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-rw-r--r--common/common.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/common/common.c b/common/common.c
index 6084176610..afab994d72 100644
--- a/common/common.c
+++ b/common/common.c
@@ -109,16 +109,23 @@ bool mp_rect_intersection(struct mp_rect *rc, const struct mp_rect *rc2)
// This works like snprintf(), except that it starts writing the first output
// character to str[strlen(str)]. This returns the number of characters the
-// string would have assuming a large enough buffer, will make sure str is
-// null-terminated, and will never write to str[size] or past.
-int mp_snprintf_append(char *str, size_t size, const char *format, ...)
+// string would have *appended* assuming a large enough buffer, will make sure
+// str is null-terminated, and will never write to str[size] or past.
+// Example:
+// int example(char *buf, size_t buf_size, double num, char *str) {
+// int n = 0;
+// n += mp_snprintf_cat(buf, size, "%f", num);
+// n += mp_snprintf_cat(buf, size, "%s", str);
+// return n; }
+// Note how this can be chained with functions similar in style.
+int mp_snprintf_cat(char *str, size_t size, const char *format, ...)
{
size_t len = strnlen(str, size);
assert(!size || len < size); // str with no 0-termination is not allowed
int r;
va_list ap;
va_start(ap, format);
- r = len + vsnprintf(str + len, size - len, format, ap);
+ r = vsnprintf(str + len, size - len, format, ap);
va_end(ap);
return r;
}