From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Sat, 10 Sep 2022 19:04:14 +0000 (-0700)
Subject: cgraph agxbuf: use an enumerated type for buffer location
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=09c47521c6188c681a0414797bba4dbbe35dc91f;p=graphviz

cgraph agxbuf: use an enumerated type for buffer location

This does not change the semantics; 0 still means heap-allocated and 1 means
stack-allocated. However this is preparation for introducing a third location a
buffer can be hosted in.

Gitlab: #2302
---

diff --git a/lib/cgraph/agxbuf.h b/lib/cgraph/agxbuf.h
index edd361576..fa1d2b6a9 100644
--- a/lib/cgraph/agxbuf.h
+++ b/lib/cgraph/agxbuf.h
@@ -16,14 +16,20 @@
 #include <stdio.h>
 #include <string.h>
 
+/// a description of where a buffer is located
+typedef enum {
+  AGXBUF_ON_HEAP = 0,  ///< buffer is dynamically allocated
+  AGXBUF_ON_STACK = 1, ///< buffer is statically allocated
+} agxbuf_loc_t;
+
 /* Extensible buffer:
  *  Malloc'ed memory is never released until agxbfree is called.
  */
 typedef struct {
-  char *buf;           // start of buffer
-  size_t size;         ///< number of characters in the buffer
-  size_t capacity;     ///< available bytes in the buffer
-  int stack_allocated; // false if buffer is malloc'ed
+  char *buf;            ///< start of buffer
+  size_t size;          ///< number of characters in the buffer
+  size_t capacity;      ///< available bytes in the buffer
+  agxbuf_loc_t located; ///< where does the backing memory for this buffer live?
 } agxbuf;
 
 /* agxbinit:
@@ -33,12 +39,12 @@ typedef struct {
 static inline void agxbinit(agxbuf *xb, unsigned int hint, char *init) {
   if (init != NULL) {
     xb->buf = init;
-    xb->stack_allocated = 1;
+    xb->located = AGXBUF_ON_STACK;
   } else {
     if (hint == 0) {
       hint = BUFSIZ;
     }
-    xb->stack_allocated = 0;
+    xb->located = AGXBUF_ON_HEAP;
     xb->buf = (char *)gv_calloc(hint, sizeof(char));
   }
   xb->size = 0;
@@ -49,7 +55,7 @@ static inline void agxbinit(agxbuf *xb, unsigned int hint, char *init) {
  * Free any malloced resources.
  */
 static inline void agxbfree(agxbuf *xb) {
-  if (!xb->stack_allocated)
+  if (xb->located == AGXBUF_ON_HEAP)
     free(xb->buf);
 }
 
@@ -86,12 +92,12 @@ static inline void agxbmore(agxbuf *xb, size_t ssz) {
   if (size + ssz > nsize)
     nsize = size + ssz;
   cnt = agxblen(xb);
-  if (!xb->stack_allocated) {
+  if (xb->located == AGXBUF_ON_HEAP) {
     nbuf = (char *)gv_recalloc(xb->buf, size, nsize, sizeof(char));
   } else {
     nbuf = (char *)gv_calloc(nsize, sizeof(char));
     memcpy(nbuf, xb->buf, cnt);
-    xb->stack_allocated = 0;
+    xb->located = AGXBUF_ON_HEAP;
   }
   xb->buf = nbuf;
   xb->capacity = nsize;
@@ -215,7 +221,7 @@ static inline void agxbclear(agxbuf *xb) { xb->size = 0; }
 static inline char *agxbdisown(agxbuf *xb) {
   char *buf;
 
-  if (xb->stack_allocated) {
+  if (xb->located == AGXBUF_ON_STACK) {
     // the buffer is not dynamically allocated, so we need to copy its contents
     // to heap memory
 
@@ -232,7 +238,7 @@ static inline char *agxbdisown(agxbuf *xb) {
   xb->buf = NULL;
   xb->size = 0;
   xb->capacity = 0;
-  xb->stack_allocated = 0;
+  xb->located = AGXBUF_ON_HEAP;
 
   return buf;
 }