`dprintf`: print formatted text directly to a file descriptor

This already existed as dprintf(3). I now feel stupid for having Implemented fd_printf.

The original post is as follows:

I wrote this while debugging some code, and thought it might be useful to others:

#define _GNU_SOURCE     /* vasprintf() */
+#include <stdarg.h>     /* va_start()/va_end() */
+#include <stdio.h>      /* vasprintf() */
+#include <stdlib.h>     /* free() */
+#include <unistd.h>     /* write() */
+
+int
+fd_printf(int fd, const char *format, ...)
+{
+    va_list arg;
+    int len;
+    char *str;
+
+    va_start(arg, format);
+    len = vasprintf(&str, format, arg);
+    va_end(arg);
+
+    write(fd, str, len);
+
+    free(str);
+    return len;
+}

It is a version of printf that prints to a file descriptor—where fprintf prints to a FILE* data structure.

The appeal of this is that FILE* I/O is buffered—which means mixing it with raw file descriptor I/O is going to produce weird results.

+ +

dprintf: print formatted text directly to a file descriptor

`dprintf`: print formatted text directly to a file descriptor