mirror of
https://github.com/jart/cosmopolitan.git
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9c6d78c26d
The C standard states:
> The fprintf function returns the number of characters transmitted,
> or a negative value if an output or encoding error occurred or if
> the implementation does not support a specified width length
> modifier.
- C Standard, 7.23.6.1.15. The fprintf function
However, cosmopolitan fails to return a negative value in the case of
an output error, meaning that a program such as:
#include <stdio.h>
int main()
{
FILE *fp = fopen("/dev/full", "w");
setbuf(fp, NULL);
printf("fprintf: %d\n", fprintf(fp, "test\n"));
printf("fflush: %d\n", fflush(fp));
}
will, under cosmopolitan, print that no error occured in either of the
calls to fprintf and fflush.
This patch fixes this, along with the associated GitHub issue,
https://github.com/jart/cosmopolitan/issues/784
34 lines
2.2 KiB
C
34 lines
2.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Gabriel Ravier │
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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/dce.h"
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#include "libc/stdio/stdio.h"
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#include "libc/testlib/testlib.h"
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TEST(fprintf, testWriteError) {
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// Only Linux, NetBSD and FreeBSD are known to have /dev/full
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if (!IsLinux() && !IsNetbsd() && !IsFreebsd()) return;
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FILE *fp = fopen("/dev/full", "w");
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ASSERT_NE(fp, NULL);
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setbuf(fp, NULL);
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ASSERT_LT(fprintf(fp, "test"), 0);
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ASSERT_EQ(fclose(fp), 0);
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}
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