"%s\",\"%s\",&f) passed\n",
		 test_strings[i], test_formats[j]);

Actual Results:  (long list; here's the summary: 57 tests passed, 105
errors reported)

strtof("inf") passed
sscanf("inf","%a%n",&f) passed
sscanf("iNfInItY","%G%n",&f) passed
strtof("+inf") passed
Error: sscanf("+inf","%a%n",&f) returned 0
Error: sscanf("-Inf","%G%n",&f) returned 0
Error: strtof("-INFinitY") scanned 4 characters
Error: sscanf("-INFinitY","%a%n",&f) returned 0

Expected Results:  All 162 tests should pass

Additional info:

c.f. WG14/N869,
Comment 1 Jakub Jelinek 2001-08-06 13:09:54 EDT
Should be fixed by http://sources.redhat.com/ml/libc-hacker/2001-08/msg00012.html
which will appear in glibc-2.2.4-2.
Comment 2 Bill Nottingham 2006-08-04 16:27:43 EDT
Red Hat Linux and Red Hat Powertools are currently no longer supported by Red
Hat, Inc. In an effort to clean up bugzilla, we are closing all bugs in MODIFIED
state for these products.

However, we do want to make sure that nothing important slips through the
cracks. If, in fact, these issues are not resolved in a current Fedora Core
Release (such as Fedora Core 5), please open a new issues stating so. Thanks.

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