142 lines
3.2 KiB
C
142 lines
3.2 KiB
C
/* getpwent(), getpwuid(), getpwnam() - password file routines
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*
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* Author: Kees J. Bot
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* 31 Jan 1994
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*/
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#define open _open
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#define fcntl _fcntl
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#define read _read
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#define close _close
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#include <sys/types.h>
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#include <pwd.h>
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#include <string.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#define arraysize(a) (sizeof(a) / sizeof((a)[0]))
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#define arraylimit(a) ((a) + arraysize(a))
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static char PASSWD[]= "/etc/passwd"; /* The password file. */
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static const char *pwfile; /* Current password file. */
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static char buf[1024]; /* Read buffer. */
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static char pwline[256]; /* One line from the password file. */
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static struct passwd entry; /* Entry to fill and return. */
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static int pwfd= -1; /* Filedescriptor to the file. */
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static char *bufptr; /* Place in buf. */
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static ssize_t buflen= 0; /* Remaining characters in buf. */
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static char *lineptr; /* Place in the line. */
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void endpwent(void)
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/* Close the password file. */
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{
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if (pwfd >= 0) {
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(void) close(pwfd);
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pwfd= -1;
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buflen= 0;
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}
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}
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int setpwent(void)
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/* Open the password file. */
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{
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if (pwfd >= 0) endpwent();
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if (pwfile == NULL) pwfile= PASSWD;
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if ((pwfd= open(pwfile, O_RDONLY)) < 0) return -1;
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(void) fcntl(pwfd, F_SETFD, fcntl(pwfd, F_GETFD) | FD_CLOEXEC);
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return 0;
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}
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void setpwfile(const char *file)
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/* Prepare for reading an alternate password file. */
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{
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endpwent();
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pwfile= file;
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}
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static int getline(void)
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/* Get one line from the password file, return 0 if bad or EOF. */
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{
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lineptr= pwline;
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do {
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if (buflen == 0) {
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if ((buflen= read(pwfd, buf, sizeof(buf))) <= 0)
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return 0;
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bufptr= buf;
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}
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if (lineptr == arraylimit(pwline)) return 0;
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buflen--;
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} while ((*lineptr++ = *bufptr++) != '\n');
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lineptr= pwline;
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return 1;
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}
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static char *scan_colon(void)
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/* Scan for a field separator in a line, return the start of the field. */
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{
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char *field= lineptr;
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char *last;
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for (;;) {
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last= lineptr;
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if (*lineptr == 0) return NULL;
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if (*lineptr == '\n') break;
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if (*lineptr++ == ':') break;
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}
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*last= 0;
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return field;
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}
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struct passwd *getpwent(void)
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/* Read one entry from the password file. */
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{
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char *p;
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/* Open the file if not yet open. */
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if (pwfd < 0 && setpwent() < 0) return NULL;
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/* Until a good line is read. */
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for (;;) {
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if (!getline()) return NULL; /* EOF or corrupt. */
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if ((entry.pw_name= scan_colon()) == NULL) continue;
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if ((entry.pw_passwd= scan_colon()) == NULL) continue;
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if ((p= scan_colon()) == NULL) continue;
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entry.pw_uid= strtol(p, NULL, 0);
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if ((p= scan_colon()) == NULL) continue;
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entry.pw_gid= strtol(p, NULL, 0);
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if ((entry.pw_gecos= scan_colon()) == NULL) continue;
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if ((entry.pw_dir= scan_colon()) == NULL) continue;
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if ((entry.pw_shell= scan_colon()) == NULL) continue;
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if (*lineptr == 0) return &entry;
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}
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}
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struct passwd *getpwuid(uid_t uid)
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/* Return the password file entry belonging to the user-id. */
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{
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struct passwd *pw;
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endpwent();
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while ((pw= getpwent()) != NULL && pw->pw_uid != uid) {}
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endpwent();
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return pw;
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}
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struct passwd *getpwnam(const char *name)
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/* Return the password file entry belonging to the user name. */
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{
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struct passwd *pw;
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endpwent();
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while ((pw= getpwent()) != NULL && strcmp(pw->pw_name, name) != 0) {}
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endpwent();
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return pw;
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}
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