From 42892465d4522cf19283b8a06bf48104bb387430 Mon Sep 17 00:00:00 2001 From: Federico Mena Quintero Date: Fri, 28 Jun 2013 20:02:20 -0500 Subject: common: Add utils.[ch] with a string_concat() function Instead of doing malloc() and repeated strcat(), which is an O(n^2) way to concatenate multiple strings, we define a single O(total_len) function that uses stpcpy(). This will also make the rest of the code more legible and safer. --- common/Makefile.am | 3 +- common/utils.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ common/utils.h | 27 +++++++++++++++++ 3 files changed, 114 insertions(+), 1 deletion(-) create mode 100644 common/utils.c create mode 100644 common/utils.h (limited to 'common') diff --git a/common/Makefile.am b/common/Makefile.am index 664e13b..20bfe4d 100644 --- a/common/Makefile.am +++ b/common/Makefile.am @@ -10,7 +10,8 @@ libinternalcommon_la_SOURCES = \ socket.c socket.h \ thread.c thread.h \ debug.c debug.h \ - userpref.c userpref.h + userpref.c userpref.h \ + utils.c utils.h if WIN32 libinternalcommon_la_LIBADD += -lole32 diff --git a/common/utils.c b/common/utils.c new file mode 100644 index 0000000..b2b3768 --- /dev/null +++ b/common/utils.c @@ -0,0 +1,85 @@ +/* + * utils.c + * Miscellaneous utilities for string manipulation + * + * Copyright (c) 2013 Federico Mena Quintero + * + * This 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 2.1 of the License, or (at your option) any later version. + * + * This 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 this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifdef HAVE_CONFIG_H +#include +#endif + +#include +#include +#include + +#include "utils.h" + +/** + * Concatenate strings into a newly allocated string + * + * @note: Specify NULL for the last string in the varargs list + * + * @str: The first string in the list + * @...: Subsequent strings. Use NULL for the last item. + * + * @return a newly allocated string, or NULL if @str is NULL. This will also + * return NULL and set errno to ENOMEM if memory is exhausted. + */ +char *string_concat(const char *str, ...) +{ + size_t len; + va_list args; + char *s; + char *result; + char *dest; + + if (!str) + return NULL; + + /* Compute final length */ + + len = strlen(str) + 1; /* plus 1 for the null terminator */ + + va_start(args, str); + s = va_arg(args, char *); + while (s) { + len += strlen(s); + s = va_arg(args, char*); + } + va_end(args); + + /* Concat each string */ + + result = malloc(len); + if (!result) + return NULL; /* errno remains set */ + + dest = result; + + dest = stpcpy(dest, str); + + va_start(args, str); + s = va_arg(args, char *); + while (s) { + dest = stpcpy(dest, s); + s = va_arg(args, char *); + } + va_end(args); + + return result; +} diff --git a/common/utils.h b/common/utils.h new file mode 100644 index 0000000..129f974 --- /dev/null +++ b/common/utils.h @@ -0,0 +1,27 @@ +/* + * utils.h + * Miscellaneous utilities for string manipulation + * + * Copyright (c) 2013 Federico Mena Quintero + * + * This 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 2.1 of the License, or (at your option) any later version. + * + * This 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 this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef __UTILS_H +#define __UTILS_H + +char *string_concat(const char *str, ...); + +#endif -- cgit v1.1-32-gdbae