X-Git-Url: http://git.thejh.net/?p=libjh.git;a=blobdiff_plain;f=io.c;h=1ef3d3df9361126266e73b0fe45d0934457d2e4f;hp=17ea4d675b04fc709e18738a3e2ec0faf5a47130;hb=c5c85660f673e4324563a486a6463074f9f5eff8;hpb=68baa08af4f48a619aaac76de0010c68cd2fe1e4

diff --git a/io.c b/io.c
index 17ea4d6..1ef3d3d 100644
--- a/io.c
+++ b/io.c
@@ -4,11 +4,10 @@ HEADER #include <sys/types.h>
 #include <unistd.h>
 #include <errno.h>
 #include <stdlib.h>
-#include <stdbool.h>
+HEADER #include <stdbool.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <string.h>
-#include <assert.h>
 #include <sys/mman.h>
 
 // Wrapper for `read` that retries on partial reads.
@@ -181,3 +180,37 @@ PUBLIC_FN void *mmap_file(void *addr, size_t length, int prot, int flags, char *
   errno = errno_;
   return (r==MAP_FAILED) ? NULL : r;
 }
+
+// on error, fd remains unchanged, no matter whether you specified "keep" or not
+HEADER #define JH_OBS_KEEPFD 1
+HEADER #define JH_OBS_BUFFER 2
+PUBLIC_FN int fopen_bistream(FILE **in, FILE **out, int fd, int flags) {
+  // check input
+  if (fd < 0) goto err_out;
+  bool keep = flags & JH_OBS_KEEPFD;
+  bool buffer = flags & JH_OBS_BUFFER;
+
+  // create input FILE*
+  int in_fd = dup(fd);
+  if (in_fd < 0) goto err_out;
+  *in = fdopen(in_fd, "r");
+  if (!*in) { close(in_fd); goto err_out; }
+
+  // create output FILE*
+  int out_fd = keep ? dup(fd) : fd;
+  if (out_fd < 0) goto err_dup_out;
+  *out = fdopen(out_fd, "w");
+  if (!*out) { if (keep) close(out_fd); goto err_dup_out; }
+
+  // avoid buffering data unless the caller really wants it
+  if (!buffer) setbuf(*out, NULL);
+
+  // success!
+  return 0;
+
+
+err_dup_out:
+  fclose(*in);
+err_out:
+  return EAI_SYSTEM;
+}