libc: implement asprintf

2 files changed, 26 insertions, 0 deletions

diff --git a/src/libc/include/stdio.h b/src/libc/include/stdio.h
index b582e8f..159bdca 100644
--- a/src/libc/include/stdio.h
+++ b/src/libc/include/stdio.h
@@ -28,10 +28,12 @@ int printf(const char *restrict fmt, ...);
 int fprintf(FILE *restrict f, const char *restrict fmt, ...);
 
 int sprintf(char *restrict s, const char *restrict fmt, ...);
+int asprintf(char **restrict sp, const char *restrict fmt, ...);
 int snprintf(char *restrict str, size_t len, const char *restrict fmt, ...);
 
 int vprintf(const char *restrict fmt, va_list ap);
 int vsprintf(char *restrict s, const char *restrict fmt, va_list ap);
+int vasprintf(char **restrict sp, const char *restrict fmt, va_list ap);
 int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap);
 
 int _klogf(const char *fmt, ...); // for kernel debugging only
diff --git a/src/libc/stdio/asprintf.c b/src/libc/stdio/asprintf.c
new file mode 100644
index 0000000..ee24e38
--- /dev/null
+++ b/src/libc/stdio/asprintf.c
@@ -0,0 +1,24 @@
+#include <shared/mem.h>
+#include <shared/printf.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int asprintf(char **restrict sp, const char *restrict fmt, ...) {
+	int ret;
+	va_list argp;
+	va_start(argp, fmt);
+	ret = vasprintf(sp, fmt, argp);
+	va_end(argp);
+	return ret;
+}
+int vasprintf(char **restrict sp, const char *restrict fmt, va_list ap) {
+	va_list ap2;
+	va_copy(ap2, ap);
+	int ret = vsnprintf(NULL, 0, fmt, ap2);
+	va_end(ap2);
+
+	if (ret < 0) return ret;
+	*sp = malloc(ret+1);
+	if (*sp == NULL) return -1;
+	return vsnprintf(*sp, ret+1, fmt, ap);
+}