[8/8] Makefile: assert correct generate-cmdlist.sh output

Commit Message

Ævar Arnfjörð Bjarmason Oct. 20, 2021, 6:39 p.m. UTC

Because generate-cmdlist.sh invokes "sed" to extract the "NAME" blurb
from the Documentation/git-*.txt files, we can end up with bad content
if those files aren't what we expected. E.g. we'll emit multiple lines
from that "sed" one-liner if the "NAME" section were to move further
down than what our "head -n 10" covers.

Let's assert that this can't happen by checking that the number of
lines we make is what we'd expect to get. This means we can remove an
assertion added in cfb22a02ab5 (help: use command-list.h for common
command list, 2018-05-10). We'll catch this during compilation
instead.

There are still other cases where it's possible to generate a bad
command-list.h, but the rest should be caught by a C compilation
error.

It would be possible to change our generated "command-list.h" to
simply include this new ".build/command-list.h.gen" instead of cat-ing
it in the Makefile, but let's leave the generated file as it is.

Signed-off-by: Ævar Arnfjörð Bjarmason <[e-mail]>
---
 Makefile            | 7 ++++++-
 generate-cmdlist.sh | 2 +-
 help.c              | 3 ---
 3 files changed, 7 insertions(+), 5 deletions(-)

Patch

diff --git a/Makefile b/Makefile
index ce4cce57eb8..711f0c064e6 100644
--- a/Makefile
+++ b/Makefile
@@ -2278,13 +2278,18 @@  $(COMMAND_LIST_GEN): .build/command-list.h.d/%.gen: Documentation/%.txt
 	$(QUIET)grep "^$(patsubst .build/command-list.h.d/%.gen,%,$@) " command-list.txt >$@.txt && \
 	./generate-cmdlist.sh --entry-only $@.txt >$@
 
+.build/command-list.h.gen: $(COMMAND_LIST_GEN)
+	$(QUIET)LC_ALL=C sort $(COMMAND_LIST_GEN) >$@ && \
+	test $$(wc -l <$@) -eq $(words $(COMMAND_LIST_GEN))
+
 command-list.h: $(COMMAND_LIST_GEN)
 command-list.h: generate-cmdlist.sh
 command-list.h: command-list.txt
+command-list.h: .build/command-list.h.gen
 	$(QUIET_GEN){ \
 		$(SHELL_PATH) ./generate-cmdlist.sh --header-only command-list.txt && \
 		echo "static struct cmdname_help command_list[] = {" && \
-		LC_ALL=C sort $(COMMAND_LIST_GEN) && \
+		cat $< && \
 		echo "};"; \
 	} >$@
 
diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
index 2bc528e8cae..bdefa151ae1 100755
--- a/generate-cmdlist.sh
+++ b/generate-cmdlist.sh
@@ -23,7 +23,7 @@  category_list () {
 }
 
 get_synopsis () {
-	head -n 10 "Documentation/$1.txt" |
+	head -n 6 "Documentation/$1.txt" |
 	sed -n '
 		/^NAME/,/'"$1"'/H
 		${
diff --git a/help.c b/help.c
index 973e47cdc30..cd6dd4c2440 100644
--- a/help.c
+++ b/help.c
@@ -57,9 +57,6 @@  static void extract_cmds(struct cmdname_help **p_cmds, uint32_t mask)
 	int i, nr = 0;
 	struct cmdname_help *cmds;
 
-	if (ARRAY_SIZE(command_list) == 0)
-		BUG("empty command_list[] is a sign of broken generate-cmdlist.sh");
-
 	ALLOC_ARRAY(cmds, ARRAY_SIZE(command_list) + 1);
 
 	for (i = 0; i < ARRAY_SIZE(command_list); i++) {