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Code Issues Releases Wiki Activity

add comments to explain why its safe and the bot is wrong

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This commit is contained in:
J. Nick Koston
2025-07-05 23:39:25 -05:00
parent e2e35bf965
commit ea308eaaa2
1 changed files with 10 additions and 0 deletions
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10
esphome/core/helpers.cpp
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@@ -465,6 +465,13 @@ static constexpr const char *BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
// Helper function to find the index of a base64 character in the lookup table.
// Returns the character's position (0-63) if found, or 0 if not found.
// NOTE: This returns 0 for both 'A' (valid base64 char at index 0) and invalid characters.
// This is safe because is_base64() is ALWAYS checked before calling this function,
// preventing invalid characters from ever reaching here. The base64_decode function
// stops processing at the first invalid character due to the is_base64() check in its
// while loop condition, making this edge case harmless in practice.
static inline uint8_t base64_find_char(char c) {
const char *pos = strchr(BASE64_CHARS, c);
return pos ? (pos - BASE64_CHARS) : 0;
@@ -532,6 +539,9 @@ std::vector<uint8_t> base64_decode(const std::string &encoded_string) {
uint8_t char_array_4[4], char_array_3[3];
std::vector<uint8_t> ret;
// SAFETY: The loop condition checks is_base64() before processing each character.
// This ensures base64_find_char() is only called on valid base64 characters,
// preventing the edge case where invalid chars would return 0 (same as 'A').
while (in_len-- && (encoded_string[in] != '=') && is_base64(encoded_string[in])) {
char_array_4[i++] = encoded_string[in];
in++;