From: Christian Franke Date: Mon, 8 May 2017 11:18:21 +0000 (+0200) Subject: lib: add sbuf X-Git-Tag: frr-4.0-dev~465^2~10 X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=31bfa0624d6257e692f51ec8710acb4b8e1b5747;p=mirror%2Ffrr.git lib: add sbuf Signed-off-by: Christian Franke --- diff --git a/lib/sbuf.c b/lib/sbuf.c new file mode 100644 index 0000000000..37c1e5283d --- /dev/null +++ b/lib/sbuf.c @@ -0,0 +1,107 @@ +/* + * Simple string buffer + * + * Copyright (C) 2017 Christian Franke + * + * This file is part of FRR. + * + * FRR is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * FRR 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with FRR; see the file COPYING. If not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA + * 02111-1307, USA. + */ +#include + +#include "sbuf.h" +#include "memory.h" + +void sbuf_init(struct sbuf *dest, char *buf, size_t size) +{ + dest->fixed = (size > 0); + if (dest->fixed) { + dest->buf = buf; + dest->size = size; + } else { + dest->buf = XMALLOC(MTYPE_TMP, 4096); + dest->size = 4096; + } + + dest->pos = 0; + dest->buf[0] = '\0'; +} + +void sbuf_reset(struct sbuf *dest) +{ + dest->pos = 0; + dest->buf[0] = '\0'; +} + +const char *sbuf_buf(struct sbuf *buf) +{ + return buf->buf; +} + +void sbuf_free(struct sbuf *buf) +{ + if (!buf->fixed) + XFREE(MTYPE_TMP, buf->buf); +} + +void sbuf_push(struct sbuf *buf, int indent, const char *format, ...) +{ + va_list args; + int written; + + if (!buf->fixed) { + char dummy; + int written1, written2; + size_t new_size; + + written1 = snprintf(&dummy, 0, "%*s", indent, ""); + va_start(args, format); + written2 = vsnprintf(&dummy, 0, format, args); + va_end(args); + + new_size = buf->size; + if (written1 >= 0 && written2 >= 0) { + while (buf->pos + written1 + written2 >= new_size) + new_size *= 2; + if (new_size > buf->size) { + buf->buf = + XREALLOC(MTYPE_TMP, buf->buf, new_size); + buf->size = new_size; + } + } + } + + written = snprintf(buf->buf + buf->pos, buf->size - buf->pos, "%*s", + indent, ""); + + if (written >= 0) + buf->pos += written; + if (buf->pos > buf->size) + buf->pos = buf->size; + + va_start(args, format); + written = vsnprintf(buf->buf + buf->pos, buf->size - buf->pos, format, + args); + va_end(args); + + if (written >= 0) + buf->pos += written; + if (buf->pos > buf->size) + buf->pos = buf->size; + + if (buf->pos == buf->size) + assert(!"Buffer filled up!"); +} diff --git a/lib/sbuf.h b/lib/sbuf.h new file mode 100644 index 0000000000..3e49ada6c2 --- /dev/null +++ b/lib/sbuf.h @@ -0,0 +1,77 @@ +/* + * Simple string buffer + * + * Copyright (C) 2017 Christian Franke + * + * This file is part of FRR. + * + * FRR is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * FRR 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with FRR; see the file COPYING. If not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA + * 02111-1307, USA. + */ +#ifndef SBUF_H +#define SBUF_H + +/* + * sbuf provides a simple string buffer. One application where this comes + * in handy is the parsing of binary data: If there is an error in the parsing + * process due to invalid input data, printing an error message explaining what + * went wrong is definitely useful. However, just printing the actual error, + * without any information about the previous parsing steps, is usually not very + * helpful. + * Using sbuf, the parser can log the whole parsing process into a buffer using + * a printf like API. When an error ocurrs, all the information about previous + * parsing steps is there in the log, without any need for backtracking, and can + * be used to give a detailed and useful error description. + * When parsing completes successfully without any error, the log can just be + * discarded unless debugging is turned on, to not spam the log. + * + * For the described usecase, the code would look something like this: + * + * int sbuf_example(..., char **parser_log) + * { + * struct sbuf logbuf; + * + * sbuf_init(&logbuf, NULL, 0); + * sbuf_push(&logbuf, 0, "Starting parser\n"); + * + * int rv = do_parse(&logbuf, ...); + * + * *parser_log = sbuf_buf(&logbuf); + * + * return 1; + * } + * + * In this case, sbuf_example uses a string buffer with undefined size, which will + * be allocated on the heap by sbuf. The caller of sbuf_example is expected to free + * the string returned in parser_log. + */ + +struct sbuf { + bool fixed; + char *buf; + size_t size; + size_t pos; + int indent; +}; + +void sbuf_init(struct sbuf *dest, char *buf, size_t size); +void sbuf_reset(struct sbuf *buf); +const char *sbuf_buf(struct sbuf *buf); +void sbuf_free(struct sbuf *buf); +#include "lib/log.h" +void sbuf_push(struct sbuf *buf, int indent, const char *format, ...) + PRINTF_ATTRIBUTE(3, 4); + +#endif diff --git a/lib/subdir.am b/lib/subdir.am index 5a1971cba7..28a4ce5579 100644 --- a/lib/subdir.am +++ b/lib/subdir.am @@ -51,6 +51,7 @@ lib_libfrr_la_SOURCES = \ lib/ptm_lib.c \ lib/qobj.c \ lib/routemap.c \ + lib/sbuf.c \ lib/sha256.c \ lib/sigevent.c \ lib/skiplist.c \ @@ -125,6 +126,7 @@ pkginclude_HEADERS += \ lib/qobj.h \ lib/route_types.h \ lib/routemap.h \ + lib/sbuf.h \ lib/sha256.h \ lib/sigevent.h \ lib/skiplist.h \