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/* uroot - User's root
* utils.c Source file with various utility functions
*
* Copyright (C) 2018 Karel Kočí
*
* 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 2
* of the License, 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include <pwd.h>
#include <grp.h>
#include "utils.h"
#include "conf.h"
// Compute the size needed (including \0) to format given message
size_t printf_len(const char *msg, ...) {
va_list args;
va_start(args, msg);
size_t result = vsnprintf(NULL, 0, msg, args);
va_end(args);
return result + 1;
}
// Like sprintf, but returs the string. Expects there's enough space.
char *printf_into(char *dst, const char *msg, ...) {
va_list args;
va_start(args, msg);
vsprintf(dst, msg, args);
va_end(args);
return dst;
}
const char *get_shell() {
const char *ret;
ret = secure_getenv("SHELL");
if (!ret)
ret = DEFAULT_SHELL;
return ret;
}
struct subid {
char *start;
char *count;
};
struct subid parse_sub(const char *idtp, const char *name) {
FILE *f = fopen(aprintf("/etc/sub%s", idtp), "r");
struct subid res = {NULL, NULL};
char *line = NULL;
ssize_t len = 0;
while ((len = getline(&line, &len, f)) != -1) {
char *firstcol = strchr(line, ':');
if (firstcol == NULL || strncmp(name, line, firstcol - line))
continue;
char *seccol = strchr(firstcol + 1, ':');
if (seccol == NULL)
continue;
res.start = strndup(firstcol + 1, (seccol - firstcol) - 1);
res.count = strndup(seccol + 1, len - 1 - (seccol - line) - (line[len - 1] == '\n' ? 1 : 0));
}
free(line);
fclose(f);
return res;
}
int new_map_id(enum mapidtype type, pid_t pid, int id) {
// TODO possibly we should use all maps provided by sub* files for given
// account. It is common that there is only one mapping but there can
// technically be multiple ones.
char const *idtp;
struct subid subid;
switch (type) {
case MAP_ID_USER:
idtp = "uid";
struct passwd *upass = getpwuid(getuid());
subid = parse_sub(idtp, upass->pw_name);
break;
case MAP_ID_GROUP:
idtp = "gid";
struct group *gpass = getgrgid(getgid());
subid = parse_sub(idtp, gpass->gr_name);
break;
}
pid_t chld = fork();
if (!chld) {
char *tool = aprintf("new%smap", idtp);
char *const args[] = {
tool,
aprintf("%d", pid),
"0", aprintf("%d", id), "1",
subid.start && subid.count ? "1" : NULL, subid.start, subid.count,
NULL
};
execvp(tool, args);
abort();
}
int stat;
waitpid(chld, &stat, 0);
return stat;
}
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