Add format_str() and vformat_str()

Simple helpers to allocate and format a string.

1 files changed, 33 insertions, 0 deletions

diff --git a/common/stringop.c b/common/stringop.c
index 7fb3fe12..c503143a 100644
--- a/common/stringop.c
+++ b/common/stringop.c
@@ -1,5 +1,6 @@
 #define _POSIX_C_SOURCE 200809L
 #include <ctype.h>
+#include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -328,3 +329,35 @@ bool expand_path(char **path) {
         wordfree(&p);
         return true;
 }
+
+char *vformat_str(const char *fmt, va_list args) {
+        char *str = NULL;
+        va_list args_copy;
+        va_copy(args_copy, args);
+
+        int len = vsnprintf(NULL, 0, fmt, args);
+        if (len < 0) {
+                sway_log_errno(SWAY_ERROR, "vsnprintf(\"%s\") failed", fmt);
+                goto out;
+        }
+
+        str = malloc(len + 1);
+        if (str == NULL) {
+                sway_log_errno(SWAY_ERROR, "malloc() failed");
+                goto out;
+        }
+
+        vsnprintf(str, len + 1, fmt, args_copy);
+
+out:
+        va_end(args_copy);
+        return str;
+}
+
+char *format_str(const char *fmt, ...) {
+        va_list args;
+        va_start(args, fmt);
+        char *str = vformat_str(fmt, args);
+        va_end(args);
+        return str;
+}