diff options
Diffstat (limited to 'common.h')
| -rw-r--r-- | common.h | 144 |
1 files changed, 143 insertions, 1 deletions
@@ -452,7 +452,7 @@ librecrypt_concat_mem_(struct concat_state *state, const char *text, size_t len) * @param state The buffer to write to, see `struct concat_state` for more information * @param text The text to copy to the buffer */ -LIBRECRYPT_NONNULL_1__ LIBRECRYPT_READ_STR__(2) HIDDEN +LIBRECRYPT_NONNULL__ LIBRECRYPT_READ_STR__(2) HIDDEN inline void librecrypt_concat_str_(struct concat_state *state, const char *text) { @@ -477,6 +477,148 @@ LIBRECRYPT_NONNULL_1__ HIDDEN void librecrypt_concat_uint_(struct concat_state *state, uintmax_t value); +/** + * Concatenate a single chracter onto a string + * + * NB! NUL termination will not be added + * + * Truncation is done to ensure the resulting string + * does not overrun it's buffer but is still has room + * for NUL terminnation (assuming the buffer is not + * zero-sized) + * + * @param state The buffer to write to, see `struct concat_state` for more information + * @param c The character to append + */ +LIBRECRYPT_NONNULL_1__ HIDDEN +inline void +librecrypt_concat_char_no_nul_(struct concat_state *state, char c) +{ + if (state->len == SIZE_MAX) + abort(); /* TODO not covered */ + state->len += 1u; + if (state->size > 1u) { + *state->buf++ = c; + state->size -= 1u; + } +} + + +/** + * Adjust a `struct concat_state` has been modified by + * another function + * + * This function will not by it self modify the buffer + * in any way. It will not add NUL-termination. This + * function will only update `*state` to reflect that + * some function wanted to write `len` bytes (but may + * have written less due to the buffer being to small). + * + * @param state The buffer to write to, see `struct concat_state` for more information + * @param len the length of the concatenated data sans NUL-termination + * @return Normally 0, -1 if `state->len` would overflow + * + * The proper error code when this function returns -1 is + * usually EOVERFLOW, however this function does not modify errno + * + * It is unspecified whether `state->buf` and `state->size` will + * be updated when -1 is returned. It is also unspecified whether + * `state->len` will be updated when -1 is returned. + * + * Precondition: `state->buf != NULL` + */ +LIBRECRYPT_NONNULL_1__ LIBRECRYPT_WUR__ HIDDEN +inline int +librecrypt_post_concat_adjust_(struct concat_state *state, size_t len) +{ + size_t n = state->size ? MIN(state->size - 1u, len) : 0u; + state->buf = &state->buf[n]; + state->size -= n; + if (state->len > SIZE_MAX - len) + return -1; + state->len += len; + return 0; +} + + +/** + * Get the base64-encoding length for some size of data + * + * @param raw_len The size of the data + * @param padded Whether the base64-encoding shall be padded to a multiple of 4 bytes + * @param ascii_len_out Output parameter for the length of the base64-encoding + * @return Normally 1, 0 if the value for `*ascii_len_out` could not be represented + * + * The proper error code when this function returns 0 is + * usually EOVERFLOW, however this function does not modify errno + */ +LIBRECRYPT_WUR__ LIBRECRYPT_NONNULL__ HIDDEN +inline int +librecrypt_raw_len_to_base64_len_(size_t raw_len, int padded, size_t *ascii_len_out) +{ + size_t q = raw_len / 3u; + size_t r = raw_len % 3u; + if (r) { + if (padded) + r = 4u; /* padding to for bytes */ + else + r += 1u; /* 3n+m bytes: 4n+m+1 chars, unless m=0 */ + } + if (q > (SIZE_MAX - r) / 4u) + return 0; + *ascii_len_out = q * 4u + r; + return 1; +} + + +/** + * Get the size of some data based on the length of its base64-encoding + * + * @param ascii_len The length of the data's unpadded base64-encoding + * @param raw_len_out Output parameter for the size of the data + * @return Normally 1, 0 if `ascii_len` doesn't have proper + * for a base64-encoding + * + * The proper error code when this function returns 0 is + * usually EINVAL, however this function does not modify errno + */ +LIBRECRYPT_WUR__ LIBRECRYPT_NONNULL__ HIDDEN +inline int +librecrypt_base64_len_to_raw_len_(size_t ascii_len, size_t *raw_len_out) +{ + size_t q = ascii_len / 4u; + size_t r = ascii_len % 4u; + if (r == 1u) + return 0; + *raw_len_out = q * 3u; + if (r) + *raw_len_out += r - 1u; + return 1; +} + + +/** + * Check whether a base64-encoding is padded to a multiple + * of 4 characters, without being excessively padded + * + * @param unpadded_len The length of the base64-encoding sans it's padding + * @param padded_len The length of the base64-encoding including any present padding + * @return Whether the base64-encoding is appropriately padded + * + * Precondition: `padded_len >= unpadded_len` + * Precondition: librecrypt_base64_len_to_raw_len_(unpadded_len, _) != 0 (i.e. `unpadded_len % 4u != 1u`) + */ +LIBRECRYPT_WUR__ CONST HIDDEN +inline int +librecrypt_is_base64_properly_padded_(size_t unpadded_len, size_t padded_len) +{ + if (padded_len % 4u) + return 0; + if (padded_len - unpadded_len >= 4u) + return 0; + return 1; +} + #ifdef TEST # include "libtest/libtest.h" |