Add asprintf(3) and vasprintf(3).

libc/Makefile

@@ -64,6 +64,7 @@ signal/sigisemptyset.o \
 signal/sigismember.o \
 signal/signotset.o \
 signal/sigorset.o \
+stdio/asprintf.o \
 stdio/clearerr.o \
 stdio/dprintf.o \
 stdio/fbufsize.o \
@@ -112,6 +113,7 @@ stdio/snprintf.o \
 stdio/sprintf.o \
 stdio/sscanf.o \
 stdio/ungetc.o \
+stdio/vasprintf.o \
 stdio/vdprintf.o \
 stdio/vfscanf.o \
 stdio/vprintf_callback.o \

libc/include/stdio.h

@@ -98,6 +98,7 @@ extern FILE* stderr;
 #define stdout stdout
 #define stderr stderr
 
+int asprintf(char** __restrict, const char* __restrict, ...);
 void clearerr(FILE* stream);
 int dprintf(int fildes, const char* __restrict format, ...);
 int fclose(FILE* stream);
@@ -152,6 +153,7 @@ int sscanf(const char* __restrict s, const char* __restrict format, ...);
 FILE* tmpfile(void);
 char* tmpnam(char* s);
 int ungetc(int c, FILE* stream);
+int vasprintf(char** __restrict, const char* __restrict, __gnuc_va_list);
 int vdprintf(int fildes, const char* __restrict format, __gnuc_va_list ap);
 int vfprintf(FILE* __restrict stream, const char* __restrict format, __gnuc_va_list ap);
 int vfscanf(FILE* __restrict stream, const char* __restrict format, __gnuc_va_list arg);

libc/stdio/asprintf.cpp

@@ -0,0 +1,38 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2014.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    stdio/asprintf.cpp
+    Prints a string to a newly allocated buffer.
+
+*******************************************************************************/
+
+#include <stdarg.h>
+#include <stdio.h>
+
+extern "C"
+int asprintf(char** restrict result_ptr,
+             const char* restrict format,
+             ...)
+{
+	va_list list;
+	va_start(list, format);
+	int result = vasprintf(result_ptr, format, list);
+	va_end(list);
+	return result;
+}

libc/stdio/vasprintf.cpp

@@ -0,0 +1,80 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2014.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    stdio/vasprintf.cpp
+    Prints a string to a newly allocated buffer.
+
+*******************************************************************************/
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+struct vasprintf_state
+{
+	char* string;
+	size_t string_length;
+	size_t string_used;
+};
+
+static size_t vasprintf_callback(void* user, const char* string, size_t length)
+{
+	struct vasprintf_state* state = (struct vasprintf_state*) user;
+	if ( !state->string )
+		return 0;
+	size_t needed_length = state->string_used + length + 1;
+	if ( state->string_length < needed_length )
+	{
+		size_t new_length = 2 * state->string_used;
+		if ( new_length < needed_length )
+			new_length = needed_length;
+		size_t new_size = new_length * sizeof(char);
+		char* new_string = (char*) realloc(state->string, new_size);
+		if ( !new_string )
+		{
+			free(state->string);
+			state->string = NULL;
+			return 0;
+		}
+		state->string = new_string;
+		state->string_length = new_length;
+	}
+	memcpy(state->string + state->string_used, string, sizeof(char) * length);
+	state->string_used += length;
+	return length;
+}
+
+extern "C"
+int vasprintf(char** restrict result_ptr,
+              const char* restrict format,
+              va_list list)
+{
+	const size_t DEFAULT_SIZE = 32;
+	struct vasprintf_state state;
+	state.string_length = DEFAULT_SIZE;
+	state.string_used = 0;
+	if ( !(state.string = (char*) malloc(state.string_length * sizeof(char))) )
+		return *result_ptr = NULL, -1;
+	vprintf_callback(vasprintf_callback, &state, format, list);
+	if ( !state.string )
+		return *result_ptr = NULL, -1;
+	state.string[state.string_used] = '\0';
+	return *result_ptr = state.string, (int) state.string_used;
+}