Trace into a file or an open fd and refactor tracing code.

If GIT_TRACE is set to an absolute path (starting with a
'/' character), we interpret this as a file path and we
trace into it.

Also if GIT_TRACE is set to an integer value greater than
1 and lower than 10, we interpret this as an open fd value
and we trace into it.

Note that this behavior is not compatible with the
previous one.

We also trace whole messages using one write(2) call to
make sure messages from processes do net get mixed up in
the middle.

This patch makes it possible to get trace information when
running "make test".

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 149 insertions, 0 deletions

diff --git a/trace.c b/trace.c
new file mode 100644
index 0000000000..ce01c34749
--- /dev/null
+++ b/trace.c
@@ -0,0 +1,149 @@
+/*
+ * 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"
+
+/* Stolen from "imap-send.c". */
+static int git_vasprintf(char **strp, const char *fmt, va_list ap)
+{
+	int len;
+	char tmp[1024];
+
+	if ((len = vsnprintf(tmp, sizeof(tmp), fmt, ap)) < 0 ||
+	    !(*strp = xmalloc(len + 1)))
+		return -1;
+	if (len >= (int)sizeof(tmp))
+		vsprintf(*strp, fmt, ap);
+	else
+		memcpy(*strp, tmp, len + 1);
+	return len;
+}
+
+/* Stolen from "imap-send.c". */
+int nfvasprintf(char **str, const char *fmt, va_list va)
+{
+	int ret = git_vasprintf(str, fmt, va);
+	if (ret < 0)
+		die("Fatal: Out of memory\n");
+	return ret;
+}
+
+/* Get a trace file descriptor from GIT_TRACE env variable. */
+static int get_trace_fd(int *need_close)
+{
+	char *trace = getenv("GIT_TRACE");
+
+	if (!trace || !strcmp(trace, "0") || !strcasecmp(trace," false"))
+		return 0;
+	if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
+		return STDERR_FILENO;
+	if (strlen(trace) == 1 && isdigit(*trace))
+		return atoi(trace);
+	if (*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));
+			return STDERR_FILENO;
+		}
+		*need_close = 1;
+		return fd;
+	}
+
+	fprintf(stderr, "What does '%s' for GIT_TRACE means ?\n", trace);
+	fprintf(stderr, "If you want to trace into a file, "
+		"then please set GIT_TRACE to an absolute pathname "
+		"(starting with /).\n");
+	fprintf(stderr, "Defaulting to tracing on stderr...\n");
+
+	return STDERR_FILENO;
+}
+
+static const char err_msg[] = "Could not trace into fd given by "
+	"GIT_TRACE environment variable";
+
+void trace_printf(const char *format, ...)
+{
+	char *trace_str;
+	va_list rest;
+	int need_close = 0;
+	int fd = get_trace_fd(&need_close);
+
+	if (!fd)
+		return;
+
+	va_start(rest, format);
+	nfvasprintf(&trace_str, format, rest);
+	va_end(rest);
+
+	write_or_whine(fd, trace_str, strlen(trace_str), err_msg);
+
+	free(trace_str);
+
+	if (need_close)
+		close(fd);
+}
+
+void trace_argv_printf(const char **argv, int count, const char *format, ...)
+{
+	char *argv_str, *format_str, *trace_str;
+	size_t argv_len, format_len, trace_len;
+	va_list rest;
+	int need_close = 0;
+	int fd = get_trace_fd(&need_close);
+
+	if (!fd)
+		return;
+
+	/* Get the argv string. */
+	argv_str = sq_quote_argv(argv, count);
+	argv_len = strlen(argv_str);
+
+	/* Get the formated string. */
+	va_start(rest, format);
+	nfvasprintf(&format_str, format, rest);
+	va_end(rest);
+
+	/* Allocate buffer for trace string. */
+	format_len = strlen(format_str);
+	trace_len = argv_len + format_len + 1; /* + 1 for \n */
+	trace_str = xmalloc(trace_len + 1);
+
+	/* Copy everything into the trace string. */
+	strncpy(trace_str, format_str, format_len);
+	strncpy(trace_str + format_len, argv_str, argv_len);
+	strcpy(trace_str + trace_len - 1, "\n");
+
+	write_or_whine(fd, trace_str, trace_len, err_msg);
+
+	free(argv_str);
+	free(format_str);
+	free(trace_str);
+
+	if (need_close)
+		close(fd);
+}