[PATCH 08/11] usage: Introduce error_errno correspoding to die_errno

[Ramkumar Ramachandra <artagnon@gmail.com>]

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 git-compat-util.h |    2 ++
 usage.c           |   34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/git-compat-util.h b/git-compat-util.h
index 40498b3..00d2815 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -240,10 +240,12 @@ extern NORETURN void usage(const char *err);
 extern NORETURN void usagef(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern NORETURN void die(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern NORETURN void die_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
+extern int error_errno(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern int error(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
 
 extern void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list params));
+extern void set_error_routine(void (*routine)(const char *err, va_list params));
 
 extern int prefixcmp(const char *str, const char *prefix);
 extern int suffixcmp(const char *str, const char *suffix);
diff --git a/usage.c b/usage.c
index b5e67e3..8724b41 100644
--- a/usage.c
+++ b/usage.c
@@ -46,6 +46,11 @@ void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list param
 	die_routine = routine;
 }
 
+void set_error_routine(void (*routine)(const char *err, va_list params))
+{
+	error_routine = routine;
+}
+
 void NORETURN usagef(const char *err, ...)
 {
 	va_list params;
@@ -97,6 +102,35 @@ void NORETURN die_errno(const char *fmt, ...)
 	va_end(params);
 }
 
+int error_errno(const char *fmt, ...)
+{
+	va_list params;
+	char fmt_with_err[1024];
+	char str_error[256], *err;
+	int i, j;
+
+	err = strerror(errno);
+	for (i = j = 0; err[i] && j < sizeof(str_error) - 1; ) {
+		if ((str_error[j++] = err[i++]) != '%')
+			continue;
+		if (j < sizeof(str_error) - 1) {
+			str_error[j++] = '%';
+		} else {
+			/* No room to double the '%', so we overwrite it with
+			 * '\0' below */
+			j--;
+			break;
+		}
+	}
+	str_error[j] = 0;
+	snprintf(fmt_with_err, sizeof(fmt_with_err), "%s: %s", fmt, str_error);
+
+	va_start(params, fmt);
+	error_routine(fmt_with_err, params);
+	va_end(params);
+	return -1;
+}
+
 int error(const char *err, ...)
 {
 	va_list params;
-- 
1.7.4.rc1.7.g2cf08.dirty