Re: [PATCH v4 3/6] usage: add show_usage_if_asked()

So here is a replacement for this step. Everything else is unaffected, so I'll wait for other comments until sending a full reroll.

Thanks.

--- >8 ---
Subject: [PATCH v5 3/6] usage: add show_usage_if_asked()

Some commands call usage() when they are asked to give the help message with "git cmd -h", but this has the same problem as we fixed with callers of usage_with_options() for the same purpose.

Introduce a helper function that captures the common pattern

	if (argc == 2 && !strcmp(argv[1], "-h"))
		usage(usage);

and replaces it with

	show_usage_if_asked(argc, argv, usage);

to help correct these code paths.

Note that this helper function still exits with status 129, and t0012 insists on it. After converting all the mistaken callers of usage_with_options() to call this new helper, we may want to address it---the end user is asking us to give the help text, and we are doing exactly as asked, so there is no reason to exit with non-zero status.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

1:  2b57538eab ! 1:  94a6fdf72f usage: add show_usage_if_asked()
    @@ Commit message
         doing exactly as asked, so there is no reason to exit with non-zero
         status.
     
    +    Helped-by: Jeff King <peff@peff.net>
         Signed-off-by: Junio C Hamano <gitster@pobox.com>
     
      ## git-compat-util.h ##
    @@ usage.c
      #include "trace2.h"
      
     -static void vreportf(const char *prefix, const char *err, va_list params)
    -+static void vfdreportf(int fd, const char *prefix, const char *err, va_list params)
    ++static void vfreportf(FILE *f, const char *prefix, const char *err, va_list params)
      {
      	char msg[4096];
      	char *p, *pend = msg + sizeof(msg);
    @@ usage.c: static void vreportf(const char *prefix, const char *err, va_list param
      	*(p++) = '\n'; /* we no longer need a NUL */
     -	fflush(stderr);
     -	write_in_full(2, msg, p - msg);
    -+	if (fd == 2)
    -+		fflush(stderr);
    -+	write_in_full(fd, msg, p - msg);
    ++	fflush(f);
    ++	write_in_full(fileno(f), msg, p - msg);
     +}
     +
     +static void vreportf(const char *prefix, const char *err, va_list params)
     +{
    -+	vfdreportf(2, prefix, err, params);
    ++	vfreportf(stderr, prefix, err, params);
      }
      
      static NORETURN void usage_builtin(const char *err, va_list params)
    @@ usage.c: void NORETURN usage(const char *err)
     +	va_list params;
     +
     +	va_start(params, err);
    -+	vfdreportf(1, _("usage: "), err, params);
    ++	vfreportf(stdout, _("usage: "), err, params);
     +	va_end(params);
     +	exit(129);
     +}

 git-compat-util.h |  2 ++
 usage.c           | 27 ++++++++++++++++++++++++---
 2 files changed, 26 insertions(+), 3 deletions(-)