[PATCH v3 4/7] MINOR: ist: Add `struct ist ist_NULL()`

[Tim Duesterhus]

`ist_NULL()` returns an `struct ist` with `.ptr = NULL` and `.len = 0`.
---
 include/common/ist.h | 8 +++++++-
 src/hpack-dec.c      | 4 ++--
 src/http.c           | 4 ++--
 src/http_htx.c       | 2 +-
 4 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/common/ist.h b/include/common/ist.h
index 0d8b45721..4d75d8607 100644
--- a/include/common/ist.h
+++ b/include/common/ist.h
@@ -183,6 +183,12 @@ static inline struct ist ist2(const void *ptr, size_t len)
        return (struct ist){ .ptr = (char *)ptr, .len = len };
 }
 
+/* returns an `ist` with `.ptr = NULL` and `.len = 0` */
+static inline struct ist ist_NULL()
+{
+       return ist2(NULL, 0);
+}
+
 /* This function MODIFIES the string to add a zero AFTER the end, and returns
  * the start pointer. The purpose is to use it on strings extracted by parsers
  * from larger strings cut with delimiters that are not important and can be
@@ -705,7 +711,7 @@ static inline struct ist istist(const struct ist ist, const 
struct ist pat)
                }
                return ist2(ret.ptr - 1, ret.len + 1);
        }
-       return ist2(NULL, 0);
+       return ist_NULL();
 }
 
 /*
diff --git a/src/hpack-dec.c b/src/hpack-dec.c
index a721fadc4..ab757de29 100644
--- a/src/hpack-dec.c
+++ b/src/hpack-dec.c
@@ -406,7 +406,7 @@ int hpack_decode_frame(struct hpack_dht *dht, const uint8_t 
*raw, uint32_t len,
                                value = ist2(vtrash, vlen);
                        }
 
-                       name = ist2(NULL, 0);
+                       name = ist_NULL();
                        if (!must_index)
                                name.len = hpack_idx_to_phdr(idx);
 
@@ -458,7 +458,7 @@ int hpack_decode_frame(struct hpack_dht *dht, const uint8_t 
*raw, uint32_t len,
        }
 
        /* put an end marker */
-       list[ret].n = list[ret].v = ist2(NULL, 0);
+       list[ret].n = list[ret].v = ist_NULL();
        ret++;
 
  leave:
diff --git a/src/http.c b/src/http.c
index 75251992a..a122ef732 100644
--- a/src/http.c
+++ b/src/http.c
@@ -551,7 +551,7 @@ struct ist http_get_authority(const struct ist uri, int 
no_userinfo)
        return ist2(start, end - start);
 
   not_found:
-       return ist2(NULL, 0);
+       return ist_NULL();
 }
 
 /* Parse the URI from the given transaction (which is assumed to be in request
@@ -601,7 +601,7 @@ struct ist http_get_path(const struct ist uri)
        return ist2(ptr, end - ptr);
 
  not_found:
-       return ist2(NULL, 0);
+       return ist_NULL();
 }
 
 /*
diff --git a/src/http_htx.c b/src/http_htx.c
index 35bb05625..a4829ff81 100644
--- a/src/http_htx.c
+++ b/src/http_htx.c
@@ -533,7 +533,7 @@ int http_remove_header(struct htx *htx, struct http_hdr_ctx 
*ctx)
                blk = htx_remove_blk(htx, blk);
                if (blk || htx_is_empty(htx)) {
                        ctx->blk = blk;
-                       ctx->value = ist2(NULL, 0);
+                       ctx->value = ist_NULL();
                        ctx->lws_before = ctx->lws_after = 0;
                }
                else {
-- 
2.25.1