/* * __getgrent.c - This file is part of the libc-8086/grp package for ELKS, * Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This 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 * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the Free * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <unistd.h> #include <stdlib.h> #include <string.h> #include "busybox.h" #include "grp_.h" /* * Define GR_SCALE_DYNAMIC if you want grp to dynamically scale its read buffer * so that lines of any length can be used. On very very small systems, * you may want to leave this undefined becasue it will make the grp functions * somewhat larger (because of the inclusion of malloc and the code necessary). * On larger systems, you will want to define this, because grp will _not_ * deal with long lines gracefully (they will be skipped). */ #undef GR_SCALE_DYNAMIC #ifndef GR_SCALE_DYNAMIC /* * If scaling is not dynamic, the buffers will be statically allocated, and * maximums must be chosen. GR_MAX_LINE_LEN is the maximum number of * characters per line in the group file. GR_MAX_MEMBERS is the maximum * number of members of any given group. */ #define GR_MAX_LINE_LEN 128 /* GR_MAX_MEMBERS = (GR_MAX_LINE_LEN-(24+3+6))/9 */ #define GR_MAX_MEMBERS 11 #endif /* !GR_SCALE_DYNAMIC */ /* * Define GR_DYNAMIC_GROUP_LIST to make initgroups() dynamically allocate * space for it's GID array before calling setgroups(). This is probably * unnecessary scalage, so it's undefined by default. */ #undef GR_DYNAMIC_GROUP_LIST #ifndef GR_DYNAMIC_GROUP_LIST /* * GR_MAX_GROUPS is the size of the static array initgroups() uses for * its static GID array if GR_DYNAMIC_GROUP_LIST isn't defined. */ #define GR_MAX_GROUPS 64 #endif /* !GR_DYNAMIC_GROUP_LIST */ /* * This is the core group-file read function. It behaves exactly like * getgrent() except that it is passed a file descriptor. getgrent() * is just a wrapper for this function. */ struct group *__getgrent(int grp_fd) { #ifndef GR_SCALE_DYNAMIC static char line_buff[GR_MAX_LINE_LEN]; static char *members[GR_MAX_MEMBERS]; #else static char *line_buff = NULL; static char **members = NULL; short line_index; short buff_size; #endif static struct group group; register char *ptr; char *field_begin; short member_num; char *endptr; int line_len; /* We use the restart label to handle malformatted lines */ restart: #ifdef GR_SCALE_DYNAMIC line_index = 0; buff_size = 256; #endif #ifndef GR_SCALE_DYNAMIC /* Read the line into the static buffer */ if ((line_len = read(grp_fd, line_buff, GR_MAX_LINE_LEN)) <= 0) return NULL; field_begin = strchr(line_buff, '\n'); if (field_begin != NULL) lseek(grp_fd, (long) (1 + field_begin - (line_buff + line_len)), SEEK_CUR); else { /* The line is too long - skip it :-\ */ do { if ((line_len = read(grp_fd, line_buff, GR_MAX_LINE_LEN)) <= 0) return NULL; } while (!(field_begin = strchr(line_buff, '\n'))); lseek(grp_fd, (long) ((field_begin - line_buff) - line_len + 1), SEEK_CUR); goto restart; } if (*line_buff == '#' || *line_buff == ' ' || *line_buff == '\n' || *line_buff == '\t') goto restart; *field_begin = '\0'; #else /* !GR_SCALE_DYNAMIC */ line_buff = realloc(line_buff, buff_size); while (1) { if ((line_len = read(grp_fd, line_buff + line_index, buff_size - line_index)) <= 0) return NULL; field_begin = strchr(line_buff, '\n'); if (field_begin != NULL) { lseek(grp_fd, (long) (1 + field_begin - (line_len + line_index + line_buff)), SEEK_CUR); *field_begin = '\0'; if (*line_buff == '#' || *line_buff == ' ' || *line_buff == '\n' || *line_buff == '\t') goto restart; break; } else { /* Allocate some more space */ line_index = buff_size; buff_size += 256; line_buff = realloc(line_buff, buff_size); } } #endif /* GR_SCALE_DYNAMIC */ /* Now parse the line */ group.gr_name = line_buff; ptr = strchr(line_buff, ':'); if (ptr == NULL) goto restart; *ptr++ = '\0'; group.gr_passwd = ptr; ptr = strchr(ptr, ':'); if (ptr == NULL) goto restart; *ptr++ = '\0'; field_begin = ptr; ptr = strchr(ptr, ':'); if (ptr == NULL) goto restart; *ptr++ = '\0'; group.gr_gid = (gid_t) strtoul(field_begin, &endptr, 10); if (*endptr != '\0') goto restart; member_num = 0; field_begin = ptr; #ifndef GR_SCALE_DYNAMIC while ((ptr = strchr(ptr, ',')) != NULL) { *ptr = '\0'; ptr++; members[member_num] = field_begin; field_begin = ptr; member_num++; } if (*field_begin == '\0') members[member_num] = NULL; else { members[member_num] = field_begin; members[member_num + 1] = NULL; } #else /* !GR_SCALE_DYNAMIC */ free(members); members = (char **) malloc((member_num + 1) * sizeof(char *)); for ( ; field_begin && *field_begin != '\0'; field_begin = ptr) { if ((ptr = strchr(field_begin, ',')) != NULL) *ptr++ = '\0'; members[member_num++] = field_begin; members = (char **) realloc(members, (member_num + 1) * sizeof(char *)); } members[member_num] = NULL; #endif /* GR_SCALE_DYNAMIC */ group.gr_mem = members; return &group; }