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Tests: Add a test for ProcFS fd interaction

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Co-authored-by: Tim Schumacher <timschumi@gmx.de>
This commit is contained in:
Kyle Ambroff-Kao 2021-06-17 18:18:53 +02:00 • committed by Andreas Kling
parent 9559ac9dd6
commit d173945dad
1 changed files with 58 additions and 0 deletions
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58
Tests/Kernel/TestProcFS.cpp Normal file
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/*
* Copyright (c) 2021, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibTest/TestCase.h>
#include <cstring>
#include <unistd.h>
TEST_CASE(test_process_fd_readlink)
{
char expected_link[MAXPATHLEN];
char buf[MAXPATHLEN];
// Read the symlink value for stdin, stdout and stderr
auto link_length = readlink("/proc/self/fd/0", expected_link, sizeof(expected_link));
expected_link[link_length] = '\0';
link_length = readlink("/proc/self/fd/1", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
link_length = readlink("/proc/self/fd/2", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
// Create a new file descriptor that is a dup of 0 with various big values in order to reproduce issue #7820.
// We should get the same link value for each fd that was duplicated.
// 255 is the first broken file descriptor that was discovered and might be used by other software (e.g. bash)
auto new_fd = dup2(0, 255);
EXPECT_EQ(new_fd, 255);
link_length = readlink("/proc/self/fd/255", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
// 215 is the last fd before we have to encode the fd using more than one byte (due to the offset by FI_MaxStaticFileIndex)
new_fd = dup2(0, 215);
EXPECT_EQ(new_fd, 215);
link_length = readlink("/proc/self/fd/215", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
// 216 is the first fd that is encoded using more than one byte
new_fd = dup2(0, 216);
EXPECT_EQ(new_fd, 216);
link_length = readlink("/proc/self/fd/216", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
// 1023 is the largest possible file descriptor
new_fd = dup2(0, 1023);
EXPECT_EQ(new_fd, 1023);
link_length = readlink("/proc/self/fd/1023", buf, sizeof(buf));
buf[link_length] = '\0';
EXPECT_EQ(0, strcmp(buf, expected_link));
}