[PATCH 1/3] var: do not print usage() with a correct invocation

From: Sean Allred via GitGitGadget <gitgitgadget@gmail.com>
Date: Nov 24, 2022, 20:22 UTC
Message-ID: <d5f571f0bb352c0ec9cd8d1162c14cc26ccfa52c.1669321369.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1434.git.1669321369.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             | 19 ++++++++++++++++++-
 2 files changed, 20 insertions(+), 2 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..776f1778ae1 100644
--- a/builtin/var.c
+++ b/builtin/var.c
@@ -56,6 +56,17 @@ static void list_vars(void)
 			printf("%s=%s\n", ptr->name, val);
 }
 
+static const struct git_var *get_git_var(const char *var)
+{
+	struct git_var *ptr;
+	for (ptr = git_vars; ptr->read; ptr++) {
+		if (strcmp(var, ptr->name) == 0) {
+			return ptr;
+		}
+	}
+	return NULL;
+}
+
 static const char *read_var(const char *var)
 {
 	struct git_var *ptr;
@@ -81,6 +92,7 @@ static int show_config(const char *var, const char *value, void *cb)
 
 int cmd_var(int argc, const char **argv, const char *prefix)
 {
+	const struct git_var *git_var = NULL;
 	const char *val = NULL;
 	if (argc != 2)
 		usage(var_usage);
@@ -91,9 +103,14 @@ int cmd_var(int argc, const char **argv, const char *prefix)
 		return 0;
 	}
 	git_config(git_default_config, NULL);
+
+	git_var = get_git_var(argv[1]);
+	if (!git_var)
+		usage(var_usage);
+
 	val = read_var(argv[1]);
 	if (!val)
-		usage(var_usage);
+		return 1;
 
 	printf("%s\n", val);

-- 
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