diff options
Diffstat (limited to 'libgnu/obstack_printf.c')
-rw-r--r-- | libgnu/obstack_printf.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/libgnu/obstack_printf.c b/libgnu/obstack_printf.c new file mode 100644 index 00000000..85a0a059 --- /dev/null +++ b/libgnu/obstack_printf.c @@ -0,0 +1,91 @@ +/* Formatted output to obstacks. + Copyright (C) 2008-2017 Free Software Foundation, Inc. + + This program 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 3, 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 General Public License for more details. + + You should have received a copy of the GNU General Public License along + with this program; if not, see <http://www.gnu.org/licenses/>. */ + +#include <config.h> + +/* Specification. */ +#include <stdio.h> + +#include "obstack.h" +#include "vasnprintf.h" + +#include <errno.h> +#include <stdarg.h> +#include <stdlib.h> + +/* Grow an obstack with formatted output. Return the number of bytes + added to OBS. No trailing nul byte is added, and the object should + be closed with obstack_finish before use. + + Upon memory allocation error, call obstack_alloc_failed_handler. + Upon other error, return -1. */ +int +obstack_printf (struct obstack *obs, const char *format, ...) +{ + va_list args; + int result; + + va_start (args, format); + result = obstack_vprintf (obs, format, args); + va_end (args); + return result; +} + +/* Grow an obstack with formatted output. Return the number of bytes + added to OBS. No trailing nul byte is added, and the object should + be closed with obstack_finish before use. + + Upon memory allocation error, call obstack_alloc_failed_handler. + Upon other error, return -1. */ +int +obstack_vprintf (struct obstack *obs, const char *format, va_list args) +{ + /* If we are close to the end of the current obstack chunk, use a + stack-allocated buffer and copy, to reduce the likelihood of a + small-size malloc. Otherwise, print directly into the + obstack. */ + enum { CUTOFF = 1024 }; + char buf[CUTOFF]; + char *base = obstack_next_free (obs); + size_t len = obstack_room (obs); + char *str; + + if (len < CUTOFF) + { + base = buf; + len = CUTOFF; + } + str = vasnprintf (base, &len, format, args); + if (!str) + { + if (errno == ENOMEM) + obstack_alloc_failed_handler (); + return -1; + } + if (str == base && str != buf) + /* The output was already computed in place, but we need to + account for its size. */ + obstack_blank_fast (obs, len); + else + { + /* The output exceeded available obstack space or we used buf; + copy the resulting string. */ + obstack_grow (obs, str, len); + if (str != buf) + free (str); + } + return len; +} |