[DTrace-devel] [PATCH v2 1/4] Rename _DTRACE_VERSION

[eugene.loh at oracle.com]

From: Eugene Loh <eugene.loh at oracle.com>

There are many DTrace version numbers (for version, API version,
package version, etc.).  Meanwhile, _DTRACE_VERSION is not a
version number at all.  It's a preprocessor macro in USDT .h header
files.  Prior to commit e2fb0ecd9
("Ensure multiple passes through dtrace -G work."), it was perhaps
not even set.  With that commit, it was always set to 1, with
the rationale:

    Also add an explicit define for _DTRACE__VERSION in the generated
    header file from 'dtrace -h' invocations.  This seems silly, but
    it is there to give people a skeleton to work with if they want to
    pre-generate header files and select whether to actually compile
    on the probes at a later time.

Rename to _DTRACE_USE_USDT for better clarity.  Define it only once
per file.  Place the definition inside an #ifndef test so that a
developer could set the value without manually changing the file.

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 libdtrace/dt_program.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/libdtrace/dt_program.c b/libdtrace/dt_program.c
index 23b91fb2e..cfb7a5fc3 100644
--- a/libdtrace/dt_program.c
+++ b/libdtrace/dt_program.c
@@ -505,13 +505,12 @@ dt_header_provider(dtrace_hdl_t *dtp, dt_provider_t *pvp, FILE *out)
 	info.dthi_pfname = alloca(strlen(pvp->desc.dtvd_name) + 1 + i);
 	dt_header_fmt_func(info.dthi_pfname, pvp->desc.dtvd_name);
 
-	if (fprintf(out, "#define _DTRACE_VERSION 1\n\n"
-			 "#if _DTRACE_VERSION\n\n") < 0)
+	if (fprintf(out, "#if _DTRACE_USE_USDT\n\n") < 0)
 		return dt_set_errno(dtp, errno);
 
 	if (dt_idhash_iter(pvp->pv_probes, dt_header_probe, &info) != 0)
 		return -1; /* dt_errno is set for us */
-	if (fprintf(out, "\n\n") < 0)
+	if (fprintf(out, "\n") < 0)
 		return dt_set_errno(dtp, errno);
 	if (dt_idhash_iter(pvp->pv_probes, dt_header_decl, &info) != 0)
 		return -1; /* dt_errno is set for us */
@@ -560,6 +559,11 @@ dtrace_program_header(dtrace_hdl_t *dtp, FILE *out, const char *fname)
 		"#endif\n\n") < 0)
 		return -1;
 
+	if (fprintf(out, "#ifndef _DTRACE_USE_USDT\n"
+			 "# define _DTRACE_USE_USDT 1\n"
+			 "#endif\n\n") < 0)
+		return -1;
+
 	while ((pvp = dt_htab_next(dtp->dt_provs, &it)) != NULL) {
 		if (dt_header_provider(dtp, pvp, out) != 0) {
 			dt_htab_next_destroy(it);
-- 
2.43.5