A bunch of protocols (git, http, mbox, etc) start with lines of data followed by a block of data, so it's natural to want to call getline() and then handle the data block. But getline() takes a FILE * and things like zlib and sendfile() take an integer file descriptor.
Posix lets me get the file descriptor out of a FILE * with fileno(), but the point of FILE * is to readahead and buffer. How do I get the buffered data out without reading more from the file descriptor? I can't find a portable way to do this? In musl I can #include <stdio_ext.h> and then use __freadahead(fp) to get the number of bytes. Various other packages do an if/else staircase mucking with the internals of every libc they personally know, ala: https://sources.debian.org/src/m4/1.4.18-2/lib/freadahead.c But I can't find a portable way to do this? Rob
