Set lib version using git release tag

Set the library patch (micro) version to the commit offset from the
last release git tag.

CMakeLists.txt

@@ -6,12 +6,11 @@ if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.15.0)
 endif()
 
 project(libMXF
-    VERSION 1.0.3
+    VERSION 1.0
     DESCRIPTION "Low-level C library for reading and writing the SMPTE ST 377-1 MXF file format"
     HOMEPAGE_URL https://github.com/bbc/libMXF
     LANGUAGES C CXX
 )
-set(PROJECT_VERSION_RELEASE 2)
 
 include("${CMAKE_CURRENT_LIST_DIR}/cmake/options.cmake")
 

cmake/git_version.cmake

@@ -1,8 +1,12 @@
-if(TARGET cmake_git_version_tracking)
+if(TARGET libmxf_cmake_git_version_tracking)
     return()
 endif()
 
 
+# Set the git release tag pattern to describe relative to
+set(GIT_DESCRIBE_TAG_PATTERN "v${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}")
+set(GIT_WORKING_DIR ${PROJECT_SOURCE_DIR})
+
 # Set to ignore git_version errors if there is no .git directory
 set(GIT_FAIL_IF_NONZERO_EXIT FALSE)
 
@@ -11,19 +15,20 @@ include(FetchContent)
 set(git_version_deps_source "${PROJECT_SOURCE_DIR}/deps/cmake-git-version-tracking")
 
 if(EXISTS ${git_version_deps_source})
-    FetchContent_Declare(cmake_git_version_tracking
+    FetchContent_Declare(libmxf_cmake_git_version_tracking
         SOURCE_DIR ${git_version_deps_source}
     )
     message("-- Build using git version source: ${git_version_deps_source}")
 else()
-    FetchContent_Declare(cmake_git_version_tracking
+    FetchContent_Declare(libmxf_cmake_git_version_tracking
         GIT_REPOSITORY "https://github.com/andrew-hardin/cmake-git-version-tracking.git"
         GIT_TAG "904dbda1336ba4b9a1415a68d5f203f576b696bb"
+        PATCH_COMMAND git apply --ignore-whitespace "${CMAKE_CURRENT_LIST_DIR}/git_version_904dbda.patch"
     )
 endif()
 
-FetchContent_GetProperties(cmake_git_version_tracking)
-if(NOT cmake_git_version_tracking_POPULATED)
-    FetchContent_Populate(cmake_git_version_tracking)
-    add_subdirectory(${cmake_git_version_tracking_SOURCE_DIR} ${cmake_git_version_tracking_BINARY_DIR})
+FetchContent_GetProperties(libmxf_cmake_git_version_tracking)
+if(NOT libmxf_cmake_git_version_tracking_POPULATED)
+    FetchContent_Populate(libmxf_cmake_git_version_tracking)
+    add_subdirectory(${libmxf_cmake_git_version_tracking_SOURCE_DIR} ${libmxf_cmake_git_version_tracking_BINARY_DIR})
 endif()

cmake/git_version_904dbda.patch

@@ -0,0 +1,125 @@
+From ba0feac4583090d45e57480a851aae95f0aeb803 Mon Sep 17 00:00:00 2001
+From: Philip de Nier <philipn@rd.bbc.co.uk>
+Date: Mon, 16 Jan 2023 15:48:26 +0000
+Subject: [PATCH] Add git describe relative to matching tag
+
+---
+ CMakeLists.txt    |  4 ++--
+ git.c.in          |  3 +++
+ git.h             |  7 +++++++
+ git_watcher.cmake | 15 ++++++++++++++-
+ 4 files changed, 26 insertions(+), 3 deletions(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 55e6d07..5a553ef 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -1,5 +1,5 @@
+ cmake_minimum_required(VERSION 3.2)
+-project(cmake_git_version_tracking
++project(libmxf_cmake_git_version_tracking
+     LANGUAGES C)
+
+ # Define the two required variables before including
+@@ -15,7 +15,7 @@ include(git_watcher.cmake)
+ # 3rdparty library.
+ add_library(${PROJECT_NAME} STATIC ${POST_CONFIGURE_FILE})
+ target_include_directories(${PROJECT_NAME} SYSTEM PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+-add_dependencies(${PROJECT_NAME} check_git)
++add_dependencies(${PROJECT_NAME} libmxf_check_git)
+
+ # The C99 standard is only required because we're using <stdbool.h>.
+ # This could be removed if it's a problem for users, but would require the
+diff --git a/git.c.in b/git.c.in
+index a26d27c..8670076 100644
+--- a/git.c.in
++++ b/git.c.in
+@@ -30,3 +30,6 @@ const char* git_Describe() {
+ const char* git_Branch() {
+     return "@GIT_BRANCH@";
+ }
++const char* git_DescribeTag() {
++    return "@GIT_DESCRIBE_TAG@";
++}
+diff --git a/git.h b/git.h
+index fee780e..e35a79e 100644
+--- a/git.h
++++ b/git.h
+@@ -52,6 +52,9 @@ const char* git_Describe();
+ /// The symbolic reference tied to HEAD.
+ const char* git_Branch();
+
++/// The commit describe relative to matching tag.
++const char* git_DescribeTag();
++
+ GIT_VERSION_TRACKING_EXTERN_C_END
+ #undef GIT_VERSION_TRACKING_EXTERN_C_BEGIN
+ #undef GIT_VERSION_TRACKING_EXTERN_C_END
+@@ -143,6 +146,10 @@ inline const StringOrView Branch() {
+   static const StringOrView kValue = internal::InitString(git_Branch());
+   return kValue;
+ }
++inline const StringOrView DescribeTag() {
++  static const StringOrView kValue = internal::InitString(git_DescribeTag());
++  return kValue;
++}
+
+ }  // namespace git
+
+diff --git a/git_watcher.cmake b/git_watcher.cmake
+index 32313a3..cf2b443 100644
+--- a/git_watcher.cmake
++++ b/git_watcher.cmake
+@@ -36,6 +36,9 @@
+ #   -- Ignore the presence of untracked files when detecting if the
+ #      working tree is dirty. This is set to FALSE by default.
+ #
++#   GIT_DESCRIBE_TAG_PATTERN (OPTIONAL)
++#   -- Git tag pattern to match against to produce the GIT_DESCRIBE_TAG variable.
++#
+ # DESIGN
+ #   - This script was designed similar to a Python application
+ #     with a Main() function. I wanted to keep it compact to
+@@ -105,6 +108,7 @@ set(_state_variable_names
+     GIT_COMMIT_BODY
+     GIT_DESCRIBE
+     GIT_BRANCH
++    GIT_DESCRIBE_TAG
+     # >>>
+     # 1. Add the name of the additional git variable you're interested in monitoring
+     #    to this list.
+@@ -242,6 +246,14 @@ function(GetGitState _working_dir)
+         set(ENV{GIT_BRANCH} "${output}")
+     endif()
+
++    # Get output of git describe relative to the matching tag
++    RunGitCommand(describe --match ${GIT_DESCRIBE_TAG_PATTERN} ${object})
++    if(NOT exit_code EQUAL 0)
++        set(ENV{GIT_DESCRIBE_TAG} "unknown")
++    else()
++        set(ENV{GIT_DESCRIBE_TAG} "${output}")
++    endif()
++
+     # >>>
+     # 2. Additional git properties can be added here via the
+     #    "execute_process()" command. Be sure to set them in
+@@ -324,7 +336,7 @@ endfunction()
+ #              check the state of git before every build. If the state has
+ #              changed, then a file is configured.
+ function(SetupGitMonitoring)
+-    add_custom_target(check_git
++    add_custom_target(libmxf_check_git
+         ALL
+         DEPENDS ${PRE_CONFIGURE_FILE}
+         BYPRODUCTS
+@@ -341,6 +353,7 @@ function(SetupGitMonitoring)
+             -DPOST_CONFIGURE_FILE=${POST_CONFIGURE_FILE}
+             -DGIT_FAIL_IF_NONZERO_EXIT=${GIT_FAIL_IF_NONZERO_EXIT}
+             -DGIT_IGNORE_UNTRACKED=${GIT_IGNORE_UNTRACKED}
++            -DGIT_DESCRIBE_TAG_PATTERN=${GIT_DESCRIBE_TAG_PATTERN}
+             -P "${CMAKE_CURRENT_LIST_FILE}")
+ endfunction()
+
+-- 
+2.25.1
+

config.h.in

@@ -5,10 +5,6 @@
 /* Library versions */
 #define LIBMXF_VERSION_MAJOR @PROJECT_VERSION_MAJOR@
 #define LIBMXF_VERSION_MINOR @PROJECT_VERSION_MINOR@
-#define LIBMXF_VERSION_MICRO @PROJECT_VERSION_PATCH@
-#define LIBMXF_VERSION_RELEASE @PROJECT_VERSION_RELEASE@
-
-#define LIBMXF_VERSION (LIBMXF_VERSION_MAJOR << 16 | LIBMXF_VERSION_MINOR << 8 | LIBMXF_VERSION_MICRO)
 
 /* Define printf size_t format specifier */
 #if defined(_WIN64)

mxf/CMakeLists.txt

@@ -110,7 +110,7 @@ target_link_libraries(MXF PRIVATE
 # Add the git version tracking library code
 include("${PROJECT_SOURCE_DIR}/cmake/git_version.cmake")
 target_link_libraries(MXF PRIVATE
-    cmake_git_version_tracking
+    libmxf_cmake_git_version_tracking
 )
 
 set_target_properties(MXF PROPERTIES

mxf/mxf_version.c

@@ -36,6 +36,8 @@
 #endif
 
 #include <string.h>
+#include <stdio.h>
+#include <limits.h>
 
 #include <mxf/mxf.h>
 #include <mxf/mxf_utils.h>
@@ -50,12 +52,6 @@
 
 
 
-static mxfProductVersion g_libmxfVersion = {LIBMXF_VERSION_MAJOR,     /* major */
-                                            LIBMXF_VERSION_MINOR,     /* minor */
-                                            LIBMXF_VERSION_MICRO,     /* patch */
-                                            0,                        /* build */
-                                            LIBMXF_VERSION_RELEASE};  /* release */
-
 static mxfProductVersion g_regtestVersion = {1,   /* major */
                                              0,   /* minor */
                                              0,   /* patch */
@@ -107,6 +103,51 @@ mxf_get_scm_version_wstring_func mxf_get_scm_version_wstring    = mxf_default_ge
 
 const mxfProductVersion* mxf_default_get_version(void)
 {
+    static mxfProductVersion g_libmxfVersion = {0};
+
+    if (g_libmxfVersion.major == 0 && g_libmxfVersion.minor == 0) {
+        g_libmxfVersion.major = LIBMXF_VERSION_MAJOR;
+        g_libmxfVersion.minor = LIBMXF_VERSION_MINOR;
+
+        // Set the patch version value to the commit offset from the release tag.
+        // The commit offset is part of the git describe tag string which has the
+        // format "<tag>-<offset>-g<commit id>"
+        const char *describe = git_DescribeTag();
+#ifdef PACKAGE_GIT_VERSION_STRING
+        if (!describe[0] || strcmp(describe, "unknown") == 0)
+            describe = PACKAGE_GIT_VERSION_STRING;
+#endif
+        if (describe[0] && strcmp(describe, "unknown") != 0) {
+            int offset;
+            int dash_count = 0;
+            const char *offset_str = &describe[strlen(describe) - 1];
+
+            // position offset_str after the second '-' in reverse order
+            while (offset_str != describe) {
+                if (*offset_str == '-') {
+                    if (dash_count >= 1) {
+                        offset_str++;
+                        break;
+                    }
+                    dash_count++;
+                }
+                offset_str--;
+            }
+            if (offset_str == describe)
+                offset_str = 0;
+
+            if (offset_str && sscanf(offset_str, "%d", &offset) == 1 && offset >= 0 && offset <= UINT16_MAX) {
+                g_libmxfVersion.patch = (uint16_t)offset;
+                if (git_AnyUncommittedChanges())
+                    g_libmxfVersion.release = 0;  /* Unknown version */
+                else if (offset == 0)
+                    g_libmxfVersion.release = 1;  /* Released version */
+                else
+                    g_libmxfVersion.release = 2;  /* Post release, development version */
+            }
+        }
+    }
+
     return &g_libmxfVersion;
 }
 
@@ -124,7 +165,10 @@ const char* mxf_default_get_scm_version_string(void)
 {
     static char version_string[64] = {0};
     if (version_string[0] == 0) {
-        const char *describe = git_Describe();
+        const char *describe = git_DescribeTag();
+        if (!describe[0] || strcmp(describe, "unknown") == 0)
+            describe = git_Describe();
+
 #ifdef PACKAGE_GIT_VERSION_STRING
         if (strcmp(describe, "unknown") == 0) {
             mxf_snprintf(version_string, ARRAY_SIZE(version_string), "%s", PACKAGE_GIT_VERSION_STRING);