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sortix--sortix/libc/pwd/fgetpwent_r.cpp
2013-12-30 20:46:22 +01:00

178 lines
4.2 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
pwd/fgetpwent_r.cpp
Reads a passwd entry from a FILE.
*******************************************************************************/
#include <sys/types.h>
#include <errno.h>
#include <inttypes.h>
#include <pwd.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static char* next_field(char** current)
{
char* result = *current;
if ( result )
{
char* next = result;
while ( *next && *next != ':' )
next++;
if ( !*next )
next = NULL;
else
*next++ = '\0';
*current = next;
}
return result;
}
static bool next_field_uintmax(char** current, uintmax_t* result)
{
char* id_str = next_field(current);
if ( !id_str )
return false;
char* id_endptr;
uintmax_t id_umax = strtoumax(id_str, &id_endptr, 10);
if ( *id_endptr )
return false;
*result = id_umax;
return true;
}
static gid_t next_field_gid(char** current, gid_t* result)
{
uintmax_t id_umax;
if ( !next_field_uintmax(current, &id_umax) )
return false;
gid_t gid = (gid_t) id_umax;
if ( (uintmax_t) gid != (uintmax_t) id_umax )
return false;
*result = gid;
return true;
}
static uid_t next_field_uid(char** current, uid_t* result)
{
uintmax_t id_umax;
if ( !next_field_uintmax(current, &id_umax) )
return false;
uid_t uid = (uid_t) id_umax;
if ( (uintmax_t) uid != (uintmax_t) id_umax )
return false;
*result = uid;
return true;
}
extern "C"
int fgetpwent_r(FILE* restrict fp,
struct passwd* restrict result,
char* restrict buf,
size_t buf_len,
struct passwd** restrict result_pointer)
{
if ( !result_pointer )
return errno = EINVAL;
if ( !fp || !result || !buf )
return *result_pointer = NULL, errno = EINVAL;
int original_errno = errno;
flockfile(fp);
off_t original_offset = ftello(fp);
if ( original_offset < 0 )
{
funlockfile(fp);
return *result_pointer = NULL, errno;
}
size_t buf_used = 0;
int ic;
while ( (ic = fgetc(fp)) != EOF )
{
if ( ic == '\n' )
break;
if ( buf_used == buf_len )
{
fseeko(fp, original_offset, SEEK_SET);
funlockfile(fp);
return *result_pointer = NULL, errno = ERANGE;
}
buf[buf_used++] = (char) ic;
}
if ( ferror(fp) )
{
int original_error = errno;
fseeko(fp, original_offset, SEEK_SET);
funlockfile(fp);
return *result_pointer = NULL, original_error;
}
if ( !buf_used && feof(fp) )
{
funlockfile(fp);
return *result_pointer = NULL, errno = original_errno, NULL;
}
if ( buf_used == buf_len )
{
fseeko(fp, original_offset, SEEK_SET);
funlockfile(fp);
return *result_pointer = NULL, errno = ERANGE;
}
buf[buf_used] = '\0';
char* parse_str = buf;
if ( !(result->pw_name = next_field(&parse_str)) )
goto parse_failure;
if ( !(result->pw_passwd = next_field(&parse_str)) )
goto parse_failure;
if ( !next_field_uid(&parse_str, &result->pw_uid) )
goto parse_failure;
if ( !next_field_gid(&parse_str, &result->pw_gid) )
goto parse_failure;
if ( !(result->pw_gecos = next_field(&parse_str)) )
goto parse_failure;
if ( !(result->pw_dir = next_field(&parse_str)) )
goto parse_failure;
if ( !(result->pw_shell = next_field(&parse_str)) )
goto parse_failure;
if ( parse_str )
goto parse_failure;
funlockfile(fp);
return *result_pointer = result, 0;
parse_failure:
fseeko(fp, original_offset, SEEK_SET);
funlockfile(fp);
return errno = EINVAL;
}