trace: refactor to support multiple env variables

Right now you turn all tracing off and on with GIT_TRACE. To
support new types of tracing without forcing the user to see
all of them, we will soon support turning each tracing area
on with GIT_TRACE_*.

This patch lays the groundwork by providing an interface
which does not assume GIT_TRACE. However, we still maintain
the trace_printf interface so that existing callers do not
need to be refactored.

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

diff --git a/cache.h b/cache.h
index 08b23b2ab96c1c20f90fbb03ad4d155b9a53bf88..2ab1bf9383994e826777da8b4c3fe7a960d6c509 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -1067,7 +1067,7 @@ extern void alloc_report(void);
 /* trace.c */
 __attribute__((format (printf, 1, 2)))
 extern void trace_printf(const char *format, ...);
-extern void trace_vprintf(const char *format, va_list ap);
+extern void trace_vprintf(const char *key, const char *format, va_list ap);
 __attribute__((format (printf, 2, 3)))
 extern void trace_argv_printf(const char **argv, const char *format, ...);
 extern void trace_repo_setup(const char *prefix);

diff --git a/trace.c b/trace.c
index 623e793e4f4a959252347c643c77747b04c80543..1d0e17e014a5268f76e1c13de2311b27866bc6a9 100644 (file)
--- a/trace.c
+++ b/trace.c
@@ -25,10 +25,10 @@
 #include "cache.h"
 #include "quote.h"
 
-/* Get a trace file descriptor from GIT_TRACE env variable. */
-static int get_trace_fd(int *need_close)
+/* Get a trace file descriptor from "key" env variable. */
+static int get_trace_fd(const char *key, int *need_close)
 {
-       char *trace = getenv("GIT_TRACE");
+       char *trace = getenv(key);
 
        if (!trace || !strcmp(trace, "") ||
            !strcmp(trace, "0") || !strcasecmp(trace, "false"))
@@ -50,10 +50,10 @@ static int get_trace_fd(int *need_close)
                return fd;
        }
 
-       fprintf(stderr, "What does '%s' for GIT_TRACE mean?\n", trace);
+       fprintf(stderr, "What does '%s' for %s mean?\n", trace, key);
        fprintf(stderr, "If you want to trace into a file, "
-               "then please set GIT_TRACE to an absolute pathname "
-               "(starting with /).\n");
+               "then please set %s to an absolute pathname "
+               "(starting with /).\n", key);
        fprintf(stderr, "Defaulting to tracing on stderr...\n");
 
        return STDERR_FILENO;
@@ -62,12 +62,12 @@ static int get_trace_fd(int *need_close)
 static const char err_msg[] = "Could not trace into fd given by "
        "GIT_TRACE environment variable";
 
-void trace_vprintf(const char *fmt, va_list ap)
+void trace_vprintf(const char *key, const char *fmt, va_list ap)
 {
        struct strbuf buf = STRBUF_INIT;
        int fd, need_close = 0;
 
-       fd = get_trace_fd(&need_close);
+       fd = get_trace_fd(key, &need_close);
        if (!fd)
                return;
 
@@ -80,11 +80,19 @@ void trace_vprintf(const char *fmt, va_list ap)
                close(fd);
 }
 
+void trace_printf_key(const char *key, const char *fmt, ...)
+{
+       va_list ap;
+       va_start(ap, fmt);
+       trace_vprintf(key, fmt, ap);
+       va_end(ap);
+}
+
 void trace_printf(const char *fmt, ...)
 {
        va_list ap;
        va_start(ap, fmt);
-       trace_vprintf(fmt, ap);
+       trace_vprintf("GIT_TRACE", fmt, ap);
        va_end(ap);
 }
 
@@ -94,7 +102,7 @@ void trace_argv_printf(const char **argv, const char *fmt, ...)
        va_list ap;
        int fd, need_close = 0;
 
-       fd = get_trace_fd(&need_close);
+       fd = get_trace_fd("GIT_TRACE", &need_close);
        if (!fd)
                return;