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LibC: Set saved_str to null in strtok_r if no tokens were found

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If we do not do this, the next call to strtok_r will start tokenizing
(and possibly modifying!) the memory pointed to by `saved_ptr`.
This commit is contained in:
Daniel Bertalan 2022-02-26 12:53:02 +01:00 • committed by Linus Groh
parent 4b4177f39c
commit ea52ba9fdc
Notes: sideshowbarker 2024-07-17 17:42:23 +09:00
2 changed files with 17 additions and 2 deletions
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13
Tests/LibC/TestLibCString.cpp
View file

@ -1,5 +1,6 @@
/*
* Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
* Copyright (c) 2022, Daniel Bertalan <dani@danielbertalan.dev>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -16,3 +17,15 @@ TEST_CASE(strerror_r_basic)
EXPECT_EQ(strerror_r(EFAULT, buf, sizeof(buf)), 0);
EXPECT_EQ(strcmp(buf, "Bad address"), 0);
}
TEST_CASE(strtok_r_delimiters_only)
{
char dummy[] = "a;";
char input[] = ";;;;;;";
char* saved_str = dummy;
EXPECT_EQ(strtok_r(input, ";", &saved_str), nullptr);
EXPECT_EQ(strtok_r(nullptr, ";", &saved_str), nullptr);
// The string to which `saved_str` initially points to shouldn't be modified.
EXPECT_EQ(strcmp(dummy, "a;"), 0);
}

6
Userland/Libraries/LibC/string.cpp
View file

@ -375,7 +375,7 @@ char* strpbrk(const char* s, const char* accept)
char* strtok_r(char* str, const char* delim, char** saved_str)
{
if (!str) {
if (!saved_str)
if (!saved_str || *saved_str == nullptr)
return nullptr;
str = *saved_str;
}
@ -407,8 +407,10 @@ char* strtok_r(char* str, const char* delim, char** saved_str)
}
}
if (str[token_start] == '\0')
if (str[token_start] == '\0') {
*saved_str = nullptr;
return nullptr;
}
if (token_end == 0) {
*saved_str = nullptr;