[PATCH v3 1/2] var: do not print usage() with a correct invocation

From: Sean Allred via GitGitGadget <gitgitgadget@gmail.com>
Date: Nov 26, 2022, 14:17 UTC
Message-ID: <889fdf877a13067ece785c9c694ed17dcde19b32.1669472277.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1434.v3.git.1669472277.gitgitgadget@gmail.com>

From: Sean Allred <allred.sean@gmail.com>

Before, git-var could print usage() even if the command was invoked correctly with a variable defined in git_vars -- provided that its read() function returned NULL.

Now, we only print usage() only if it was called with a logical variable that wasn't defined -- regardless of read().

Since we now know the variable is valid when we call read_var(), we can avoid printing usage() here (and exiting with code 129) and instead exit quietly with code 1. While exiting with a different code can be a breaking change, it's far better than changing the exit status more generally from 'failure' to 'success'.

Signed-off-by: Sean Allred <allred.sean@gmail.com>
---
 Documentation/git-var.txt |  3 ++-
 builtin/var.c             | 22 +++++++++++++---------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/Documentation/git-var.txt b/Documentation/git-var.txt
index 6aa521fab23..0ab5bfa7d72 100644
--- a/Documentation/git-var.txt
+++ b/Documentation/git-var.txt
@@ -13,7 +13,8 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-Prints a Git logical variable.
+Prints a Git logical variable. Exits with code 1 if the variable has
+no value.
 
 OPTIONS
 -------
diff --git a/builtin/var.c b/builtin/var.c
index 491db274292..5cbe32ec890 100644
--- a/builtin/var.c
+++ b/builtin/var.c
@@ -56,18 +56,15 @@ static void list_vars(void)
 			printf("%s=%s\n", ptr->name, val);
 }
 
-static const char *read_var(const char *var)
+static const struct git_var *get_git_var(const char *var)
 {
 	struct git_var *ptr;
-	const char *val;
-	val = NULL;
 	for (ptr = git_vars; ptr->read; ptr++) {
 		if (strcmp(var, ptr->name) == 0) {
-			val = ptr->read(IDENT_STRICT);
-			break;
+			return ptr;
 		}
 	}
-	return val;
+	return NULL;
 }
 
 static int show_config(const char *var, const char *value, void *cb)
@@ -81,7 +78,9 @@ static int show_config(const char *var, const char *value, void *cb)
 
 int cmd_var(int argc, const char **argv, const char *prefix)
 {
-	const char *val = NULL;
+	const struct git_var *git_var;
+	const char *val;
+
 	if (argc != 2)
 		usage(var_usage);
 
@@ -91,10 +90,15 @@ int cmd_var(int argc, const char **argv, const char *prefix)
 		return 0;
 	}
 	git_config(git_default_config, NULL);
-	val = read_var(argv[1]);
-	if (!val)
+
+	git_var = get_git_var(argv[1]);
+	if (!git_var)
 		usage(var_usage);
 
+	val = git_var->read(IDENT_STRICT);
+	if (!val)
+		return 1;
+
 	printf("%s\n", val);
 
 	return 0;

-- 
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