include alloca header

[libjh.git] / io.c

diff --git a/io.c b/io.c
index 17ea4d6..a0c2ec2 100644 (file)
--- 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.
@@ -42,7 +41,7 @@ PUBLIC_FN ssize_t read_nointr(int fd, void *buf, size_t count, int *last_res) {
 //  - -1: error
 //  - 0: stream ended
 //  - 1: no problems occured
-PUBLIC_FN ssize_t write_nointr(int fd, void *buf, ssize_t count, int *last_res) {
+PUBLIC_FN ssize_t write_nointr(int fd, const void *buf, ssize_t count, int *last_res) {
   if (count == -1) count = strlen(buf);
   errno = 0;
   size_t done = 0;
@@ -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;
+}