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77 lines
2.2 KiB
77 lines
2.2 KiB
#define _GNU_SOURCE
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#include <dlfcn.h>
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#include <errno.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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int strlcpy(char *restrict dest, const char *restrict src, size_t bufsize) {
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size_t i;
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for (i = 0; i < bufsize; ++i) {
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dest[i] = src[i];
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if (src[i] == '\0') {
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return 0;
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}
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}
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return ERANGE;
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}
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char *getlogin(void) {
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return getenv("USER");
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}
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int getlogin_r(char *buf, size_t bufsize) {
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const char *login = getlogin();
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if (login == NULL) {
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return ENOENT;
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}
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return strlcpy(buf, login, bufsize);
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}
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struct passwd *getpwuid(uid_t uid) {
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struct passwd *(*getpwuid)(uid_t) = dlsym(RTLD_NEXT, "getpwuid");
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if (getpwuid == NULL) {
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fprintf(stderr, "Unable to find the adress of the getpwuid function: %s\n", dlerror());
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return NULL;
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}
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struct passwd *pass = getpwuid(uid);
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if (pass == NULL) {
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return NULL;
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}
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char *name = getenv("USER");
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if (name == NULL) {
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fprintf(stderr, "Could not find the USER environment variable. Using the real username.\n");
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return pass;
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}
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pass->pw_name = name;
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return pass;
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}
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int getpwuid_r(uid_t uid, struct passwd *pw, char *buf, size_t size, struct passwd **res) {
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int prev_err = errno;
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*res = NULL;
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struct passwd *pass = getpwuid(uid);
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if (pass == NULL || errno != prev_err) {
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return errno;
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}
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memcpy(pw, pass, sizeof(struct passwd));
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size_t name_len = strlen(pass->pw_name) + 1;
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size_t passwd_len = strlen(pass->pw_passwd) + 1;
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size_t gecos_len = strlen(pass->pw_gecos) + 1;
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size_t dir_len = strlen(pass->pw_dir) + 1;
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size_t shell_len = strlen(pass->pw_shell) + 1;
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if ((name_len + passwd_len + gecos_len + dir_len + shell_len) > size) {
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return ERANGE;
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}
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pw->pw_name = memcpy(buf, pass->pw_name, name_len);
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pw->pw_passwd = memcpy(buf + name_len, pass->pw_passwd, passwd_len);
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pw->pw_gecos = memcpy(buf + name_len + passwd_len, pass->pw_gecos, gecos_len);
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pw->pw_dir = memcpy(buf + name_len + passwd_len + gecos_len, pass->pw_dir, dir_len);
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pw->pw_shell = memcpy(buf + name_len + passwd_len + gecos_len + dir_len, pass->pw_shell, shell_len);
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*res = pw;
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return 0;
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}
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