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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - ASan strotol interceptor breaks errno on Windows"
href="https://bugs.llvm.org/show_bug.cgi?id=35137">35137</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>ASan strotol interceptor breaks errno on Windows
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rnk@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Running this program on Windows prints "errno: 34" without asan and "errno: 0"
with asan:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
void print_strtol_results(const char *input) {
char *end = 0;
long result = strtol(input, &end, 10);
int err = errno;
printf("input: %s, end: %s, result: %ld, errno: %d\n", input, end, result,
err);
}
int main() {
//print_strtol_results("2147483647");
print_strtol_results("2147483648");
printf("&errno: %p, errno: %d\n", &errno, errno);
return 0;
}
This is because ASan intercepts many versions of strtol and redirects them all
to itself. It then delegates to ntdll!strtol, which doesn't set errno, because
errno is a CRT concept, and ntdll is layered below the CRT.</pre>
</div>
</p>
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