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getgrent_r.c
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getgrent_r.c
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/*
* ----------------------------------------------------------------------
* Copyright © 2005-2014 Rich Felker, et al.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
* ----------------------------------------------------------------------
*
* Adapted from http://www.musl-libc.org/ for libnss-cache
* Copyright © 2015 Kevin Bowling <k@kev009.com>
*/
// This compat layer is only built for BSD, or Linux without the GNU C
// Library.
#if defined(BSD) || (defined(__linux__) && !defined(__GLIBC__))
#include <errno.h>
#include <grp.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ALIGNBYTES (sizeof(uintptr_t) - 1)
#define ALIGN(p) ((((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES))
static unsigned atou(char **s) {
unsigned x;
for (x = 0; **s - '0' < 10U; ++*s) x = 10 * x + (**s - '0');
return x;
}
int fgetgrent_r(FILE *f, struct group *gr, char *line, size_t size,
struct group **res) {
char *s, *mems;
size_t i, nmem, need;
int rv = 0;
int ep;
ptrdiff_t remain;
for (;;) {
line[size - 1] = '\xff';
if ((fgets(line, size, f) == NULL) || ferror(f) ||
(line[size - 1] != '\xff')) {
rv = (line[size - 1] != '\xff') ? ERANGE : ENOENT;
line = 0;
gr = 0;
goto end;
}
ep = strcspn(line, "\n");
line[ep] = 0;
s = line;
gr->gr_name = s++;
if (!(s = strchr(s, ':'))) continue;
*s++ = 0;
gr->gr_passwd = s;
if (!(s = strchr(s, ':'))) continue;
*s++ = 0;
gr->gr_gid = atou(&s);
if (*s != ':') continue;
*s++ = 0;
mems = s;
break;
}
for (nmem = !!*s; *s; s++)
if (*s == ',') ++nmem;
++ep;
remain = (void *)&line[size] - (void *)&line[ep];
need = (sizeof(char *) * (nmem + 1)) + ALIGNBYTES;
if (need > remain) {
rv = ERANGE;
line = 0;
gr = 0;
goto end;
}
memset(&line[ep], 0, need);
gr->gr_mem = (char **)ALIGN(&line[ep]);
if (*mems) {
gr->gr_mem[0] = mems;
for (s = mems, i = 0; *s; s++)
if (*s == ',') *s++ = 0, gr->gr_mem[++i] = s;
gr->gr_mem[++i] = 0;
} else {
gr->gr_mem[0] = 0;
}
end:
*res = gr;
if (rv) errno = rv;
return rv;
}
#endif //#if defined(BSD) || defined(__linux__) && !defined(__GLIBC__)