[GSoC][RFC][PATCH 1/2] STRBUF_INIT_CONST: a new way to initialize strbuf

[Robear Selwans <rwagih.rw@gmail.com>]

A new function `STRBUF_INIT_CONST(const_str)` was added to allow for a
quick initialization of strbuf.

Details:
Using `STRBUF_INIT_CONST(str)` creates a new struct of type `strbuf` and
initializes its `buf`, `len` and `alloc` as `str`, `strlen(str)` and
`0`, respectively.

Use Case:
This is meant to be used to initialize strbufs with constant values and
thus, only allocating memory when needed.

Usage Example:
```
strbuf env_var = STRBUF_INIT_CONST("dev");
```

This was added according to the issue opened at [https://github.com/gitgitgadget/git/issues/398]

Signed-off-by: Robear Selwans <robear.selwans@outlook.com>
---
 strbuf.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/strbuf.h b/strbuf.h
index bfa66569a4..1a1753424c 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -71,6 +71,7 @@ struct strbuf {
 
 extern char strbuf_slopbuf[];
 #define STRBUF_INIT  { .alloc = 0, .len = 0, .buf = strbuf_slopbuf }
+#define STRBUF_INIT_CONST(const_str)  { .alloc = 0, .len = strlen(const_str), .buf = const_str }
 
 /*
  * Predeclare this here, since cache.h includes this file before it defines the
-- 
2.17.1