Add variadic and va_list functions, xa{v}sprintf, which appends a
formatted string to an existing string and re-allocate the string buffer
if necessary. xasprintf becomes just a special case of xasprintf_append
with a NULL starting string.
Rather than looping to get a big enough buffer, simply the implementation
by assuming we have a C99 compliant vsnprintf implementation to return the
necessary size. A side effect is glibc 2.0 support is dropped which seems
unnecessary.
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
util.c | 60 ++++++++++++++++++++++++++++++++++++++--------------------
util.h | 2 ++
2 files changed, 41 insertions(+), 21 deletions(-)
diff --git a/util.c b/util.c
index a69b7a13463d..9c6fb5f286ae 100644
--- a/util.c
+++ b/util.c
@@ -46,36 +46,54 @@ char *xstrdup(const char *s)
return d;
}
-/* based in part from (3) vsnprintf */
-int xasprintf(char **strp, const char *fmt, ...)
+int xavsprintf_append(char **strp, const char *fmt, va_list ap)
{
- int n, size = 128; /* start with 128 bytes */
+ int n, size = 0; /* start with 128 bytes */
char *p;
- va_list ap;
+ va_list ap_copy;
- /* initial pointer is NULL making the fist realloc to be malloc */
- p = NULL;
- while (1) {
- p = xrealloc(p, size);
+ p = *strp;
+ if (p)
+ size = strlen(p);
- /* Try to print in the allocated space. */
- va_start(ap, fmt);
- n = vsnprintf(p, size, fmt, ap);
- va_end(ap);
+ va_copy(ap_copy, ap);
+ n = vsnprintf(NULL, 0, fmt, ap_copy) + 1;
+ va_end(ap_copy);
+
+ p = xrealloc(p, size + n);
+
+ n = vsnprintf(p + size, n, fmt, ap);
- /* If that worked, return the string. */
- if (n > -1 && n < size)
- break;
- /* Else try again with more space. */
- if (n > -1) /* glibc 2.1 */
- size = n + 1; /* precisely what is needed */
- else /* glibc 2.0 */
- size *= 2; /* twice the old size */
- }
*strp = p;
return strlen(p);
}
+int xasprintf_append(char **strp, const char *fmt, ...)
+{
+ int n;
+ va_list ap;
+
+ va_start(ap, fmt);
+ n = xavsprintf_append(strp, fmt, ap);
+ va_end(ap);
+
+ return n;
+}
+
+int xasprintf(char **strp, const char *fmt, ...)
+{
+ int n;
+ va_list ap;
+
+ *strp = NULL;
+
+ va_start(ap, fmt);
+ n = xavsprintf_append(strp, fmt, ap);
+ va_end(ap);
+
+ return n;
+}
+
char *join_path(const char *path, const char *name)
{
int lenp = strlen(path);
diff --git a/util.h b/util.h
index f6cea8274174..7658781a6200 100644
--- a/util.h
+++ b/util.h
@@ -72,6 +72,8 @@ static inline void *xrealloc(void *p, size_t len)
extern char *xstrdup(const char *s);
extern int PRINTF(2, 3) xasprintf(char **strp, const char *fmt, ...);
+extern int PRINTF(2, 3) xasprintf_append(char **strp, const char *fmt, ...);
+extern int xavsprintf_append(char **strp, const char *fmt, va_list ap);
extern char *join_path(const char *path, const char *name);
/**
--
2.19.1
