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https://github.com/jart/cosmopolitan.git
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*scanf() fixes to make TeX work (#1109)
* Fix reading the same symbol twice when using `{f,}scanf()`
PR #924 appears to use `unget()` subtly incorrectly when parsing
floating point numbers. The rest of the code only uses `unget()`
immediately followed by `goto Done;` to return back the symbol that
can't possibly belong to the directive we're processing.
With floating-point, however, the ungot characters could very well
be valid for the *next* directive, so we will essentially read them
twice. It can't be seen in `sscanf()` tests because `unget()` is a
no-op there, but the test I added for `fscanf()` fails like this:
...
EXPECT_EQ(0xDEAD, i1)
need 57005 (or 0xdead) =
got 908973 (or 0x000ddead)
...
EXPECT_EQ(0xBEEF, i2)
need 48879 (or 0xbeef) =
got 769775 (or 0x000bbeef)
This means we read 0xDDEAD instead of 0xDEAD and 0xBBEEF instead of
0xBEEF. I checked that both musl and glibc read 0xDEAD/0xBEEF, as
expected.
Fix the failing test by removing the unneeded `unget()` calls.
* Don't read invalid floating-point numbers in `*scanf()`
Currently, we just ignore any errors from `strtod()`. They can
happen either because no valid float can be parsed at all, or
because the state machine recognizes only a prefix of a valid
floating-point number.
Fix this by making sure `strtod()` parses everything we recognized,
provided it's non-empty. This requires to pop the last character
off the FP buffer, which is supposed to be parsed by the next
`*scanf()` directive.
* Make `%c` parsing in `*scanf()` respect the C standard
Currently, `%c`-style directives always succeed even if there
are actually fewer characters in the input than requested.
Before the fix, the added test fails like this:
...
EXPECT_EQ(2, sscanf("ab", "%c %c %c", &c2, &c3, &c4))
need 2 (or 0x02 or '\2' or ENOENT) =
got 3 (or 0x03 or '\3' or ESRCH)
...
EXPECT_EQ(0, sscanf("abcd", "%5c", s2))
need 0 (or 0x0 or '\0') =
got 1 (or 0x01 or '\1' or EPERM)
musl and glibc pass this test.
This commit is contained in:
Ivan Komarov
GitHub
parent
3afe3a3646
commit
f7ff515961
3 changed files with 89 additions and 22 deletions
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@ -50,6 +50,12 @@
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} \
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c; \
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})
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#define UNBUFFER \
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({ \
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if (c != -1) { \
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fpbuf[--fpbufcur] = '\0'; \
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} \
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})
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/**
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* String / file / stream decoder.
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@ -369,10 +375,11 @@ int __vcscanf(int callback(void *), //
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}
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} while ((c = BUFFER) != -1 && c != ')');
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if (c == ')') {
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c = BUFFER;
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c = READ;
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}
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goto GotFloatingPointNumber;
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} else {
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UNBUFFER;
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goto GotFloatingPointNumber;
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}
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} else {
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@ -410,9 +417,7 @@ int __vcscanf(int callback(void *), //
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goto Done;
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}
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} else {
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if (c != -1 && unget) {
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unget(c, arg);
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}
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UNBUFFER;
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goto GotFloatingPointNumber;
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}
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} else {
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@ -465,13 +470,24 @@ int __vcscanf(int callback(void *), //
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Continue:
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continue;
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Break:
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if (c != -1 && unget) {
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unget(c, arg);
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}
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UNBUFFER;
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break;
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} while ((c = BUFFER) != -1);
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GotFloatingPointNumber:
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fp = strtod((char *)fpbuf, NULL);
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/* An empty buffer can't be a valid float; don't even bother parsing. */
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bool valid = fpbufcur > 0;
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if (valid) {
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char *ep;
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fp = strtod((char *)fpbuf, &ep);
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/* We should have parsed the whole buffer. */
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valid = ep == (char *)fpbuf + fpbufcur;
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}
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free(fpbuf);
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fpbuf = NULL;
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fpbufcur = fpbufsize = 0;
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if (!valid) {
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goto Done;
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}
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if (!discard) {
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++items;
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void *out = va_arg(va, void *);
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@ -481,9 +497,6 @@ int __vcscanf(int callback(void *), //
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*(double *)out = (double)fp;
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}
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}
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free(fpbuf);
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fpbuf = NULL;
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fpbufcur = fpbufsize = 0;
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continue;
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ReportConsumed:
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n_ptr = va_arg(va, int *);
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@ -537,6 +550,11 @@ int __vcscanf(int callback(void *), //
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if (!j && c == -1 && !items) {
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items = -1;
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goto Done;
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} else if (rawmode && j != width) {
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/* The C standard says that %c "matches a sequence of characters of
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* **exactly** the number specified by the field width". If we have
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* fewer characters, what we've just read is invalid. */
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goto Done;
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} else if (!rawmode && j < bufsize) {
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if (charbytes == sizeof(char)) {
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buf[j] = '\0';
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33
test/libc/stdio/fscanf_test.c
Normal file
33
test/libc/stdio/fscanf_test.c
Normal file
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@ -0,0 +1,33 @@
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2024 Ivan Komarov │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/math.h"
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#include "libc/stdio/stdio.h"
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#include "libc/testlib/testlib.h"
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TEST(fscanf, test_readAfterFloat) {
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FILE *f = fmemopen("infDEAD-.125e-2BEEF", 19, "r");
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float f1 = 666.666f, f2 = f1;
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int i1 = 666, i2 = i1;
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EXPECT_EQ(4, fscanf(f, "%f%x%f%x", &f1, &i1, &f2, &i2));
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EXPECT_TRUE(isinf(f1));
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EXPECT_EQ(0xDEAD, i1);
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EXPECT_EQ(-0.125e-2f, f2);
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EXPECT_EQ(0xBEEF, i2);
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fclose(f);
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}
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@ -69,9 +69,17 @@ TEST(sscanf, testNonDirectiveCharacterMatching) {
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}
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TEST(sscanf, testCharacter) {
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char c = 0;
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EXPECT_EQ(1, sscanf("a", "%c", &c));
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EXPECT_EQ('a', c);
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char c1 = 0, c2 = c1, c3 = c2, c4 = c3;
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char s1[32] = {0}, s2[32] = {0};
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EXPECT_EQ(1, sscanf("a", "%c", &c1));
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EXPECT_EQ(2, sscanf("ab", "%c %c %c", &c2, &c3, &c4));
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EXPECT_EQ(1, sscanf("abcde", "%5c", s1));
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EXPECT_EQ(0, sscanf("abcd", "%5c", s2));
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EXPECT_EQ('a', c1);
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EXPECT_EQ('a', c2);
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EXPECT_EQ('b', c3);
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EXPECT_STREQ("abcde", &s1[0]);
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}
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TEST(sscanf, testStringBuffer) {
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@ -394,6 +402,20 @@ TEST(sscanf, floating_point_infinity_double_precision) {
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EXPECT_TRUE(isinf(g));
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}
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TEST(sscanf, floating_point_invalid) {
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float dummy;
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EXPECT_EQ(0, sscanf("junk", "%f", &dummy));
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EXPECT_EQ(0, sscanf("e9", "%f", &dummy));
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EXPECT_EQ(0, sscanf("-e9", "%f", &dummy));
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}
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TEST(sscanf, floating_point_invalid_double_precision) {
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double dummy;
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EXPECT_EQ(0, sscanf("junk", "%lf", &dummy));
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EXPECT_EQ(0, sscanf("e9", "%lf", &dummy));
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EXPECT_EQ(0, sscanf("-e9", "%lf", &dummy));
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}
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TEST(sscanf, floating_point_documentation_examples) {
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float a = 666.666f, b = a, c = b, d = c, e = d, f = e, g = f, h = g, i = h,
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j = i;
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@ -401,7 +423,7 @@ TEST(sscanf, floating_point_documentation_examples) {
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EXPECT_EQ(2, sscanf("111.11 -2.22", "%f %f", &a, &b));
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EXPECT_EQ(3, sscanf("Nan nan(2) inF", "%f %f %f", &c, &d, &e));
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EXPECT_EQ(
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5, sscanf("0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz -0.0000000123junk junk",
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2, sscanf("0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz -0.0000000123junk junk",
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"%f %f %f %f %f", &f, &g, &h, &i, &j));
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EXPECT_EQ(111.11f, a);
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@ -411,9 +433,6 @@ TEST(sscanf, floating_point_documentation_examples) {
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EXPECT_TRUE(isinf(e));
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EXPECT_EQ(0X1.BC70A3D70A3D7P+6f, f);
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EXPECT_TRUE(isinf(g));
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EXPECT_EQ(-0.0000000123f, h);
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EXPECT_EQ(.0f, i);
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EXPECT_EQ(.0f, j);
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}
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TEST(sscanf, floating_point_documentation_examples_double_precision) {
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@ -423,7 +442,7 @@ TEST(sscanf, floating_point_documentation_examples_double_precision) {
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EXPECT_EQ(2, sscanf("111.11 -2.22", "%lf %lf", &a, &b));
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EXPECT_EQ(3, sscanf("Nan nan(2) inF", "%lf %lf %lf", &c, &d, &e));
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EXPECT_EQ(
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5, sscanf("0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz -0.0000000123junk junk",
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2, sscanf("0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz -0.0000000123junk junk",
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"%lf %lf %lf %lf %lf", &f, &g, &h, &i, &j));
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EXPECT_EQ(111.11, a);
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@ -433,9 +452,6 @@ TEST(sscanf, floating_point_documentation_examples_double_precision) {
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EXPECT_TRUE(isinf(e));
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EXPECT_EQ(0X1.BC70A3D70A3D7P+6, f);
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EXPECT_TRUE(isinf(g));
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EXPECT_EQ(-0.0000000123, h);
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EXPECT_EQ(.0, i);
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EXPECT_EQ(.0, j);
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}
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TEST(sscanf, luplus) {
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