curl/docs/DYNBUF.md

dynbuf

This is the internal module for creating and handling "dynamic buffers". This means buffers that can be appended to, dynamically and grow to adapt.

There will always be a terminating zero put at the end of the dynamic buffer.

The struct dynbuf is used to hold data for each instance of a dynamic buffer. The members of that struct MUST NOT be accessed or modified without using the dedicated dynbuf API.

Curl_dyn_init

void Curl_dyn_init(struct dynbuf *s, size_t toobig);

This initializes a struct to use for dynbuf and it cannot fail. The toobig value must be set to the maximum size we allow this buffer instance to grow to. The functions below will return CURLE_OUT_OF_MEMORY when hitting this limit.

Curl_dyn_free

void Curl_dyn_free(struct dynbuf *s);

Free the associated memory and clean up. After a free, the dynbuf struct can be reused to start appending new data to.

Curl_dyn_addn

CURLcode Curl_dyn_addn(struct dynbuf *s, const void *mem, size_t len);

Append arbitrary data of a given length to the end of the buffer.

If this function fails it calls Curl_dyn_free on dynbuf.

Curl_dyn_add

CURLcode Curl_dyn_add(struct dynbuf *s, const char *str);

Append a C string to the end of the buffer.

If this function fails it calls Curl_dyn_free on dynbuf.

Curl_dyn_addf

CURLcode Curl_dyn_addf(struct dynbuf *s, const char *fmt, ...);

Append a printf()-style string to the end of the buffer.

If this function fails it calls Curl_dyn_free on dynbuf.

Curl_dyn_vaddf

CURLcode Curl_dyn_vaddf(struct dynbuf *s, const char *fmt, va_list ap);

Append a vprintf()-style string to the end of the buffer.

If this function fails it calls Curl_dyn_free on dynbuf.

Curl_dyn_reset

void Curl_dyn_reset(struct dynbuf *s);

Reset the buffer length, but leave the allocation.

Curl_dyn_tail

CURLcode Curl_dyn_tail(struct dynbuf *s, size_t length);

Keep length bytes of the buffer tail (the last length bytes of the buffer). The rest of the buffer is dropped. The specified length must not be larger than the buffer length. To instead keep the leading part, see Curl_dyn_setlen().

Curl_dyn_ptr

char *Curl_dyn_ptr(const struct dynbuf *s);

Returns a char * to the buffer if it has a length, otherwise may return NULL. Since the buffer may be reallocated, this pointer should not be trusted or used anymore after the next buffer manipulation call.

Curl_dyn_uptr

unsigned char *Curl_dyn_uptr(const struct dynbuf *s);

Returns an unsigned char * to the buffer if it has a length, otherwise may return NULL. Since the buffer may be reallocated, this pointer should not be trusted or used anymore after the next buffer manipulation call.

Curl_dyn_len

size_t Curl_dyn_len(const struct dynbuf *s);

Returns the length of the buffer in bytes. Does not include the terminating zero byte.

Curl_dyn_setlen

CURLcode Curl_dyn_setlen(struct dynbuf *s, size_t len);

Sets the new shorter length of the buffer in number of bytes. Keeps the leftmost set number of bytes, discards the rest. To instead keep the tail part of the buffer, see Curl_dyn_tail().