174 lines
4.0 KiB
C
174 lines
4.0 KiB
C
/*
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* Copyright (c) 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* pwd/fgetpwent_r.c
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* Reads a passwd entry from a FILE.
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <pwd.h>
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#include <stdbool.h>
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#include <stddef.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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static char* next_field(char** current)
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{
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char* result = *current;
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if ( result )
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{
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char* next = result;
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while ( *next && *next != ':' )
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next++;
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if ( !*next )
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next = NULL;
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else
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*next++ = '\0';
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*current = next;
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}
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return result;
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}
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static bool next_field_uintmax(char** current, uintmax_t* result)
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{
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char* id_str = next_field(current);
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if ( !id_str )
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return false;
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char* id_endptr;
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uintmax_t id_umax = strtoumax(id_str, &id_endptr, 10);
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if ( *id_endptr )
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return false;
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*result = id_umax;
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return true;
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}
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static gid_t next_field_gid(char** current, gid_t* result)
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{
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uintmax_t id_umax;
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if ( !next_field_uintmax(current, &id_umax) )
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return false;
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gid_t gid = (gid_t) id_umax;
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if ( (uintmax_t) gid != (uintmax_t) id_umax )
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return false;
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*result = gid;
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return true;
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}
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static uid_t next_field_uid(char** current, uid_t* result)
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{
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uintmax_t id_umax;
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if ( !next_field_uintmax(current, &id_umax) )
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return false;
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uid_t uid = (uid_t) id_umax;
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if ( (uintmax_t) uid != (uintmax_t) id_umax )
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return false;
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*result = uid;
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return true;
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}
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int fgetpwent_r(FILE* restrict fp,
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struct passwd* restrict result,
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char* restrict buf,
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size_t buf_len,
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struct passwd** restrict result_pointer)
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{
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if ( !result_pointer )
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return errno = EINVAL;
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if ( !fp || !result || !buf )
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return *result_pointer = NULL, errno = EINVAL;
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int original_errno = errno;
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flockfile(fp);
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off_t original_offset = ftello(fp);
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if ( original_offset < 0 )
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{
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funlockfile(fp);
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return *result_pointer = NULL, errno;
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}
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size_t buf_used = 0;
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int ic;
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while ( (ic = fgetc(fp)) != EOF )
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{
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if ( ic == '\n' )
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break;
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if ( buf_used == buf_len )
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{
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fseeko(fp, original_offset, SEEK_SET);
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funlockfile(fp);
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return *result_pointer = NULL, errno = ERANGE;
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}
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buf[buf_used++] = (char) ic;
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}
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if ( ferror(fp) )
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{
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int original_error = errno;
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fseeko(fp, original_offset, SEEK_SET);
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funlockfile(fp);
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return *result_pointer = NULL, original_error;
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}
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if ( !buf_used && feof(fp) )
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{
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funlockfile(fp);
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return *result_pointer = NULL, errno = original_errno, 0;
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}
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if ( buf_used == buf_len )
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{
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fseeko(fp, original_offset, SEEK_SET);
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funlockfile(fp);
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return *result_pointer = NULL, errno = ERANGE;
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}
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buf[buf_used] = '\0';
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char* parse_str = buf;
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if ( !(result->pw_name = next_field(&parse_str)) )
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goto parse_failure;
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if ( !(result->pw_passwd = next_field(&parse_str)) )
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goto parse_failure;
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if ( !next_field_uid(&parse_str, &result->pw_uid) )
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goto parse_failure;
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if ( !next_field_gid(&parse_str, &result->pw_gid) )
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goto parse_failure;
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if ( !(result->pw_gecos = next_field(&parse_str)) )
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goto parse_failure;
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if ( !(result->pw_dir = next_field(&parse_str)) )
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goto parse_failure;
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if ( !(result->pw_shell = next_field(&parse_str)) )
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goto parse_failure;
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if ( parse_str )
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goto parse_failure;
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funlockfile(fp);
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return *result_pointer = result, 0;
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parse_failure:
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fseeko(fp, original_offset, SEEK_SET);
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funlockfile(fp);
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return errno = EINVAL;
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}
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