John Fawcett:
> for an inexistent user for strings up to 31 chars. From 32 chars onwards
> instead of returning not found it retuns EINVAL (invalid argument).
>
> ./test AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
> Not found
> ./test AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
> getpwnam_r: Invalid argument
Perhaps they want programs to call sysconf(_SC_LOGIN_NAME_MAX)
(note that the result includes the null terminator).
Wietse
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
int main(int argc, char *argv[])
{
struct passwd pwd;
struct passwd *result;
char *buf;
size_t bufsize;
int s;
if (argc != 2) {
fprintf(stderr, "Usage: %s username\n", argv[0]);
exit(EXIT_FAILURE);
}
bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
if (bufsize == -1) /* Value was indeterminate */
bufsize = 16384; /* Should be more than enough */
buf = malloc(bufsize);
if (buf == NULL) {
perror("malloc");
exit(EXIT_FAILURE);
}
/* _SC_LOGIN_NAME_MAX includes the null terminator */
if (strlen(argv[1]) >= sysconf(_SC_LOGIN_NAME_MAX)) {
fprintf(stderr, "warning: name exceeds _SC_LOGIN_NAME_MAX\n");
result = 0;
s = 0;
} else {
s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
}
if (result == NULL) {
if (s == 0)
printf("Not found\n");
else {
errno = s;
perror("getpwnam_r");
}
exit(EXIT_FAILURE);
}
printf("Name: %s; UID: %ld\n", pwd.pw_gecos, (long) pwd.pw_uid);
free(buf);
exit(EXIT_SUCCESS);
}
