trace: add infrastructure to augment trace output with additional info

[thirdparty/git.git] / trace.c

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) 2000-2002 Michael R. Elkins <me@mutt.org>
 * Copyright (C) 2002-2004 Oswald Buddenhagen <ossi@users.sf.net>
 * Copyright (C) 2004 Theodore Y. Ts'o <tytso@mit.edu>
 * Copyright (C) 2006 Mike McCormack
 * Copyright (C) 2006 Christian Couder
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "cache.h"
#include "quote.h"

/* Get a trace file descriptor from "key" env variable. */
static int get_trace_fd(struct trace_key *key)
{
	static struct trace_key trace_default = { "GIT_TRACE" };
	const char *trace;

	/* use default "GIT_TRACE" if NULL */
	if (!key)
		key = &trace_default;

	/* don't open twice */
	if (key->initialized)
		return key->fd;

	trace = getenv(key->key);

	if (!trace || !strcmp(trace, "") ||
	    !strcmp(trace, "0") || !strcasecmp(trace, "false"))
		key->fd = 0;
	else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
		key->fd = STDERR_FILENO;
	else if (strlen(trace) == 1 && isdigit(*trace))
		key->fd = atoi(trace);
	else if (is_absolute_path(trace)) {
		int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
		if (fd == -1) {
			fprintf(stderr,
				"Could not open '%s' for tracing: %s\n"
				"Defaulting to tracing on stderr...\n",
				trace, strerror(errno));
			key->fd = STDERR_FILENO;
		} else {
			key->fd = fd;
			key->need_close = 1;
		}
	} else {
		fprintf(stderr, "What does '%s' for %s mean?\n"
			"If you want to trace into a file, then please set "
			"%s to an absolute pathname (starting with /).\n"
			"Defaulting to tracing on stderr...\n",
			trace, key->key, key->key);
		key->fd = STDERR_FILENO;
	}

	key->initialized = 1;
	return key->fd;
}

void trace_disable(struct trace_key *key)
{
	if (key->need_close)
		close(key->fd);
	key->fd = 0;
	key->initialized = 1;
	key->need_close = 0;
}

static const char err_msg[] = "Could not trace into fd given by "
	"GIT_TRACE environment variable";

static int prepare_trace_line(struct trace_key *key, struct strbuf *buf)
{
	if (!trace_want(key))
		return 0;

	set_try_to_free_routine(NULL);	/* is never reset */

	/* add line prefix here */

	return 1;
}

static void print_trace_line(struct trace_key *key, struct strbuf *buf)
{
	/* append newline if missing */
	if (buf->len && buf->buf[buf->len - 1] != '\n')
		strbuf_addch(buf, '\n');

	write_or_whine_pipe(get_trace_fd(key), buf->buf, buf->len, err_msg);
	strbuf_release(buf);
}

static void trace_vprintf(struct trace_key *key, const char *format, va_list ap)
{
	struct strbuf buf = STRBUF_INIT;

	if (!prepare_trace_line(key, &buf))
		return;

	strbuf_vaddf(&buf, format, ap);
	print_trace_line(key, &buf);
}

void trace_printf_key(struct trace_key *key, const char *format, ...)
{
	va_list ap;
	va_start(ap, format);
	trace_vprintf(key, format, ap);
	va_end(ap);
}

void trace_printf(const char *format, ...)
{
	va_list ap;
	va_start(ap, format);
	trace_vprintf(NULL, format, ap);
	va_end(ap);
}

void trace_strbuf(struct trace_key *key, const struct strbuf *data)
{
	struct strbuf buf = STRBUF_INIT;

	if (!prepare_trace_line(key, &buf))
		return;

	strbuf_addbuf(&buf, data);
	print_trace_line(key, &buf);
}

void trace_argv_printf(const char **argv, const char *format, ...)
{
	struct strbuf buf = STRBUF_INIT;
	va_list ap;

	if (!prepare_trace_line(NULL, &buf))
		return;

	va_start(ap, format);
	strbuf_vaddf(&buf, format, ap);
	va_end(ap);

	sq_quote_argv(&buf, argv, 0);
	print_trace_line(NULL, &buf);
}

static const char *quote_crnl(const char *path)
{
	static char new_path[PATH_MAX];
	const char *p2 = path;
	char *p1 = new_path;

	if (!path)
		return NULL;

	while (*p2) {
		switch (*p2) {
		case '\\': *p1++ = '\\'; *p1++ = '\\'; break;
		case '\n': *p1++ = '\\'; *p1++ = 'n'; break;
		case '\r': *p1++ = '\\'; *p1++ = 'r'; break;
		default:
			*p1++ = *p2;
		}
		p2++;
	}
	*p1 = '\0';
	return new_path;
}

/* FIXME: move prefix to startup_info struct and get rid of this arg */
void trace_repo_setup(const char *prefix)
{
	static struct trace_key key = TRACE_KEY_INIT(SETUP);
	const char *git_work_tree;
	char cwd[PATH_MAX];

	if (!trace_want(&key))
		return;

	if (!getcwd(cwd, PATH_MAX))
		die("Unable to get current working directory");

	if (!(git_work_tree = get_git_work_tree()))
		git_work_tree = "(null)";

	if (!prefix)
		prefix = "(null)";

	trace_printf_key(&key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
	trace_printf_key(&key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
	trace_printf_key(&key, "setup: cwd: %s\n", quote_crnl(cwd));
	trace_printf_key(&key, "setup: prefix: %s\n", quote_crnl(prefix));
}

int trace_want(struct trace_key *key)
{
	return !!get_trace_fd(key);
}