[Libguestfs] [0/5] guestfish: detect stdout-write failure

Nearly any program that writes to standard output can benefit from this sort of fix. Without it, running e.g., ./guestfish --version > /dev/full would exit successfully, even though it got ENOSPC when writing to the full device. That means regular output redirected to a file on a full partition may also fail to be written, and the error ignored. Before: $ guestfish --version > /dev/full After: $ ./guestfish --version > /dev/full /w/co/libguestfs/fish/.libs/lt-guestfish: write error: No space left on device Obviously, including the absolute program name in the diagnostic is a bug. It should be "guestfish", and there's already code to perform that sanitization in the patch below. It fixes everything except the glibc global variable, program_invocation_name, used by error, called by atexit+close_stdout. I'll fix that via gnulib's progname module later today or tomorrow. Note that all other diagnostics (e.g., below) do use the sanitized name. The second patch is to make guestfish write --help output to stdout, not stderr, per convention. Also, since --help output is pretty long, I find it clearer (e.g., when I misspell an option) to write a brief diagnostic, like $ ./guestfish --fjd guestfish: unrecognized option '--fjd' Try `guestfish --help' for more information. [Exit 1] The third patch is another small improvement: let getopt diagnose failures. Before, using --mount with no option-argument would print a misleading diagnostic: $ ./guestfish -m guestfish: unexpected command line option 0x3f ...all --help output... [Exit 1] Now it prints this: $ ./guestfish -m guestfish: option requires an argument -- 'm' Try `guestfish --help' for more information. [Exit 1] ------------------------------ The fourth patch makes the Before/After change demonstrated above. The last patch avoids new cpp macro redefinition warnings. Now that we're using a few more gnulib modules, they end up defining _GNU_SOURCE via a definition in config.h, so the explicit definitons in various *.c files evoke warnings. $ wc -l 00* 45 0001-build-avoid-some-autoconf-warnings.patch 353 0002-guestfish-write-help-to-stdout-use-gnulib-s-progname.patch 27 0003-guestfish-don-t-try-to-diagnose-getopt-failure.patch 53 0004-guestfish-diagnose-stdout-write-failure.patch 88 0005-build-don-t-define-_GNU_SOURCE-manually.patch 566 total $ diffstat 00* b/bootstrap | 1 b/configure.ac | 11 ++-- b/fish/Makefile.am | 3 - b/fish/destpaths.c | 2 b/fish/fish.c | 125 ++++++++++++++++++++++++++++++++++------------------- b/src/guestfs.c | 2 bootstrap | 8 ++- fish/fish.c | 9 +-- 8 files changed, 100 insertions(+), 61 deletions(-)