[PATCH v4 4/7] trace.c: introduce trace_run_command()

[Nguyễn Thái Ngọc Duy]

This is the same as the old code that uses trace_argv_printf() in
run-command.c. This function will be improved in later patches to
print more information from struct child_process.

A slight regression: the old code would print run-command.c:xxx as the
trace location site while the new code prints trace.c:xxx. This should
be fine until the second call site is added, then we might need a macro
wrapper named trace_run_command() to capture the right source location.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
---
 run-command.c |  3 ++-
 trace.c       | 15 +++++++++++++++
 trace.h       |  3 +++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/run-command.c b/run-command.c
index 31fc5ea86e..002074b128 100644
--- a/run-command.c
+++ b/run-command.c
@@ -624,7 +624,8 @@ int start_command(struct child_process *cmd)
                cmd->err = fderr[0];
        }
 
-       trace_argv_printf(cmd->argv, "trace: run_command:");
+       trace_run_command(cmd);
+
        fflush(NULL);
 
 #ifndef GIT_WINDOWS_NATIVE
diff --git a/trace.c b/trace.c
index 7f3b08e148..25c333709b 100644
--- a/trace.c
+++ b/trace.c
@@ -23,6 +23,7 @@
 
 #include "cache.h"
 #include "quote.h"
+#include "run-command.h"
 
 struct trace_key trace_default_key = { "GIT_TRACE", 0, 0, 0 };
 struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);
@@ -275,6 +276,20 @@ void trace_performance_fl(const char *file, int line, 
uint64_t nanos,
 #endif /* HAVE_VARIADIC_MACROS */
 
 
+void trace_run_command(const struct child_process *cp)
+{
+       struct strbuf buf = STRBUF_INIT;
+
+       if (!prepare_trace_line(__FILE__, __LINE__,
+                               &trace_default_key, &buf))
+               return;
+
+       strbuf_addf(&buf, "trace: run_command:");
+
+       sq_quote_argv_pretty(&buf, cp->argv);
+       print_trace_line(&trace_default_key, &buf);
+}
+
 static const char *quote_crnl(const char *path)
 {
        static struct strbuf new_path = STRBUF_INIT;
diff --git a/trace.h b/trace.h
index 88055abef7..e54c687f26 100644
--- a/trace.h
+++ b/trace.h
@@ -4,6 +4,8 @@
 #include "git-compat-util.h"
 #include "strbuf.h"
 
+struct child_process;
+
 struct trace_key {
        const char * const key;
        int fd;
@@ -17,6 +19,7 @@ extern struct trace_key trace_default_key;
 extern struct trace_key trace_perf_key;
 
 extern void trace_repo_setup(const char *prefix);
+extern void trace_run_command(const struct child_process *cp);
 extern int trace_want(struct trace_key *key);
 extern void trace_disable(struct trace_key *key);
 extern uint64_t getnanotime(void);
-- 
2.15.1.600.g899a5f85c6