memstream: helper for in-memory formatted output stream

include/vlc_memstream.h

@@ -0,0 +1,65 @@
+/*****************************************************************************
+ * vlc_memstream.h:
+ *****************************************************************************
+ * Copyright (C) 2016 Rémi Denis-Courmont
+ *
+ * This program 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 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifndef VLC_MEMSTREAM_H
+# define VLC_MEMSREAM_H 1
+
+# include <stdarg.h>
+# include <stdio.h>
+
+struct vlc_memstream
+{
+    union
+    {
+        FILE *stream;
+        int error;
+    };
+    char *ptr;
+    size_t length;
+};
+
+VLC_API
+int vlc_memstream_open(struct vlc_memstream *ms);
+
+VLC_API
+int vlc_memstream_flush(struct vlc_memstream *ms) VLC_USED;
+
+VLC_API
+int vlc_memstream_close(struct vlc_memstream *ms) VLC_USED;
+
+VLC_API
+size_t vlc_memstream_write(struct vlc_memstream *ms,
+                           const void *ptr, size_t len);
+
+VLC_API
+int vlc_memstream_putc(struct vlc_memstream *ms, int c);
+
+VLC_API
+int vlc_memstream_puts(struct vlc_memstream *ms, const char *str);
+
+VLC_API
+int vlc_memstream_vprintf(struct vlc_memstream *ms, const char *fmt,
+                          va_list args);
+
+VLC_API
+int vlc_memstream_printf(struct vlc_memstream *s, const char *fmt,
+                         ...) VLC_FORMAT(2,3);
+
+#endif /* VLC_MEMSTREAM_H */

src/Makefile.am

@@ -66,6 +66,7 @@ pluginsinclude_HEADERS = \
 	../include/vlc_meta.h \
 	../include/vlc_meta_fetcher.h \
 	../include/vlc_media_library.h \
+	../include/vlc_memstream.h \
 	../include/vlc_mime.h \
 	../include/vlc_modules.h \
 	../include/vlc_mouse.h \
@@ -423,6 +424,7 @@ SOURCES_libvlc_common = \
 	network/rootbind.c \
 	network/tls.c \
 	text/charset.c \
+	text/memstream.c \
 	text/strings.c \
 	text/unicode.c \
 	text/url.c \

src/libvlccore.sym

@@ -273,6 +273,14 @@ module_provides
 module_unneed
 vlc_module_load
 vlc_module_unload
+vlc_memstream_open
+vlc_memstream_flush
+vlc_memstream_close
+vlc_memstream_write
+vlc_memstream_putc
+vlc_memstream_puts
+vlc_memstream_vprintf
+vlc_memstream_printf
 vlc_Log
 vlc_LogSet
 vlc_vaLog

src/text/memstream.c

@@ -0,0 +1,189 @@
+/*****************************************************************************
+ * memstream.c: heap-based output streams
+ *****************************************************************************
+ * Copyright (C) 2016 Rémi Denis-Courmont
+ *
+ * This program 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 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_memstream.h>
+
+#ifdef HAVE_OPEN_MEMSTREAM
+int vlc_memstream_open(struct vlc_memstream *ms)
+{
+    ms->stream = open_memstream(&ms->ptr, &ms->length);
+    return likely(ms->stream != NULL) ? 0 : EOF;
+}
+
+int vlc_memstream_flush(struct vlc_memstream *ms)
+{
+    if (unlikely(ms->stream == NULL))
+        return EOF;
+
+    if (ferror(ms->stream))
+        return EOF;
+
+    return fflush(ms->stream);
+}
+
+int vlc_memstream_close(struct vlc_memstream *ms)
+{
+    FILE *stream = ms->stream;
+    int ret;
+
+    if (unlikely(stream == NULL))
+        return EOF;
+
+    ms->stream = NULL;
+    ret = ferror(stream);
+
+    if (fclose(stream))
+        return EOF;
+
+    if (unlikely(ret))
+    {
+        free(ms->ptr);
+        return EOF;
+    }
+    return 0;
+} 
+
+size_t vlc_memstream_write(struct vlc_memstream *ms, const void *ptr,
+                           size_t len)
+{
+    if (unlikely(ms->stream == NULL))
+        return 0;
+
+    return fwrite(ptr, 1, len, ms->stream);
+}
+
+int vlc_memstream_putc(struct vlc_memstream *ms, int c)
+{
+    if (unlikely(ms->stream == NULL))
+        return EOF;
+
+    return fputc(c, ms->stream);
+}
+
+int vlc_memstream_puts(struct vlc_memstream *ms, const char *str)
+{
+    if (unlikely(ms->stream == NULL))
+        return EOF;
+
+    return fputs(str, ms->stream);
+}
+
+int vlc_memstream_vprintf(struct vlc_memstream *ms, const char *fmt,
+                          va_list args)
+{
+    if (unlikely(ms->stream == NULL))
+        return EOF;
+
+    return vfprintf(ms->stream, fmt, args);
+}
+
+#else
+#include <stdlib.h>
+
+int vlc_memstream_open(struct vlc_memstream *ms)
+{
+    ms->error = 0;
+    ms->ptr = NULL;
+    ms->length = 0;
+    return 0;
+}
+
+int vlc_memstream_flush(struct vlc_memstream *ms)
+{
+    return ms->error;
+}
+
+int vlc_memstream_close(struct vlc_memstream *ms)
+{
+    if (ms->error)
+        free(ms->ptr);
+    return ms->error;
+} 
+
+size_t vlc_memstream_write(struct vlc_memstream *ms, const void *ptr,
+                           size_t len)
+{
+    char *base = realloc(ms->ptr, ms->length + len + 1u);
+    if (ptr == NULL)
+        goto error;
+
+    memcpy(base + ms->length, ptr, len);
+    ms->ptr = base;
+    ms->length += len;
+    base[ms->length] = '\0';
+    return len;
+
+error:
+    ms->error = EOF;
+    return EOF;
+}
+
+int vlc_memstream_putc(struct vlc_memstream *ms, int c)
+{
+    return (vlc_memstream_write(ms, &(unsigned char){ c }, 1u) == 1) ? c : EOF;
+}
+
+int vlc_memstream_puts(struct vlc_memstream *ms, const char *str)
+{
+    size_t len = strlen(str);
+    return (vlc_memstream_write(ms, str, len) == len) ? 0 : EOF;
+}
+
+int vlc_memstream_vprintf(struct vlc_memstream *ms, const char *fmt,
+                          va_list args)
+{
+    va_list ap;
+    char *ptr;
+    int len;
+
+    va_copy(ap, args);
+    len = vsnprintf(NULL, 0, fmt, ap);
+    va_end(ap);
+
+    ptr = realloc(ms->ptr, ms->length + len + 1);
+    if (ptr == NULL)
+        goto error;
+
+    vsnprintf(ptr + ms->length, len + 1, fmt, args);
+    ms->ptr = ptr;
+    ms->length += len;
+    return len;
+
+error:
+    ms->error = EOF;
+    return EOF;
+}
+#endif
+
+int vlc_memstream_printf(struct vlc_memstream *ms, const char *fmt, ...)
+{
+    va_list ap;
+    int ret;
+
+    va_start(ap, fmt);
+    ret = vlc_memstream_vprintf(ms, fmt, ap);
+    va_end(ap);
+    return ret;
+}