un-nest curl

curl-8.15.0/docs/internals/DYNBUF.md

@@ -0,0 +1,145 @@
+<!--
+Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+
+SPDX-License-Identifier: curl
+-->
+
+# 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 is always 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.
+
+## `curlx_dyn_init`
+
+```c
+void curlx_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 return `CURLE_OUT_OF_MEMORY` when hitting this
+limit.
+
+## `curlx_dyn_free`
+
+```c
+void curlx_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.
+
+## `curlx_dyn_addn`
+
+```c
+CURLcode curlx_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 `curlx_dyn_free` on `dynbuf`.
+
+## `curlx_dyn_add`
+
+```c
+CURLcode curlx_dyn_add(struct dynbuf *s, const char *str);
+```
+
+Append a C string to the end of the buffer.
+
+If this function fails it calls `curlx_dyn_free` on `dynbuf`.
+
+## `curlx_dyn_addf`
+
+```c
+CURLcode curlx_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 `curlx_dyn_free` on `dynbuf`.
+
+## `curlx_dyn_vaddf`
+
+```c
+CURLcode curlx_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 `curlx_dyn_free` on `dynbuf`.
+
+## `curlx_dyn_reset`
+
+```c
+void curlx_dyn_reset(struct dynbuf *s);
+```
+
+Reset the buffer length, but leave the allocation.
+
+## `curlx_dyn_tail`
+
+```c
+CURLcode curlx_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
+`curlx_dyn_setlen()`.
+
+## `curlx_dyn_ptr`
+
+```c
+char *curlx_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.
+
+## `curlx_dyn_uptr`
+
+```c
+unsigned char *curlx_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.
+
+## `curlx_dyn_len`
+
+```c
+size_t curlx_dyn_len(const struct dynbuf *s);
+```
+
+Returns the length of the buffer in bytes. Does not include the terminating
+zero byte.
+
+## `curlx_dyn_setlen`
+
+```c
+CURLcode curlx_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 `curlx_dyn_tail()`.
+
+## `curlx_dyn_take`
+
+```c
+char *curlx_dyn_take(struct dynbuf *s, size_t *plen);
+```
+
+Transfers ownership of the internal buffer to the caller. The dynbuf
+resets to its initial state. The returned pointer may be `NULL` if the
+dynbuf never allocated memory. The returned length is the amount of
+data written to the buffer. The actual allocated memory might be larger.