Support stdin and stdout in file stream utils

src/main/c/util/fstream.h

@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include "../error/error.c"
 
-#define HBU_FSTREAM_BUILD_INFRA(type, mode, noun, verb) \
+#define HBU_FSTREAM_BUILD_INFRA(type, mode, noun, verb, std) \
   typedef struct hbu_fstream##type##_s { \
     const char *name; \
     FILE *fd; \
@@ -13,16 +13,22 @@
   \
   hbu_fstream##type##_t hbu_fstream##type##_create(char *path) { \
     hbu_fstream##type##_t fstream = malloc(sizeof(struct hbu_fstream##type##_s)); \
-    fstream->name = path; \
     \
-    FILE *fd = fopen(path, mode); \
-    \
-    if (fd == NULL) { \
-      hbe_fatal(HBE_IO_FOPEN_FAIL, "Failed to open file %s for " verb " with error %d", fstream->name, errno); \
+    if (path == NULL) { \
+      fstream->name = #std; \
+      fstream->fd = std; \
+    } else { \
+      fstream->name = path; \
+      \
+      FILE *fd = fopen(path, mode); \
+      \
+      if (fd == NULL) { \
+        hbe_fatal(HBE_IO_FOPEN_FAIL, "Failed to open file %s for " verb " with error %d", fstream->name, errno); \
+      } \
+      \
+      fstream->fd = fd; \
     } \
     \
-    fstream->fd = fd; \
-    \
     return fstream; \
   } \
   \

src/main/c/util/fstreamin.c

@@ -7,7 +7,7 @@
 #include "../error/error.c"
 #include "fstream.h"
 
-HBU_FSTREAM_BUILD_INFRA(in, "r", "read", "reading")
+HBU_FSTREAM_BUILD_INFRA(in, "r", "read", "reading", stdin)
 
 hb_eod_char_t hbu_fstreamin_read(hbu_fstreamin_t fstreamin) {
   hb_char_t c;

src/main/c/util/fstreamout.c

@@ -6,7 +6,7 @@
 #include "../error/error.c"
 #include "fstream.h"
 
-HBU_FSTREAM_BUILD_INFRA(out, "w", "write", "writing")
+HBU_FSTREAM_BUILD_INFRA(out, "w", "write", "writing", stdout)
 
 void hbu_fstreamout_write(hbu_fstreamout_t fstreamout, hb_char_t c) {
   if (fwrite(&c, SIZEOF_CHAR, 1, fstreamout->fd) != SIZEOF_CHAR) {