[PATCH] diff.c: guard config parser from value=NULL

[Christian Couder <chriscool@tuxfamily.org>]

In fact we also guard for value="" as it doesn't make more sense
for the variables here.

We do that by using a new function 'xstrdup_confval' to avoid code
duplication.

By the way this changes a 'strdup' into 'xstrdup'.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 diff.c |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/diff.c b/diff.c
index 5b8afdc..d51aecb 100644
--- a/diff.c
+++ b/diff.c
@@ -60,6 +60,14 @@ static struct ll_diff_driver {
 	char *cmd;
 } *user_diff, **user_diff_tail;
 
+static int xstrdup_confval(const char *dest, const char *var, const char *value)
+{
+	if (!value || !*value)
+		return error("%s: lacks value", var);
+	dest = xstrdup(value);
+	return 0;
+}
+
 /*
  * Currently there is only "diff.<drivername>.command" variable;
  * because there are "diff.color.<slot>" variables, we are parsing
@@ -86,10 +94,7 @@ static int parse_lldiff_command(const char *var, const char *ep, const char *val
 		user_diff_tail = &(drv->next);
 	}
 
-	if (!value)
-		return error("%s: lacks value", var);
-	drv->cmd = strdup(value);
-	return 0;
+	return xstrdup_confval(drv->cmd, var, value);
 }
 
 /*
@@ -123,8 +128,8 @@ static int parse_funcname_pattern(const char *var, const char *ep, const char *v
 	}
 	if (pp->pattern)
 		free(pp->pattern);
-	pp->pattern = xstrdup(value);
-	return 0;
+
+	return xstrdup_confval(pp->pattern, var, value);
 }
 
 /*
@@ -157,10 +162,8 @@ int git_diff_ui_config(const char *var, const char *value)
 		diff_auto_refresh_index = git_config_bool(var, value);
 		return 0;
 	}
-	if (!strcmp(var, "diff.external")) {
-		external_diff_cmd_cfg = xstrdup(value);
-		return 0;
-	}
+	if (!strcmp(var, "diff.external"))
+		return xstrdup_confval(external_diff_cmd_cfg, var, value);
 	if (!prefixcmp(var, "diff.")) {
 		const char *ep = strrchr(var, '.');
 
-- 
1.5.4.35.g3360