diff options
| -rw-r--r-- | src/libmdsserver/mds-message.c | 255 | ||||
| -rw-r--r-- | src/libmdsserver/mds-message.h | 9 |
2 files changed, 164 insertions, 100 deletions
diff --git a/src/libmdsserver/mds-message.c b/src/libmdsserver/mds-message.c index b05b0cf..739244a 100644 --- a/src/libmdsserver/mds-message.c +++ b/src/libmdsserver/mds-message.c @@ -89,6 +89,62 @@ void mds_message_destroy(mds_message_t* restrict this) /** + * Extend the header list's allocation + * + * @param this The message + * @param extent The number of additional entries + * @return Zero on success, -1 on error + */ +int mds_message_extend_headers(mds_message_t* restrict this, size_t extent) +{ + char** new_headers = this->headers; + if (xrealloc(new_headers, this->header_count + extent, char*)) + return -1; + this->headers = new_headers; + return 0; +} + + +/** + * Extend the read buffer by way of doubling + * + * @param this The message + * @return Zero on success, -1 on error + */ +static int mds_message_extend_buffer(mds_message_t* restrict this) +{ + char* new_buf = this->buffer; + if (xrealloc(new_buf, this->buffer_size << 1, char)) + return -1; + this->buffer = new_buf; + this->buffer_size <<= 1; + return 0; +} + + +/** + * Reset the header list and the payload + * + * @param this The message + */ +static void reset_message(mds_message_t* restrict this) +{ + if (this->headers != NULL) + { + size_t i; + xfree(this->headers, this->header_count); + this->headers = NULL; + } + this->header_count = 0; + + free(this->payload); + this->payload = NULL; + this->payload_size = 0; + this->payload_ptr = 0; +} + + +/** * Read the headers the message and determine, and store, its payload's length * * @param this The message @@ -154,6 +210,68 @@ static void unbuffer_beginning(mds_message_t* restrict this, size_t length, int /** + * Remove the header–payload delimiter from the buffer, + * get the payload's size and allocate the payload + * + * @param this The message + * @return The return value follows the rules of `mds_message_read` + */ +static int initialise_payload(mds_message_t* restrict this) +{ + /* Remove the \n (end of empty line) we found from the buffer. */ + unbuffer_beginning(this, 1, 1); + + /* Get the length of the payload. */ + if (get_payload_length(this) < 0) + return -2; /* Malformated value, enters unrecoverable state. */ + + /* Allocate the payload buffer. */ + if (this->payload_size > 0) + if (xmalloc(this->payload, this->payload_size, char)) + return -1; + + return 0; +} + + +/** + * Create a header from the buffer and store it + * + * @param this The message + * @param length The length of the header, including LF-termination + * @return The return value follows the rules of `mds_message_read` + */ +static int store_header(mds_message_t* restrict this, size_t length) +{ + char* header; + + /* Allocate the header. */ + if (xmalloc(header, length, char)) + return -1; + /* Copy the header data into the allocated header, */ + memcpy(header, this->buffer, length * sizeof(char)); + /* and NUL-terminate it. */ + header[length - 1] = '\0'; + + /* Remove the header data from the read buffer. */ + unbuffer_beginning(this, length, 1); + + /* Make sure the the header syntax is correct so that + the program does not need to care about it. */ + if (validate_header(header, length)) + { + free(header); + return -2; + } + + /* Store the header in the header list. */ + this->headers[this->header_count++] = header; + + return 0; +} + + +/** * Read the next message from a file descriptor * * @param this Memory slot in which to store the new message @@ -169,24 +287,15 @@ static void unbuffer_beginning(mds_message_t* restrict this, size_t length, int int mds_message_read(mds_message_t* restrict this, int fd) { size_t header_commit_buffer = 0; + int r; + +#define try(INSTRUCTION) if ((r = INSTRUCTION) < 0) return r /* If we are at stage 2, we are done and it is time to start over. - This is important because the function coul have been interrupted. */ + This is important because the function could have been interrupted. */ if (this->stage == 2) { - if (this->headers != NULL) - { - size_t i; - xfree(this->headers, this->header_count); - this->headers = NULL; - } - this->header_count = 0; - - free(this->payload); - this->payload = NULL; - this->payload_size = 0; - this->payload_ptr = 0; - + reset_message(this); this->stage = 0; } @@ -196,76 +305,36 @@ int mds_message_read(mds_message_t* restrict this, int fd) size_t n; ssize_t got; char* p; + size_t length; /* Stage 0: headers. */ - if (this->stage == 0) - /* Read all headers that we have stored into the read buffer. */ - while ((p = memchr(this->buffer, '\n', this->buffer_ptr * sizeof(char))) != NULL) + /* Read all headers that we have stored into the read buffer. */ + while ((this->stage == 0) && + ((p = memchr(this->buffer, '\n', this->buffer_ptr * sizeof(char))) != NULL)) + if ((length = (size_t)(p - this->buffer))) { - size_t len = (size_t)(p - this->buffer) + 1; - char* header; - - /* We have found an empty line, i.e. the end of the headers. */ - if (len == 1) - { - /* Remove the \n (end of empty line) we found from the buffer. */ - unbuffer_beginning(this, 1, 1); - - /* Get the length of the payload. */ - if (get_payload_length(this) < 0) - return -2; /* Malformated value, enters unrecoverable state. */ - - /* Allocate the payload buffer. */ - if (this->payload_size > 0) - if (xmalloc(this->payload, this->payload_size, char)) - return -1; - - /* Mark end of stage, next stage is getting the payload. */ - this->stage = 1; - - /* Stop searching for headers. */ - break; - } - /* We have found a header. */ - /* One every eighth header found with this function call, + /* On every eighth header found with this function call, we prepare the header list for eight more headers so that it does not need to be reallocated again and again. */ if (header_commit_buffer == 0) - { - char** old_headers = this->headers; - header_commit_buffer = 8; - n = this->header_count + header_commit_buffer; - if (xrealloc(this->headers, n, char*)) - { - this->headers = old_headers; - return -1; - } - } - - /* Allocate the header. */ - if (xmalloc(header, len, char)) - return -1; - /* Copy the header data into the allocated header, */ - memcpy(header, this->buffer, len * sizeof(char)); - /* and NUL-terminate it. */ - header[len - 1] = '\0'; + try (mds_message_extend_headers(this, header_commit_buffer = 8)); - /* Remove the header data from the read buffer. */ - unbuffer_beginning(this, len, 1); + /* Create and store header. */ + try (store_header(this, length + 1)); + header_commit_buffer -= 1; + } + else + { + /* We have found an empty line, i.e. the end of the headers. */ - /* Make sure the the header syntax is correct so that - the program does not need to care about it. */ - if (validate_header(header, len)) - { - free(header); - return -2; - } + /* Remove the header–payload delimiter from the buffer, + get the payload's size and allocate the payload. */ + try (initialise_payload(this)); - /* Store the header in the heaer list. */ - this->headers[this->header_count++] = header; - header_commit_buffer -= 1; + /* Mark end of stage, next stage is getting the payload. */ + this->stage = 1; } /* Stage 1: payload. */ @@ -274,30 +343,19 @@ int mds_message_read(mds_message_t* restrict this, int fd) this->stage = 2; return 0; } - if ((this->stage == 1) && (this->payload_size > 0)) /* FIXME: next message fails if not LF-terminated. */ + if ((this->stage == 1) && (this->payload_size > 0)) { /* How much of the payload that has not yet been filled. */ size_t need = this->payload_size - this->payload_ptr; - if (this->buffer_ptr <= need) - /* If we have everything that we need, just copy it into the payload buffer. */ - memcpy(this->payload + this->payload_ptr, this->buffer, this->buffer_ptr * sizeof(char)); - else - { - /* Otherwise, copy what we have, and remove it from the the read buffer. */ - memcpy(this->payload + this->payload_ptr, this->buffer, need * sizeof(char)); - unbuffer_beginning(this, need, 0); - } + /* How much we have of that what is needed. */ + size_t move = min(this->payload_ptr, need); + + /* Copy what we have, and remove it from the the read buffer. */ + memcpy(this->payload + this->payload_ptr, this->buffer, move * sizeof(char)); + unbuffer_beginning(this, move, 1); /* Keep track of how much we have read. */ - this->payload_ptr += this->buffer_ptr; - if (this->buffer_ptr <= need) - /* Reset the read pointer as the read buffer is empty now. */ - this->buffer_ptr = 0; - else - /* But if we head left over data that is for the next message, - just move the pointer back as much as we read. (Which is - actually what we do even we did not have excess data.) */ - this->buffer_ptr -= need; + this->payload_ptr += move; /* If we have filled the payload, make the end of this stage, i.e. that the message is complete, and return with success. */ @@ -313,16 +371,11 @@ int mds_message_read(mds_message_t* restrict this, int fd) /* Figure out how much space we have left in the read buffer. */ n = this->buffer_size - this->buffer_ptr; - /* If we do not have too much left, grow the buffer, */ + /* If we do not have too much left, */ if (n < 128) { - char* old_buffer = this->buffer; - if (xrealloc(this->buffer, this->buffer_size <<= 1, char)) - { - this->buffer = old_buffer; - this->buffer_size >>= 1; - return -1; - } + /* grow the buffer, */ + try (mds_message_extend_buffer(this)); /* and recalculate how much space we have left. */ n = this->buffer_size - this->buffer_ptr; @@ -340,6 +393,8 @@ int mds_message_read(mds_message_t* restrict this, int fd) return -1; } } + +#undef try } diff --git a/src/libmdsserver/mds-message.h b/src/libmdsserver/mds-message.h index fc1df99..72e1735 100644 --- a/src/libmdsserver/mds-message.h +++ b/src/libmdsserver/mds-message.h @@ -108,6 +108,15 @@ void mds_message_zero_initialise(mds_message_t* restrict this); void mds_message_destroy(mds_message_t* restrict this); /** + * Extend the header list's allocation + * + * @param this The message + * @param extent The number of additional entries + * @return Zero on success, -1 on error + */ +int mds_message_extend_headers(mds_message_t* restrict this, size_t extent); + +/** * Read the next message from a file descriptor * * @param this Memory slot in which to store the new message |