| 1 | |
| 2 | |
| 3 | * WMI string utility functions.
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| 4 | *
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| 5 | * Copyright (C) 2025 Armin Wolf <[email protected]>
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| 6 |
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| 7 |
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| 8 | #include <linux/build_bug.h>
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| 9 | #include <linux/compiler_types.h>
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| 10 | #include <linux/err.h>
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| 11 | #include <linux/export.h>
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| 12 | #include <linux/nls.h>
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| 13 | #include <linux/limits.h>
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| 14 | #include <linux/types.h>
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| 15 | #include <linux/wmi.h>
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| 16 |
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| 17 | #include <asm/byteorder.h>
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| 18 |
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| 19 | static_assert(sizeof(__le16) == sizeof(wchar_t));
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| 20 |
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| 21 | |
| 22 | * wmi_string_to_utf8s - Convert a WMI string into a UTF8 string.
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| 23 | * @str: WMI string representation
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| 24 | * @dst: Buffer to fill with UTF8 characters
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| 25 | * @length: Length of the destination buffer
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| 26 | *
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| 27 | * Convert as WMI string into a standard UTF8 string. The conversion will stop
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| 28 | * once a NUL character is detected or when the buffer is full. Any invalid UTF16
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| 29 | * characters will be ignored. The resulting UTF8 string will always be NUL-terminated
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| 30 | * when this function returns successfully.
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| 31 | *
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| 32 | * Return: Length of the resulting UTF8 string or negative errno code on failure.
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| 33 |
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| 34 | ssize_t wmi_string_to_utf8s(const struct wmi_string *str, u8 *dst, size_t length)
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| 35 | {
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| 36 |
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| 37 | int inlen = le16_to_cpu(str->length) / 2;
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| 38 | int ret;
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| 39 |
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| 40 | if (length < 1)
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| 41 | return -EINVAL;
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| 42 |
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| 43 |
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| 44 | ret = utf16s_to_utf8s((__force const wchar_t *)str->chars, inlen, UTF16_LITTLE_ENDIAN, dst,
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| 45 | length - 1);
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| 46 | if (ret < 0)
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| 47 | return ret;
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| 48 |
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| 49 | dst[ret] = '\0';
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| 50 |
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| 51 | return ret;
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| 52 | }
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| 53 | EXPORT_SYMBOL_GPL(wmi_string_to_utf8s);
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| 54 |
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| 55 | |
| 56 | * wmi_string_from_utf8s - Convert a UTF8 string into a WMI string.
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| 57 | * @str: WMI string representation
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| 58 | * @max_chars: Maximum number of UTF16 code points to store inside the WMI string
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| 59 | * @src: UTF8 string to convert
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| 60 | * @src_length: Length of the source string without any trailing NUL-characters
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| 61 | *
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| 62 | * Convert a UTF8 string into a WMI string. The conversion will stop when the WMI string is
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| 63 | * full. The resulting WMI string will always be NUL-terminated and have its length field set
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| 64 | * to and appropriate value when this function returns successfully.
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| 65 | *
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| 66 | * Return: Number of UTF16 code points inside the WMI string or negative errno code on failure.
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| 67 |
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| 68 | ssize_t wmi_string_from_utf8s(struct wmi_string *str, size_t max_chars, const u8 *src,
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| 69 | size_t src_length)
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| 70 | {
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| 71 | size_t str_length;
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| 72 | int ret;
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| 73 |
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| 74 | if (max_chars < 1)
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| 75 | return -EINVAL;
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| 76 |
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| 77 |
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| 78 | ret = utf8s_to_utf16s(src, src_length, UTF16_LITTLE_ENDIAN, (__force wchar_t *)str->chars,
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| 79 | max_chars - 1);
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| 80 | if (ret < 0)
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| 81 | return ret;
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| 82 |
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| 83 | str_length = (ret + 1) * sizeof(u16);
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| 84 | if (str_length > U16_MAX)
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| 85 | return -EOVERFLOW;
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| 86 |
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| 87 | str->length = cpu_to_le16(str_length);
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| 88 | str->chars[ret] = '\0';
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| 89 |
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| 90 | return ret;
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| 91 | }
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| 92 | EXPORT_SYMBOL_GPL(wmi_string_from_utf8s);
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