fix(cmake): properly fetch dev version by appending latest Falco tag, delta between master and tag, and hash.

`describe` can no more be used as tags are now made on release branches.

Signed-off-by: Federico Di Pierro <nierro92@gmail.com>

cmake/modules/GetFalcoVersion.cmake

@@ -16,18 +16,32 @@ include(GetGitRevisionDescription)
 
 # Create the falco version variable according to git index
 if(NOT FALCO_VERSION)
-  string(STRIP "${FALCO_HASH}" FALCO_HASH)
   # Try to obtain the exact git tag
   git_get_exact_tag(FALCO_TAG)
   if(NOT FALCO_TAG)
-    # Obtain the closest tag
-    git_describe(FALCO_VERSION "--always" "--tags" "--abbrev=7")
-    # Fallback version
-    if(FALCO_VERSION MATCHES "NOTFOUND$")
+      # Fetch current hash
+      get_git_head_revision(refspec FALCO_HASH)
+      if(NOT FALCO_HASH OR FALCO_HASH MATCHES "NOTFOUND$")
         set(FALCO_VERSION "0.0.0")
-    endif()
+      else()
+        # Obtain the closest tag
+        git_get_latest_tag(FALCO_LATEST_TAG)
+        if(NOT FALCO_LATEST_TAG OR FALCO_LATEST_TAG MATCHES "NOTFOUND$")
+          set(FALCO_VERSION "0.0.0")
+        else()
+          # Compute commit delta since tag
+          git_get_delta_from_tag(FALCO_DELTA ${FALCO_LATEST_TAG} ${FALCO_HASH})
+          if(NOT FALCO_DELTA OR FALCO_DELTA MATCHES "NOTFOUND$")
+            set(FALCO_VERSION "0.0.0")
+          else()
+            # Cut hash to 7 bytes
+            string(SUBSTRING ${FALCO_HASH} 0 7 FALCO_HASH)
             # Format FALCO_VERSION to be semver with prerelease and build part
-    string(REPLACE "-g" "+" FALCO_VERSION "${FALCO_VERSION}")
+            set(FALCO_VERSION
+                  "${FALCO_LATEST_TAG}-${FALCO_DELTA}+${FALCO_HASH}")
+           endif()
+        endif()
+      endif()
   else()
     # A tag has been found: use it as the Falco version
     set(FALCO_VERSION "${FALCO_TAG}")

cmake/modules/GetGitRevisionDescription.cmake

@@ -86,6 +86,111 @@ function(get_git_head_revision _refspecvar _hashvar)
       PARENT_SCOPE)
 endfunction()
 
+function(git_get_latest_tag _var)
+  if(NOT GIT_FOUND)
+    find_package(Git QUIET)
+  endif()
+
+  # We use git describe --tags `git rev-list --tags --max-count=1`
+  execute_process(COMMAND
+          "${GIT_EXECUTABLE}"
+          rev-list
+          --tags
+          --max-count=1
+          WORKING_DIRECTORY
+          "${CMAKE_CURRENT_SOURCE_DIR}"
+          COMMAND tail -n1
+          RESULT_VARIABLE
+          res
+          OUTPUT_VARIABLE
+          tag_hash
+          ERROR_QUIET
+          OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(NOT res EQUAL 0)
+    set(out "${tag_hash}-${res}-NOTFOUND" PARENT_SCOPE)
+    return()
+  endif()
+
+  execute_process(COMMAND
+    "${GIT_EXECUTABLE}"
+    describe
+    --tags
+    ${tag_hash}
+    WORKING_DIRECTORY
+    "${CMAKE_CURRENT_SOURCE_DIR}"
+    RESULT_VARIABLE
+    res
+    OUTPUT_VARIABLE
+    out
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(NOT res EQUAL 0)
+    set(out "${out}-${res}-NOTFOUND")
+  endif()
+  set(${_var} "${out}" PARENT_SCOPE)
+endfunction()
+
+function(git_get_delta_from_tag _var tag hash)
+  if(NOT GIT_FOUND)
+    find_package(Git QUIET)
+  endif()
+
+  # Count commits in HEAD
+  execute_process(COMMAND
+    "${GIT_EXECUTABLE}"
+    rev-list
+    --count
+    ${hash}
+    WORKING_DIRECTORY
+    "${CMAKE_CURRENT_SOURCE_DIR}"
+    RESULT_VARIABLE
+    res
+    OUTPUT_VARIABLE
+    out_counter_head
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(NOT res EQUAL 0)
+    set(${_var} "HEADCOUNT-NOTFOUND" PARENT_SCOPE)
+    return()
+  endif()
+
+  # Count commits in latest tag
+  execute_process(COMMAND
+    "${GIT_EXECUTABLE}"
+    rev-list
+    --count
+    ${tag}
+    WORKING_DIRECTORY
+    "${CMAKE_CURRENT_SOURCE_DIR}"
+    RESULT_VARIABLE
+    res
+    OUTPUT_VARIABLE
+    out_counter_tag
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(NOT res EQUAL 0)
+    set(${_var} "TAGCOUNT-NOTFOUND" PARENT_SCOPE)
+    return()
+  endif()
+
+  execute_process(COMMAND
+    expr
+    ${out_counter_head} - ${out_counter_tag}
+    WORKING_DIRECTORY
+    "${CMAKE_CURRENT_SOURCE_DIR}"
+    RESULT_VARIABLE
+    res
+    OUTPUT_VARIABLE
+    out_delta
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(NOT res EQUAL 0)
+    set(${_var} "DELTA-NOTFOUND" PARENT_SCOPE)
+    return()
+  endif()
+  set(${_var} "${out_delta}" PARENT_SCOPE)
+endfunction()
+
 function(git_describe _var)
   if(NOT GIT_FOUND)
     find_package(Git QUIET)

userspace/falco/config_falco.h.in

@@ -16,8 +16,6 @@ limitations under the License.
 
 #pragma once
 
-#define FALCO_BRANCH "@FALCO_REF@"
-#define FALCO_HASH "@FALCO_HASH@"
 #define FALCO_VERSION "@FALCO_VERSION@"
 #define FALCO_VERSION_MAJOR @FALCO_VERSION_MAJOR@
 #define FALCO_VERSION_MINOR @FALCO_VERSION_MINOR@