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Kernel: Add safe_memcpy, safe_memset and safe_strnlen

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These special functions can be used to safely copy/set memory or
determine the length of a string, e.g. provided by user mode.

In the event of a page fault, safe_memcpy/safe_memset will return
false and safe_strnlen will return -1.
This commit is contained in:
Tom 2020-09-10 19:49:31 -06:00 • committed by Andreas Kling
parent 1c86ab0108
commit 7d1b8417bd
2 changed files with 180 additions and 3 deletions
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4
Kernel/Arch/i386/CPU.h
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@ -279,6 +279,10 @@ void flush_idt();
void load_task_register(u16 selector);
void handle_crash(RegisterState&, const char* description, int signal, bool out_of_memory = false);
[[nodiscard]] bool safe_memcpy(void* dest_ptr, const void* src_ptr, size_t n, void*& fault_at);
[[nodiscard]] ssize_t safe_strnlen(const char* str, size_t max_n, void*& fault_at);
[[nodiscard]] bool safe_memset(void* dest_ptr, int c, size_t n, void*& fault_at);
#define LSW(x) ((u32)(x)&0xFFFF)
#define MSW(x) (((u32)(x) >> 16) & 0xFFFF)
#define LSB(x) ((x)&0xFF)