[PATCH v2 14/19] libctf: library version enforcement

[Nick Alcock <nick dot alcock at oracle dot com>]

This old Solaris standard allows callers to specify that they are
expecting one particular API and/or CTF file format from the library.

It is basically vestigial and I would be amenable to dropping it.

Changes from v1:
 - Correct erroneous license (GPLv2+ -> v3+) and reset copyright years.
 - Adjust to ctf_free() prototype changes
 - Migrate into ctf-subr.c, since ctf-lib.c is gone

libctf/
	* ctf-impl.h (_libctf_version): New declaration.
	* ctf-subr.c (_libctf_version): Define it.
	(ctf_version): New.

include/
	* ctf-api.h (ctf_version): New.
---
 include/ctf-api.h |  1 +
 libctf/ctf-impl.h |  1 +
 libctf/ctf-subr.c | 27 +++++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/ctf-api.h b/include/ctf-api.h
index 049062ea80..81f790dafd 100644
--- a/include/ctf-api.h
+++ b/include/ctf-api.h
@@ -239,6 +239,7 @@ extern void *ctf_getspecific (ctf_file_t *);
 
 extern int ctf_errno (ctf_file_t *);
 extern const char *ctf_errmsg (int);
+extern int ctf_version (int);
 
 extern int ctf_func_info (ctf_file_t *, unsigned long, ctf_funcinfo_t *);
 extern int ctf_func_args (ctf_file_t *, unsigned long, uint32_t, ctf_id_t *);
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 91c46d5d5a..a067e0f4d0 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -364,6 +364,7 @@ extern const char *ctf_lookup_symbol_name (ctf_file_t *fp, unsigned long symidx)
 extern const char _CTF_SECTION[];	/* name of CTF ELF section */
 extern const char _CTF_NULLSTR[];	/* empty string */
 
+extern int _libctf_version;	/* library client version */
 extern int _libctf_debug;	/* debugging messages enabled */
 
 #ifdef	__cplusplus
diff --git a/libctf/ctf-subr.c b/libctf/ctf-subr.c
index 3103e28a3f..09ec2951e5 100644
--- a/libctf/ctf-subr.c
+++ b/libctf/ctf-subr.c
@@ -27,6 +27,7 @@
 #include <unistd.h>
 
 static size_t _PAGESIZE _libctf_unused_;
+int _libctf_version = CTF_VERSION;	      /* Library client version.  */
 int _libctf_debug = 0;			      /* Debugging messages enabled.  */
 
 _libctf_malloc_ void *
@@ -190,6 +191,32 @@ ctf_strerror (int err)
   return (const char *) (strerror (err));
 }
 
+/* Set the CTF library client version to the specified version.  If version is
+   zero, we just return the default library version number.  */
+int
+ctf_version (int version)
+{
+  if (version < 0)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
+  if (version > 0)
+    {
+      /*  Dynamic version switching is not presently supported. */
+      if (version != CTF_VERSION)
+	{
+	  errno = ENOTSUP;
+	  return -1;
+	}
+      ctf_dprintf ("ctf_version: client using version %d\n", version);
+      _libctf_version = version;
+    }
+
+  return _libctf_version;
+}
+
 void
 libctf_init_debug (void)
 {
-- 
2.21.0.237.gd0cfaa883d