patchRefactoring tracing code in "git.c" and "exec_cmd.c".

exec_cmd.c, git.c, quote.c, quote.h

diff --git a/exec_cmd.c b/exec_cmd.c
index e30936d..5688e0b 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -98,14 +98,8 @@ int execv_git_cmd(const char **argv)
 		argv[0] = git_command;
 
 		if (getenv("GIT_TRACE")) {
-			const char **p = argv;
-			fputs("trace: exec:", stderr);
-			while (*p) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, *p);
-				++p;
-			}
-			putc('\n', stderr);
+			sq_quote_argv_printf(stderr, argv, -1,
+					     "trace: exec: ARGV\n");
 			fflush(stderr);
 		}
 
diff --git a/git.c b/git.c
index 930998b..d13b841 100644
--- a/git.c
+++ b/git.c
@@ -180,14 +180,9 @@ static int handle_alias(int *argcp, cons
 			die("recursive alias: %s", alias_command);
 
 		if (getenv("GIT_TRACE")) {
-			int i;
-			fprintf(stderr, "trace: alias expansion: %s =>",
-				alias_command);
-			for (i = 0; i < count; ++i) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, new_argv[i]);
-			}
-			fputc('\n', stderr);
+			sq_quote_argv_printf(stderr, new_argv, count,
+					     "trace: alias expansion: %s => ARGV\n",
+					     alias_command);
 			fflush(stderr);
 		}
 
@@ -292,13 +287,8 @@ static void handle_internal_command(int 
 		if (p->option & USE_PAGER)
 			setup_pager();
 		if (getenv("GIT_TRACE")) {
-			int i;
-			fprintf(stderr, "trace: built-in: git");
-			for (i = 0; i < argc; ++i) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, argv[i]);
-			}
-			putc('\n', stderr);
+			sq_quote_argv_printf(stderr, argv, argc,
+					     "trace: built-in: git ARGV\n");
 			fflush(stderr);
 		}
 
diff --git a/quote.c b/quote.c
index e220dcc..84d0b7b 100644
--- a/quote.c
+++ b/quote.c
@@ -74,6 +74,84 @@ char *sq_quote(const char *src)
 	return buf;
 }
 
+char *sq_quote_argv(const char** argv, int count)
+{
+	char *buf, *to;
+	int i;
+	size_t len;
+
+	/* Count argv if needed. */
+	if (count < 0) {
+		char **p = (char **)argv;
+		count = 0;
+		while (*p++) count++;
+	}
+
+	/* Get destination buffer length. */
+	len = count ? count : 1;
+	for (i = 0; i < count; ++i)
+		len += sq_quote_buf(NULL, 0, argv[i]);
+
+	/* Alloc destination buffer. */
+	to = buf = xmalloc(len);
+
+	/* Copy into destination buffer. */
+	for (i = 0; i < count; ++i) {
+		if (i) *to++ = ' ';
+		to += sq_quote_buf(to, len, argv[i]);
+	}
+
+	if (!count)
+		*buf = 0;
+	
+	return buf;
+}
+
+/* Return a newly allocated copy of "format" where the
+ * first occurence of "old" has been replaced by "new". */
+static char *str_subst(const char *format, const char *old, const char *new)
+{
+	/* Get destination buffer length. */
+	size_t fmt_len = strlen(format);
+	size_t old_len = strlen(old);
+	size_t new_len = strlen(new);
+	size_t len = fmt_len - old_len + new_len + 1;
+
+	/* Get the first occurence of old. */ 
+	char *pos = strstr(format, old);
+	if (!pos)
+		return strcpy(xmalloc(fmt_len + 1), format);
+	size_t start_len = pos - format;
+
+	/* Alloc destination buffer. */
+	char *result = xmalloc(len);
+
+	/* Copy into destination buffer. */
+	strncpy(result, format, start_len);
+	strncpy(result + start_len, new, new_len);
+	strcpy(result + start_len + new_len,
+	       format + start_len + old_len);
+
+	return result;
+}
+
+void sq_quote_argv_printf(FILE* out, const char **argv, int count,
+			   const char *format, ...)
+{
+	/* Replace the string "ARGV" in format with the quoted arg values. */
+	char *argv_str = sq_quote_argv(argv, count);
+	char *new_format = str_subst(format, "ARGV", argv_str);
+
+	/* Print into "out" using the new format. */
+	va_list rest;
+	va_start(rest, format);
+	vfprintf(out, new_format, rest);
+	va_end(rest);
+
+	free(new_format);
+	free(argv_str);	
+}
+
 char *sq_dequote(char *arg)
 {
 	char *dst = arg;
diff --git a/quote.h b/quote.h
index fc5481e..2bbf196 100644
--- a/quote.h
+++ b/quote.h
@@ -31,6 +31,9 @@ #include <stdio.h>
 extern char *sq_quote(const char *src);
 extern void sq_quote_print(FILE *stream, const char *src);
 extern size_t sq_quote_buf(char *dst, size_t n, const char *src);
+extern char *sq_quote_argv(const char** argv, int count);
+extern void sq_quote_argv_printf(FILE* out, const char **argv, int count,
+				 const char *format, ...);
 
 /* This unwraps what sq_quote() produces in place, but returns
  * NULL if the input does not look like what sq_quote would have