busybox/libbb/fgets_str.c
Ron Yorston 6ad38d66d0 libbb: code shrink fgets_str
Use a NULL value of maxsz_p to indicate to xmalloc_fgets_internal()
that the caller doesn't care about the maximum size of the buffer.
This allows the default maximum size to be set once in
xmalloc_fgets_internal() instead of separately in each caller.

function                                             old     new   delta
xmalloc_fgets_internal                               273     287     +14
xmalloc_fgets_str                                     30       9     -21
xmalloc_fgetline_str                                  33      12     -21
xmalloc_fgets_str_len                                 38      10     -28
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 14/-70)            Total: -56 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2021-02-03 20:43:07 +01:00

79 lines
1.9 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) many different people.
* If you wrote this, please acknowledge your work.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
static char *xmalloc_fgets_internal(FILE *file, const char *terminating_string, int chop_off, size_t *maxsz_p)
{
char *linebuf = NULL;
const int term_length = strlen(terminating_string);
int end_string_offset;
int linebufsz = 0;
int idx = 0;
int ch;
size_t maxsz = maxsz_p ? *maxsz_p : INT_MAX - 4095;
while (1) {
ch = fgetc(file);
if (ch == EOF) {
if (idx == 0)
return linebuf; /* NULL */
break;
}
if (idx >= linebufsz) {
linebufsz += 200;
linebuf = xrealloc(linebuf, linebufsz);
if (idx >= maxsz) {
linebuf[idx] = ch;
idx++;
break;
}
}
linebuf[idx] = ch;
idx++;
/* Check for terminating string */
end_string_offset = idx - term_length;
if (end_string_offset >= 0
&& memcmp(&linebuf[end_string_offset], terminating_string, term_length) == 0
) {
if (chop_off)
idx -= term_length;
break;
}
}
/* Grow/shrink *first*, then store NUL */
linebuf = xrealloc(linebuf, idx + 1);
linebuf[idx] = '\0';
if (maxsz_p)
*maxsz_p = idx;
return linebuf;
}
/* Read up to TERMINATING_STRING from FILE and return it,
* including terminating string.
* Non-terminated string can be returned if EOF is reached.
* Return NULL if EOF is reached immediately. */
char* FAST_FUNC xmalloc_fgets_str(FILE *file, const char *terminating_string)
{
return xmalloc_fgets_internal(file, terminating_string, 0, NULL);
}
char* FAST_FUNC xmalloc_fgets_str_len(FILE *file, const char *terminating_string, size_t *maxsz_p)
{
return xmalloc_fgets_internal(file, terminating_string, 0, maxsz_p);
}
char* FAST_FUNC xmalloc_fgetline_str(FILE *file, const char *terminating_string)
{
return xmalloc_fgets_internal(file, terminating_string, 1, NULL);
}